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Sample records for calcium handling mechanisms

  1. The effects of excess calcium on the handling and mechanical properties of hydrothermal derived calcium phosphate bone cement

    Science.gov (United States)

    Razali, N. N.; Sukardi, M. A.; Sopyan, I.; Mel, M.; Salleh, H. M.; Rahman, M. M.

    2018-01-01

    The objective of this study is to determine the effects of excess calcium on the handling and mechanical properties of hydrothermal derived calcium phosphate cement (CPC) for bone filling applications. Hydroxyapatite powder was synthesized via hydrothermal method using calcium oxide, CaO and ammonium dihydrogen phosphate, NH4H2PO4 as the calcium and phosphorus precursors respectively. The effects of calcium excess were evaluated by varying the CaO content at 0, 5 and 15 mole %. The precursors were then refluxed in distilled water at 90-100°C and dried overnight until the calcium phosphate powder was formed. CPC was then produced by mixing the synthesized powder with distilled water at the powder-to-liquid (P/L) ratio of 1.5. The result from the morphological properties of CPC shows the increase in agglomeration and particles size with 5 mole % of calcium excess but decreased with 15 mole % of calcium excess in CPC. This result was in agreement with the compressive strength result where the CPC increased its strength with 5 mole % of calcium excess but reduced with 15 mole % of calcium excess. The excess in calcium precursor also significantly improved the setting time but reduced the injectability of CPC.

  2. SR calcium handling and calcium after-transients in a rabbit model of heart failure

    NARCIS (Netherlands)

    Baartscheer, Antonius; Schumacher, Cees A.; Belterman, Charly N. W.; Coronel, Ruben; Fiolet, Jan W. T.

    2003-01-01

    Objective: After-depolarization associated arrhythmias are frequently observed in heart failure and associated with spontaneous calcium release from sarcoplasmic reticulum (SR), calcium after-transients. We hypothesize that disturbed SR calcium handling underlies calcium after-transients in heart

  3. DDOS ATTACK DETECTION SIMULATION AND HANDLING MECHANISM

    Directory of Open Access Journals (Sweden)

    Ahmad Sanmorino

    2013-11-01

    Full Text Available In this study we discuss how to handle DDoS attack that coming from the attacker by using detection method and handling mechanism. Detection perform by comparing number of packets and number of flow. Whereas handling mechanism perform by limiting or drop the packets that detected as a DDoS attack. The study begins with simulation on real network, which aims to get the real traffic data. Then, dump traffic data obtained from the simulation used for detection method on our prototype system called DASHM (DDoS Attack Simulation and Handling Mechanism. From the result of experiment that has been conducted, the proposed method successfully detect DDoS attack and handle the incoming packet sent by attacker.

  4. Transfer Area Mechanical Handling Calculation

    International Nuclear Information System (INIS)

    Dianda, B.

    2004-01-01

    This calculation is intended to support the License Application (LA) submittal of December 2004, in accordance with the directive given by DOE correspondence received on the 27th of January 2004 entitled: ''Authorization for Bechtel SAX Company L.L. C. to Include a Bare Fuel Handling Facility and Increased Aging Capacity in the License Application, Contract Number DE-AC--28-01R W12101'' (Arthur, W.J., I11 2004). This correspondence was appended by further Correspondence received on the 19th of February 2004 entitled: ''Technical Direction to Bechtel SAIC Company L.L. C. for Surface Facility Improvements, Contract Number DE-AC--28-OIRW12101; TDL No. 04-024'' (BSC 2004a). These documents give the authorization for a Fuel Handling Facility to be included in the baseline. The purpose of this calculation is to establish preliminary bounding equipment envelopes and weights for the Fuel Handling Facility (FHF) transfer areas equipment. This calculation provides preliminary information only to support development of facility layouts and preliminary load calculations. The limitations of this preliminary calculation lie within the assumptions of section 5 , as this calculation is part of an evolutionary design process. It is intended that this calculation is superseded as the design advances to reflect information necessary to support License Application. The design choices outlined within this calculation represent a demonstration of feasibility and may or may not be included in the completed design. This calculation provides preliminary weight, dimensional envelope, and equipment position in building for the purposes of defining interface variables. This calculation identifies and sizes major equipment and assemblies that dictate overall equipment dimensions and facility interfaces. Sizing of components is based on the selection of commercially available products, where applicable. This is not a specific recommendation for the future use of these components or their

  5. Mechanism of store-operated calcium entry

    Indian Academy of Sciences (India)

    Activation of receptors coupled to the phospholipase C/IP3 signalling pathway results in a rapid release of calcium from its intracellular stores, eventually leading to depletion of these stores. Calcium store depletion triggers an influx of extracellular calcium across the plasma membrane, a mechanism known as the ...

  6. Calcium versus strontium handling by the heart muscle.

    Science.gov (United States)

    Hendrych, Michal; Olejnickova, Veronika; Novakova, Marie

    2016-01-01

    Calcium plays a crucial role in numerous processes in living systems, from both intracellular and intercellular signalling to blood clotting. Calcium can be replaced by strontium in various intracellular processes due to high level of their similarity and strontium thus may serve as a valuable tool for different experimental studies. On the other hand, strontium is also used in clinical medicine and is commonly taken to the human body with food and water. The negative cardiac side effects of strontium therapy of osteoporosis and bone metastases are well known, but still not fully explained. This fact explains enhanced interest in this element and its impact on human body. This article reviews effects of calcium and strontium on several biochemical and physiological processes, with special emphasis on cardiac muscle.

  7. Effects of inorganic phosphate and ADP on calcium handling by the sarcoplasmic reticulum in rat skinned cardiac muscles.

    Science.gov (United States)

    Xiang, J Z; Kentish, J C

    1995-03-01

    The aim was to investigate whether, and how, increases in inorganic phosphate (Pi) and ADP, similar to those occurring intracellularly during early myocardial ischaemia, affect the calcium handling of the sarcoplasmic reticulum. Rat ventricular trabeculae were permeabilised with saponin. The physiological process of calcium induced calcium release (CICR) from the muscle sarcoplasmic reticulum was triggered via flash photolysis of the "caged Ca2+", nitr-5. Alternatively, calcium release was induced by rapid application of caffeine to give an estimate of sarcoplasmic reticular calcium loading. The initial rate of sarcoplasmic reticular calcium pumping was also assessed by photolysis of caged ATP at saturating [Ca2+]. Myoplasmic [Ca2+] (using fluo-3) and isometric force were measured. Pi (2-20 mM) significantly depressed the magnitude of CICR and the associated force transient. Sarcoplasmic reticular calcium loading was inhibited even more than CICR by Pi, suggesting that reduced calcium loading could account for all of the inhibitory effect of Pi on CICR and that Pi may slightly activate the calcium release mechanism. The reduced sarcoplasmic reticular calcium loading seemed to be due to a fall in the free energy of ATP hydrolysis (delta GATP) available for the calcium pump, since equal decreases in delta GATP produced by adding both Pi and ADP in various ratios caused similar falls in the calcium loading of the sarcoplasmic reticulum. The caged ATP experiments indicated that Pi (20 mM) did not affect the rate constant of sarcoplasmic reticular calcium uptake. ADP (10 mM) alone, or with 1 mM Pi, inhibited calcium loading. In spite of this, ADP (10 mM) did not alter CICR and, when 1 mM Pi was added, ADP increased CICR above control. An increase in intracellular Pi reduces sarcoplasmic reticular calcium loading and thus depresses the CICR. This could be an important contributing factor in the hypoxic or ischaemic contractile failure of the myocardium. However the

  8. Vestibule and Cask Preparation Mechanical Handling Calculation

    International Nuclear Information System (INIS)

    Ambre, N.

    2004-01-01

    The scope of this document is to develop the size, operational envelopes, and major requirements of the equipment to be used in the vestibule, cask preparation area, and the crane maintenance area of the Fuel Handling Facility. This calculation is intended to support the License Application (LA) submittal of December 2004, in accordance with the directive given by DOE correspondence received on the 27th of January 2004 entitled: ''Authorization for Bechtel SAIC Company L.L.C. to Include a Bare Fuel Handling Facility and Increased Aging Capacity in the License Application, Contract Number DE-AC--28-01R W12101'' (Ref. 167124). This correspondence was appended by further correspondence received on the 19th of February 2004 entitled: ''Technical Direction to Bechtel SAIC Company L.L. C. for Surface Facility Improvements, Contract Number DE-AC--28-01R W12101; TDL No. 04-024'' (Ref. 16875 1). These documents give the authorization for a Fuel Handling Facility to be included in the baseline. The limitations of this preliminary calculation lie within the assumptions of section 5 , as this calculation is part of an evolutionary design process

  9. Maternal protein restriction compromises myocardial contractility in the young adult rat by changing proteins involved in calcium handling.

    Science.gov (United States)

    de Belchior, Aucelia C S; Freire, David D; da Costa, Carlos P; Vassallo, Dalton V; Padilha, Alessandra S; Dos Santos, Leonardo

    2016-02-01

    Maternal protein restriction (MPR) during pregnancy is associated with increased cardiovascular risk in the offspring in adulthood. In this study we evaluated the cardiac function of young male rats born from mothers subjected to MPR during pregnancy, focusing on the myocardial mechanics and calcium-handling proteins. After weaning, rats received normal diet until 3 mo old, when the following parameters were assessed: arterial and left ventricular hemodynamics and in vitro cardiac contractility in isolated papillary muscles. The body weight was lower and arterial pressure higher in the MPR group compared with young adult offspring of female rats that received standard diet (controls); and left ventricle time derivatives increased in the MPR group. The force developed by the cardiac muscle was similar; but time to peak and relaxation time were longer, and the derivatives of force were depressed in the MPR. In addition, MPR group exhibited decreased post-pause potentiation of force, suggesting reduced reuptake function of the sarcoplasmic reticulum. Corroborating, the myocardial content of SERCA-2a and phosphorylated PLB-Ser16/total PLB ratio was decreased and sodium-calcium exchanger was increased in the MPR group. The contraction dependent on transsarcolemmal influx of calcium was higher in MPR if compared with the control group. In summary, young rats born from mothers subjected to protein restriction during pregnancy exhibit changes in the myocardial mechanics with altered expression of calcium-handling proteins, reinforcing the hypothesis that maternal malnutrition is related to increased cardiovascular risk in the offspring, not only for hypertension, but also cardiac dysfunction. Copyright © 2016 the American Physiological Society.

  10. Electrophysiological properties and calcium handling of embryonic stem cell-derived cardiomyocytes

    Directory of Open Access Journals (Sweden)

    Jae Boum Youm

    2016-03-01

    Full Text Available Embryonic stem cell-derived cardiomyocytes (ESC-CMs hold great interest in many fields of research including clinical applications such as stem cell and gene therapy for cardiac repair or regeneration. ESC-CMs are also used as a platform tool for pharmacological tests or for investigations of cardiac remodeling. ESC-CMs have many different aspects of morphology, electrophysiology, calcium handling, and bioenergetics compared with adult cardiomyocytes. They are immature in morphology, similar to sinus nodal-like in the electrophysiology, higher contribution of trans-sarcolemmal Ca2+ influx to Ca2+ handling, and higher dependence on anaerobic glycolysis. Here, I review a detailed electrophysiology and Ca2+ handling features of ESC-CMs during differentiation into adult cardiomyocytes to gain insights into how all the developmental changes are related to each other to display cardinal features of developing cardiomyocytes.

  11. High Fibroblast Growth Factor 23 concentrations in experimental renal failure impair calcium handling in cardiomyocytes.

    Science.gov (United States)

    Verkaik, Melissa; Oranje, Maarten; Abdurrachim, Desiree; Goebel, Max; Gam, Zeineb; Prompers, Jeanine J; Helmes, Michiel; Ter Wee, Pieter M; van der Velden, Jolanda; Kuster, Diederik W; Vervloet, Marc G; Eringa, Etto C

    2018-04-01

    The overwhelming majority of patients with chronic kidney disease (CKD) die prematurely before reaching end-stage renal disease, mainly due to cardiovascular causes, of which heart failure is the predominant clinical presentation. We hypothesized that CKD-induced increases of plasma FGF23 impair cardiac diastolic and systolic function. To test this, mice were subjected to 5/6 nephrectomy (5/6Nx) or were injected with FGF23 for seven consecutive days. Six weeks after surgery, plasma FGF23 was higher in 5/6Nx mice compared to sham mice (720 ± 31 vs. 256 ± 3 pg/mL, respectively, P = 0.034). In cardiomyocytes isolated from both 5/6Nx and FGF23 injected animals the rise of cytosolic calcium during systole was slowed (-13% and -19%, respectively) as was the decay of cytosolic calcium during diastole (-15% and -21%, respectively) compared to controls. Furthermore, both groups had similarly decreased peak cytosolic calcium content during systole. Despite lower cytosolic calcium contents in CKD or FGF23 pretreated animals, no changes were observed in contractile parameters of cardiomyocytes between the groups. Expression of calcium handling proteins and cardiac troponin I phosphorylation were similar between groups. Blood pressure, the heart weight:tibia length ratio, α-MHC/β-MHC ratio and ANF mRNA expression, and systolic and diastolic function as measured by MRI did not differ between groups. In conclusion, the rapid, CKD-induced rise in plasma FGF23 and the similar decrease in cardiomyocyte calcium transients in modeled kidney disease and following 1-week treatment with FGF23 indicate that FGF23 partly mediates cardiomyocyte dysfunction in CKD. © 2018 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

  12. Single-molecule mechanics of protein-labelled DNA handles

    Directory of Open Access Journals (Sweden)

    Vivek S. Jadhav

    2016-01-01

    Full Text Available DNA handles are often used as spacers and linkers in single-molecule experiments to isolate and tether RNAs, proteins, enzymes and ribozymes, amongst other biomolecules, between surface-modified beads for nanomechanical investigations. Custom DNA handles with varying lengths and chemical end-modifications are readily and reliably synthesized en masse, enabling force spectroscopic measurements with well-defined and long-lasting mechanical characteristics under physiological conditions over a large range of applied forces. Although these chemically tagged DNA handles are widely used, their further individual modification with protein receptors is less common and would allow for additional flexibility in grabbing biomolecules for mechanical measurements. In-depth information on reliable protocols for the synthesis of these DNA–protein hybrids and on their mechanical characteristics under varying physiological conditions are lacking in literature. Here, optical tweezers are used to investigate different protein-labelled DNA handles in a microfluidic environment under different physiological conditions. Digoxigenin (DIG-dsDNA-biotin handles of varying sizes (1000, 3034 and 4056 bp were conjugated with streptavidin or neutravidin proteins. The DIG-modified ends of these hybrids were bound to surface-modified polystyrene (anti-DIG beads. Using different physiological buffers, optical force measurements showed consistent mechanical characteristics with long dissociation times. These protein-modified DNA hybrids were also interconnected in situ with other tethered biotinylated DNA molecules. Electron-multiplying CCD (EMCCD imaging control experiments revealed that quantum dot–streptavidin conjugates at the end of DNA handles remain freely accessible. The experiments presented here demonstrate that handles produced with our protein–DNA labelling procedure are excellent candidates for grasping single molecules exposing tags suitable for molecular

  13. Structures of apicomplexan calcium-dependent protein kinases reveal mechanism of activation by calcium

    Energy Technology Data Exchange (ETDEWEB)

    Wernimont, Amy K; Artz, Jennifer D.; Jr, Patrick Finerty; Lin, Yu-Hui; Amani, Mehrnaz; Allali-Hassani, Abdellah; Senisterra, Guillermo; Vedadi, Masoud; Tempel, Wolfram; Mackenzie, Farrell; Chau, Irene; Lourido, Sebastian; Sibley, L. David; Hui, Raymond (Toronto); (WU-MED)

    2010-09-21

    Calcium-dependent protein kinases (CDPKs) have pivotal roles in the calcium-signaling pathway in plants, ciliates and apicomplexan parasites and comprise a calmodulin-dependent kinase (CaMK)-like kinase domain regulated by a calcium-binding domain in the C terminus. To understand this intramolecular mechanism of activation, we solved the structures of the autoinhibited (apo) and activated (calcium-bound) conformations of CDPKs from the apicomplexan parasites Toxoplasma gondii and Cryptosporidium parvum. In the apo form, the C-terminal CDPK activation domain (CAD) resembles a calmodulin protein with an unexpected long helix in the N terminus that inhibits the kinase domain in the same manner as CaMKII. Calcium binding triggers the reorganization of the CAD into a highly intricate fold, leading to its relocation around the base of the kinase domain to a site remote from the substrate binding site. This large conformational change constitutes a distinct mechanism in calcium signal-transduction pathways.

  14. Baroreflex deficiency induces additional impairment of vagal tone, diastolic function and calcium handling proteins after myocardial infarction

    Science.gov (United States)

    Mostarda, Cristiano; Rodrigues, Bruno; Medeiros, Alessandra; Moreira, Edson D; Moraes-Silva, Ivana C; Brum, Patricia C; Angelis, Katia De; Irigoyen, Maria-Cláudia

    2014-01-01

    Baroreflex dysfunction has been considered an important mortality predictor after myocardial infarction (MI). However, the impact of baroreflex deficiency prior to MI on tonic autonomic control and cardiac function, and on the profile of proteins associated with intracellular calcium handling has not yet been studied. The aim of the present study was to analyze how the impairment of baroreflex induced by sinoaortic denervation (SAD) prior to MI in rats affects the tonic autonomic control, ventricular function and cardiomyocyte calcium handling proteins. After 15 days of following or SAD surgery, rats underwent MI. Echocardiographic, hemodynamic, autonomic and molecular evaluations were performed 90 days after MI. Baroreflex impairment led to additional damage on: left ventricular remodeling, diastolic function, vagal tonus and intrinsic heart rate after MI. The loss of vagal component of the arterial baroreflex and vagal tonus were correlated with changes in the cardiac proteins involved in intracellular calcium homeostasis. Furthermore, additional increase in sodium calcium exchanger expression levels was associated with impaired diastolic function in experimental animals. Our findings strongly suggest that previous arterial baroreflex deficiency may induce additional impairment of vagal tonus, which was associated with calcium handling proteins abnormalities, probably triggering ventricular diastolic dysfunction after MI in rats. PMID:24936224

  15. Versatile cable handling mechanisms for remote operator control

    Energy Technology Data Exchange (ETDEWEB)

    Collie, A.A.; White, T.S.; Christopher, M.D.; Hewer, N.D. [Portech Ltd., Portsmouth (United Kingdom)

    1996-12-31

    This paper describes a system of cable management for keeping the umbilical cables of remote operating vehicles and manipulators tidy and contained without direct intervention by operators. Two distinct types of winding mechanism have been designed. One mechanism is a fixed reel type where the cable is wound onto the reel by a rotating bail arm. The other mechanism consists of a pair of curved belts held against each other between which cable is passed. The complete system includes tension measuring and slack loop take-up devices. The whole system is controlled by a servo system in conjunction with a PC based visual graphic environment which allows a variety of mechanisms to be built up into a system able to handle up to four umbilical cables simultaneously. The control system provides additional tension sensors and cable odometers connected to the control system so that the operator has immediate perception of all the cable parameters, and by defining rules, can set up a variety of alarm situations. (Author).

  16. Versatile cable handling mechanisms for remote operator control

    International Nuclear Information System (INIS)

    Collie, A.A.; White, T.S.; Christopher, M.D.; Hewer, N.D.

    1996-01-01

    This paper describes a system of cable management for keeping the umbilical cables of remote operating vehicles and manipulators tidy and contained without direct intervention by operators. Two distinct types of winding mechanism have been designed. One mechanism is a fixed reel type where the cable is wound onto the reel by a rotating bail arm. The other mechanism consists of a pair of curved belts held against each other between which cable is passed. The complete system includes tension measuring and slack loop take-up devices. The whole system is controlled by a servo system in conjunction with a PC based visual graphic environment which allows a variety of mechanisms to be built up into a system able to handle up to four umbilical cables simultaneously. The control system provides additional tension sensors and cable odometers connected to the control system so that the operator has immediate perception of all the cable parameters, and by defining rules, can set up a variety of alarm situations. (Author)

  17. Versatile cable handling mechanisms for remote operator control

    International Nuclear Information System (INIS)

    Collie, A.A.; White, T.S.; Christopher, M.D.; Hewer, N.D.

    1996-01-01

    This paper describes a system of cable management for keeping the umbilical cables of remote operating vehicles and manipulators tidy and contained without direct intervention by operators. Two distinct types of winding mechanism have been designed. One mechanism is a fixed reel type where the cable is wound onto the reel by a rotating bail arm. The other mechanism consists of a pair of curved belts held against each other, between which cable is passed. The complete system includes tension measuring and slack loop take-up devices. The whole system is controlled by a servo system in conjunction with a PC based visual graphic environment which allows a variety of mechanisms to be built up into a system able to handle up to four umbilical cables simultaneously. The control system provides additional tension sensors and cable odometers connected to the control system so that the operator has immediate perception of all the cable parameters, and by defining rules, can set up a variety of alarm situations. (UK)

  18. Dual Optical Recordings for Action Potentials and Calcium Handling in Induced Pluripotent Stem Cell Models of Cardiac Arrhythmias Using Genetically Encoded Fluorescent Indicators

    Science.gov (United States)

    Song, LouJin; Awari, Daniel W.; Han, Elizabeth Y.; Uche-Anya, Eugenia; Park, Seon-Hye E.; Yabe, Yoko A.; Chung, Wendy K.

    2015-01-01

    Reprogramming of human somatic cells to pluripotency has been used to investigate disease mechanisms and to identify potential therapeutics. However, the methods used for reprogramming, in vitro differentiation, and phenotyping are still complicated, expensive, and time-consuming. To address the limitations, we first optimized a protocol for reprogramming of human fibroblasts and keratinocytes into pluripotency using single lipofection and the episomal vectors in a 24-well plate format. This method allowed us to generate multiple lines of integration-free and feeder-free induced pluripotent stem cells (iPSCs) from seven patients with cardiac diseases and three controls. Second, we differentiated human iPSCs derived from patients with Timothy syndrome into cardiomyocytes using a monolayer differentiation method. We found that Timothy syndrome cardiomyocytes showed slower, irregular contractions and abnormal calcium handling compared with the controls. The results are consistent with previous reports using a retroviral method for reprogramming and an embryoid body-based method for cardiac differentiation. Third, we developed an efficient approach for recording the action potentials and calcium transients simultaneously in control and patient cardiomyocytes using genetically encoded fluorescent indicators, ArcLight and R-GECO1. The dual optical recordings enabled us to observe prolonged action potentials and abnormal calcium handling in Timothy syndrome cardiomyocytes. We confirmed that roscovitine rescued the phenotypes in Timothy syndrome cardiomyocytes and that these findings were consistent with previous studies using conventional electrophysiological recordings and calcium imaging with dyes. The approaches using our optimized methods and dual optical recordings will improve iPSC applicability for disease modeling to investigate mechanisms underlying cardiac arrhythmias and to test potential therapeutics. PMID:25769651

  19. Simulating and visualizing deflections of a remote handling mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Saarinen, Hannu, E-mail: hannu.saarinen@vtt.fi [VTT, Technical Research Centre of Finland, Tekniikankatu 1, 33720 Tampere (Finland); Hämäläinen, Vesa; Karjalainen, Jaakko; Määttä, Timo; Siuko, Mikko [VTT, Technical Research Centre of Finland, Tekniikankatu 1, 33720 Tampere (Finland); Esqué, Salvador [Fusion for Energy, Torres Diagonal Litoral B3, Josep Pla 2, 08019 Barcelona (Spain); Hamilton, David [ITER Organization, Route de Vinon sur Verdon, 13115 Saint Paul Lez Durance (France)

    2013-10-15

    Highlights: ► An infinitesimal transformation represents elastic deflections. ► Equivalent spring factor is used to combine several deformations. ► Initial VR model accuracy improved from 80 to 5 mm. ► The deflection model is capable of adapting to changes in load at the end-effector. ► The algorithms and approach described are generic and can be adopted for other mechanisms. -- Abstract: Continuing ITER divertor second cassette (SC) remote handling (RH) test campaign has been carried out at divertor test platform (DTP2) in Finland. One of the goals has been to develop and implement efficient algorithms and software tools for simulating and visualizing for the operator the non-instrumented deflections of the RH mechanisms under loading conditions. Based on assumptions of the classical beam theory, the presented solution suggests utilization of an infinitesimal transformation to represent elastic deflections in a mechanical structure. Both structural analysis and measurements of the real structure are utilised during the process. The solution suggests one possible implementation strategy of a software component called structural simulator (SS), which is a software component of the remote handling control system (RHCS) architectural model specified by ITER organisation. Utilisation of the proposed SS necessitates modification of the initial virtual reality (VR) model of RH equipment to a format, which can visually represent the structural deflections. In practise this means adding virtual joints into the model. This will improve the accuracy of the VR visualization and will ensure that the virtual representation of the RH equipment closely aligns with the actual RH equipment. Cassette multifunctional mover (CMM) and second cassette end effector (SCEE) carrying SC were selected to be the initial target system for developing the approach. Demonstrations proved that the approach used can give high levels of accuracy even in complex structures such as the CMM

  20. Simulating and visualizing deflections of a remote handling mechanism

    International Nuclear Information System (INIS)

    Saarinen, Hannu; Hämäläinen, Vesa; Karjalainen, Jaakko; Määttä, Timo; Siuko, Mikko; Esqué, Salvador; Hamilton, David

    2013-01-01

    Highlights: ► An infinitesimal transformation represents elastic deflections. ► Equivalent spring factor is used to combine several deformations. ► Initial VR model accuracy improved from 80 to 5 mm. ► The deflection model is capable of adapting to changes in load at the end-effector. ► The algorithms and approach described are generic and can be adopted for other mechanisms. -- Abstract: Continuing ITER divertor second cassette (SC) remote handling (RH) test campaign has been carried out at divertor test platform (DTP2) in Finland. One of the goals has been to develop and implement efficient algorithms and software tools for simulating and visualizing for the operator the non-instrumented deflections of the RH mechanisms under loading conditions. Based on assumptions of the classical beam theory, the presented solution suggests utilization of an infinitesimal transformation to represent elastic deflections in a mechanical structure. Both structural analysis and measurements of the real structure are utilised during the process. The solution suggests one possible implementation strategy of a software component called structural simulator (SS), which is a software component of the remote handling control system (RHCS) architectural model specified by ITER organisation. Utilisation of the proposed SS necessitates modification of the initial virtual reality (VR) model of RH equipment to a format, which can visually represent the structural deflections. In practise this means adding virtual joints into the model. This will improve the accuracy of the VR visualization and will ensure that the virtual representation of the RH equipment closely aligns with the actual RH equipment. Cassette multifunctional mover (CMM) and second cassette end effector (SCEE) carrying SC were selected to be the initial target system for developing the approach. Demonstrations proved that the approach used can give high levels of accuracy even in complex structures such as the CMM

  1. The mechanical environment modulates intracellular calcium oscillation activities of myofibroblasts.

    Directory of Open Access Journals (Sweden)

    Charles Godbout

    Full Text Available Myofibroblast contraction is fundamental in the excessive tissue remodeling that is characteristic of fibrotic tissue contractures. Tissue remodeling during development of fibrosis leads to gradually increasing stiffness of the extracellular matrix. We propose that this increased stiffness positively feeds back on the contractile activities of myofibroblasts. We have previously shown that cycles of contraction directly correlate with periodic intracellular calcium oscillations in cultured myofibroblasts. We analyze cytosolic calcium dynamics using fluorescent calcium indicators to evaluate the possible impact of mechanical stress on myofibroblast contractile activity. To modulate extracellular mechanics, we seeded primary rat subcutaneous myofibroblasts on silicone substrates and into collagen gels of different elastic modulus. We modulated cell stress by cell growth on differently adhesive culture substrates, by restricting cell spreading area on micro-printed adhesive islands, and depolymerizing actin with Cytochalasin D. In general, calcium oscillation frequencies in myofibroblasts increased with increasing mechanical challenge. These results provide new insight on how changing mechanical conditions for myofibroblasts are encoded in calcium oscillations and possibly explain how reparative cells adapt their contractile behavior to the stresses occurring in normal and pathological tissue repair.

  2. Effects of tetracaine on insulin release and calcium handling by rat pancreatic islets

    International Nuclear Information System (INIS)

    Abdel El Motal, S.M.A.; Pian-Smith, M.C.M.; Sharp, G.W.G.

    1987-01-01

    The effects of tetracaine on insulin release and 45 Ca 2+ handling by rat pancreatic islets have been studied under basal, glucose-stimulated, and 3-isobutyl-1-methylxanthine (IBMX)-stimulated conditions. Islets were isolated by the use of collagenase and used either directly (freshly isolated islets) or after a period under tissue culture conditions. Tetracaine was found to stimulate insulin release under basal conditions, to inhibit glucose-stimulated insulin release, and to potentiate insulin release stimulated by IBMX. In studies on the mechanisms underlying these effects, tetracaine was found to decrease glucose-stimulated net retention of 45 Ca 2+ (by an action to block the voltage-dependent Ca channels) and to mobilize Ca 2+ from intracellular stores. These two actions form the basis for the inhibition of glucose-stimulated insulin release, which depends heavily on Ca 2+ entry via the voltage-dependent channels and the synergism with IBMX to potentiate release. No inhibition of IBMX-stimulated release occurs because IBMX does not use the voltage-dependent channels to raise intracellular Ca 2+

  3. Calcium handling by platelets from normal and malignant hyperthermia-susceptible pigs

    International Nuclear Information System (INIS)

    Miller, K.E.; Brooks, R.R.; Bonk, K.R.; Carpenter, J.F.

    1991-01-01

    Platelets from normal and malignant hyperthermia (MH)-susceptible pigs were evaluated for differences in 45 calcium uptake in the absence or presence of caffeine, halothane, or halothane and caffeine together. There were no statistically significant differences in basal or halothane-inhibited calcium uptake by platelets from either source. There was a small statistically significant difference in calcium uptake between platelets from normal and MH-susceptible pigs in the presence of 16 mM caffeine and 0.5% halothane. Calcium uptake by platelets from one pedigree of MH-susceptible pigs were stimulated in a concentration-dependent manner by caffeine. These data suggest that exposure of platelets to caffeine may have potential for identifying MH-susceptibility

  4. Cellular Mechanisms of Calcium-Mediated Triggered Activity

    Science.gov (United States)

    Song, Zhen

    Life-threatening cardiac arrhythmias continue to pose a major health problem. Ventricular fibrillation, which is a complex form of electrical wave turbulence in the lower chambers of the heart, stops the heart from pumping and is the largest cause of natural death in the United States. Atrial fibrillation, a related form of wave turbulence in the upper heart chambers, is in turn the most common arrhythmia diagnosed in clinical practice. Despite extensive research to date, mechanisms of cardiac arrhythmias remain poorly understood. It is well established that both spatial disorder of the refractory period of heart cells and triggered activity (TA) jointly contribute to the initiation and maintenance of arrhythmias. TA broadly refers to the abnormal generation of a single or a sequence of abnormal excitation waves from a small submillimeter region of the heart in the interval of time between two normal waves generated by the heart's natural pacemaker (the sinoatrial node). TA has been widely investigated experimentally and occurs in several pathological conditions where the intracellular concentration of free Ca2+ ions in heart cells becomes elevated. Under such conditions, Ca2+ can be spontaneously released from intracellular stores, thereby driving an electrogenic current that exchanges 3Na+ ions for one Ca2+ ion across the cell membrane. This current in turn depolarizes the membrane of heart cells after a normal excitation. If this calcium-mediated "delayed after depolarization'' (DAD) is sufficiently large, it can generate an action potential. While the arrhythmogenic importance of spontaneous Ca2+ release and DADs is well appreciated, the conditions under which they occur in heart pathologies remain poorly understood. Calcium overload is only one factor among several other factors that can promote DADs, including sympathetic nerve stimulation, different expression levels of membrane ion channels and calcium handling proteins, and different mutations of those

  5. Impairment of mitochondrial calcium handling in a mtSOD1 cell culture model of motoneuron disease

    Directory of Open Access Journals (Sweden)

    Zippelius Annette

    2009-06-01

    Full Text Available Abstract Background Amyotrophic lateral sclerosis (ALS is a fatal neurodegenerative disorder characterized by the selective loss of motor neurons (MN in the brain stem and spinal cord. Intracellular disruptions of cytosolic and mitochondrial calcium have been associated with selective MN degeneration, but the underlying mechanisms are not well understood. The present evidence supports a hypothesis that mitochondria are a target of mutant SOD1-mediated toxicity in familial amyotrophic lateral sclerosis (fALS and intracellular alterations of cytosolic and mitochondrial calcium might aggravate the course of this neurodegenerative disease. In this study, we used a fluorescence charged cool device (CCD imaging system to separate and simultaneously monitor cytosolic and mitochondrial calcium concentrations in individual cells in an established cellular model of ALS. Results To gain insights into the molecular mechanisms of SOD1G93A associated motor neuron disease, we simultaneously monitored cytosolic and mitochondrial calcium concentrations in individual cells. Voltage – dependent cytosolic Ca2+ elevations and mitochondria – controlled calcium release mechanisms were monitored after loading cells with fluorescent dyes fura-2 and rhod-2. Interestingly, comparable voltage-dependent cytosolic Ca2+ elevations in WT (SH-SY5YWT and G93A (SH-SY5YG93A expressing cells were observed. In contrast, mitochondrial intracellular Ca2+ release responses evoked by bath application of the mitochondrial toxin FCCP were significantly smaller in G93A expressing cells, suggesting impaired calcium stores. Pharmacological experiments further supported the concept that the presence of G93A severely disrupts mitochondrial Ca2+ regulation. Conclusion In this study, by fluorescence measurement of cytosolic calcium and using simultaneous [Ca2+]i and [Ca2+]mito measurements, we are able to separate and simultaneously monitor cytosolic and mitochondrial calcium concentrations

  6. Mechanism of calcium oxide excitation by atom hydrogen

    International Nuclear Information System (INIS)

    Kharlamov, V.F.

    1991-01-01

    Heterogeneous recombination of hydrogen atoms on the surface of calcium oxide proceeds according to the Langmuir-Hinshelwood mechanism with participation of atoms in two different states, belonging to adsorption centres of the same type. CaO excitation is broughty about by vibration-electron transitions during associative desorption of H 2 molecules

  7. Intracellular Calcium Dynamics and Autonomic Stimulation in Atrial Fibrillation: Mechanisms and Implications

    Directory of Open Access Journals (Sweden)

    Chung-Chuan Chou, MD

    2008-01-01

    Full Text Available While atrial fibrillation is characterized by the co-existence of multiple activation waves within the atria, rapid activations in the pulmonary veins play an important role for the initiation and maintenance of atrial fibrillation. In addition to reentry, non-reentrant mechanisms resulting from abnormal intracellular calcium handling and intracellular calcium overload can also be responsible for these rapid activations in the pulmonary veins. Meanwhile, alterations of autonomic tone, involving both the sympathetic and parasympathetic nervous system, have been implicated in initiating paroxysmal atrial fibrillation. But the effectiveness of autonomic modulation as an adjunctive therapeutic strategy to catheter ablation of atrial fibrillation has been inconsistent. The interactions between the autonomic nervous system and atrial fibrillation are more complex than currently understood and further mechanistic and clinical studies are warranted.

  8. Altered calcium handling and increased contraction force in human embryonic stem cell derived cardiomyocytes following short term dexamethasone exposure

    Energy Technology Data Exchange (ETDEWEB)

    Kosmidis, Georgios; Bellin, Milena; Ribeiro, Marcelo C.; Meer, Berend van; Ward-van Oostwaard, Dorien [Department of Anatomy and Embryology, Leiden University Medical Center, Leiden (Netherlands); Passier, Robert [Department of Anatomy and Embryology, Leiden University Medical Center, Leiden (Netherlands); MIRA, University of Twente (Netherlands); Tertoolen, Leon G.J.; Mummery, Christine L. [Department of Anatomy and Embryology, Leiden University Medical Center, Leiden (Netherlands); Casini, Simona, E-mail: s.casini@amc.uva.nl [Department of Anatomy and Embryology, Leiden University Medical Center, Leiden (Netherlands)

    2015-11-27

    One limitation in using human pluripotent stem cell derived cardiomyocytes (hPSC-CMs) for disease modeling and cardiac safety pharmacology is their immature functional phenotype compared with adult cardiomyocytes. Here, we report that treatment of human embryonic stem cell derived cardiomyocytes (hESC-CMs) with dexamethasone, a synthetic glucocorticoid, activated glucocorticoid signaling which in turn improved their calcium handling properties and contractility. L-type calcium current and action potential properties were not affected by dexamethasone but significantly faster calcium decay, increased forces of contraction and sarcomeric lengths, were observed in hESC-CMs after dexamethasone exposure. Activating the glucocorticoid pathway can thus contribute to mediating hPSC-CMs maturation. - Highlights: • Dexamethasone accelerates Ca{sup 2+} transient decay in hESC-CMs. • Dexamethasone enhances SERCA and NCX function in hESC-CMs. • Dexamethasone increases force of contraction and sarcomere length in hESC-CMs. • Dexamethasone does not alter I{sub Ca,L} and action potential characteristics in hESC-CMs.

  9. Altered calcium handling and increased contraction force in human embryonic stem cell derived cardiomyocytes following short term dexamethasone exposure

    International Nuclear Information System (INIS)

    Kosmidis, Georgios; Bellin, Milena; Ribeiro, Marcelo C.; Meer, Berend van; Ward-van Oostwaard, Dorien; Passier, Robert; Tertoolen, Leon G.J.; Mummery, Christine L.; Casini, Simona

    2015-01-01

    One limitation in using human pluripotent stem cell derived cardiomyocytes (hPSC-CMs) for disease modeling and cardiac safety pharmacology is their immature functional phenotype compared with adult cardiomyocytes. Here, we report that treatment of human embryonic stem cell derived cardiomyocytes (hESC-CMs) with dexamethasone, a synthetic glucocorticoid, activated glucocorticoid signaling which in turn improved their calcium handling properties and contractility. L-type calcium current and action potential properties were not affected by dexamethasone but significantly faster calcium decay, increased forces of contraction and sarcomeric lengths, were observed in hESC-CMs after dexamethasone exposure. Activating the glucocorticoid pathway can thus contribute to mediating hPSC-CMs maturation. - Highlights: • Dexamethasone accelerates Ca"2"+ transient decay in hESC-CMs. • Dexamethasone enhances SERCA and NCX function in hESC-CMs. • Dexamethasone increases force of contraction and sarcomere length in hESC-CMs. • Dexamethasone does not alter I_C_a_,_L and action potential characteristics in hESC-CMs.

  10. Resveratrol and Calcium Signaling: Molecular Mechanisms and Clinical Relevance

    Directory of Open Access Journals (Sweden)

    Audrey E. McCalley

    2014-06-01

    Full Text Available Resveratrol is a naturally occurring compound contributing to cellular defense mechanisms in plants. Its use as a nutritional component and/or supplement in a number of diseases, disorders, and syndromes such as chronic diseases of the central nervous system, cancer, inflammatory diseases, diabetes, and cardiovascular diseases has prompted great interest in the underlying molecular mechanisms of action. The present review focuses on resveratrol, specifically its isomer trans-resveratrol, and its effects on intracellular calcium signaling mechanisms. As resveratrol’s mechanisms of action are likely pleiotropic, its effects and interactions with key signaling proteins controlling cellular calcium homeostasis are reviewed and discussed. The clinical relevance of resveratrol’s actions on excitable cells, transformed or cancer cells, immune cells and retinal pigment epithelial cells are contrasted with a review of the molecular mechanisms affecting calcium signaling proteins on the plasma membrane, cytoplasm, endoplasmic reticulum, and mitochondria. The present review emphasizes the correlation between molecular mechanisms of action that have recently been identified for resveratrol and their clinical implications.

  11. Mechanically induced intracellular calcium waves in osteoblasts demonstrate calcium fingerprints in bone cell mechanotransduction.

    Science.gov (United States)

    Godin, Lindsay M; Suzuki, Sakiko; Jacobs, Christopher R; Donahue, Henry J; Donahue, Seth W

    2007-11-01

    An early response to mechanical stimulation of bone cells in vitro is an increase in intracellular calcium concentration ([Ca (2+)](i)). This study analyzed the [Ca (2+)](i) wave area, magnitude, duration, rise time, fall time, and time to onset in individual osteoblasts for two identical bouts of mechanical stimulation separated by a 30-min rest period. The area under the [Ca (2+)](i) wave increased in the second loading bout compared to the first. This suggests that rest periods may potentiate mechanically induced intracellular calcium signals. Furthermore, many of the [Ca (2+)](i) wave parameters were strongly, positively correlated between the two bouts of mechanical stimulation. For example, in individual primary osteoblasts, if a cell had a large [Ca (2+)](i) wave area in the first bout it was likely to have a large [Ca (2+)](i) wave area in the second bout (r (2) = 0.933). These findings support the idea that individual bone cells have "calcium fingerprints" (i.e., a unique [Ca (2+)](i) wave profile that is reproducible for repeated exposure to a given stimulus).

  12. Design of startup neutron detector handling mechanism instrumentation

    International Nuclear Information System (INIS)

    Upadhyay, Chandra Kant; Sivaramakrishna, M.; Nagaraj, C.P.; Madhusoodanan, K.

    2010-01-01

    In PFBR, to monitor the reactor during first fuel loading and low power operation, special provision is made in the central fuel subassembly to accommodate the neutron detectors. During fuel handling operations, these detectors need to be lifted up to facilitate plug rotation. These detectors are also need to be lifted from the core to save their life, during intermediate and high power operations. Towards this, a mobile assembly containing these detectors is made with lowering and retracting provision. To control this operation, constant speed motor, torque limiter, proximity switch, wire drawn potentiometer, magnetic reed switches are provided. To ensure a smooth and safe handling of this assembly, control logic with necessary interlocks is developed. (author)

  13. Mechanisms of calcium transport in small intestine. Final report

    International Nuclear Information System (INIS)

    DeLuca, H.F.

    1982-01-01

    The vitamin D hormone, 1,25-dihydroxyvitamin D 3 , was demonstrated to be the prime hormonal agent regulating intestinal absorption of divalent cations. Production of the vitamin D hormone is, in turn, regulated by parathyroid hormone, low dietary calcium, low plasma phosphorus, and is suppressed by 1,25-dihydroxyvitamin D 3 , by high plasma phosphorus, high plasma calcium, and the absence of parathyroid hormone. A variety of analogs of the vitamin D hormone were prepared. In addition, the preparation of radiolabeled vitamin D hormone was accomplished using chemical synthesis, and this highly radioactive substance was found to localize in the nuclei of the intestinal villus cells that promote intestinal absorption of calcium. A receptor for the vitamin D hormone was also located, and the general mechanism of response to the vitamin D hormone included the binding to a receptor molecule, transfer to the nucleus, transcription of specific genes followed by translation to transport proteins. Methods were developed for the discovery of the appropriate gene products that play a role in calcium transport

  14. Mechanical properties of polypropylene/calcium carbonate nanocomposites

    Directory of Open Access Journals (Sweden)

    Daniel Eiras

    2009-01-01

    Full Text Available The aim of this work was to study the influence of calcium carbonate nanoparticles in both tensile and impact mechanical properties of a polypropylene homopolymer. Four compositions of PP/CaCO3 nanocomposites were prepared in a co-rotational twin screw extruder machine with calcium carbonate content of 3, 5, 7 and 10 wt. (% The tests included SEM analyzes together with EDS analyzer and FTIR spectroscopy for calcium carbonate, tensile and impact tests for PP and the nanocomposites. The results showed an increase in PP elastic modulus and a little increase in yield stress. Brittle-to-ductile transition temperature was reduced and the impact resistance increased with the addition of nanoparticles. From the stress-strain curves we determined the occurrence of debonding process before yielding leading to stress softening. Debonding stress was determined from stress-strain curves corresponding to stress in 1% strain. We concluded that the tensile properties depend on the surface contact area of nanoparticles and on their dispersion. Finally we believe that the toughening was due to the formation of diffuse shear because of debonding process.

  15. Calcium

    Science.gov (United States)

    ... You can get decent amounts of calcium from baked beans, navy beans, white beans, and others. Canned fish. You're in luck if you like sardines and canned salmon with bones. Almond milk. Working Calcium Into Your ...

  16. Mechanical properties of experimental composites with different calcium phosphates fillers.

    Science.gov (United States)

    Okulus, Zuzanna; Voelkel, Adam

    2017-09-01

    Calcium phosphates (CaPs)-containing composites have already shown good properties from the point of view of dental restorative materials. The purpose of this study was to examine the crucial mechanical properties of twelve hydroxyapatite- or tricalcium phosphate-filled composites. The raw and surface-treated forms of both CaP fillers were applied. As a reference materials two experimental glass-containing composites and one commercial dental restorative composite were applied. Nano-hardness, elastic modulus, compressive, flexural and diametral tensile strength of all studied materials were determined. Application of statistical methods (one-way analysis of variance and cluster agglomerative analysis) allowed for assessing the similarities between examined materials according to the values of studied parameters. The obtained results show that in almost all cases the mechanical properties of experimental CaPs-composites are comparable or even better than mechanical properties of examined reference materials. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Modern power station practice mechanical boilers, fuel-, and ash-handling plant

    CERN Document Server

    Sherry, A; Cruddace, AE

    2014-01-01

    Modern Power Station Practice, Second Edition, Volume 2: Mechanical (Boilers, Fuel-, and Ash-Handling Plant) focuses on the design, manufacture and operation of boiler units and fuel-and ash-handling plants.This book is organized into five main topics-furnace and combustion equipment, steam and water circuits, ancillary plant and fittings, dust extraction and draught plant, and fuel-and ash-handling plant.In these topics, this text specifically discusses the influence of nature of coal on choice of firing equipment; oil-burner arrangements, ignition and control; disposition of the heating surf

  18. Mechatronics of fuel handling mechanism for fast experimental reactor 'Joyo'

    Energy Technology Data Exchange (ETDEWEB)

    Fujiwara, Akikazu (Power Reactor and Nuclear Fuel Development Corp., Oarai, Ibaraki (Japan). Oarai Engineering Center)

    1984-01-01

    The outline of the fast experimental reactor ''Joyo'' is introduced, and the fuel handling mechanism peculiar to fast reactors is described. The objectives of the construction of Joyo are to obtain the techniques for the design, construction, manufacture, installation, operation and maintenance of sodium-cooled fast reactors independently, and to use it as an irradiation facility for the development of fuel and materials for fast breeder reactors. At present, the reactor is operated at 100 MW maximum thermal output for the second objective. Since liquid sodium is used as the coolant, the atmosphere of the fuel handling course changes such as liquid sodium at 250 deg C, argon gas at 200 deg C and water, in addition, the spent fuel taken out has the decay heat of 2.1 kW at maximum. The fuel handling works in the reactor and fuel transfer works, and the fuel handling mechanism of a fuel exchanger and that of a cask car for fuel handling are described. Relay sequence control system is used for the fuel handling mechanism of Joyo.

  19. Calcium Handling by Endoplasmic Reticulum and Mitochondria in a Cell Model of Huntington’s Disease

    Science.gov (United States)

    De Mario, Agnese; Scarlatti, Chiara; Costiniti, Veronica; Primerano, Simona; Lopreiato, Raffaele; Calì, Tito; Brini, Marisa; Giacomello, Marta; Carafoli, Ernesto

    2016-01-01

    Huntington disease (HD) is caused by the CAG (Q) expansion in exon 1 of the IT15 gene encoding a polyglutamine (poly-Q) stretch of the Huntingtin protein (Htt). In the wild type protein, the repeats specify a stretch of up 34 Q in the N-terminal portion of Htt. In the pathological protein (mHtt) the poly-Q tract is longer. Proteolytic cleavage of the protein liberates an N-terminal fragment containing the expanded poly-Q tract becomes harmful to cells, in particular to striatal neurons. The fragments cause the transcriptional dysfunction of genes that are essential for neuronal survival. Htt, however, could also have non-transcriptional effects, e.g. it could directly alter Ca2+ homeostasis and/or mitochondrial morphology and function. Ca2+ dyshomeostasis and mitochondrial dysfunction are considered important in the molecular aetiology of the disease. Here we have analyzed the effect of the overexpression of Htt fragments (18Q, wild type form, wtHtt and 150Q mutated form, mHtt) on Ca2+ homeostasis in striatal neuronal precursor cells (Q7/7). We have found that the transient overexpression of the Htt fragments increases Ca2+ transients in the mitochondria of cells stimulated with Ca2+-mobilizing agonists. The bulk Ca2+ transients in the cytosol were unaffected, but the Ca2+ content of the endoplasmic reticulum was significantly decreased in the case of mHtt expression. To rule out possible transcriptional effects due to the presence of mHtt, we have measured the mRNA level of a subunit of the respiratory chain complex II, whose expression is commonly altered in many HD models. No effects on the mRNA level was found suggesting that, in our experimental condition, transcriptional action of Htt is not occurring and that the effects on Ca2+ homeostasis were dependent to non-transcriptional mechanisms. PMID:26819834

  20. Calcium Handling by Endoplasmic Reticulum and Mitochondria in a Cell Model of Huntington's Disease.

    Science.gov (United States)

    De Mario, Agnese; Scarlatti, Chiara; Costiniti, Veronica; Primerano, Simona; Lopreiato, Raffaele; Calì, Tito; Brini, Marisa; Giacomello, Marta; Carafoli, Ernesto

    2016-01-06

    Huntington disease (HD) is caused by the CAG (Q) expansion in exon 1 of the IT15 gene encoding a polyglutamine (poly-Q) stretch of the Huntingtin protein (Htt). In the wild type protein, the repeats specify a stretch of up 34 Q in the N-terminal portion of Htt. In the pathological protein (mHtt) the poly-Q tract is longer. Proteolytic cleavage of the protein liberates an N-terminal fragment containing the expanded poly-Q tract becomes harmful to cells, in particular to striatal neurons. The fragments cause the transcriptional dysfunction of genes that are essential for neuronal survival. Htt, however, could also have non-transcriptional effects, e.g. it could directly alter Ca2+ homeostasis and/or mitochondrial morphology and function. Ca2+ dyshomeostasis and mitochondrial dysfunction are considered important in the molecular aetiology of the disease. Here we have analyzed the effect of the overexpression of Htt fragments (18Q, wild type form, wtHtt and 150Q mutated form, mHtt) on Ca2+ homeostasis in striatal neuronal precursor cells (Q7/7). We have found that the transient overexpression of the Htt fragments increases Ca2+ transients in the mitochondria of cells stimulated with Ca2+-mobilizing agonists. The bulk Ca2+ transients in the cytosol were unaffected, but the Ca2+ content of the endoplasmic reticulum was significantly decreased in the case of mHtt expression. To rule out possible transcriptional effects due to the presence of mHtt, we have measured the mRNA level of a subunit of the respiratory chain complex II, whose expression is commonly altered in many HD models. No effects on the mRNA level was found suggesting that, in our experimental condition, transcriptional action of Htt is not occurring and that the effects on Ca2+ homeostasis were dependent to non-transcriptional mechanisms.

  1. The influence of ergonomic devices on mechanical load during patient handling activities in nursing homes.

    Science.gov (United States)

    Koppelaar, Elin; Knibbe, Hanneke J J; Miedema, Harald S; Burdorf, Alex

    2012-07-01

    Mechanical load during patient handling activities is an important risk factor for low back pain among nursing personnel. The aims of this study were to describe required and actual use of ergonomic devices during patient handling activities and to assess the influence of these ergonomic devices on mechanical load during patient handling activities. For each patient, based on national guidelines, it was recorded which specific ergonomic devices were required during distinct patient handling activities, defined by transferring a patient, providing personal care, repositioning patients in the bed, and putting on and taking off anti-embolism stockings. During real-time observations over ~60 h among 186 nurses on 735 separate patient handling activities in 17 nursing homes, it was established whether ergonomic devices were actually used. Mechanical load was assessed through observations of frequency and duration of a flexed or rotated trunk >30° and frequency of pushing, pulling, lifting or carrying requiring forces 230 N from start to end of each separate patient handling activity. The number of patients and nurses per ward and the ratio of nurses per patient were used as ward characteristics with potential influence on mechanical load. A mixed-effect model for repeated measurements was used to determine the influence of ergonomic devices and ward characteristics on mechanical load. Use of ergonomic devices was required according to national guidelines in 520 of 735 (71%) separate patient handling activities, and actual use was observed in 357 of 520 (69%) patient handling activities. A favourable ratio of nurses per patient was associated with a decreased duration of time spent in awkward back postures during handling anti-embolism stocking (43%), patient transfers (33%), and personal care of patients (24%) and also frequency of manually lifting patients (33%). Use of lifting devices was associated with a lower frequency of forces exerted (64%), adjustable bed and

  2. In vivo experimental stroke and in vitro organ culture induce similar changes in vasoconstrictor receptors and intracellular calcium handling in rat cerebral arteries

    DEFF Research Database (Denmark)

    Povlsen, Gro Klitgaard; Waldsee, Roya; Ahnstedt, Hilda

    2012-01-01

    Cerebral arteries subjected to different types of experimental stroke upregulate their expression of certain G-protein-coupled vasoconstrictor receptors, a phenomenon that worsens the ischemic brain damage. Upregulation of contractile endothelin B (ET(B)) and 5-hydroxytryptamine 1B (5-HT(1B......)) receptors has been demonstrated after subarachnoid hemorrhage and global ischemic stroke, but the situation is less clear after focal ischemic stroke. Changes in smooth muscle calcium handling have been implicated in different vascular diseases but have not hitherto been investigated in cerebral arteries...... and extracellular sources, whereas 5-HT(1B) receptor-mediated contraction was solely dependent on extracellular calcium. Organ culture and stroke increased basal intracellular calcium levels in MCA smooth muscle cells and decreased the expression of inositol triphosphate receptor and transient receptor potential...

  3. Kinetics and Mechanism of Calcium Hydroxide Conversion into Calcium Alkoxides: Implications in Heritage Conservation Using Nanolimes.

    Science.gov (United States)

    Rodriguez-Navarro, Carlos; Vettori, Irene; Ruiz-Agudo, Encarnacion

    2016-05-24

    Nanolimes are alcohol dispersions of Ca(OH)2 nanoparticles used in the conservation of cultural heritage. Although it was believed that Ca(OH)2 particles were inert when dispersed in short-chain alcohols, it has been recently shown that they can undergo transformation into calcium alkoxides. Little is known, however, about the mechanism and kinetics of such a phase transformation as well as its effect on the performance of nanolimes. Here we show that Ca(OH)2 particles formed after lime slaking react with ethanol and isopropanol and partially transform (fractional conversion, α up to 0.08) into calcium ethoxide and isopropoxide, respectively. The transformation shows Arrhenius behavior, with apparent activation energy Ea of 29 ± 4 and 37 ± 6 kJ mol(-1) for Ca-ethoxide and Ca-isopropoxide conversion, respectively. High resolution transmission electron microscopy analyses of reactant and product phases show that the alkoxides replace the crystalline structure of Ca(OH)2 along specific [hkl] directions, preserving the external hexagonal (platelike) morphology of the parent phase. Textural and kinetic results reveal that this pseudomorphic replacement involves a 3D diffusion-controlled deceleratory advancement of the reaction front. The results are consistent with an interface-coupled dissolution-precipitation replacement mechanism. Analysis of the carbonation of Ca(OH)2 particles with different degree of conversion into Ca-ethoxide (α up to 0.08) and Ca-isopropoxide (α up to 0.04) exposed to air (20 °C, 80% relative humidity) reveals that Ca-alkoxides significantly reduce the rate of transformation into cementing CaCO3 and induce the formation of metastable vaterite, as opposed to stable calcite which forms in untransformed Ca(OH)2 samples. Similar effects are obtained when a commercial nanolime partially transformed into Ca-ethoxide is subjected to carbonation. Such effects may hamper/delay the strengthening or consolidation effects of nanolimes, thus having

  4. Paclitaxel Induces Apoptosis in Breast Cancer Cells through Different Calcium—Regulating Mechanisms Depending on External Calcium Conditions

    Science.gov (United States)

    Pan, Zhi; Avila, Andrew; Gollahon, Lauren

    2014-01-01

    Previously, we reported that endoplasmic reticulum calcium stores were a direct target for paclitaxel initiation of apoptosis. Furthermore, the actions of paclitaxel attenuated Bcl-2 resistance to apoptosis through endoplasmic reticulum-mediated calcium release. To better understand the calcium-regulated mechanisms of paclitaxel-induced apoptosis in breast cancer cells, we investigated the role of extracellular calcium, specifically; whether influx of extracellular calcium contributed to and/or was necessary for paclitaxel-induced apoptosis. Our results demonstrated that paclitaxel induced extracellular calcium influx. This mobilization of extracellular calcium contributed to subsequent cytosolic calcium elevation differently, depending on dosage. Under normal extracellular calcium conditions, high dose paclitaxel induced apoptosis-promoting calcium influx, which did not occur in calcium-free conditions. In the absence of extracellular calcium an “Enhanced Calcium Efflux” mechanism in which high dose paclitaxel stimulated calcium efflux immediately, leading to dramatic cytosolic calcium decrease, was observed. In the absence of extracellular calcium, high dose paclitaxel’s stimulatory effects on capacitative calcium entry and apoptosis could not be completely restored. Thus, normal extracellular calcium concentrations are critical for high dose paclitaxel-induced apoptosis. In contrast, low dose paclitaxel mirrored controls, indicating that it occurs independent of extracellular calcium. Thus, extracellular calcium conditions only affect efficacy of high dose paclitaxel-induced apoptosis. PMID:24549172

  5. Mechanical design issues associated with mounting, maintenance, and handling of an ITER divertor

    International Nuclear Information System (INIS)

    Goranson, D.L.; Fogarty, D.J.; Jones, G.H.

    1992-01-01

    Several designs that address plasma-facing plate configurations and thermal-hydraulic design issues have been developed for the ITER divertor. Design criteria growing out of physics requirements, physical constraints, and remote handling requirements impose severe mechanical requirements on the support structure and its attachments. These pose a challenge to the mechanical design of a divertor, which must be addressed before a functional divertor is practical that is, one that can be remotely handled, aligned, and maintained; that functions reliably under thermal loading and disruptions; and that gives the required life in the nuclear environment predicted for ITER. This paper discusses the design criteria for the divertor mounting structure and identifies the mechanical design issues that need to be addressed

  6. Biocompatibility of calcium phosphate bone cement with optimized mechanical properties.

    Science.gov (United States)

    Palmer, Iwan; Nelson, John; Schatton, Wolfgang; Dunne, Nicholas J; Buchanan, Fraser J; Clarke, Susan A

    2016-02-01

    The broad aim of this work was to investigate and optimize the properties of calcium phosphate bone cements (CPCs) for use in vertebroplasty to achieve effective primary fixation of spinal fractures. The incorporation of collagen, both bovine and from a marine sponge (Chondrosia reniformis), into a CPC was investigated. The biological properties of the CPC and collagen-CPC composites were assessed in vitro through the use of human bone marrow stromal cells. Cytotoxicity, proliferation, and osteoblastic differentiation were evaluated using lactate dehydrogenase, PicoGreen, and alkaline phosphatase activity assays, respectively. The addition of both types of collagen resulted in an increase in cytotoxicity, albeit not to a clinically relevant level. Cellular proliferation after 1, 7, and 14 days was unchanged. The osteogenic potential of the CPC was reduced through the addition of bovine collagen but remained unchanged in the case of the marine collagen. These findings, coupled with previous work showing that incorporation of marine collagen in this way can improve the physical properties of CPCs, suggest that such a composite may offer an alternative to CPCs in applications where low setting times and higher mechanical stability are important. © 2015 The Authors. Journal of Biomedical Materials Research Part B: Applied Biomaterials Published by Wiley Periodicals, Inc.

  7. Pitavastatin-attenuated cardiac dysfunction in mice with dilated cardiomyopathy via regulation of myocardial calcium handling proteins

    Directory of Open Access Journals (Sweden)

    Hu Wei

    2014-03-01

    Full Text Available C57BL/6 mice with dilated cardiomyopathy (DCM were randomly divided to receive placebo or pitavastatin at a dose of 1 or 3 mg kg-1d-1. After 8 weeks treatment, mice with dilated cardiomyopathy developed serious cardiac dysfunction characterized by significantly enhanced left ventricular end-diastolic diameter (LVIDd, decreased left ventricular ejection fraction (LVEF as well as left ventricular short axis fractional shortening (LVFS, accompanied with enlarged cardiomyocytes, and increased plasma levels of N-terminal pro-B type natriuretic peptide (NT-proBNP and plasma angiotensin II (AngII concentration. Moreover, myocardium sarcoplasmic reticulum Ca2+ pump (SERCA-2 activity was decreased. The ratio of phosphorylated phospholamban (PLB to total PLB decreased significantly with the down-regulation of SERCA- -2a and ryanodine receptor (RyR2 expression. Pitavastatin was found to ameliorate the cardiac dysfunction in mice with dilated cardiomyopathy by reversing the changes in the ratios of phosphorylated PLB to total PLB, SERCA-2a and RyR2 via reducing the plasma AngII concentration and the expressions of myocardium angiotensin II type 1 receptor (AT1R and protein kinase C (PKCb2. The possible underlying mechanism might be the regulation of myocardial AT1R-PKCb2-Ca2+ handling proteins.

  8. Density and mechanical properties of calcium aluminate cement

    Science.gov (United States)

    Ahmed, Syed Taqi Uddin; Ahmmad, Shaik Kareem

    2018-04-01

    Calcium aluminate cements are a special type of cements which have their composition mainly dominated by the presence of Monocalcium Aluminates. In the present paper for the first time we have shown theoretical density and elastic constants for various calcium aluminate cements. The density of the present CAS decrease with aluminates presents in the cement. Using the density data, the elastic moduli namely Young's modulus, bulk and shear modulus show strong linear dependence as a function of compositional parameter.

  9. Biocompatibility of calcium phosphate bone cement with optimised mechanical properties: an in vivo study.

    Science.gov (United States)

    Palmer, Iwan; Nelson, John; Schatton, Wolfgang; Dunne, Nicholas J; Buchanan, Fraser; Clarke, Susan A

    2016-12-01

    This work establishes the in vivo performance of modified calcium phosphate bone cements for vertebroplasty of spinal fractures using a lapine model. A non-modified calcium phosphate bone cement and collagen-calcium phosphate bone cements composites with enhanced mechanical properties, utilising either bovine collagen or collagen from a marine sponge, were compared to a commercial poly(methyl methacrylate) cement. Conical cement samples (8 mm height × 4 mm base diameter) were press-fit into distal femoral condyle defects in New Zealand White rabbits and assessed after 5 and 10 weeks. Bone apposition and tartrate-resistant acid phosphatase activity around cements were assessed. All implants were well tolerated, but bone apposition was higher on calcium phosphate bone cements than on poly(methyl methacrylate) cement. Incorporation of collagen showed no evidence of inflammatory or immune reactions. Presence of positive tartrate-resistant acid phosphatase staining within cracks formed in calcium phosphate bone cements suggested active osteoclasts were present within the implants and were actively remodelling within the cements. Bone growth was also observed within these cracks. These findings confirm the biological advantages of calcium phosphate bone cements over poly(methyl methacrylate) and, coupled with previous work on enhancement of mechanical properties through collagen incorporation, suggest collagen-calcium phosphate bone cement composite may offer an alternative to calcium phosphate bone cements in applications where low setting times and higher mechanical stability are important.

  10. Molecular mechanism of crystallization impacting calcium phosphate cements

    Energy Technology Data Exchange (ETDEWEB)

    Giocondi, J L; El-Dasher, B S; Nancollas, G H; Orme, C A

    2009-05-31

    In summary, SPM data has shown that (1) Mg inhibits growth on all steps but relatively high Mg/Ca ratios are needed. Extracting the mechanism of interaction requires more modeling of the kinetic data, but step morphology is consistent with incorporation. (2) Citrate has several effects depending on the citrate/Ca ratio. At the lowest concentrations, citrate increases the step free energy without altering the step kinetics; at higher concentrations, the polar step is slowed. (3) Oxalate also slows the polar step but additionally stabilizes a new facet, with a [100]{sub Cc} step. (4) Etidronate has the greatest kinetic impact of the molecules studied. At 7{micro}M concentrations, the polar step slows by 60% and a new polar step appears. However, at the same time the [10-1]{sub Cc} increases by 67%. It should be noted that all of these molecules complex calcium and can effect kinetics by altering the solution supersaturation or the Ca to HPO{sub 4}{sup 2-} ratio. For the SPM data shown, this effect was corrected for to distinguish the effect of the molecule at the crystal surface from the effect of the molecule on the solution speciation. The goal of this paper is to draw connections between fundamental studies of atomic step motion and potential strategies for materials processing. It is not our intent to promote the utility of SPM for investigating processes in cement dynamics. The conditions are spectacularly different in many ways. The data shown in this paper are fairly close to equilibrium (S=1.6) whereas the nucleation of cements is initiated at supersaturation ratios in the thousands to millions. Of course, after the initial nucleation phase, the growth will occur at more modest supersaturations and as the cement evolves towards equilibrium certainly some of the growth will occur in regimes such as shown here. In addition to the difference in supersaturation, cements tend to have lower additive to calcium ratios. As an example, the additive to Ca ratio is

  11. Single-molecule folding mechanism of an EF-hand neuronal calcium sensor

    DEFF Research Database (Denmark)

    Heiðarsson, Pétur Orri; Otazo, Mariela R.; Bellucci, Luca

    2013-01-01

    EF-hand calcium sensors respond structurally to changes in intracellular Ca2+ concentration, triggering diverse cellular responses and resulting in broad interactomes. Despite impressive advances in decoding their structure-function relationships, the folding mechanism of neuronal calcium sensors...... of the N domain, showing striking interdomain dependence. Molecular dynamics results reveal the atomistic details of the unfolding process and rationalize the different domain stabilities during mechanical unfolding. Through constant-force experiments and hidden Markov model analysis, the free energy...

  12. Mathematical modeling of calcium waves induced by mechanical stimulation in keratinocytes.

    Directory of Open Access Journals (Sweden)

    Yasuaki Kobayashi

    Full Text Available Recent studies have shown that the behavior of calcium in the epidermis is closely related to the conditions of the skin, especially the differentiation of the epidermal keratinocytes and the permeability barrier function, and therefore a correct understanding of the calcium dynamics is important in explaining epidermal homeostasis. Here we report on experimental observations of in vitro calcium waves in keratinocytes induced by mechanical stimulation, and present a mathematical model that can describe the experimentally observed wave behavior that includes finite-range wave propagation and a ring-shaped pattern. A mechanism of the ring formation hypothesized by our model may be related to similar calcium propagation patterns observed during the wound healing process in the epidermis. We discuss a possible extension of our model that may serve as a tool for investigating the mechanisms of various skin diseases.

  13. Pharmacological Characterization of the Mechanisms Involved in Delayed Calcium Deregulation in SH-SY5Y Cells Challenged with Methadone

    Directory of Open Access Journals (Sweden)

    Sergio Perez-Alvarez

    2012-01-01

    Full Text Available Previously, we have shown that SH-SY5Y cells exposed to high concentrations of methadone died due to a necrotic-like cell death mechanism related to delayed calcium deregulation (DCD. In this study, we show that, in terms of their Ca2+ responses to 0.5 mM methadone, SH-SY5Y cells can be pooled into four different groups. In a broad pharmacological survey, the relevance of different Ca2+-related mechanisms on methadone-induced DCD was investigated including extracellular calcium, L-type Ca2+ channels, μ-opioid receptor, mitochondrial inner membrane potential, mitochondrial ATP synthesis, mitochondrial Ca2+/2Na+-exchanger, reactive oxygen species, and mitochondrial permeability transition. Only those compounds targeting mitochondria such as oligomycin, FCCP, CGP 37157, and cyclosporine A were able to amend methadone-induced Ca2+ dyshomeostasis suggesting that methadone induces DCD by modulating the ability of mitochondria to handle Ca2+. Consistently, mitochondria became dramatically shorter and rounder in the presence of methadone. Furthermore, analysis of oxygen uptake by isolated rat liver mitochondria suggested that methadone affected mitochondrial Ca2+ uptake in a respiratory substrate-dependent way. We conclude that methadone causes failure of intracellular Ca2+ homeostasis, and this effect is associated with morphological and functional changes of mitochondria. Likely, this mechanism contributes to degenerative side effects associated with methadone treatment.

  14. Mechanism of calcium phosphates precipitation in liquid crystals

    International Nuclear Information System (INIS)

    Prelot, B.; Zemb, T.

    2004-04-01

    The possibility of using as a precursor an easily wet meso-porous powder would be a breakthrough in the preparation of nuclear waste storage ceramics. A concentrated solution containing ions to be stored would wet a dry powder and then, subjected to mild compression, lead to a micro-crystalline matrix of calcium phosphate at acceptable temperatures. Since no porous calcium phosphate different from calcined bone (patented) is described as porous precursor, we have compared the different synthesis routes towards meso-porous ceramics. First, we considered homogeneous precipitation of slats in water: using initially off-stoichiometry in reaction, micron-sized hydroxyapatite particles are produced with a specific surface up to 100 m 2 /g. Then, we consider the classical route of precipitation of an hybrid material in the miscibility gap of a phase diagram, when an hexagonal liquid crystal is used a matrix for precipitation. The surfactant family consists in single chain surfactants containing phosphates as head-group to poison the growing surface of calcium phosphate nano-domains. Since the reaction is still too brutal, we considered using a cat-anionic precursor material of controllable surface charge. For certain concentrations and molar ratios, a new structure not yet described in surfactant precipitation literature is observed: since the periodicity is lower than twice the chain length, a disordered constant curvature monolayer (instead of the classical cylinder of twice chain length diameter) of surfactant is implied. Finally, we have investigated synthesis routes implying slow dissolution of pre-formed calcium phosphate in an already existing hexagonal matrix. For all these routes of synthesis, micro-structural determinations using SAXS, WARS and BET are performed, with a special attention to comparison of the precipitation material, the matrix obtained with all elements present, and also the material obtained after calcinations. (authors)

  15. Novel Additive Manufacturing Pneumatic Actuators and Mechanisms for Food Handling Grippers

    Directory of Open Access Journals (Sweden)

    Carlos Blanes

    2014-07-01

    Full Text Available Conventional pneumatic grippers are widely used in industrial pick and place robot processes for rigid objects. They are simple, robust and fast, but their design, motion and features are limited, and they do not fulfil the final purpose. Food products have a wide variety of shapes and textures and are susceptible to damaged. Robot grippers for food handling should adapt to this wide range of dimensions and must be fast, cheap, reasonably reliable, and with cheap and reasonable maintenance costs. They should not damage the product and must meet hygienic conditions. The additive manufacturing (AM process is able to manufacture parts without significant restrictions, and is Polyamide approved as food contact material by FDA. This paper presents that, taking the best of plastic flexibility, AM allows the implementation of novel actuators, original compliant mechanisms and practical grippers that are cheap, light, fast, small and easily adaptable to specific food products. However, if they are not carefully designed, the results can present problems, such as permanent deformations, low deformation limits, and low operation speed. We present possible solutions for the use of AM to design proper robot grippers for food handling. Some successful results, such as AM actuators based on deformable air chambers, AM compliant mechanisms, and grippers developed in a single part will be introduced and discussed.

  16. Altered mechanical properties of titin immunoglobulin domain 27 in the presence of calcium.

    Science.gov (United States)

    DuVall, Michael M; Gifford, Jessica L; Amrein, Matthias; Herzog, Walter

    2013-04-01

    Titin (connectin) based passive force regulation has been an important physiological mechanism to adjust to varying muscle stretch conditions. Upon stretch, titin behaves as a spring capable of modulating its elastic response in accordance with changes in muscle biochemistry. One such mechanism has been the calcium-dependent stiffening of titin domains that renders the spring inherently more resistant to stretch. This transient titin-calcium interaction may serve a protective function in muscle, which could preclude costly unfolding of select domains when muscles elongate to great lengths. To test this idea, fluorescence spectroscopy was performed revealing a change in the microenvironment of the investigated immunoglobulin domain 27 (I27) of titin with calcium. Additionally, an atomic force microscope was used to evaluate the calcium-dependent regulation of passive force by stretching eight linked titin I27 domains until they unfolded. When stretching in the presence of calcium, the I27 homopolymer chain became stabilized, displaying three novel properties: (1) higher stretching forces were needed to unfold the domains, (2) the stiffness, measured as a persistence length (PL), increased and (3) the peak-to-peak distance between adjacent I27 domains increased. Furthermore, a peak order dependence became apparent for both force and PL, reflecting the importance of characterizing the dynamic unfolding history of a polymer with this approach. Together, this novel titin Ig-calcium interaction may serve to stabilize the I27 domain permitting titin to tune passive force within stretched muscle in a calcium-dependent manner.

  17. Mechanical work as a determinant of prey-handling behavior in the tokay gecko (Gekko gecko).

    Science.gov (United States)

    Andrews, C; Bertram, J E

    1997-01-01

    In this study an in vitro analysis of the force and mechanical work required to bite prey items of different size and physical character is combined with an in vivo analysis of prey-handling behavior in the tokay gecko (Gekko gecko). The force required to bite and the work of biting increase with prey size, but the rate of increase is prey specific, with crickets (Acheta domestica) requiring substantially more force and work per bite than larvae (Galleria mellonella and Manduca sexta) for all but the smallest prey. Prey-handling behavior is also prey specific. Geckos exert more bites per feeding event on small crickets than on small insect larvae, but the number of bites increases faster with prey mass for larvae than for crickets. Combination of the in vitro mechanical measurements with the in vivo behavior analysis allows the calculation of total mechanical work per feeding event and indicates that total work increases with prey size but that the difference between prey types is far less than predicted from the differences in structural properties of the prey. This occurs because the number of bites and work per bite relationships tend to cancel the differences in the total work necessary to process each prey type. Thus, when considering the effect of prey size, a 13-fold greater rate of increase in bite force and an 18-fold greater rate of increase of work per bit for crickets over larvae was partially compensated for by a threefold increase in the number of bites used on larvae relative to crickets. These results can be interpreted in two ways. The effect of mechanical work in feeding behavior suggests that the energetics of jaw adductor musculature could play a greater role in governing the feeding behavior of this lizard than has previously been expected. Alternatively, the scaling of work in feeding over a range of prey sizes suggests distinct differences in the geometric features of the prey that determine how they are processed.

  18. Mechanical behavior of a composite interface: Calcium-silicate-hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Palkovic, Steven D.; Moeini, Sina; Büyüköztürk, Oral, E-mail: obuyuk@mit.edu [Department of Civil and Environmental Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Yip, Sidney [Department of Nuclear Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)

    2015-07-21

    The generalized stacking fault (GSF) is a conceptual procedure historically used to assess shear behavior of defect-free crystalline structures through molecular dynamics or density functional theory simulations. We apply the GSF technique to the spatially and chemically complex quasi-layered structure of calcium-silicate-hydrates (C-S-H), the fundamental nanoscale binder within cementitious materials. A failure plane is enforced to calculate the shear traction-displacement response along a composite interface containing highly confined water molecules, hydroxyl groups, and calcium ions. GSF simulations are compared with affine (homogeneous) shear simulations, which allow strain to localize naturally in response to the local atomic environment. Comparison of strength and deformation behavior for the two loading methods shows the composite interface controls bulk shear deformation. Both models indicate the maximum shear strength of C-S-H exhibits a normal-stress dependency typical of cohesive-frictional materials. These findings suggest the applicability of GSF techniques to inhomogeneous structures and bonding environments, including other layered systems such as biological materials containing organic and inorganic interfaces.

  19. Mechanical Properties of Densified Tectosilicate Calcium-Aluminosilicate Glasses

    DEFF Research Database (Denmark)

    Johnson, Nicole; Lamberson, Lisa; Smedskjær, Morten Mattrup

    Aluminosilicate glasses are widely used in applications such as LCD glass, touchscreens for hand held devices and car windows. We have shown that the tectosilicate compositions exhibit an interesting non-monotonic variation in hardness with increasing SiO2 content. From 40% to 85 mol% SiO2......, hardness and indentation modulus both decrease, consistent with the topological constraint theory. Above 85 mol% SiO2 , hardness increases rapidly with increasing SiO2 content while modulus continues to decrease. A switch from shear to densification based on the species present in the glass has been...... proposed to explain this behavior. To reduce densification and study shear deformation independently, a series of calcium aluminosilicate glasses with tectosilicate compositions were densified by isostatic compression in a gas pressure chamber at elevated temperatures. The compressed glasses have increased...

  20. Thermal and mechanical properties of aluminized fabrics for use in ferrous metal handling operations.

    Science.gov (United States)

    Wren, J E; Scott, W D; Bates, C E

    1977-11-01

    Protective garments are normally worn in molten handling operations to provide some protection against molten metal splashes. These garments are also intended to provide protection against radiant heat, and they should be as heat resistant and comfortable as possible. Asbestos-based fabrics have been employed for many years, but recently some concern has been expressed over possible asbestos exposure. This program was undertaken to explore the ability of several types of fabrics to resist heat transfer during molten metal impact. A molten metal splash test, along with standard methods for determining tensile strength, flame resistance, and abrasion-flexing resistance were used to evaluate several classes of protective fabrics. The results indicate that there are materials available that offer equal or better mechanical properties and thermal protection compared to aluminized asbestos.

  1. Innovative design for FAST divertor compatible with remote handling, electromagnetic and mechanical analyses

    Energy Technology Data Exchange (ETDEWEB)

    Di Gironimo, Giuseppe, E-mail: giuseppe.digironimo@unina.it [CREATE, University of Naples Federico II, P.le Tecchio 80, 80125 Napoli (Italy); Cacace, Maurizio [CREATE, University of Naples Federico II, P.le Tecchio 80, 80125 Napoli (Italy); Crescenzi, Fabio [ENEA, Unità Tecnica Fusione, ENEA C. R. Frascati, via E. Fermi 45, 00044 Frascati, Roma (Italy); Labate, Carmelenzo [CREATE, University of Naples Parthenope, Via Acton 38, 80133 Napoli (Italy); Lanzotti, Antonio [CREATE, University of Naples Federico II, P.le Tecchio 80, 80125 Napoli (Italy); Lucca, Flavio [LT Calcoli srl, Piazza Prinetti 26/B, 23807 Merate, LC (Italy); Marzullo, Domenico; Mozzillo, Rocco [CREATE, University of Naples Federico II, P.le Tecchio 80, 80125 Napoli (Italy); Pagani, Irene [LT Calcoli srl, Piazza Prinetti 26/B, 23807 Merate, LC (Italy); Ramogida, Giuseppe; Roccella, Selanna [ENEA, Unità Tecnica Fusione, ENEA C. R. Frascati, via E. Fermi 45, 00044 Frascati, Roma (Italy); Viganò, Fabio [LT Calcoli srl, Piazza Prinetti 26/B, 23807 Merate, LC (Italy)

    2015-10-15

    Highlights: • The conceptual design of FAST divertor has been carried out through a continuous process of requirements refinement and design optimization (V-model approach), in order to achieve a design suited to the needs, RH compatible and ITER-like. • Thermal, structural and electromagnetic analyses have been performed, resulting in requirements refinement. • FAST divertor is now characterized by more realistic, reliable and functional features, satisfying thermo-mechanical capabilities and the remote handling (RH) compatibility. - Abstract: Divertor is a crucial component in Tokamaks, aiming to exhaust the heat power and particles fluxes coming from the plasma during discharges. This paper focuses on the optimization process of FAST divertor, aimed at achieving required thermo-mechanical capabilities and the remote handling (RH) compatibility. Divertor RH system final layout has been chosen between different concept solutions proposed and analyzed within the principles of Theory of Inventive Problem Solving (TRIZ). The design was aided by kinematic simulations performed using Digital Mock-Up capabilities of Catia software. Considerable electromagnetic (EM) analysis efforts and top-down CAD approach enabled the design of a final and consistent concept, starting from a very first dimensioning for EM loads. In the final version here presented, the divertor cassette supports a set of tungsten (W) actively cooled tiles which compose the inner and outer vertical targets, facing the plasma and exhausting the main part of heat flux. W-tiles are assembled together considering a minimum gap tolerance (0.1–0.5 mm) to be mandatorily respected. Cooling channels have been re-dimensioned to optimize the geometry and the layout of coolant volume inside the cassette has been modified as well to enhance the general efficiency.

  2. Effect of calcium deficiency on the mechanical properties of hydroxyapatite crystals

    International Nuclear Information System (INIS)

    Viswanath, B.; Shastry, V.V.; Ramamurty, U.; Ravishankar, N.

    2010-01-01

    The deterioration of the mechanical properties of bone with age is related to several factors including the structure, organization and chemistry of the constituent phases; however, the relative contribution of each of these factors is not well understood. In this study, we have investigated the effect of chemistry (calcium deficiency) on the mechanical properties of single crystals of hydroxyapatite. Single crystals of stoichiometric crystals grown by the flux method and calcium-deficient platelet crystals grown using wet chemical methods were used as model systems. Using nanoindentation, we show that calcium deficiency leads to an 80% reduction in the hardness and elastic modulus and at least a 75% reduction in toughness in plate-shaped hydroxyapatite crystals. Measurement of local mechanical properties using nanoindentation and nanoscale chemistry through elemental mapping in a transmission electron microscope points to a direct correlation between the observed spatial variation in composition and the large scatter in the measured hardness and modulus values.

  3. Phytoplankton calcification as an effective mechanism to alleviate cellular calcium poisoning

    Science.gov (United States)

    Müller, M. N.; Ramos, J. Barcelos e.; Schulz, K. G.; Riebesell, U.; Kaźmierczak, J.; Gallo, F.; Mackinder, L.; Li, Y.; Nesterenko, P. N.; Trull, T. W.; Hallegraeff, G. M.

    2015-11-01

    Marine phytoplankton have developed the remarkable ability to tightly regulate the concentration of free calcium ions in the intracellular cytosol at a level of ~ 0.1 μmol L-1 in the presence of seawater Ca2+ concentrations of 10 mmol L-1. The low cytosolic calcium ion concentration is of utmost importance for proper cell signalling function. While the regulatory mechanisms responsible for the tight control of intracellular Ca2+ concentration are not completely understood, phytoplankton taxonomic groups appear to have evolved different strategies, which may affect their ability to cope with changes in seawater Ca2+ concentrations in their environment on geological timescales. For example, the Cretaceous (145 to 66 Ma), an era known for the high abundance of coccolithophores and the production of enormous calcium carbonate deposits, exhibited seawater calcium concentrations up to 4 times present-day levels. We show that calcifying coccolithophore species (Emiliania huxleyi, Gephyrocapsa oceanica and Coccolithus braarudii) are able to maintain their relative fitness (in terms of growth rate and photosynthesis) at simulated Cretaceous seawater calcium concentrations, whereas these rates are severely reduced under these conditions in some non-calcareous phytoplankton species (Chaetoceros sp., Ceratoneis closterium and Heterosigma akashiwo). Most notably, this also applies to a non-calcifying strain of E. huxleyi which displays a calcium sensitivity similar to the non-calcareous species. We hypothesize that the process of calcification in coccolithophores provides an efficient mechanism to alleviate cellular calcium poisoning and thereby offered a potential key evolutionary advantage, responsible for the proliferation of coccolithophores during times of high seawater calcium concentrations. The exact function of calcification and the reason behind the highly ornate physical structures of coccoliths remain elusive.

  4. Phytoplankton calcification as an effective mechanism to prevent cellular calcium poisoning

    Science.gov (United States)

    Müller, M. N.; Ramos, J. Barcelos e.; Schulz, K. G.; Riebesell, U.; Kaźmierczak, J.; Gallo, F.; Mackinder, L.; Li, Y.; Nesterenko, P. N.; Trull, T. W.; Hallegraeff, G. M.

    2015-08-01

    Marine phytoplankton has developed the remarkable ability to tightly regulate the concentration of free calcium ions in the intracellular cytosol at a level of ~ 0.1 μmol L-1 in the presence of seawater Ca2+ concentrations of 10 mmol L-1. The low cytosolic calcium ion concentration is of utmost importance for proper cell signalling function. While the regulatory mechanisms responsible for the tight control of intracellular Ca2+ concentration are not completely understood, phytoplankton taxonomic groups appear to have evolved different strategies, which may affect their ability to cope with changes in seawater Ca2+ concentrations in their environment on geological time scales. For example, the Cretaceous (145 to 66 Ma ago), an era known for the high abundance of coccolithophores and the production of enormous calcium carbonate deposits, exhibited seawater calcium concentrations up to four times present-day levels. We show that calcifying coccolithophore species (Emiliania huxleyi, Gephyrocapsa oceanica and Coccolithus braarudii) are able to maintain their relative fitness (in terms of growth rate and photosynthesis) at simulated Cretaceous seawater calcium concentrations, whereas these rates are severely reduced under these conditions in some non-calcareous phytoplankton species (Chaetoceros sp., Ceratoneis closterium and Heterosigma akashiwo). Most notably, this also applies to a non-calcifying strain of E. huxleyi which displays a calcium-sensitivity similar to the non-calcareous species. We hypothesize that the process of calcification in coccolithophores provides an efficient mechanism to prevent cellular calcium poisoning and thereby offered a potential key evolutionary advantage, responsible for the proliferation of coccolithophores during times of high seawater calcium concentrations.

  5. Optimization of calcium chloride content on bioactivity and mechanical properties of white Portland cement

    International Nuclear Information System (INIS)

    Torkittikul, Pincha; Chaipanich, Arnon

    2012-01-01

    This research investigates the optimization of calcium chloride content on the bioactivity and mechanical properties of white Portland cement. Calcium chloride was used as an addition of White Portland cement at 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10% by weight. Calcium chloride was dissolved in sterile distilled water and blended with White Portland cement using a water to cement ratio of 0.5. Analysis of the bioactivity and pH of white Portland cement pastes with calcium chloride added at various amounts was carried out in simulated body fluid. Setting time, density, compressive strength and volume of permeable voids were also investigated. The characteristics of cement pastes were examined by X-ray diffractometer and scanning electron microscope linked to an energy-dispersive X-ray analyzer. The result indicated that the addition of calcium chloride could accelerate the hydration of white Portland cement, resulting in a decrease in setting time and an increase in early strength of the pastes. The compressive strength of all cement pastes with added calcium chloride was higher than that of the pure cement paste, and the addition of calcium chloride at 8 wt.% led to achieving the highest strength. Furthermore, white Portland cement pastes both with and without calcium chloride showed well-established bioactivity with respect to the formation of a hydroxyapatite layer on the material within 7 days following immersion in simulated body fluid; white Portland cement paste with added 3%CaCl 2 exhibited the best bioactivity. - Highlights: ► Optimization CaCl 2 content on the bioactivity and mechanical properties. ► CaCl 2 was used as an addition at 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10% by weight. ► CaCl 2 resulted in a decrease in setting time and an increase in early strength. ► Addition of 3%CaCl 2 exhibited the optimum formation of hydroxyapatite.

  6. Fouling control mechanisms of demineralized water backwash: Reduction of charge screening and calcium bridging effects

    KAUST Repository

    Li, Sheng

    2011-12-01

    This paper investigates the impact of the ionic environment on the charge of colloidal natural organic matter (NOM) and ultrafiltration (UF) membranes (charge screening effect) and the calcium adsorption/bridging on new and fouled membranes (calcium bridging effect) by measuring the zeta potentials of membranes and colloidal NOM. Fouling experiments were conducted with natural water to determine whether the reduction of the charge screening effect and/or calcium bridging effect by backwashing with demineralized water can explain the observed reduction in fouling. Results show that the charge of both membranes and NOM, as measured by the zeta potential, became more negative at a lower pH and a lower concentration of electrolytes, in particular, divalent electrolytes. In addition, calcium also adsorbed onto the membranes, and consequently bridged colloidal NOM and membranes via binding with functional groups. The charge screening effect could be eliminated by flushing NOM and membranes with demineralized water, since a cation-free environment was established. However, only a limited amount of the calcium bridging connection was removed with demineralized water backwashes, so the calcium bridging effect mostly could not be eliminated. As demineralized water backwash was found to be effective in fouling control, it can be concluded that the reduction of the charge screening is the dominant mechanism for this. © 2011 Elsevier Ltd.

  7. Porcine malignant hyperthermia susceptibility: hypersensitive calcium-release mechanism of skeletal muscle sarcoplasmic reticulum.

    Science.gov (United States)

    O'Brien, P J

    1986-01-01

    This study tested the hypothesis that calcium-release from sarcoplasmic reticulum isolated from malignant hyperthermia swine had abnormal concentration-dependency on release modulators. Halothane stimulated half-maximal calcium-release at similar concentrations for malignant hyperthermia and control sarcoplasmic reticulum (0.10 +/- 0.04 mM). However, concentrations causing half-maximal calcium-release were lower for malignant hyperthermia sarcoplasmic reticulum (P less than 0.001) by an order of magnitude for Ca2+ (28.1 +/- 8.3 versus 1.23 +/- 0.45 nM), adenosine triphosphate (0.33 +/- 0.09 versus 0.023 +/- 0.014 mM) and caffeine (7.79 +/- 1.56 versus 0.80 +/- 0.44 mM). Half-maximal inhibition by Mg2+ occurred at threefold higher concentrations for malignant hyperthermia sarcoplasmic reticulum (0.23 +/- 0.02 versus 0.78 +/- 0.17 mM). The Ca2+-sensitivity curves for calcium-release by sarcoplasmic reticulum isolated from heterozygotes for the malignant hyperthermia-defect were indistinguishable from the averages of the curves for controls and malignant hyperthermia-homozygotes. Results of this study suggest that malignant hyperthermia is initiated due to a hypersensitive calcium-release mechanism which is inherited in an autosomal, codominant pattern and may be diagnosed using calcium-release sensitivity-tests on isolated sarcoplasmic reticulum. Images Fig. 1. PMID:3742367

  8. The mechanical properties and hydration characteristics of cement pastes containing added-calcium coal gangue

    Energy Technology Data Exchange (ETDEWEB)

    Dongxu Li; Xuyan Song [Nanjing University of Technology, Nanjing (China). College of Material Science and Engineering

    2008-04-15

    The mechanical properties of several kinds of coal gangue calcined with limestone were researched so as to find the optimum way of calcinations with limestone. The microstructure and property of hydration process of cement pastes containing added-calcium coal gangue were analyzed by means of scanning electron microscope (SEM) and the method of mercury in trusion poremeasurement. When the proper amounst of gypsum and fluorite were taken as mineralizers in the course of calcinations of added-calcium coal gangue, the activity of coal gangue can be effectively improved. The results of mechanical property and structural characteristics such as hydration, hydration products and microstructure etc. of cement pastes containing added-calcium coal gangue are consistent.

  9. Thick filament mechano-sensing is a calcium-independent regulatory mechanism in skeletal muscle.

    Science.gov (United States)

    Fusi, L; Brunello, E; Yan, Z; Irving, M

    2016-10-31

    Recent X-ray diffraction studies on actively contracting fibres from skeletal muscle showed that the number of myosin motors available to interact with actin-containing thin filaments is controlled by the stress in the myosin-containing thick filaments. Those results suggested that thick filament mechano-sensing might constitute a novel regulatory mechanism in striated muscles that acts independently of the well-known thin filament-mediated calcium signalling pathway. Here we test that hypothesis using probes attached to the myosin regulatory light chain in demembranated muscle fibres. We show that both the extent and kinetics of thick filament activation depend on thick filament stress but are independent of intracellular calcium concentration in the physiological range. These results establish direct control of myosin motors by thick filament mechano-sensing as a general regulatory mechanism in skeletal muscle that is independent of the canonical calcium signalling pathway.

  10. Performance and mechanism of sludge dewaterability enhanced by potassium ferrate pretreatment and calcium chloride addition

    Directory of Open Access Journals (Sweden)

    Yali Liu

    2017-06-01

    Full Text Available The potential benefits and mechanisms of potassium ferrate pretreatment and calcium chloride addition on sludge dewaterability were investigated in this study. The capillary suction time (CST was used to evaluate sludge dewaterability. Results indicated that potassium ferrate of 0.1 g/g total solids (TS and calcium chloride of 0.4 g/g TS were optimal parameters, and corresponding CST reached 43.7 s. Soluble organics in extracellular polymeric substances (EPS were determined by three-dimensional excitation-emission matrix fluorescence spectroscopy, which was used to explain the mechanism of sludge dewaterability. The fluorescence intensities of protein-like and humic-like substances in EPS had a negative relationship with the CST. Scanning electron microscopy images indicated that calcium chloride neutralized the surface charge of particles, making the soluble protein-like substances agglomerate and form bigger flocs, consequently enhancing sludge dewaterability.

  11. Alpha-2 adrenoceptors and imidazoline receptors in cardiomyocytes mediate counterbalancing effect of agmatine on NO synthesis and intracellular calcium handling.

    Science.gov (United States)

    Maltsev, Alexander V; Kokoz, Yuri M; Evdokimovskii, Edward V; Pimenov, Oleg Y; Reyes, Santiago; Alekseev, Alexey E

    2014-03-01

    Evidence suggests that intracellular Ca(2+) levels and contractility of cardiomyocytes can be modulated by targeting receptors other than already identified adrenergic or non-adrenergic sarcolemmal receptors. This study uncovers the presence in myocardial cells of adrenergic α2 (α2-AR) and imidazoline I1 (I1R) receptors. In isolated left ventricular myocytes generating stationary spontaneous Ca(2+) transients in the absence of triggered action potentials, the prototypic agonist of both receptors agmatine can activate corresponding signaling cascades with opposing outcomes on nitric oxide (NO) synthesis and intracellular Ca(2+) handling. Specifically, activation of α2-AR signaling through PI3 kinase and Akt/protein kinase B stimulates NO production and abolishes Ca(2+) transients, while targeting of I1R signaling via phosphatidylcholine-specific phospholipase C (PC-PLC) and protein kinase C (PKC) suppresses NO synthesis and elevates averaged intracellular Ca(2+). We identified that endothelial NO synthase (eNOS) is a major effector for both signaling cascades. According to the established eNOS transitions between active (Akt-dependent) and inactive (PKC-dependent) conformations, we suggest that balance between α2-AR and I1R signaling pathways sets eNOS activity, which by defining operational states of myocellular sarcoplasmic reticulum Ca(2+)-ATPase (SERCA) can adjust Ca(2+) re-uptake and thereby cardiac inotropy. These results indicate that the conventional catalog of cardiomyocyte sarcolemmal receptors should be expanded by the α2-AR and I1R populations, unveiling previously unrecognized targets for endogenous ligands as well as for existing and potential pharmacological agents in cardiovascular medicine. Copyright © 2014 Elsevier Ltd. All rights reserved.

  12. Calcium in the Mechanism of Ammonia-Induced Astrocyte Swelling

    Science.gov (United States)

    Jayakumar, A.R.; Rao, K.V. Rama; Tong, X.Y; Norenberg, M.D.

    2016-01-01

    Brain edema, due largely to astrocyte swelling, is an important clinical problem in patients with acute liver failure. While mechanisms underlying astrocyte swelling in this condition are not fully understood, ammonia and associated oxidative/nitrosative stress (ONS) appear to be involved. Mechanisms responsible for the increase in reactive oxygen/nitrogen species (RONS) and their role in ammonia-induced astrocyte swelling, however, are poorly understood. Recent studies have demonstrated a transient increase in intracellular Ca2+ in cultured astrocytes exposed to ammonia. As Ca2+ is a known inducer of RONS, we investigated potential mechanisms by which Ca2+ may be responsible for the production of RONS and cell swelling in cultured astrocytes after treatment with ammonia. Exposure of cultured astrocytes to ammonia (5 mM) increased the formation of free radicals, including nitric oxide, and such increase was significantly diminished by treatment with the Ca2+ chelator BAPTA-AM. We then examined the activity of Ca2+-dependent enzymes that are known to generate RONS and found that ammonia significantly increased the activities of NADPH oxidase (NOX), constitutive nitric oxide synthase (cNOS) and phospholipase A2 (PLA2) and such increases in activity were significantly diminished by BAPTA. Pretreatment of cultures with 7-nitroindazole, apocyanin and quinacrine, respective inhibitors of cNOS, NOX and PLA2, all significantly diminished RONS production. Additionally, treatment of cultures with BAPTA or with inhibitors of cNOS, NOX and PLA2 reduced ammonia-induced astrocyte swelling. These studies suggest that the ammonia-induced rise in intracellular Ca2+ activates free radical producing enzymes that ultimately contribute to the mechanism of astrocyte swelling. PMID:19393035

  13. Regulatory inspection practices for industrial safety (electrical, mechanical, material handling and conventional aspects)

    International Nuclear Information System (INIS)

    Agarwal, K.

    2017-01-01

    Regulatory Inspection (RI) of BARC facilities and projects are carried out under the guidance of BARC Safety Council (BSC) Secretariat. Basically facilities and projects have been divided into two board categories viz. radiological facilities and non-radiological facilities. The Rls of radiological facilities should be carried out under OPSRC and of non-radiological facilities under CFSRC. Periodicity of inspection shall be at least once in a year. The RI of projects is carried out under concerned DSRC. RI practices with industrial safety which includes electrical, mechanical, material handling and conventional aspect for these facilities starts with check lists. The inspection areas are prepared in the form of checklists which includes availability of approved documents, compliance status of previous RIT and various safety committee's recommendations, radiological status of facilities, prompt reporting of safety related unusual occurrences, major incident, site visit for verification of actual status of system/plant. The practices for inspection in the area of electrical safety shall include checking of maintenance procedure for all critical class IV system equipment's such as HT panel, LT panel, transformer and motors. Load testing of Class III system such as D.G. set etc. shall be carried out as technical specification surveillance schedule. Status of aviation lights, number of qualified staff, availability of qualified staff etc. shall be form of inspection

  14. Calcium transport mechanism in molting crayfish revealed by microanalysis

    International Nuclear Information System (INIS)

    Mizuhira, V.; Ueno, M.

    1983-01-01

    Crayfish provide a good model in which to study the transport mechanism of Ca ions. During the molting stage, decalcified Ca ions are transferred into the blood and accumulate in the gastrolith epithelium, after which a gastrolith is formed on the surface of the epithelium. The gastrolith is dissolved in the stomach after molting, and the Ca is reabsorbed and redistributed throughout the newly formed exoskeleton. We studied the mechanism of Ca transport by cytochemical precipitation of Ca ions and by electron microanalysis, including X-ray microanalysis (EDX) and electron energy-loss spectroscopy (EELS), with a computer. In EDX analysis, the fine precipitates of K-antimonate in the gastrolith mitochondria clearly defined Ca with antimony; we also observed a large amount of Ca-oxalate in the mitochondria, and Ca-K X-ray pulses were clearly defined. Ca-K X-rays were also detected from fresh freeze-substituted mitochondria. Finally, we succeeded in taking a Ca-L EELS image from the mitochondria of fresh freeze-substituted thin sections. Only a very small amount of Ca was detected from the cell membrane and other organelles. Ca-adenosine triphosphatase (ATPase) and Mg-ATPase activity was also very clearly demonstrated in the mitochondria. These enzymes may play an important role in Ca metabolism

  15. Scientific conception on mechanisms of calcium homeostasis disorders under low dose effect of ionizing radiation

    International Nuclear Information System (INIS)

    Abylaev, Zh.A.; Dospolova, Zh.G.

    1997-01-01

    Scientific conception of probable consequences of calcium homeostasis disorders in personals, exposed to low dose effect of ionizing radiation has been developed. Principle positions of the conception is that pathologic processes development have different ways of conducting. During predominance of low doses of external gamma-radiation there is leading pathologic mechanism (mechanism 1) of disorder neuroendocrine regulation of both the calcium and the phosphor. In this case sicks have disorders of both the vegetative tonus and the endocrine status. Under internal irradiation (mechanism 2) there is disfunction of organs and systems (bore changes and disorders of hormone status). These changes are considered as consequence of negative action on organism of incorporated long-living radionuclides. Radio-toxic factors action (mechanism 3) provokes the excess of hormones, which acting on bone tissue and could be cause of steroid osteoporosis. Influence of chronic stress factor (mechanism 4) enlarges and burden action on organism of low radiation doses. It is emphasized, that decisive role in development of pathologic processes has mechanism of disturbance of neuroendocrine regulation of calcium exchange

  16. On issues of constructing an exception handling mechanism for CSP-based process-oriented concurrent software

    NARCIS (Netherlands)

    Jovanovic, D.S.; Orlic, B.; Broenink, Johannes F.; Broenink, J.F.; Roebers, H.W.; Sunter, J.P.E.; Welch, P.H.; Wood, D.C.

    2005-01-01

    This paper discusses issues, possibilities and existing approaches for fitting an exception handling mechanism (EHM) in CSP-based process-oriented software architectures. After giving a survey on properties desired for a concurrent EHM, specific problems and a few principal ideas for including

  17. Mechanical properties of calcium phosphate cements obtained by solution combustion synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Volkmer, Tiago M.; Barreiro, Oscar; Souza, Vania Caldas; Santos, Luis Alberto dos, E-mail: tiagovolkmer@gmail.com, E-mail: oscarbafer@hotmail.com, E-mail: vania.souza@ufrgs.br, E-mail: luis.santos@ufrgs.br [Universidade Federal do Rio Grande do Sul (UFRS), Porto Alegre, RS (Brazil). Laboratorio de Biomateriais

    2009-07-01

    Bioceramics based on calcium phosphates, especially hydroxyapatite and tricalcium phosphates (TCP) are the most used biomaterials as bone substitutes. The objective of this work is to evaluate the mechanical properties of α-tricalcium phosphate (α-TCP) synthesized by the solution combustion method. The solution combustion synthesis (SCS) can be considered as faster and simpler as other methods, furthermore it allows the obtainment of high purity α-TCP. In the calcium phosphates (CPC), α-TCP reacts with water forming needle like HA, which restrain the movement of grains, increasing mechanical resistance. In the present paper the influence of particle size on mechanical properties of α-TCP cements were evaluated. The α-TCP powder were characterized by XRD, TEM, BET and laser diffraction to asses particle size while the CPC bodies by SEM, Arquimedes method and compression tests. Increasing the milling time, the particle size decreases, resulting in samples with less porosity and consequently with higher compression resistance. (author)

  18. Drosophila wing imaginal discs respond to mechanical injury via slow InsP3R-mediated intercellular calcium waves

    Science.gov (United States)

    Restrepo, Simon; Basler, Konrad

    2016-08-01

    Calcium signalling is a highly versatile cellular communication system that modulates basic functions such as cell contractility, essential steps of animal development such as fertilization and higher-order processes such as memory. We probed the function of calcium signalling in Drosophila wing imaginal discs through a combination of ex vivo and in vivo imaging and genetic analysis. Here we discover that wing discs display slow, long-range intercellular calcium waves (ICWs) when mechanically stressed in vivo or cultured ex vivo. These slow imaginal disc intercellular calcium waves (SIDICs) are mediated by the inositol-3-phosphate receptor, the endoplasmic reticulum (ER) calcium pump SERCA and the key gap junction component Inx2. The knockdown of genes required for SIDIC formation and propagation negatively affects wing disc recovery after mechanical injury. Our results reveal a role for ICWs in wing disc homoeostasis and highlight the utility of the wing disc as a model for calcium signalling studies.

  19. Effect of Calcium Sprays on Mechanical Strength and Cell Wall Fractions of Herbaceous Peony (Paeonia Lactiflora Pall. Inflorescence Stems

    Directory of Open Access Journals (Sweden)

    Jintao Ge

    2012-04-01

    Full Text Available Calcium is an essential element and imparts significant structural rigidity to the plant cell walls, which provide the main mechanical support to the entire plant. In order to increase the mechanical strength of the inflorescence stems of herbaceous peony, the stems are treated with calcium chloride. The results shows that preharvest sprays with 4% (w/v calcium chloride three times after bud emergence are the best at strengthening “Da Fugui” peonies’ stems. Calcium sprays increased the concentrations of endogenous calcium, total pectin content as well as cell wall fractions in herbaceous peonies stems, and significantly increased the contents of them in the top segment. Correlation analysis showed that the breaking force of the top segment of peonies’ stems was positively correlated with the ratio of water insoluble pectin to water soluble pectin (R = 0.673 as well as lignin contents (R = 0.926 after calcium applications.

  20. Inhibition Mechanism of Uranyl Reduction Induced by Calcium-Carbonato Complexes

    Science.gov (United States)

    Jones, M. E.; Bargar, J.; Fendorf, S. E.

    2015-12-01

    Uranium mobility in the subsurface is controlled by the redox state and chemical speciation, generally as minimally soluble U(IV) or soluble U(VI) species. In the presence of even low carbonate concentrations the uranyl-carbonato complex quickly becomes the dominant aqueous species; they are, in fact, the primary aqueous species in most groundwaters. Calcium in groundwater leads to ternary calcium-uranyl-carbonato complexes that limit the rate and extent of U(VI) reduction. This decrease in reduction rate has been attributed to surface processes, thermodynamic limitations, and kinetic factors. Here we present a new mechanism for the inhibition of ferrous iron reduction of uranyl-carbonato species in the presence of calcium. A series of experiments under variable Ca conditions were preformed to determine the role of Ca in the inhibition of U reduction by ferrous iron. Calcium ions in the Ca2UO2(CO3)3 complex sterically prevent the interaction of Fe(II) with U(VI), in turn preventing the Fe(II)-U(VI) distance required for electron transfer. The mechanism described here helps to predict U redox transformations in suboxic environments and clarifies the role of Ca in the fate and mobility of U. Electrochemical measurements further show the decrease of the U(VI) to U(V) redox potential of the uranyl-carbonato complex with decreasing pH suggesting the first electron transfer is critical determining the rate and extent of uranium reduction.

  1. Studies on the mechanisms underlying the transfer of calcium and phosphate from bone to blood

    Energy Technology Data Exchange (ETDEWEB)

    Brommage, Jr., Robert J. [Univ. of Rochester, NY (United States)

    1978-01-01

    The skeleton is recognized as a crucial organ in the minute-to-minute regulation of the blood levels of calcium and phosphate. The fluxes of calcium and phosphate to and from bone greatly exceed the entry and exit of these ions occurring in the intestine and kidneys. Parathyroid hormone, calcitonin, and 1,25-dihydroxyvitamin D3 (1,25-(OH)2D3 are known to influence the transfer of calcium and phosphate from bone to blood. Three mechanisms have been proposed to explain the hormonal control of the calcium and phosphate effluxes from bone. The concept of a bone membrane maintaining a distinct bone extracellular fluid composition has led to the pump and pH gradient theories. An alternate solubilizer theory proposes that bone cells secrete a substance which increases the solubility of the bone mineral. The bone membrane concept was originally proposed to explain the presence of the apparent anomalously high concentrations of potassium in the bone extracellular fluid. However, the available evidence does not allow an unambiguous decision concerning the presence of a bone membrane. Calvarial lactate production was unaltered by 1,25-(OH)2D3 treatment and consequently 1,25-(OH)2D3 does not appear to promote the mobilization of bone mineral through a lactate-mediated pH gradient mechanism. 1,25-(OH)2D3 did increase the solubility of non-vital bone, clearly demonstrating that the solubilizer mechanism is at least partially responsible for the mobilization of bone mineral and the regulation of blood levels of calcium and phosphate. Vitamin D-deficient female rats fed a 0.2% calcium, 0.4% phosphorous diet and supplemented with daily injections of 0.75 pmole of 1,25-(OH)2D3 were shown to be capable of bearing young. When the injections of 1,25-(OH)2D3 were terminated at delivery, the dams and pups showed signs of vitamin D deficiency

  2. Insights into the activation mechanism of calcium ions on the sericite surface: A combined experimental and computational study

    Science.gov (United States)

    Hu, Yuehua; He, Jianyong; Zhang, Chenhu; Zhang, Chenyang; Sun, Wei; Zhao, Dongbo; Chen, Pan; Han, Haisheng; Gao, Zhiyong; Liu, Runqing; Wang, Li

    2018-01-01

    The adsorption behaviors and the activation mechanism of calcium ions (Ca2+) on sericite surface have been investigated by Zeta potential measurements, Fourier transform infrared spectroscopy (FT-IR), Micro-flotation tests and First principle calculations. Zeta potential tests results show that the sericite surface potential increases due to the adsorption of calcium ions on the surface. Micro-flotation tests demonstrate that sericite recovery remarkably rise by 10% due to the calcium ions activation on sericite surface. However, the characteristic adsorption bands of calcium oleate do not appear in the FT-IR spectrum, suggesting that oleate ions just physically adsorb on the sericite surface. The first principle calculations based on the density functional theory (DFT) further reveals the microscopic adsorption mechanism of calcium ions on the sericite surface before and after hydration.

  3. Glutamate-induced glutamate release: A proposed mechanism for calcium bursting in astrocytes

    Science.gov (United States)

    Larter, Raima; Craig, Melissa Glendening

    2005-12-01

    Here we present a new model for the generation of complex calcium-bursting patterns in astrocytes, a type of brain cell recently implicated in a variety of neural functions including memory formation. The model involves two positive feedback processes, in which the key feedback species are calcium ion and glutamate. The latter is the most abundant excitatory neurotransmitter in the brain and has been shown to be involved in bidirectional communication between astrocytes and nearby neurons. The glutamate feedback process considered here is shown to be critical for the generation of complex bursting oscillations in the astrocytes and to, perhaps, code for information which may be passed from neuron to neuron via the astrocyte. These processes may be involved in memory storage and formation as well as in mechanisms which lead to dynamical diseases such as epilepsy.

  4. Predictive Mechanical Characterization of Macro-Molecular Material Chemistry Structures of Cement Paste at Nano Scale - Two-phase Macro-Molecular Structures of Calcium Silicate Hydrate, Tri-Calcium Silicate, Di-Calcium Silicate and Calcium Hydroxide

    Science.gov (United States)

    Padilla Espinosa, Ingrid Marcela

    Concrete is a hierarchical composite material with a random structure over a wide range of length scales. At submicron length scale the main component of concrete is cement paste, formed by the reaction of Portland cement clinkers and water. Cement paste acts as a binding matrix for the other components and is responsible for the strength of concrete. Cement paste microstructure contains voids, hydrated and unhydrated cement phases. The main crystalline phases of unhydrated cement are tri-calcium silicate (C3S) and di-calcium silicate (C2S), and of hydrated cement are calcium silicate hydrate (CSH) and calcium hydroxide (CH). Although efforts have been made to comprehend the chemical and physical nature of cement paste, studies at molecular level have primarily been focused on individual components. Present research focuses on the development of a method to model, at molecular level, and analysis of the two-phase combination of hydrated and unhydrated phases of cement paste as macromolecular systems. Computational molecular modeling could help in understanding the influence of the phase interactions on the material properties, and mechanical performance of cement paste. Present work also strives to create a framework for molecular level models suitable for potential better comparisons with low length scale experimental methods, in which the sizes of the samples involve the mixture of different hydrated and unhydrated crystalline phases of cement paste. Two approaches based on two-phase cement paste macromolecular structures, one involving admixed molecular phases, and the second involving cluster of two molecular phases are investigated. The mechanical properties of two-phase macromolecular systems of cement paste consisting of key hydrated phase CSH and unhydrated phases C3S or C2S, as well as CSH with the second hydrated phase CH were calculated. It was found that these cement paste two-phase macromolecular systems predicted an isotropic material behavior. Also

  5. Calcium oscillations in wounded fibroblast monolayers are spatially regulated through substrate mechanics

    Science.gov (United States)

    Lembong, Josephine; Sabass, Benedikt; Stone, Howard A.

    2017-08-01

    The maintenance of tissue integrity is essential for the life of multicellular organisms. Healing of a skin wound is a paradigm for how various cell types localize and repair tissue perturbations in an orchestrated fashion. To investigate biophysical mechanisms associated with wound localization, we focus on a model system consisting of a fibroblast monolayer on an elastic substrate. We find that the creation of an edge in the monolayer causes cytosolic calcium oscillations throughout the monolayer. The oscillation frequency increases with cell density, which shows that wound-induced calcium oscillations occur collectively. Inhibition of myosin II reduces the number of oscillating cells, demonstrating a coupling between actomyosin activity and calcium response. The spatial distribution of oscillating cells depends on the stiffness of the substrate. For soft substrates with a Young’s modulus E ~ 360 Pa, oscillations occur on average within 0.2 mm distance from the wound edge. Increasing substrate stiffness leads to an average localization of oscillations away from the edge (up to ~0.6 mm). In addition, we use traction force microscopy to determine stresses between cells and substrate. We find that an increase of substrate rigidity leads to a higher traction magnitude. For E    ~8 kPa, traction magnitude is on average almost uniform beneath the monolayer. Thus, the spatial occurrence of calcium oscillations correlates with the cell-substrate traction. Overall, the experiments with fibroblasts demonstrate a collective, chemomechanical localization mechanism at the edge of a wound with a potential physiological role.

  6. Effect of calcium hydroxide on mechanical strength and biological properties of bioactive glass.

    Science.gov (United States)

    Shah, Asma Tufail; Batool, Madeeha; Chaudhry, Aqif Anwar; Iqbal, Farasat; Javaid, Ayesha; Zahid, Saba; Ilyas, Kanwal; Bin Qasim, Saad; Khan, Ather Farooq; Khan, Abdul Samad; Ur Rehman, Ihtesham

    2016-08-01

    In this manuscript for the first time calcium hydroxide (Ca(OH)2) has been used for preparation of bioactive glass (BG-2) by co-precipitation method and compared with glass prepared using calcium nitrate tetrahydrate Ca(NO3)2·4H2O (BG-1), which is a conventional source of calcium. The new source positively affected physical, biological and mechanical properties of BG-2. The glasses were characterized by Fourier transform infrared (FTIR), X-Ray Diffractometer (XRD), Scanning Electron Microscopy (SEM), Thermogravimetric Analysis/Differential Scanning Calorimetry (TGA-DSC), BET surface area analysis and Knoop hardness. The results showed that BG-2 possessed relatively larger surface properties (100m(2)g(-1) surface area) as compared to BG-1 (78m(2)g(-1)), spherical morphology and crystalline phases (wollastonite and apatite) after sintering at lower than conventional temperature. These properties contribute critical role in both mechanical and biological properties of glasses. The Knoop hardness measurements revealed that BG-2 possessed much better hardness (0.43±0.06GPa at 680°C and 2.16±0.46GPa at 980°C) than BG-1 (0.24±0.01 at 680°C and 0.57±0.07GPA at 980°C) under same conditions. Alamar blue Assay and confocal microscopy revealed that BG-2 exhibited better attachment and proliferation of MG63 cells. Based on the improved biological properties of BG-2 as a consequent of novel calcium source selection, BG-2 is proposed as a bioactive ceramic for hard tissue repair and regeneration applications. Copyright © 2016 Elsevier Ltd. All rights reserved.

  7. Structural characterization and mechanical performance of calcium phosphate scaffolds and natural bones: a comparative study.

    Science.gov (United States)

    Fuentes, Elena; Sáenz de Viteri, Virginia; Igartua, Amaya; Martinetti, Roberta; Dolcini, Laura; Barandika, Gotzone

    2010-01-01

    The knowledge of the mechanical response of bones and their substitutes is pertinent to numerous medical problems. Understanding the effects of mechanical influence on the body is the first step toward developing innovative treatment and rehabilitation concepts for orthopedic disorders. This was a comparative study of 5 synthetic scaffolds based on porous calcium phosphates and natural bones, with regard to their microstructural, chemical, and mechanical characterizations. The structural and chemical characterizations of the scaffolds were examined by means of X-ray diffraction, scanning electron microscopy, and X-ray spectroscopy analysis. The mechanical characterization of bones and bone graft biomaterials was carried out through compression tests using samples with noncomplex geometry. Analysis of the chemical composition, surface features, porosity, and compressive strength indicates that hydroxyapatite-based materials and trabecular bone have similar properties.

  8. Evaluation of the Chemical and Mechanical Properties of Hardening High-Calcium Fly Ash Blended Concrete.

    Science.gov (United States)

    Fan, Wei-Jie; Wang, Xiao-Yong; Park, Ki-Bong

    2015-09-07

    High-calcium fly ash (FH) is the combustion residue from electric power plants burning lignite or sub-bituminous coal. As a mineral admixture, FH can be used to produce high-strength concrete and high-performance concrete. The development of chemical and mechanical properties is a crucial factor for appropriately using FH in the concrete industry. To achieve sustainable development in the concrete industry, this paper presents a theoretical model to systematically evaluate the property developments of FH blended concrete. The proposed model analyzes the cement hydration, the reaction of free CaO in FH, and the reaction of phases in FH other than free CaO. The mutual interactions among cement hydration, the reaction of free CaO in FH, and the reaction of other phases in FH are also considered through the calcium hydroxide contents and the capillary water contents. Using the hydration degree of cement, the reaction degree of free CaO in FH, and the reaction degree of other phases in FH, the proposed model evaluates the calcium hydroxide contents, the reaction degree of FH, chemically bound water, porosity, and the compressive strength of hardening concrete with different water to binder ratios and FH replacement ratios. The evaluated results are compared to experimental results, and good consistencies are found.

  9. Physico-functional and mechanical properties of chitosan and calcium salts incorporated fish gelatin scaffolds.

    Science.gov (United States)

    Jeevithan, E; Jeya Shakila, R; Varatharajakumar, A; Jeyasekaran, G; Sukumar, D

    2013-09-01

    Four types of fish gelatin scaffolds viz. gelatin (G), gelatin-chitosan (GC), gelatin-calcium acetate (GCA) and gelatin-chitosan-calcium acetate (GCCA) prepared were investigated for their functional properties, biomechanical strength, microstructural changes in relation to biodegradation. GC scaffold was superior with pH 3.15 and viscosity 9.40 cP. Chitosan and calcium acetate improved tensile strength (TS) and Young's modulus (YM), but lowered elongation at break (EAB). GCCA scaffold possessed moderate TS of 19.6 MPa, EAB of 4.76% and YM of 185 MPa. Foaming ability ratio of GC scaffold was high (3.41). GCA and GCCA scaffolds remained for 4 days before complete in vitro biodegradation. GC scaffold had larger cavities (180-300 μm) that were responsible for low swelling ratios and shrinkage factor. GCCA scaffold with moderate swelling rates, mechanical, functional properties and lowered biodegradation rate were found more suitable for biomedical applications. Copyright © 2013 Elsevier B.V. All rights reserved.

  10. Application of chemical methods to assess the mechanism of alkali activation in low calcium fly ash

    Energy Technology Data Exchange (ETDEWEB)

    Arjunan, P.; Silsbee, M.R.; Roy, D.M. [Pennsylvania State Univ., PA (United States). Materials Research Lab.

    1999-11-01

    A better understanding of the amount of fly ash unreacted remaining after alkali activation of low calcium fly ash is necessary for elucidating the underlying alkali activation mechanism. An approach to this determination is reported in this study which utilizes an ethylenediamine tetraacetic acid/triethanolamine/NaOH mixture to determine the unreacted fly ash particles present in an OPC-low calcium fly ash mixture, with and without alkali activation. This study also uses another chemical technique called orthophosphoric acid dissolution method to assess the amount of unreacted crystalline phases present in hydrated OPC-ash mixtures at different ages of hydration. The information obtained from these two chemical techniques was used to identify the nature of unreacted fly ash particles present in the hydrated samples. The amount of unreacted fly ash and the compressive strength data were correlated to assess the extent of influence of alkali activation on the reactivity of the amorphous and crystalline phase content of the low calcium fly ash.

  11. Viral lysis of photosynthesizing microbes as a mechanism for calcium carbonate nucleation in seawater

    Science.gov (United States)

    Lisle, John T.; Robbins, Lisa L.

    2016-01-01

    Removal of carbon through the precipitation and burial of calcium carbonate in marine sediments constitutes over 70% of the total carbon on Earth and is partitioned between coastal and pelagic zones. The precipitation of authigenic calcium carbonate in seawater, however, has been hotly debated because despite being in a supersaturated state, there is an absence of persistent precipitation. One of the explanations for this paradox is the geochemical conditions in seawater cannot overcome the activation energy barrier for the first step in any precipitation reaction; nucleation. Here we show that virally induced rupturing of photosynthetic cyanobacterial cells releases cytoplasmic-associated bicarbonate at concentrations ~23-fold greater than in the surrounding seawater, thereby shifting the carbonate chemistry toward the homogenous nucleation of one or more of the calcium carbonate polymorphs. Using geochemical reaction energetics, we show the saturation states (Ω) in typical seawater for calcite (Ω = 4.3), aragonite (Ω = 3.1), and vaterite (Ω = 1.2) are significantly elevated following the release and diffusion of the cytoplasmic bicarbonate (Ωcalcite = 95.7; Ωaragonite = 68.5; Ωvaterite = 25.9). These increases in Ω significantly reduce the activation energy for nuclei formation thresholds for all three polymorphs, but only vaterite nucleation is energetically favored. In the post-lysis seawater, vaterite's nuclei formation activation energy is significantly reduced from 1.85 × 10−17 J to 3.85 × 10−20 J, which increases the nuclei formation rate from highly improbable (nucleation of calcium carbonate in seawater describes a mechanism through which the initial step in the production of carbonate sediments may proceed. It also presents an additional role of photosynthesizing microbes and their viruses in marine carbon cycles and reveals these microorganisms are a collective repository for concentrated and reactive dissolved inorganic carbon (DIC

  12. Behind the curtain: cellular mechanisms for allosteric modulation of calcium-sensing receptors

    Science.gov (United States)

    Cavanaugh, Alice; Huang, Ying; Breitwieser, Gerda E

    2012-01-01

    Calcium-sensing receptors (CaSR) are integral to regulation of systemic Ca2+ homeostasis. Altered expression levels or mutations in CaSR cause Ca2+ handling diseases. CaSR is regulated by both endogenous allosteric modulators and allosteric drugs, including the first Food and Drug Administration-approved allosteric agonist, Cinacalcet HCl (Sensipar®). Recent studies suggest that allosteric modulators not only alter function of plasma membrane-localized CaSR, but regulate CaSR stability at the endoplasmic reticulum. This brief review summarizes our current understanding of the role of membrane-permeant allosteric agonists in cotranslational stabilization of CaSR, and highlights additional, indirect, signalling-dependent role(s) for membrane-impermeant allosteric drugs. Overall, these studies suggest that allosteric drugs act at multiple cellular organelles to control receptor abundance and hence function, and that drug hydrophobicity can bias the relative contributions of plasma membrane and intracellular organelles to CaSR abundance and signalling. LINKED ARTICLES This article is part of a themed section on the Molecular Pharmacology of G Protein-Coupled Receptors (GPCRs). To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-6. To view the 2010 themed section on the same topic visit http://onlinelibrary.wiley.com/doi/10.1111/bph.2010.159.issue-5/issuetoc PMID:21470201

  13. Shigella entry unveils a calcium/calpain-dependent mechanism for inhibiting sumoylation

    Science.gov (United States)

    Lhocine, Nouara; Andrieux, Alexandra; Nigro, Giulia; Mounier, Joëlle

    2017-01-01

    Disruption of the sumoylation/desumoylation equilibrium is associated with several disease states such as cancer and infections, however the mechanisms regulating the global SUMO balance remain poorly defined. Here, we show that infection by Shigella flexneri, the causative agent of human bacillary dysentery, switches off host sumoylation during epithelial cell infection in vitro and in vivo and that this effect is mainly mediated by a calcium/calpain-induced cleavage of the SUMO E1 enzyme SAE2, thus leading to sumoylation inhibition. Furthermore, we describe a mechanism by which Shigella promotes its own invasion by altering the sumoylation state of RhoGDIα, a master negative regulator of RhoGTPase activity and actin polymerization. Together, our data suggest that SUMO modification is essential to restrain pathogenic bacterial entry by limiting cytoskeletal rearrangement induced by bacterial effectors. Moreover, these findings identify calcium-activated calpains as powerful modulators of cellular sumoylation levels with potentially broad implications in several physiological and pathological situations. PMID:29231810

  14. Electrochemical deposition mechanism of calcium phosphate coating in dilute Ca-P electrolyte system

    Energy Technology Data Exchange (ETDEWEB)

    Hu Ren [State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, CNRS Laboratoire International Associe XiamENS, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Department of Biology, College of Life Science, Xiamen University, Xiamen, Fujian 361005 (China); Lin Changjian, E-mail: cjlin@xmu.edu.cn [State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, CNRS Laboratoire International Associe XiamENS, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005 (China); Shi Haiyan; Wang Hui [State Key Laboratory of Physical Chemistry of Solid Surfaces and Department of Chemistry, CNRS Laboratoire International Associe XiamENS, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005 (China)

    2009-06-15

    In this work, the electrochemical deposition behavior of calcium phosphate coating from an aqueous electrolyte containing very dilute calcium and phosphorus species (Ca-P) was studied. The effects of three process parameters, i.e. temperature, current density and duration, were systematically investigated and the underlying mechanism was thoroughly analyzed. It was observed that the coating is mainly composed of hydroxyapatite (HA) in a wide range of temperature and current densities. The temperature had a significant effect on the deposition velocity. An apparent activation energy of 174.9 kJ mol{sup -1} was subsequently derived, indicating the mass-transfer control mechanism for the coating formation. The current density was identified to be an important parameter for structure controllability. The results of DR-FTIR/Raman spectroscopic studies of the initial deposition phase strongly suggested that the HA coating was instantaneously and directly precipitated on the substrate; neither induction period nor precursor was detected in this dilute Ca-P electrolyte system. Finally, a phase diagram of the Ca-P electrolyte system was constructed, which offered a thermodynamic reason for the direct single-phase HA precipitation observed only in this system, but not in conventional concentrated systems.

  15. Electrochemical deposition mechanism of calcium phosphate coating in dilute Ca-P electrolyte system

    International Nuclear Information System (INIS)

    Hu Ren; Lin Changjian; Shi Haiyan; Wang Hui

    2009-01-01

    In this work, the electrochemical deposition behavior of calcium phosphate coating from an aqueous electrolyte containing very dilute calcium and phosphorus species (Ca-P) was studied. The effects of three process parameters, i.e. temperature, current density and duration, were systematically investigated and the underlying mechanism was thoroughly analyzed. It was observed that the coating is mainly composed of hydroxyapatite (HA) in a wide range of temperature and current densities. The temperature had a significant effect on the deposition velocity. An apparent activation energy of 174.9 kJ mol -1 was subsequently derived, indicating the mass-transfer control mechanism for the coating formation. The current density was identified to be an important parameter for structure controllability. The results of DR-FTIR/Raman spectroscopic studies of the initial deposition phase strongly suggested that the HA coating was instantaneously and directly precipitated on the substrate; neither induction period nor precursor was detected in this dilute Ca-P electrolyte system. Finally, a phase diagram of the Ca-P electrolyte system was constructed, which offered a thermodynamic reason for the direct single-phase HA precipitation observed only in this system, but not in conventional concentrated systems.

  16. Mechanism of calcium phosphates precipitation in liquid crystals; Mecanisme de precipitation de phosphates de calcium dans des cristaux liquides

    Energy Technology Data Exchange (ETDEWEB)

    Prelot, B.; Zemb, T

    2004-04-01

    The possibility of using as a precursor an easily wet meso-porous powder would be a breakthrough in the preparation of nuclear waste storage ceramics. A concentrated solution containing ions to be stored would wet a dry powder and then, subjected to mild compression, lead to a micro-crystalline matrix of calcium phosphate at acceptable temperatures. Since no porous calcium phosphate different from calcined bone (patented) is described as porous precursor, we have compared the different synthesis routes towards meso-porous ceramics. First, we considered homogeneous precipitation of slats in water: using initially off-stoichiometry in reaction, micron-sized hydroxyapatite particles are produced with a specific surface up to 100 m{sup 2}/g. Then, we consider the classical route of precipitation of an hybrid material in the miscibility gap of a phase diagram, when an hexagonal liquid crystal is used a matrix for precipitation. The surfactant family consists in single chain surfactants containing phosphates as head-group to poison the growing surface of calcium phosphate nano-domains. Since the reaction is still too brutal, we considered using a cat-anionic precursor material of controllable surface charge. For certain concentrations and molar ratios, a new structure not yet described in surfactant precipitation literature is observed: since the periodicity is lower than twice the chain length, a disordered constant curvature monolayer (instead of the classical cylinder of twice chain length diameter) of surfactant is implied. Finally, we have investigated synthesis routes implying slow dissolution of pre-formed calcium phosphate in an already existing hexagonal matrix. For all these routes of synthesis, micro-structural determinations using SAXS, WARS and BET are performed, with a special attention to comparison of the precipitation material, the matrix obtained with all elements present, and also the material obtained after calcinations. (authors)

  17. Calcification mechanism and bony bonding studies of calcium carbonate and composite aluminosilicate/calcium phosphate applied as biomaterials by using radioactivation methods

    International Nuclear Information System (INIS)

    Oudadesse, H.; Derrien, A.C.; Lucas-Girot, A.; Martin, S.; Cathelieau, G.

    2007-01-01

    Bony grafts are used as a filling biomaterial for defective bone. The introduction of new range of synthetic materials offers to surgeons additional possibilities to avoid virus transmission risks by using natural grafts in bony surgery. In this work, two materials, synthetic calcium carbonate and composite aluminosilicate/calcium phosphate were synthesized by an original method and experimented 'in vivo' as biomaterials for bony filling. Extracted biopsies were studied by several physico chemical and biological methods. The aim was to evaluate the kinetic resorption and bioconsolidation of these materials. We focused on the bioconsolidation between implant and bone by realising cartographies from the implant to the bone and on the calcification mechanism by determination of the origin of Ca and Sr responsible of the neo-formed bone. Neutron activation analysis (NAA), radiotracers 45 Ca* and 85 Sr* and proton-induced X-ray emission (PIXE) were used. Concerning the synthetic calcium carbonate, results show that twelve months after implantation, the mineral composition of implant becomes similar to that of the mature bone. The neoformed bone is composed with Ca and Sr coming from the organism when the Ca and Sr of the implant were progressively eliminated. Concerning the composite geopolymer/calcium phosphate, PIXE and histological studies reveal the intimate links between the bone and the implant starting with the first month after implantation. (author)

  18. Viral lysis of photosynthesizing microbes as a mechanism for calcium carbonate nucleation in seawater

    Science.gov (United States)

    Lisle, John T.; Robbins, Lisa L.

    2016-01-01

    Removal of carbon through the precipitation and burial of calcium carbonate in marine sediments constitutes over 70% of the total carbon on Earth and is partitioned between coastal and pelagic zones. The precipitation of authigenic calcium carbonate in seawater, however, has been hotly debated because despite being in a supersaturated state, there is an absence of persistent precipitation. One of the explanations for this paradox is the geochemical conditions in seawater cannot overcome the activation energy barrier for the first step in any precipitation reaction; nucleation. Here we show that virally induced rupturing of photosynthetic cyanobacterial cells releases cytoplasmic-associated bicarbonate at concentrations ~23-fold greater than in the surrounding seawater, thereby shifting the carbonate chemistry toward the homogenous nucleation of one or more of the calcium carbonate polymorphs. Using geochemical reaction energetics, we show the saturation states (Ω) in typical seawater for calcite (Ω = 4.3), aragonite (Ω = 3.1), and vaterite (Ω = 1.2) are significantly elevated following the release and diffusion of the cytoplasmic bicarbonate (Ωcalcite = 95.7; Ωaragonite = 68.5; Ωvaterite = 25.9). These increases in Ω significantly reduce the activation energy for nuclei formation thresholds for all three polymorphs, but only vaterite nucleation is energetically favored. In the post-lysis seawater, vaterite's nuclei formation activation energy is significantly reduced from 1.85 × 10−17 J to 3.85 × 10−20 J, which increases the nuclei formation rate from highly improbable (seawater describes a mechanism through which the initial step in the production of carbonate sediments may proceed. It also presents an additional role of photosynthesizing microbes and their viruses in marine carbon cycles and reveals these microorganisms are a collective repository for concentrated and reactive dissolved inorganic carbon (DIC) that is currently not accounted for

  19. Machine assembly with a new material handling mechanism in the sewing machine

    Directory of Open Access Journals (Sweden)

    Umarova Z.M.

    2017-05-01

    Full Text Available the paper presents the dynamic model of the machine assembly with a recommended mechanism for moving material and the definition of the law of rails motion under various system parameters. The author has suggested the solution implemented by the system of differential equations numerically on the PC and the system describing the motion of the machine set. Recommended values ​​of the parameters of elastic links of material transfer mechanism have been obtained. The researcher has developed the methods of kinematic and dynamic analysis of the material transfer mechanism with elastic elements of the sewing machine and has approved the parameters and development of the design.

  20. A Proposed Mechanism for the Thermal Denaturation of a Recombinant Bacillus Halmapalus Alpha-amylase - the Effect of Calcium Ions

    Science.gov (United States)

    Nielsen, Anders D.; Pusey, Marc L.; Fuglsang, Claus C.; Westh, Peter

    2003-01-01

    The thermal stability of a recombinant alpha-amylase from Bacillus halmapalus alpha-amylase (BHA) has been investigated using circular dichroism spectroscopy (CD) and differential scanning calorimetry (DSC). This alpha-amylase is homologous to other Bacillus alpha-amylases where previous crystallographic studies have identified the existence of 3 calcium binding sites in the structure. Denaturation of BHA is irreversible with a Tm of approximately 89 C, and DSC thermograms can be described using a one-step irreversible model. A 5 C increase in T(sub m) in the presence of 10 fold excess CaCl2 was observed. However, a concomitant increase in the tendency to aggregate was also observed. The presence of 30-40 fold excess calcium chelator (EDTA or EGTA) results in a large destabilization of BHA corresponding to about 40 C lower T(sub m), as determined by both CD and DSC. Ten fold excess EGTA reveals complex DSC thermograms corresponding to both reversible and irreversible transitions, which possibly originate from different populations of BHA:calcium complexes. The observations in the present study have, in combination with structural information of homologous alpha-amylases, provided the basis for the proposal of a simple denaturation mechanism of BHA. The proposed mechanism describes the irreversible thermal denaturation of different BHA:calcium complexes and the calcium binding equilibrium involved. Furthermore, the model accounts for a temperature induced reversible structural change associated with calcium binding.

  1. Microstructure and mechanical properties of stainless steel/calcium silicate composites manufactured by selective laser melting.

    Science.gov (United States)

    Zheng, Zeng; Wang, Lianfeng; Jia, Min; Cheng, Lingyu; Yan, Biao

    2017-02-01

    Selective laser melting (SLM) is raised as one kind of additive manufacturing (AM) which is based on the discrete-stacking concept. This technique can fabricate advanced composites with desirable properties directly from 3D CAD data. In this research, 316L stainless steel (316L SS) and different fractions of calcium silicate (CaSiO 3 ) composites (weight fractions of calcium silicate are 0%, 5%,10% and 15%, respectively) were prepared by SLM technique with a purpose to develop biomedical metallic materials. The relative density, tensile, microhardness and elastic modulus of the composites were tested, their microstructures and fracture morphologies were observed using optical microscope (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that the addition of CaSiO 3 particles influenced the microstructure and mechanical properties of specimens significantly. The CaSiO 3 precipitates from the overlap of adjacent tracks and became the origin of the defects. The tensile strength of specimens range 320-722MPa. The microhardness and elastic modulus are around 250HV and 215GPa respectively. These composites were ductile materials and the fracture mode of the composites was mixed mode of ductile and brittle fracture. The 316L SS/CaSiO 3 composites can be a potential biomedical metallic materials in the medical field. Copyright © 2016. Published by Elsevier B.V.

  2. Mechanisms of the gabapentinoids and α 2 δ-1 calcium channel subunit in neuropathic pain.

    Science.gov (United States)

    Patel, Ryan; Dickenson, Anthony H

    2016-04-01

    The gabapentinoid drugs gabapentin and pregabalin are key front-line therapies for various neuropathies of peripheral and central origin. Originally designed as analogs of GABA, the gabapentinoids bind to the α 2 δ-1 and α 2 δ-2 auxiliary subunits of calcium channels, though only the former has been implicated in the development of neuropathy in animal models. Transgenic approaches also identify α 2 δ-1 as key in mediating the analgesic effects of gabapentinoids, however the precise molecular mechanisms remain unclear. Here we review the current understanding of the pathophysiological role of the α 2 δ-1 subunit, the mechanisms of analgesic action of gabapentinoid drugs and implications for efficacy in the clinic. Despite widespread use, the number needed to treat for gabapentin and pregabalin averages from 3 to 8 across neuropathies. The failure to treat large numbers of patients adequately necessitates a novel approach to treatment selection. Stratifying patients by sensory profiles may imply common underlying mechanisms, and a greater understanding of these mechanisms could lead to more direct targeting of gabapentinoids.

  3. Light Hydrocarbons Adsorption Mechanisms in Two Calcium-based Microporous Metal Organic Frameworks

    KAUST Repository

    Plonka, Anna M.

    2016-01-25

    The adsorption mechanism of ethane, ethylene and acetylene (C2Hn; n=2, 4, 6) on two microporous metal organic frameworks (MOFs) is described here that is consistent with observations from single crystal and powder X-ray diffraction, calorimetric measurments and gas adsorption isotherm measurements. Two calcium-based MOFs, designated as SBMOF-1 and SBMOF-2 (SB: Stony Brook), form three-dimensional frameworks with one-dimensional open channels. As determined form single crystal diffraction experiments channel geometries of both SBMOF-1 and SBMOF-2 provide multiple adsorption sites for hydrocarbon molecules trough C-H…π and C-H…O interactions, similarly to interactions in the molecular and protein crystals. Both materials selectively adsorb C2 hydrocarbon gases over methane as determined with IAST and breakthrough calculations, with C2H6/CH4 selectivity as high as 74 in SBMOF-1.

  4. Microstructure and mechanical properties of stainless steel/calcium silicate composites manufactured by selective laser melting

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Zeng [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Shanghai Key Lab. of D& A for Metal-Functional Materials, Shanghai 201804 (China); Wang, Lianfeng [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Shanghai Aerospace Equipments Manufacturer, Shanghai 200240 (China); Jia, Min [Shanghai Aircraft Manufacturing Co., Ltd, Shanghai 200436 (China); Cheng, Lingyu [Shanghai Aerospace Equipments Manufacturer, Shanghai 200240 (China); Yan, Biao, E-mail: 84016@tongji.edu.cn [School of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Shanghai Key Lab. of D& A for Metal-Functional Materials, Shanghai 201804 (China)

    2017-02-01

    Selective laser melting (SLM) is raised as one kind of additive manufacturing (AM) which is based on the discrete-stacking concept. This technique can fabricate advanced composites with desirable properties directly from 3D CAD data. In this research, 316L stainless steel (316L SS) and different fractions of calcium silicate (CaSiO{sub 3}) composites (weight fractions of calcium silicate are 0%, 5%,10% and 15%, respectively) were prepared by SLM technique with a purpose to develop biomedical metallic materials. The relative density, tensile, microhardness and elastic modulus of the composites were tested, their microstructures and fracture morphologies were observed using optical microscope (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). It was found that the addition of CaSiO{sub 3} particles influenced the microstructure and mechanical properties of specimens significantly. The CaSiO{sub 3} precipitates from the overlap of adjacent tracks and became the origin of the defects. The tensile strength of specimens range 320–722 MPa. The microhardness and elastic modulus are around 250 HV and 215 GPa respectively. These composites were ductile materials and the fracture mode of the composites was mixed mode of ductile and brittle fracture. The 316L SS/CaSiO{sub 3} composites can be a potential biomedical metallic materials in the medical field. - Highlights: • 316L SS/CaSiO{sub 3} composites were fabricated by selective laser melting. • Microstructure, mechanical properties, corrosion resistance of samples was studied. • Composites is a ductile material and mixed mode of ductile and brittle fracture. • Composites is a potential biomedical metallic materials in the medical field.

  5. A model of propagating calcium-induced calcium release mediated by calcium diffusion

    NARCIS (Netherlands)

    Backx, P. H.; de Tombe, P. P.; van Deen, J. H.; Mulder, B. J.; ter Keurs, H. E.

    1989-01-01

    The effect of sudden local fluctuations of the free sarcoplasmic [Ca++]i in cardiac cells on calcium release and calcium uptake by the sarcoplasmic reticulum (SR) was calculated with the aid of a simplified model of SR calcium handling. The model was used to evaluate whether propagation of calcium

  6. Mechanisms of calcium transport in small intestine. Overall review of the contract, September 1, 1972--March 1, 1975

    International Nuclear Information System (INIS)

    DeLuca, H.F.

    1975-01-01

    During the past three years considerable advance has been registered in our understanding of the mechanism of intestinal calcium transport, which is activated in response to 1,25-(OH) 2 D 3 , the active form of the vitamin in the system. In brush borders isolated from vitamin D-deficient chicks, a 200,000 molecular weight protein has been found by disc gel electrophoresis which is not present in chicks given vitamin D. This protein does not bind calcium and does not possess calcium dependent adenosine triphosphatase activity. Following the administration of 1,25-(OH) 2 D 3 to the deficient chicks this protein disappears from the disc gel profiles and a protein of molecular weight 220,000 appears in the gel profiles. This protein has been isolated and shown to possess calcium adenosine triphosphatase activity, alkaline phosphatase activity and it binds calcium. Work is progressing on the purification of these proteins with the ultimate aim of discerning what role they have in intestinal calcium transport. (U.S.)

  7. An Artificial Immune System with Feedback Mechanisms for Effective Handling of Population Size

    Science.gov (United States)

    Gao, Shangce; Wang, Rong-Long; Ishii, Masahiro; Tang, Zheng

    This paper represents a feedback artificial immune system (FAIS). Inspired by the feedback mechanisms in the biological immune system, the proposed algorithm effectively manipulates the population size by increasing and decreasing B cells according to the diversity of the current population. Two kinds of assessments are used to evaluate the diversity aiming to capture the characteristics of the problem on hand. Furthermore, the processing of adding and declining the number of population is designed. The validity of the proposed algorithm is tested for several traveling salesman benchmark problems. Simulation results demonstrate the efficiency of the proposed algorithm when compared with the traditional genetic algorithm and an improved clonal selection algorithm.

  8. Fault Diagnosis for Nonlinear Hydraulic-Mechanical Drilling Pipe Handling System

    DEFF Research Database (Denmark)

    Choux, Martin; Blanke, Mogens

    2011-01-01

    Leakage and increased friction are common faults in hydraulic cylinders that can have serious consequences if they are not detected at early stage. In this paper, the design of a fault detector for a nonlinear hydraulic mechanical system is presented. By considering the system in steady state, two...... residual signals are generated and analysed with a composite hypothesis test which accommodates for unknown parameters. The resulting detector is able to detect abrupt changes in leakage or friction given the noisy pressure and position measurements. Test rig measurements validate the properties...

  9. Calcium specificity signaling mechanisms in abscisic acid signal transduction in Arabidopsis guard cells

    Science.gov (United States)

    Brandt, Benjamin; Munemasa, Shintaro; Wang, Cun; Nguyen, Desiree; Yong, Taiming; Yang, Paul G; Poretsky, Elly; Belknap, Thomas F; Waadt, Rainer; Alemán, Fernando; Schroeder, Julian I

    2015-01-01

    A central question is how specificity in cellular responses to the eukaryotic second messenger Ca2+ is achieved. Plant guard cells, that form stomatal pores for gas exchange, provide a powerful system for in depth investigation of Ca2+-signaling specificity in plants. In intact guard cells, abscisic acid (ABA) enhances (primes) the Ca2+-sensitivity of downstream signaling events that result in activation of S-type anion channels during stomatal closure, providing a specificity mechanism in Ca2+-signaling. However, the underlying genetic and biochemical mechanisms remain unknown. Here we show impairment of ABA signal transduction in stomata of calcium-dependent protein kinase quadruple mutant plants. Interestingly, protein phosphatase 2Cs prevent non-specific Ca2+-signaling. Moreover, we demonstrate an unexpected interdependence of the Ca2+-dependent and Ca2+-independent ABA-signaling branches and the in planta requirement of simultaneous phosphorylation at two key phosphorylation sites in SLAC1. We identify novel mechanisms ensuring specificity and robustness within stomatal Ca2+-signaling on a cellular, genetic, and biochemical level. DOI: http://dx.doi.org/10.7554/eLife.03599.001 PMID:26192964

  10. Evaluation of mechanical strength and hydrate products evolution of calcium aluminate cement, for endodontic applications

    International Nuclear Information System (INIS)

    Luz, A.P.; Borba, N.Z.; Pandolfelli, V.C.

    2011-01-01

    Mineral trioxide aggregate (MTA) is the most used retrograde filling cement in the endodontic area. Nevertheless, although its composition is similar to the conventional Portland cement, its high cost, long setting time and low mechanical strength have led to a continuous search for new alternative materials. Considering these aspects, the mechanical strength and crystalline phase evolution of a calcium aluminate cement (CAC), during its hydration process, have been evaluated in this work aiming to apply such material for endodontic treatments. Secar 71 cement samples were prepared and kept in contact with water or SBF (simulated body fluid) during 15 days at 37 deg C. Compressive strength, apparent porosity, X ray diffraction and thermogravimetric tests were carried out for the samples evaluation after 1, 3, 7 and 15 days. The main identified phases were CAH_1_0, C_2AH_8, C_3AH_6 and AH_3. Moreover, when in the presence of SBF, some changes in the amount of the hydrates in the CAC samples were observed, which affected the mechanical behavior of the cement. (author)

  11. Mechanical and microstructure of reinforced hydroxyapatite/calcium silicate nano-composites materials

    International Nuclear Information System (INIS)

    Beheri, Hanan H.; Mohamed, Khaled R.; El-Bassyouni, Gehan T.

    2013-01-01

    Highlights: ► Nano sized of HA and CS powders were prepared. ► Mechanical of HACS composites enhanced with content of CS. ► The apatite formation onto the composites is proved. -- Abstract: In this study, the nano sized hydroxyapatite (HA) and calcium silicate (CS) powders prepared by both chemical precipitation and sol–gel methods respectively. Biphasic nano-composites materials containing different ratios of HA and CS were fabricated and assessed using X-ray diffraction (XRD), Fourier transmission infrared reflectance (FT-IR), transmission electron microscopy (TEM) and scanning electron microscopy (SEM) techniques. The effect of variation of ratios between HA and CS on mechanical properties, microstructure and in vitro study was studied. The results proved that the mechanical properties were enhanced with increasing the CS ratio in the composite. In vitro study proved the formation and nucleation of apatite onto composites surfaces which contain low content of CS after one week of immersion. Finally, it is concluded that the HACS composites containing high HA content at the expense of CS content will be promising for bone substitute’s applications, especially in load bearing sites.

  12. Big data handling mechanisms in the healthcare applications: A comprehensive and systematic literature review.

    Science.gov (United States)

    Pashazadeh, Asma; Jafari Navimipour, Nima

    2018-04-12

    Healthcare provides many services such as diagnosing, treatment, prevention of diseases, illnesses, injuries, and other physical and mental disorders. Large-scale distributed data processing applications in healthcare as a basic concept operates on large amounts of data. Therefore, big data application functions are the main part of healthcare operations, but there was not any comprehensive and systematic survey about studying and evaluating the important techniques in this field. Therefore, this paper aims at providing the comprehensive, detailed, and systematic study of the state-of-the-art mechanisms in the big data related to healthcare applications in five categories, including machine learning, cloud-based, heuristic-based, agent-based, and hybrid mechanisms. Also, this paper displayed a systematic literature review (SLR) of the big data applications in the healthcare literature up to the end of 2016. Initially, 205 papers were identified, but a paper selection process reduced the number of papers to 29 important studies. Copyright © 2018 Elsevier Inc. All rights reserved.

  13. Your body mechanics in motion : proactive training for stepping, handling, lifting

    Energy Technology Data Exchange (ETDEWEB)

    Hanchara, L.; Strong, J. [Kinetic Safety Consulting Inc., Grande Prairie, AB (Canada)

    2007-07-01

    Over a third of all injuries in the oil and gas industry are caused by strains. Nearly 50 per cent of back injuries in the industry are reported by workers on the job for less than 6 months. This presentation provided details of Mechanics in Motion, a program designed to promote proactive and safe conditions for workers in the petroleum industry. The program presented methods of improving posture when lifting, stepping, reaching, and carrying. The program was created in 2005 in order to serve as a preventative tool in the oilfield. Outlines of body fulcrums and levers were presented, as well as the types of joints that are most prone to workplace injuries. Field and office ergonomics were reviewed, and various correct lifting techniques were presented. Worksite warm-up programs were provided, as well as a set of stretches designed specifically for the back. It was concluded that understanding oilfield ergonomics and the mechanical principles of the body may help to prevent injuries in the workplace. tabs., figs.

  14. Bacterial foraging-optimized PID control of a two-wheeled machine with a two-directional handling mechanism.

    Science.gov (United States)

    Goher, K M; Fadlallah, S O

    2017-01-01

    This paper presents the performance of utilizing a bacterial foraging optimization algorithm on a PID control scheme for controlling a five DOF two-wheeled robotic machine with two-directional handling mechanism. The system under investigation provides solutions for industrial robotic applications that require a limited-space working environment. The system nonlinear mathematical model, derived using Lagrangian modeling approach, is simulated in MATLAB/Simulink ® environment. Bacterial foraging-optimized PID control with decoupled nature is designed and implemented. Various working scenarios with multiple initial conditions are used to test the robustness and the system performance. Simulation results revealed the effectiveness of the bacterial foraging-optimized PID control method in improving the system performance compared to the PID control scheme.

  15. Inconceivable events in handling material in a heavy mechanical engineering industry

    International Nuclear Information System (INIS)

    Oestberg, G.; Hoffstedt, H.; Holm, G.; Klingenstierna, B.; Rydnert, B.; Samsonowitz, V.; Sjoeberg, L.

    1977-05-01

    This report accounts for an exploratory project concerning so-called inconceivable events in a manufacturing process. The study was performed at a medium-sized mechanical engineering company manufacturing heavy welded constructions with high demands on reliability and safety. On the basis of experience gained in the present study the main study shall deal with inconceivable events during the manufacture of welded nuclear pressure vessels. First, a description is given of the background and conditions of the project. On this follows a technical description of the studied process, and an account is given of observations and results of interviews at the company as well. In the light of this, an attempt to find a pattern of inconceivable events was done, and a model for analysis of rare events was developed. By means of this model and earlier described events, causes of unpredicted or unexpected events are discussed. Finally the methodology applied in the study is accounted for and discussed

  16. The predominant mechanism of intercellular calcium wave propagation changes during long-term culture of human osteoblast-like cells

    DEFF Research Database (Denmark)

    Henriksen, Zanne; Hiken, Jeffrey F; Steinberg, Thomas H

    2006-01-01

    cells still responded to addition of ATP, but P2Y desensitization did not inhibit ICW propagation. Our data indicate that the relative role of P2Y-mediated and gap junction-mediated ICW changes during osteoblast differentiation in vitro. In less differentiated cells, P2Y-mediated ICW predominate......Intercellular calcium waves (ICW) are calcium transients that spread from cell to cell in response to different stimuli. We previously demonstrated that human osteoblast-like cells in culture propagate ICW in response to mechanical stimulation by two mechanisms. One mechanism involves autocrine...... activation of P2Y receptors, and the other requires gap junctional communication. In the current work we ask whether long-term culture of osteoblast-like cells affects the propagation of ICW by these two mechanisms. Human osteoblast-like cells were isolated from bone marrow. Mechanically induced ICW were...

  17. Physical-Mechanical Properties and Micromorphology of Calcium Cements Exposed to Polyacrylic and Phosphoric Acids.

    Science.gov (United States)

    de Souza, Gustavo Fernandes; Arrais, Ana Beatriz; Aragão, Cícero Flávio Soares; Ferreira, Isana Alvares; Borges, Boniek Castillo Dutra

    2018-01-01

    To evaluate if physical and mechanical properties of self-curing calcium hydroxide cements were affected by contact with polyacrylic and phosphoric acids. Resin-containing (Life (LF)) and resin-free (Hydro C (HyC)) materials were subjected to polyacrylic acid conditioning and rinsing (POL); phosphoric acid conditioning and rinsing (PHO); rinsing only; and no treatment ( n = 10). Water sorption/solubility, release of hydroxyl ions (pH), roughness (Ra), and impact resistance were evaluated. Additional samples ( n = 1) were prepared for scanning electron microscopy (SEM) analysis of the surface morphology. Data were analyzed by two-way ANOVA and Tukey post hoc test ( P < 0.05). Water sorption was significantly higher for LF when in contact with PHO and lower for POL ( P < 0.05). The mean solubility was higher with POL for both cements ( P < 0.05). PHO increased the mean surface roughness for HyC ( P < 0.01); a significant decrease was noted for LF after contact with both acids ( P < 0.01). PHO promoted lower release of hydroxyl ions on both cements ( P < 0.05). For LF, rinsing, PHO, and POL presented similar morphology, differing from the control group. For HyC, PHO and POL presented similar morphology, differing from the control group. PHO had a negative effect on the physical properties of the cements tested, except for the solubility test. POL affected roughness and solubility of HyC cement. Clinical procedures that require polyacrylic and phosphoric acid conditioning must be done carefully on self-curing calcium hydroxide cements in order to avoid negative impact on their properties.

  18. Role of thin descending limb urea transport in renal urea handling and the urine concentrating mechanism

    Science.gov (United States)

    Lei, Tianluo; Zhou, Lei; Layton, Anita T.; Zhou, Hong; Zhao, Xuejian; Bankir, Lise

    2011-01-01

    Urea transporters UT-A2 and UT-B are expressed in epithelia of thin descending limb of Henle's loop and in descending vasa recta, respectively. To study their role and possible interaction in the context of the urine concentration mechanism, a UT-A2 and UT-B double knockout (UT-A2/B knockout) mouse model was generated by targeted deletion of the UT-A2 promoter in embryonic stem cells with UT-B gene knockout. The UT-A2/B knockout mice lacked detectable UT-A2 and UT-B transcripts and proteins and showed normal survival and growth. Daily urine output was significantly higher in UT-A2/B knockout mice than that in wild-type mice and lower than that in UT-B knockout mice. Urine osmolality in UT-A2/B knockout mice was intermediate between that in UT-B knockout and wild-type mice. The changes in urine osmolality and flow rate, plasma and urine urea concentration, as well as non-urea solute concentration after an acute urea load or chronic changes in protein intake suggested that UT-A2 plays a role in the progressive accumulation of urea in the inner medulla. These results suggest that in wild-type mice UT-A2 facilitates urea absorption by urea efflux from the thin descending limb of short loops of Henle. Moreover, UT-A2 deletion in UT-B knockout mice partially remedies the urine concentrating defect caused by UT-B deletion, by reducing urea loss from the descending limbs to the peripheral circulation; instead, urea is returned to the inner medulla through the loops of Henle and the collecting ducts. PMID:21849488

  19. Testosterone increases urinary calcium excretion and inhibits expression of renal calcium transport proteins.

    NARCIS (Netherlands)

    Hsu, Y.J.; Dimke, H.; Schoeber, J.P.H.; Hsu, S.C.; Lin, S.H.; Chu, P.; Hoenderop, J.G.J.; Bindels, R.J.M.

    2010-01-01

    Although gender differences in the renal handling of calcium have been reported, the overall contribution of androgens to these differences remains uncertain. We determined here whether testosterone affects active renal calcium reabsorption by regulating calcium transport proteins. Male mice had

  20. The kinetics and mechanisms of amorphous calcium carbonate (ACC) crystallization to calcite, via vaterite.

    Science.gov (United States)

    Rodriguez-Blanco, Juan Diego; Shaw, Samuel; Benning, Liane G

    2011-01-01

    The kinetics and mechanisms of nanoparticulate amorphous calcium carbonate (ACC) crystallization to calcite, via vaterite, were studied at a range of environmentally relevant temperatures (7.5-25 °C) using synchrotron-based in situ time-resolved Energy Dispersive X-ray Diffraction (ED-XRD) in conjunction with high-resolution electron microscopy, ex situ X-ray diffraction and infrared spectroscopy. The crystallization process occurs in two stages; firstly, the particles of ACC rapidly dehydrate and crystallize to form individual particles of vaterite; secondly, the vaterite transforms to calcite via a dissolution and reprecipitation mechanism with the reaction rate controlled by the surface area of calcite. The second stage of the reaction is approximately 10 times slower than the first. Activation energies of calcite nucleation and crystallization are 73±10 and 66±2 kJ mol(-1), respectively. A model to calculate the degree of calcite crystallization from ACC at environmentally relevant temperatures (7.5-40 °C) is also presented.

  1. Effect of the leaching of calcium hydroxide from cement paste on mechanical and physical properties

    International Nuclear Information System (INIS)

    Carde, C.; Francois, R.

    1997-01-01

    This paper deals with the effect of the leaching process of cement based materials on their mechanical and physical properties. In order to characterize this effect, the authors have performed experiments on cement paste samples. The leaching process was achieved by the use of a 50% concentrate solution of ammonium nitrate. Both compression tests and water porosity tests were conducted on micro-cylinder samples (10, 12, 14 and 20 mm of diameter) because of the slow kinetics of degradation due to the leaching. The deterioration of the cement paste and the mortar exposed to the action of the ammonium nitrate was manifested by a peripheral zone of less resistance. This process induces mainly a total leaching of Ca(OH) 2 and a progressive decalcification of C-S-H which leads to a gradient of C/S ratio in the leaching zone. Both mechanical tests and water porosity tests show that there is a linear variation of the loss of strength and the increase in porosity in relation to the ratio of degraded area over total area of the sample A d /A t . It means that both compressive resistance and water porosity of the leaching zone are constant whatever the size of the degraded zone and then whatever the time of exposure to the chemical attack. So the authors could venture the hypothesis that the dissolution of calcium hydroxide is the essential parameter governing both decrease in strength and increase in porosity

  2. Lithium doped calcium phosphate cement maintains physical mechanical properties and promotes osteoblast proliferation and differentiation.

    Science.gov (United States)

    Li, Li; Wang, Renchong; Li, Baichuan; Liang, Wei; Pan, Haobo; Cui, Xu; Tang, Jingli; Li, Bing

    2017-07-01

    Calcium phosphate cement (CPC) has been widely used in bone tissue repairing due to its physical mechanical properties and biocompatibility. Addition of trace element to CPC has shown promising evidence to improve the physical properties and biological activities of CPC. Lithium (Li) has effect on osteoblast proliferation and differentiation. In this study, we incorporated Li to CPC and examined the physical properties of Li/CPC and its effect on osteoblast proliferation and differentiation. We found that Li doped CPC maintained similar setting time, pore size distribution, compressive strength, composition, and morphology as CPC without Li. Additionally, Li doped CPC improved osteoblast proliferation and differentiation significantly compared to CPC without Li. To our knowledge, our results, for the first time, show that Li doped CPC has beneficial effect on osteoblast in cell culture while keeps the excellent physical-mechanical properties of CPC. This study will lead to potential application of Li doped CPC in bone tissue engineering. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 944-952, 2017. © 2016 Wiley Periodicals, Inc.

  3. [The anti-tumour effect of Wuxing soup and its mechanism in inducing apoptosis of tumour cells mediated by calcium].

    Science.gov (United States)

    Mo, Fei; Hu, Jing-Ying; Gan, Yu; Zhao, Yang-Xing; Zhao, Xin-Tai

    2008-09-01

    To confirm the anti-cancer effect and mechanism of Wuxing soup. Inhibition of cellular growth under Wuxing soup treatment was observed by MTT; Apoptosis was detected by gel electrophoresis, transmission electron microscopy and FACS; The concentration of calcium was measured by fluorescence probe. After SGC-7901 cell being treated by Wuxing soup, it showed that: 1) Wuxing soup could specifically inhibit cancer cells proliferation in a time and dose dependent manner; 2) Typical apoptotic morphological changes and DNA ladder of SGC-7901 cells were observed; 3) calcium inhibitor Bapta AM could reduce the apoptotic rate and protect SGC-7901 cells in a dose dependent manner. Wuxing soup has an effective inhibition on cancer cells, and can induce SGC-7901 cells to apoptosis by calcium.

  4. Transcellular transport of calcium

    Energy Technology Data Exchange (ETDEWEB)

    Terepka, A R; Coleman, J R; Armbrecht, H J; Gunter, T E

    1976-01-01

    Studies of two calcium transporting epithelia, embryonic chick chorioallantoic membrane and the small intestine of rat and chick, have strongly suggested that the transfer of calcium across a cell involves processes distinctly different from intracellular calcium ion regulation. In the proposed model, transcellular calcium transport is considered as a specialized process developed only by certain cells in those tissues charged with bulk transfer of calcium. The overall effect of the endocytotic mechanism is bulk calcium movement across a cell, protection of mitochondria from exposure to high concentrations of calcium, and the avoidance of wide and potentially toxic fluctuations in cytosol ionic calcium levels. (MFB)

  5. Can Randall's plug composed of calcium oxalate form via the free particle mechanism?

    Science.gov (United States)

    Grases, F; Söhnel, O

    2017-09-08

    The likelihood of a Randall's plug composed of calcium oxalate monohydrate (COM) forming by the free particle mechanism in a model of kidney with a structure recently described by Robertson was examined at the most favourable conditions for the considered mechanism. The Robertson model of the kidney is used in the following development. The classical theory of crystallization was used for calculations. Initial COM nuclei were assumed to form at the beginning of the ascending loop of Henle where the supersaturation with respect to COM has been shown to reach the threshold level for spontaneous nucleation. Nucleation proceeds by a heterogeneous mechanism. The formed particles are transported in the nephron by a laminar flow of liquid with a parabolic velocity profile. Particles travel with a velocity dependent on their position in the cross-section of the nephron assumed to be straight tubule with smooth walls and without any sharp bends and kinks. These particles move faster with time as they grow as a result of being surrounded by the supersaturated liquid. Individual COM particles (crystals) can reach maximum diameter of 5.2 × 10 -6  m, i.e. 5.2 μm, at the opening of the CD and would thus always be washed out of the CD into the calyx regardless of the orientation of the CD. Agglomeration of COM crystals forms a fractal object with an apparent density lower than the density of solid COM. The agglomerate that can block the beginning of the CD is composed of more crystals than are available even during crystaluria. Moreover the settling velocity of agglomerate blocking the opening of the CD is lower than the liquid flow and thus such agglomerate would be washed out even from upward-draining CD. The free particle mechanism may be responsible for the formation of a Randall's plug composed by COM only in specific infrequent cases such as an abnormal structure of kidney. Majority of incidences of Randall's plug development by COM are caused by mechanism different

  6. Calcium-Magnesium-Aluminosilicate (CMAS) Reactions and Degradation Mechanisms of Advanced Environmental Barrier Coatings

    Science.gov (United States)

    Ahlborg, Nadia L.; Zhu, Dongming

    2013-01-01

    The thermochemical reactions between calcium-magnesium-aluminosilicate- (CMAS-) based road sand and several advanced turbine engine environmental barrier coating (EBC) materials were studied. The phase stability, reaction kinetics and degradation mechanisms of rare earth (RE)-silicates Yb2SiO5, Y2Si2O7, and RE-oxide doped HfO2 and ZrO2 under the CMAS infiltration condition at 1500 C were investigated, and the microstructure and phase characteristics of CMAS-EBC specimens were examined using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). Experimental results showed that the CMAS dissolved RE-silicates to form crystalline, highly non-stoichiometric apatite phases, and in particular attacking the silicate grain boundaries. Cross-section images show that the CMAS reacted with specimens and deeply penetrated into the EBC grain boundaries and formed extensive low-melting eutectic phases, causing grain boundary recession with increasing testing time in the silicate materials. The preliminary results also showed that CMAS reactions also formed low melting grain boundary phases in the higher concentration RE-oxide doped HfO2 systems. The effect of the test temperature on CMAS reactions of the EBC materials will also be discussed. The faster diffusion exhibited by apatite and RE-doped oxide phases and the formation of extensive grain boundary low-melting phases may limit the CMAS resistance of some of the environmental barrier coatings at high temperatures.

  7. Study and understanding of the ageing mechanisms in lead-calcium alloys

    International Nuclear Information System (INIS)

    Rossi, F.

    2006-12-01

    The data available in the literature about ageing and over-ageing of lead-calcium alloys are often incomplete and inconsistent. It is undoubtedly due to the experimental difficulties encountered to observe the structure transformations which are numerous. As a result there is a certain confusion among the results of the different authors. Moreover, small variations in the process parameters and chemical composition may have some influence on the alloy behaviour. This work enabled us to obtain a set of TTT diagrams, more realistic and accurate than the ones available in the literature. Experimental techniques developed (particularly the preservation of the cold chain with is essential for the guaranty of the results repeatability), enabled particularly the study of the first transformations and better control the five stages of ageing and over-ageing. Our work have enabled to determine precisely the kinetics and the mechanisms of the transformations. This work constitutes a thorough analysis of the ageing and over-ageing of theses alloys. (author)

  8. Structural mechanism of ligand activation in human calcium-sensing receptor

    Energy Technology Data Exchange (ETDEWEB)

    Geng, Yong; Mosyak, Lidia; Kurinov, Igor; Zuo, Hao; Sturchler, Emmanuel; Cheng, Tat Cheung; Subramanyam, Prakash; Brown, Alice P.; Brennan, Sarah C.; Mun, Hee-chang; Bush, Martin; Chen, Yan; Nguyen, Trang X.; Cao, Baohua; Chang, Donald D.; Quick, Matthias; Conigrave, Arthur D.; Colecraft, Henry M.; McDonald, Patricia; Fan, Qing R.

    2016-07-19

    Human calcium-sensing receptor (CaSR) is a G-protein-coupled receptor (GPCR) that maintains extracellular Ca2+homeostasis through the regulation of parathyroid hormone secretion. It functions as a disulfide-tethered homodimer composed of three main domains, the Venus Flytrap module, cysteine-rich domain, and seven-helix transmembrane region. Here, we present the crystal structures of the entire extracellular domain of CaSR in the resting and active conformations. We provide direct evidence that L-amino acids are agonists of the receptor. In the active structure, L-Trp occupies the orthosteric agonist-binding site at the interdomain cleft and is primarily responsible for inducing extracellular domain closure to initiate receptor activation. Our structures reveal multiple binding sites for Ca2+and PO43-ions. Both ions are crucial for structural integrity of the receptor. While Ca2+ions stabilize the active state, PO43-ions reinforce the inactive conformation. The activation mechanism of CaSR involves the formation of a novel dimer interface between subunits.

  9. Light Hydrocarbons Adsorption Mechanisms in Two Calcium-based Microporous Metal Organic Frameworks

    KAUST Repository

    Plonka, Anna M.; Chen, Xianyin; Wang, Hao; Krishna, Rajamani; Dong, Xinglong; Banerjee, Debasis; Woerner, William R.; Han, Yu; Li, Jing; Parise, John B.

    2016-01-01

    measurments and gas adsorption isotherm measurements. Two calcium-based MOFs, designated as SBMOF-1 and SBMOF-2 (SB: Stony Brook), form three-dimensional frameworks with one-dimensional open channels. As determined form single crystal diffraction experiments

  10. Effect of triorganotin compounds on calcium transport mechanisms in rat cardiac sarcoplasmic reticulum

    International Nuclear Information System (INIS)

    Cameron, J.A.; Kodavanti, P.R.S.; Yallapragada, P.R.; Desaiah, D.

    1990-01-01

    Although organotin compounds, in general, are neurotoxicants, recent studies indicate that these tin compounds affect heme metabolism as well as cardiovascular system. Sarcoplasmic reticulum (SR) calcium pump together with phosphorylation of phospholamban has an important role in myocardial contraction and relaxation. Since organotin compounds interfere with cardiovascular system, we have studied the in vitro as well as in vivo effects of tributyltin bromide (TBT), triethyltin bromide (TET) and trimethyltin chloride (TMT) on cardiac SR Ca 2+ -pump activity, in order to know the relative potency of these tin compounds. SR was isolated from heart ventricles of male Sprague-Dawley rats and used for in vitro studies. For in vivo studies, rats were treated orally in corn oil for 6 days with different doses of TET (0.5, 1.0 and 1.5 mg/kg/d), TMT (0.75, 1.5 and 2.5 mg/kg/d) and TBT (0.75, 1.5 and 2.5 mg/kg/d). Rats were sacrificed 24 hr after the last dosage and cardiac SR was prepared. Cardiac SR Ca 2+ -ATPase and 45 Ca-uptake were measured. All the three tin compounds inhibited Ca 2+ -ATPase and 45 Ca-uptake in vitro in a concentration dependent manner. The order of potency for Ca 2+ -ATPase as determined IC 50 , is TBT (2 uM) > TET (63 uM) > TMT (280 uM). For 45 Ca-uptake, if followed the same order i.e., TBT (0.35 uM) > TET (10 uM) > TMT (440 uM). In agreement with in vitro results, both SR Ca 2+ -ATPase and 45 Ca-uptake were significantly inhibited in rats treated with these tin compounds. These studies indicate that triorganotin compounds affect Ca 2+ -pumping mechanisms and thereby alter cardiac contraction-relaxation process

  11. A strategy of precipitated calcium carbonate (CaCO{sub 3}) fillers for enhancing the mechanical properties of polypropylene polymers

    Energy Technology Data Exchange (ETDEWEB)

    Thenepalli, Thriveni; Ahn, Ji Whan [Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon (Korea, Republic of); Ahn, Young Jun; Han, Choon [Kwangwoon University, Seoul (Korea, Republic of); Ramakrishna, Chilakala [Hanil Cement, Danyang (Korea, Republic of)

    2015-06-15

    A wide variety of fillers are currently used in more than twenty types of polymer resins, although four of them alone (polypropylene, polyamides, thermoplastic polyesters, and polyvinyl chloride) account for 90% of the market of mineral fillers in plastics. Polypropylene (PP) and PVC dominate the market for calcium carbonate. PP is a versatile reinforcement material that can meet engineering and structural specifications and is widely used for automotive components, home appliances, and industrial applications. Talc, mica, clay, kaolin, wollastonite, calcium carbonates, feldspar, aluminum hydroxide, glass fibers, and natural fibers are commonly used in fillers. Among these, calcium carbonate (both natural and synthetic) is the mos abundant and affords the possibility of improved surface finishing, control over the manufacture of products, and increased electric resistance and impact resistance. Meeting the global challenge to reduce the weight of vehicles by using plastics is a significant issue. The current the global plastic and automobile industry cannot survive without fillers, additives, and reinforcements. Polypropylene is a major component of the modern plastic industry, and currently is used in dashboards, wheel covers, and some engine parts in automobiles. This article reports that the use of calcium carbonate fillers with polypropylene is the best choice to enhance the mechanical properties of plastic parts used in automobiles.

  12. A strategy of precipitated calcium carbonate (CaCO3) fillers for enhancing the mechanical properties of polypropylene polymers

    International Nuclear Information System (INIS)

    Thenepalli, Thriveni; Ahn, Ji Whan; Ahn, Young Jun; Han, Choon; Ramakrishna, Chilakala

    2015-01-01

    A wide variety of fillers are currently used in more than twenty types of polymer resins, although four of them alone (polypropylene, polyamides, thermoplastic polyesters, and polyvinyl chloride) account for 90% of the market of mineral fillers in plastics. Polypropylene (PP) and PVC dominate the market for calcium carbonate. PP is a versatile reinforcement material that can meet engineering and structural specifications and is widely used for automotive components, home appliances, and industrial applications. Talc, mica, clay, kaolin, wollastonite, calcium carbonates, feldspar, aluminum hydroxide, glass fibers, and natural fibers are commonly used in fillers. Among these, calcium carbonate (both natural and synthetic) is the mos abundant and affords the possibility of improved surface finishing, control over the manufacture of products, and increased electric resistance and impact resistance. Meeting the global challenge to reduce the weight of vehicles by using plastics is a significant issue. The current the global plastic and automobile industry cannot survive without fillers, additives, and reinforcements. Polypropylene is a major component of the modern plastic industry, and currently is used in dashboards, wheel covers, and some engine parts in automobiles. This article reports that the use of calcium carbonate fillers with polypropylene is the best choice to enhance the mechanical properties of plastic parts used in automobiles

  13. Dietary pectin and calcium inhibit colonic proliferation in vivo by differing mechanisms.

    Science.gov (United States)

    Umar, S; Morris, A P; Kourouma, F; Sellin, J H

    2003-12-01

    Diet plays an important role in promoting and/or preventing colon cancer; however, the effects of specific nutrients remain uncertain because of the difficulties in correlating epidemiological and basic observations. Transmissible murine colonic hyperplasia (TMCH) induced by Citrobacter rodentium, causes significant hyperproliferation and hyperplasia in the mouse distal colon and increases the risk of subsequent neoplasia. We have recently shown that TMCH is associated with an increased abundance of cellular beta-catenin and its nuclear translocation coupled with up-regulation of its downstream targets, c-myc and cyclin D1. In this study, we examined the effects of two putatively protective nutrients, calcium and soluble fibre pectin, on molecular events linked to proliferation in the colonic epithelium during TMCH. Dietary intervention incorporating changes in calcium [high (1.0%) and low (0.1%)] and alterations in fibre content (6% pectin and fibre-free) were compared with the standard AIN-93 diet (0.5% calcium, 5% cellulose), followed by histomorphometry and immunochemical assessment of potential oncogenes. Dietary interventions did not alter the time course of Citrobacter infection. Both 1.0% calcium and 6% pectin diet inhibited increases in proliferation and crypt length typically seen in TMCH. Neither the low calcium nor fibre-free diets had significant effect. Pectin diet blocked increases in cellular beta-catenin, cyclin D1 and c-myc levels associated with TMCH by 70%, whereas neither high nor low calcium diet had significant effect on these molecules. Diets supplemented with either calcium or pectin therefore, exert anti-proliferative effects in mouse distal colon involving different molecular pathways. TMCH is thus a diet-sensitive model for examining the effect of specific nutrients on molecular characteristics of the pre-neoplastic colonic epithelium.

  14. Aluminum deoxidation equilibria and inclusion modification mechanism by calcium treatment of stainless steel melts

    International Nuclear Information System (INIS)

    Park, Joo Hyun; Kim, Dong Sik; Kim, Yong Hwan; Lee, Sang Beom

    2005-01-01

    A thermodynamic equilibrium between aluminum and oxygen along with the inclusion morphology in Fe-16%Cr stainless steel was investigated to understand the fundamentals of aluminum deoxidation technology for ferritic stainless steels. Further, the effects of calcium addition on the changes in chemistry and morphology of inclusions were discussed. The measured results for aluminum-oxygen equilibria exhibit relatively good agreement with the calculated values, indicating that the introduction of the first- and second-order interaction parameters, recently reported, is reasonable to numerically express aluminum deoxidation equilibrium in a ferritic stainless steel. In the composition of dissolved aluminum content greater than about 60 ppm, pure alumina particles were observed, while the alumino-manganese silicates containing Cr 2 O 3 were appeared at less than 20 mass ppm of dissolved aluminum. The formation of calcium aluminate inclusions after Ca treatment could be discussed based on the thermodynamic equilibrium with calcium, aluminum, and oxygen in the steel melts. In the composition of steel melt with relatively high content of calcium and low aluminum, the log(X CaO /X Al 2 O 3 ) of inclusions linearly increases with increasing the log [a Ca /a Al 2 ·a O 2 ] with the slope close to unity. However, the slope of the line is significantly lower than the expected value in the composition of steel melt with relatively low calcium and high aluminum contents

  15. Leaching of both calcium hydroxide and C-S-H from cement paste: Modeling the mechanical behavior

    International Nuclear Information System (INIS)

    Carde, C.; Torrenti, J.M.; Francois, R.

    1996-01-01

    This paper deals with the effect of the leaching process of cement based materials on their mechanical properties. This process induces mainly a total leaching of Ca(OH) 2 and a progressive decalcification of C-S-H which leads to a gradient of C/S ratio in the leaching zone. In a previous work, the authors venture the hypothesis that the dissolution of calcium hydroxide was the essential parameter governing both decrease in strength and increase in porosity in the case of a paste sample made with an OPC cement which leads to a 20% content of calcium. In order to quantify the effect of the decrease of C/S ratio in C-S-H, the authors have performed experiments on paste samples with the admixture of silica fume to reduce the content of calcium hydroxide and thus emphasize the effect of C/S ratio decrease of the C-S-H. The leaching process was achieved by the use of a 50% concentrate solution of ammonium nitrate. Compression tests were conducted on micro-cylinder samples (10, 12, 14, 20 and 30 mm of diameter) because of the slow kinetics of degradation due to the leaching. The deterioration of the cement paste and the mortar exposed to the action of the ammonium nitrate was indicated by a peripheral zone of less resistance. The experimental results allow the modeling of the mechanical behavior of cement pastes in relation to the ratio of degraded area over total area of the sample A d /A t . The model thus defined allows separation of the effect of calcium hydroxide leaching and C-S-H leaching, and shows the importance of the first one. The current research program tries to characterize the deterioration of the mechanical properties of the concrete surrounding radioactive wastes, due to the water flow during storage

  16. Rapid and Localized Mechanical Stimulation and Adhesion Assay: TRPM7 Involvement in Calcium Signaling and Cell Adhesion.

    Directory of Open Access Journals (Sweden)

    Wagner Shin Nishitani

    Full Text Available A cell mechanical stimulation equipment, based on cell substrate deformation, and a more sensitive method for measuring adhesion of cells were developed. A probe, precisely positioned close to the cell, was capable of a vertical localized mechanical stimulation with a temporal frequency of 207 Hz, and strain magnitude of 50%. This setup was characterized and used to probe the response of Human Umbilical Endothelial Vein Cells (HUVECs in terms of calcium signaling. The intracellular calcium ion concentration was measured by the genetically encoded Cameleon biosensor, with the Transient Receptor Potential cation channel, subfamily M, member 7 (TRPM7 expression inhibited. As TRPM7 expression also regulates adhesion, a relatively simple method for measuring adhesion of cells was also developed, tested and used to study the effect of adhesion alone. Three adhesion conditions of HUVECs on polyacrylamide gel dishes were compared. In the first condition, the substrate is fully treated with Sulfo-SANPAH crosslinking and fibronectin. The other two conditions had increasingly reduced adhesion: partially treated (only coated with fibronectin, with no use of Sulfo-SANPAH, at 5% of the normal amount and non-treated polyacrylamide gels. The cells showed adhesion and calcium response to the mechanical stimulation correlated to the degree of gel treatment: highest for fully treated gels and lowest for non-treated ones. TRPM7 inhibition by siRNA on HUVECs caused an increase in adhesion relative to control (no siRNA treatment and non-targeting siRNA, but a decrease to 80% of calcium response relative to non-targeting siRNA which confirms the important role of TRPM7 in mechanotransduction despite the increase in adhesion.

  17. In vitro degradation and mechanical integrity of calcium-containing magnesium alloys in modified-simulated body fluid.

    Science.gov (United States)

    Kannan, M Bobby; Raman, R K Singh

    2008-05-01

    The successful applications of magnesium-based alloys as degradable orthopaedic implants are mainly inhibited due to their high degradation rates in physiological environment and consequent loss in the mechanical integrity. This study examines the degradation behaviour and the mechanical integrity of calcium-containing magnesium alloys using electrochemical techniques and slow strain rate test (SSRT) method, respectively, in modified-simulated body fluid (m-SBF). Potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) results showed that calcium addition enhances the general and pitting corrosion resistances of magnesium alloys significantly. The corrosion current was significantly lower in AZ91Ca alloy than that in AZ91 alloy. Furthermore, AZ91Ca alloy exhibited a five-fold increase in the surface film resistance than AZ91 alloy. The SSRT results showed that the ultimate tensile strength and elongation to fracture of AZ91Ca alloy in m-SBF decreased only marginally (approximately 15% and 20%, respectively) in comparison with these properties in air. The fracture morphologies of the failed samples are discussed in the paper. The in vitro study suggests that calcium-containing magnesium alloys to be a promising candidate for their applications in degradable orthopaedic implants, and it is worthwhile to further investigate the in vivo corrosion behaviour of these alloys.

  18. Mechanical characterization and ion release of bioactive dental composites containing calcium phosphate particles.

    Science.gov (United States)

    Natale, Livia C; Rodrigues, Marcela C; Alania, Yvette; Chiari, Marina D S; Boaro, Leticia C C; Cotrim, Marycel; Vega, Oscar; Braga, Roberto R

    2018-08-01

    to verify the effect of the addition of dicalcium phosphate dihydrate (DCPD) particles functionalized with di- or triethylene glycol dimethacrylate (DEGDMA or TEGDMA) on the degree of conversion (DC), post-gel shrinkage (PS), mechanical properties, and ion release of experimental composites. Four composites were prepared containing a BisGMA/TEGDMA matrix and 60 vol% of fillers. The positive control contained only barium glass fillers, while in the other composites 15 vol% of the barium was replaced by DCPD. Besides the functionalized particles, non-functionalized DCPD was also tested. DC after 24 h (n = 3) was determined by FTIR spectroscopy. The strain gage method was used to obtain PS 5 min after photoactivation (n = 5). Flexural strength and modulus (n = 10) were calculated based on the biaxial flexural test results, after specimen storage for 24 h or 60 days in water. The same storage times were used for fracture toughness testing (FT, n = 10). Calcium and phosphate release up to 60 days was quantified by ICP-OES (n = 3). Data were analyzed by ANOVA/Tukey test (alpha: 5%). Composites containing functionalized DCPD presented higher DC than the control (p composites (p composite with DEGDMA-functionalized DCPD presented fracture strength similar to the control, while for flexural modulus only the composite with TEGDMA-functionalized particles was lower than the control (p composites containing DCPD was higher than the control after 60 days (p composite with non-functionalized DCPD at 15 days and no significant reductions were observed for composites with functionalized DCPD during the observation period (p composites, phosphate release was higher at 15 days than in the subsequent periods, and no difference among them was recorded at 45 and 60 days (p composite with DEGDMA-functionalized particles was the only material with strength similar to the control after 60 days in water; however, it also presented the highest

  19. Mechanism and evolution of calcium transport across the plant plasma membrane

    Science.gov (United States)

    Calcium is an essential plant nutrient, thus the influx of Ca(2+) into plant cells is a critical process. In addition, the efflux of Ca(2+) out of a cell is important to prevent toxicity resulting from Ca(2+) excess, and to modulate levels of cytosolic Ca(2+) required for signaling functions. Bioc...

  20. Mechanisms of pyrethroid insecticide-induced stimulation of calcium influx in neocortical neurons

    Science.gov (United States)

    Pyrethroid insecticides bind to voltage-gated sodium channels (VGSCs) and modify their gating kinetics, thereby disrupting neuronal function. Pyrethroids have also been reported to alter the function of other channel types, including activation of voltage-gated Ca2+ calcium chann...

  1. Alcohol enhances oxysterol-induced apoptosis in human endothelial cells by a calcium-dependent mechanism.

    Science.gov (United States)

    Spyridopoulos, I; Wischhusen, J; Rabenstein, B; Mayer, P; Axel, D I; Fröhlich, K U; Karsch, K R

    2001-03-01

    Controversy exists about the net effect of alcohol on atherogenesis. A protective effect is assumed, especially from the tannins and phenolic compounds in red wine, owing to their inhibition of low density lipoprotein (LDL) oxidation. However, increased atherogenesis occurs in subjects with moderate to heavy drinking habits. The purpose of this study was to investigate the influence of alcohol in combination with oxysterols on the endothelium. Cultured human arterial endothelial cells (HAECs) served as an in vitro model to test the cellular effects of various oxysterols. Oxysterols (7beta-hydroxycholesterol, 7-ketocholesterol, and cholesterol-5,6-epoxides), which are assumed to be the most toxic constituents of oxidized LDL, induced apoptosis in HAECs through calcium mobilization followed by activation of caspase-3. Ethanol, methanol, isopropanol, tert-butanol, and red wine all potentiated oxysterol-induced cell death up to 5-fold, paralleled by further induction of caspase-3. The alcohol effect occurred in a dose-dependent manner and reached a plateau at 0.05% concentration. Alcohol itself did not affect endothelial cell viability, nor did other solvents such as dimethyl sulfoxide mimic the alcohol effect. So far as the physiologically occurring oxysterols are concerned, this effect was apparent only for oxysterols oxidized at the steran ring. The possibility of alcohol facilitating the uptake of oxysterols into the cell was not supported by the data from an uptake study with radiolabeled compounds. Finally, alcohol in combination with oxysterols did cause a dramatic increase in cytosolic calcium influx. Blockage of calcium influx by the calcium channel blocker aurintricarboxylic acid or the calcium chelator ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid abrogated the alcohol-mediated enhancement of oxysterol toxicity. We describe for the first time a mechanistic concept explaining possible adverse effects of alcohol in conjunction with

  2. Three dimensional printed calcium phosphate and poly(caprolactone) composites with improved mechanical properties and preserved microstructure.

    Science.gov (United States)

    Vella, Joseph B; Trombetta, Ryan P; Hoffman, Michael D; Inzana, Jason; Awad, Hani; Benoit, Danielle S W

    2018-03-01

    Biphasic calcium phosphate scaffolds formed via three dimensional (3D) printing technology to exhibit porosity and chemical resorbability to promote osseointegration often lack the strength and toughness required to withstand loading in bone tissue engineering applications. Herein, sintering and CaP:poly(caprolactone) (PCL) composite formation were explored to improve 3D printed scaffold strength and toughness. Hydroxyapatite and α-tricalcium phosphate (α-TCP) biphasic calcium powders were printed using phosphoric acid binder, which generated monetite and hydroxyapatite scaffolds. Upon sintering, evolution of β-TCP was observed along with an increase in flexural strength and modulus but no effect on fracture toughness was observed. Furthermore, scaffold porosity increased with sintering. Additionally, two techniques of PCL composite formation were employed: postprint precipitation and 3D print codeposition to further augment scaffold mechanical properties. While both techniques significantly improved flexural strength, flexural modulus, and fracture toughness under most conditions explored, precipitation yielded more substantial increases in these properties, which is attributed to better continuity of the PCL phase. However, precipitation also compromised surface porosity due to PCL passivation of the calcium phosphate surface, which may subsequently hinder scaffold integration and bone regeneration. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 663-672, 2018. © 2017 Wiley Periodicals, Inc.

  3. Quantum-mechanical calculations of the electronic structure of calcium and cadmium vanadate apatites

    International Nuclear Information System (INIS)

    Karbovskij, V.L.; Soroka, A.P.; Kasiyanenko, V.Kh.; Shpak, A.P.

    2011-01-01

    Electronic structures of compounds Me 10 (VO 4 ) 6 X 2 , where Me = Ca or Cd and X = F, Cl, OH are investigated using the full potential APW + lo method. The degrees of distortions of VO 4- tetrahedra with respect to the Td point group are analyzed using a relaxation of atomic positions. Apatites in the form of Ca 10 (VO 4 ) 6 X 2 , where X = F, Cl, OH, are established to decrease the band gap by 0.5-1.0 eV under the isomorphic substitution of calcium for cadmium. Apatites Ca 10 (VO 4 ) 6 X 2 , where X = F, Cl, OH are proven to decrease the degree of covalency of the oxygen-halogen bond under the isomorphic substitution of calcium for cadmium.

  4. Structural studies of calcium phosphate doped with titanium and zirconium obtained by high-energy mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Silva, C C; Sombra, A S B [Telecommunications and Materials Science and Engineering Laboratory (LOCEM), Physics Department, Federal University of Ceara, Campus do Pii, Postal Code 6030, 60455-760, Fortaleza-Ceara (Brazil)], E-mail: sombra@fisica.ufc.br

    2009-12-15

    In this paper, we present a new variation of the solid-state procedure on the synthesis of bioceramics with titanium (CapTi) and zirconium (CapZr), considering that zirconium (ZrO{sub 2}) and titanium oxide (TiO{sub 2}) are strengthening agents, due to their superb force and fracture toughness. The high efficiency of the calcination process opens a new way of producing commercial amounts of nanocrystalline bioceramics. In this work, a new variation of the solid-state procedure method was used to produce nanocrystalline powders of titanium and zirconium, using two different experimental chemical routes: CapTi: Ca(H{sub 2}PO{sub 4}){sub 2}+TiO{sub 2} and CapZr: Ca(H{sub 2}PO{sub 4}){sub 2}+ZrO{sub 2}. The powders were submitted to calcination processes (CapTic and CapZrc) at 800, 900 and 1000 deg. C. The calcium titanium phosphate phase, CaTi{sub 4}P{sub 6}O{sub 24}, was obtained in the CapTic reaction and the calcium zirconium phosphate, CaZr{sub 4}P{sub 6}O{sub 24}, was obtained in the CapZrc reaction. The obtained ceramics were characterized by x-ray powder diffraction (XRD), infrared (IR) spectroscopy, Raman scattering spectroscopy (RSS) and scanning electron microscopy (SEM) analysis. This method was compared with the milling process (CapTim and CapZrm), where in the last process the melting is not necessary and the powder obtained is nanocrystalline. The calcium titanium phosphate phase, CaTi{sub 4}P{sub 6}O{sub 24}, was obtained in the reaction CapTim, but in CapZrm the formation of any calcium phosphate phase even after 15 h of dry mechanical alloying was not observed.

  5. Calcium sensing receptor as a novel mediator of adipose tissue dysfunction: mechanisms and potential clinical implications

    Directory of Open Access Journals (Sweden)

    Roberto Bravo

    2016-09-01

    Full Text Available Obesity is currently a serious worldwide public health problem, reaching pandemic levels. For decades, dietary and behavioral approaches have failed to prevent this disease from expanding, and health authorities are challenged by the elevated prevalence of co-morbid conditions. Understanding how obesity-associated diseases develop from a basic science approach is recognized as an urgent task to face this growing problem. White adipose tissue is an active endocrine organ, with a crucial influence on whole-body homeostasis. White adipose tissue dysfunction plays a key role linking obesity with its associated diseases such as type 2 diabetes mellitus, cardiovascular disease and some cancers. Among the regulators of white adipose tissue physiology, the calcium-sensing receptor has arisen as a potential mediator of white adipose tissue dysfunction. Expression of the receptor has been described in human preadipocytes, adipocytes, and the human adipose cell lines LS14 and SW872. The evidence suggests that calcium-sensing receptor activation in the visceral (i.e. unhealthy white adipose tissue is associated with an increased proliferation of adipose progenitor cells and elevated adipocyte differentiation. In addition, exposure of adipose cells to calcium-sensing receptor activators in vitro elevates proinflammatory cytokine expression and secretion. An increased proinflammatory environment in white adipose tissue plays a key role in the development of white adipose tissue dysfunction that leads to peripheral organ fat deposition and insulin resistance, among other consequences. We propose that calcium-sensing receptor may be one relevant therapeutic target in the struggle to confront the health consequences of the current worldwide obesity pandemic.

  6. Study and understanding of the ageing mechanisms in lead-calcium alloys; Etude et comprehension des mecanismes de vieillissement des alliages de plomb-calcium

    Energy Technology Data Exchange (ETDEWEB)

    Rossi, F

    2006-12-15

    The data available in the literature about ageing and over-ageing of lead-calcium alloys are often incomplete and inconsistent. It is undoubtedly due to the experimental difficulties encountered to observe the structure transformations which are numerous. As a result there is a certain confusion among the results of the different authors. Moreover, small variations in the process parameters and chemical composition may have some influence on the alloy behaviour. This work enabled us to obtain a set of TTT diagrams, more realistic and accurate than the ones available in the literature. Experimental techniques developed (particularly the preservation of the cold chain with is essential for the guaranty of the results repeatability), enabled particularly the study of the first transformations and better control the five stages of ageing and over-ageing. Our work have enabled to determine precisely the kinetics and the mechanisms of the transformations. This work constitutes a thorough analysis of the ageing and over-ageing of theses alloys. (author)

  7. Mechanical and physical properties of calcium silicate/alumina composite for biomedical engineering applications.

    Science.gov (United States)

    Shirazi, F S; Mehrali, M; Oshkour, A A; Metselaar, H S C; Kadri, N A; Abu Osman, N A

    2014-02-01

    The focus of this study is to investigate the effect of Al2O3 on α-calcium silicate (α-CaSiO3) ceramic. α-CaSiO3 was synthesized from CaO and SiO2 using mechanochemical method followed by calcinations at 1000°C. α-CaSiO3 and alumina were grinded using ball mill to create mixtures, containing 0-50w% of Al2O3 loadings. The powders were uniaxially pressed and followed by cold isostatic pressing (CIP) in order to achieve greater uniformity of compaction and to increase the shape capability. Afterward, the compaction was sintered in a resistive element furnace at both 1150°C and 1250°C with a 5h holding time. It was found that alumina reacted with α-CaSiO3 and formed alumina-rich calcium aluminates after sintering. An addition of 15wt% of Al2O3 powder at 1250°C were found to improve the hardness and fracture toughness of the calcium silicate. It was also observed that the average grain sizes of α-CaSiO3 /Al2O3 composite were maintained 500-700nm after sintering process. © 2013 Published by Elsevier Ltd.

  8. Divergent biophysical properties, gating mechanisms, and possible functions of the two skeletal muscle Ca(V)1.1 calcium channel splice variants.

    Science.gov (United States)

    Tuluc, Petronel; Flucher, Bernhard E

    2011-12-01

    Voltage-gated calcium channels are multi-subunit protein complexes that specifically allow calcium ions to enter the cell in response to membrane depolarization. But, for many years it seemed that the skeletal muscle calcium channel Ca(V)1.1 is the exception. The classical splice variant Ca(V)1.1a activates slowly, has a very small current amplitude and poor voltage sensitivity. In fact adult muscle fibers work perfectly well even in the absence of calcium influx. Recently a new splice variant of the skeletal muscle calcium channel Ca(V)1.1e has been characterized. The lack of the 19 amino acid exon 29 in this splice variant results in a rapidly activating calcium channel with high current amplitude and good voltage sensitivity. Ca(V)1.1e is the dominant channel in embryonic muscle, where the expression of this high calcium-conducting Ca(V)1.1 isoform readily explains developmental processes depending on L-type calcium currents. Moreover, the availability of these two structurally similar but functionally distinct channel variants facilitates the analysis of the molecular mechanisms underlying the unique current properties of the classical Ca(V)1.1a channel.

  9. The 1 Repetition Maximum Mechanics of a High-Handle Hexagonal Bar Deadlift Compared With a Conventional Deadlift as Measured by a Linear Position Transducer.

    Science.gov (United States)

    Lockie, Robert G; Moreno, Matthew R; Lazar, Adrina; Risso, Fabrice G; Liu, Tricia M; Stage, Alyssa A; Birmingham-Babauta, Samantha A; Torne, Ibett A; Stokes, John J; Giuliano, Dominic V; Davis, DeShaun L; Orjalo, Ashley J; Callaghan, Samuel J

    2018-01-01

    Lockie, RG, Moreno, MR, Lazar, A, Risso, FG, Liu, TM, Stage, AA, Birmingham-Babauta, SA, Torne, IA, Stokes, JJ, Giuliano, DV, Davis, DL, Orjalo, AJ, and Callaghan, SJ. The 1 repetition maximum mechanics of a high-handle hexagonal bar deadlift compared with a conventional deadlift as measured by a linear position transducer. J Strength Cond Res 32(1): 150-161, 2018-The high-handle hexagonal bar deadlift (HHBD), a variation of the conventional deadlift (CD), is said to reduce the lift range of motion, which may change the mechanics of the lift. However, no research has investigated this. This study compared the mechanics between a 1 repetition maximum (1RM) CD and HHBD. Thirty-one strength-trained subjects (21 men, 10 women) completed a 1RM CD and HHBD. A linear position transducer measured lift distance, duration, and work; and peak and mean power, velocity, and force. The presence of a sticking region (SR) was determined for each lift. A repeated-measures analysis of variance (ANOVA) calculated differences between 1RM CD and HHBD mechanics. A one-way ANOVA compared the mechanics of each lift between subjects who exhibited an SR or not, and the SR between the CD and HHBD. Significance was set at p mechanics between subjects with or without an SR, and no differences in SR region distance or duration between the CD and HHBD. Greater force can be generated in the HHBD, which could have implications for strength-training adaptations over time.

  10. Calcium en cardioplegie

    NARCIS (Netherlands)

    Ruigrok, T.J.C.; Meijler, F.L.

    1985-01-01

    Coronary perfusion with a calcium-free solution, followed by reperfusion with a calcium containing solution, may result in acute myocardial cell death and in irreversible loss of the e1ectrical and mechanical activity of the heart. This phenomenon is known as the calcium paradox. A number of

  11. Synthesis, mechanical properties, and in vitro biocompatibility with osteoblasts of calcium silicate-reduced graphene oxide composites.

    Science.gov (United States)

    Mehrali, Mehdi; Moghaddam, Ehsan; Shirazi, Seyed Farid Seyed; Baradaran, Saeid; Mehrali, Mohammad; Latibari, Sara Tahan; Metselaar, Hendrik Simon Cornelis; Kadri, Nahrizul Adib; Zandi, Keivan; Osman, Noor Azuan Abu

    2014-03-26

    Calcium silicate (CaSiO3, CS) ceramics are promising bioactive materials for bone tissue engineering, particularly for bone repair. However, the low toughness of CS limits its application in load-bearing conditions. Recent findings indicating the promising biocompatibility of graphene imply that graphene can be used as an additive to improve the mechanical properties of composites. Here, we report a simple method for the synthesis of calcium silicate/reduced graphene oxide (CS/rGO) composites using a hydrothermal approach followed by hot isostatic pressing (HIP). Adding rGO to pure CS increased the hardness of the material by ∼40%, the elastic modulus by ∼52%, and the fracture toughness by ∼123%. Different toughening mechanisms were observed including crack bridging, crack branching, crack deflection, and rGO pull-out, thus increasing the resistance to crack propagation and leading to a considerable improvement in the fracture toughness of the composites. The formation of bone-like apatite on a range of CS/rGO composites with rGO weight percentages ranging from 0 to 1.5 has been investigated in simulated body fluid (SBF). The presence of a bone-like apatite layer on the composite surface after soaking in SBF was demonstrated by X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM). The biocompatibility of the CS/rGO composites was characterized using methyl thiazole tetrazolium (MTT) assays in vitro. The cell adhesion results showed that human osteoblast cells (hFOB) can adhere to and develop on the CS/rGO composites. In addition, the proliferation rate and alkaline phosphatase (ALP) activity of cells on the CS/rGO composites were improved compared with the pure CS ceramics. These results suggest that calcium silicate/reduced graphene oxide composites are promising materials for biomedical applications.

  12. Development of composite calcium hydroxide sorbent in mechanical operations and evaluation of its basic sorption properties

    Directory of Open Access Journals (Sweden)

    Gara Paweł

    2017-01-01

    Full Text Available This article presents the results of research carried out on the possibility of obtaining composite calcium hydroxide sorbent in the process of two-step granulation, containing additional compounds of Al, Mg and Fe, and their textural and sorption studies. For this purpose, attempts were undertaken to compact commercial calcium hydroxide powder with six additives in the laboratory roll press. The resulting compacts were crushed and sieved in order to achieve the assumed sieve fraction. Based on the obtained results, basic parameters of the process of formation of composite sorbent have been determined. Both, the selected composite sorbents fractions and additives were subsequently subjected to textural studies (determination of the specific surface area and porosity and sorption capacity performance. In addition, for the better interpretation of the results, thermogravimetric studies were carried out both for the additives and composite sorbents, as well as the grain size distribution of the additives. The results of the physicochemical tests of the obtained composite sorbents were compared with analogic results from the study on fine-grained hydroxide sorbent without additives and carbonate sorbent. The presented results showed that in a two-step granulation process it is possible to obtain the granular Ca(OH2 sorbent, as well as composite sorbents possessing better SO2 sorption capacity in comparison to the powder Ca(OH2 and/or to the calcium carbonate sorbent. This can be attributed to the combination of capability of the sorbent to appropriate thermal decomposition and the formation of a group of pores in the range of 0.07-0.3 microns.

  13. Mechanical Properties and Durability of Advanced Environmental Barrier Coatings in Calcium-Magnesium-Alumino-Silicate Environments

    Science.gov (United States)

    Miladinovich, Daniel S.; Zhu, Dongming

    2011-01-01

    Environmental barrier coatings are being developed and tested for use with SiC/SiC ceramic matrix composite (CMC) gas turbine engine components. Several oxide and silicate based compositons are being studied for use as top-coat and intermediate layers in a three or more layer environmental barrier coating system. Specifically, the room temperature Vickers-indentation-fracture-toughness testing and high-temperature stability reaction studies with Calcium Magnesium Alumino-Silicate (CMAS or "sand") are being conducted using advanced testing techniques such as high pressure burner rig tests as well as high heat flux laser tests.

  14. Dynamic and Mechanical Properties of Calcium Borophosphate Glasses in Relation to Structure and Topology

    DEFF Research Database (Denmark)

    Hermansen, Christian; Yue, Yuanzheng

    Calcium borophosphate glasses and glass ceramics are of interest as bone-replacement implants as they can bond to bone through an apatite layer, and dissolve in vitro at a rate comparable to the growth rate of natural bone. We investigate the pseudo-binary join between CaO•P2O5 and CaO•2B2O3...... the crystallization behavior of this glass series. The compositional variation of these properties is analyzed using the Phillips-Thorpe rigidity percolation paradigm and the temperature dependent constraint theory. This analysis gives insight into the link between properties and composition in borophosphate glasses....

  15. Calcium and Mitosis

    Science.gov (United States)

    Hepler, P.

    1983-01-01

    Although the mechanism of calcium regulation is not understood, there is evidence that calcium plays a role in mitosis. Experiments conducted show that: (1) the spindle apparatus contains a highly developed membrane system that has many characteristics of sarcoplasmic reticulum of muscle; (2) this membrane system contains calcium; and (3) there are ionic fluxes occurring during mitosis which can be seen by a variety of fluorescence probes. Whether the process of mitosis can be modulated by experimentally modulating calcium is discussed.

  16. Trends in Modern Exception Handling

    Directory of Open Access Journals (Sweden)

    Marcin Kuta

    2003-01-01

    Full Text Available Exception handling is nowadays a necessary component of error proof information systems. The paper presents overview of techniques and models of exception handling, problems connected with them and potential solutions. The aspects of implementation of propagation mechanisms and exception handling, their effect on semantics and general program efficiency are also taken into account. Presented mechanisms were adopted to modern programming languages. Considering design area, formal methods and formal verification of program properties we can notice exception handling mechanisms are weakly present what makes a field for future research.

  17. Handling of Highly Radioactive Radiation Sources in a Hot Cell Using a Mechanically Driven Cell Crane - 13452

    Energy Technology Data Exchange (ETDEWEB)

    Klute, Stefan; Huber, Wolfgang-Bruno [Siempelkamp Nukleartechnik GmbH, Am Taubenfeld 25/1, 69123 Heidelberg (Germany); Meyer, Franz [Nuclear Engineering Seibersdorf GmbH, 2444 Seibersdorf (Austria)

    2013-07-01

    In 2010, Siempelkamp Nukleartechnik GmbH was awarded the contract for design and erection of a Hot Cell for handling and storage of highly radioactive radiation sources. This Hot Cell is part of a new hot cell laboratory, constructed for the NHZ (Neues Handhabungszentrum = New Handling Center) of the Nuclear Engineering Seibersdorf GmbH (NES). All incurring radioactive materials from Austria are collected in the NHZ, where they are safely conditioned and stored temporarily until their final storage. The main tasks of the NES include, apart from the collection, conditioning and storage of radioactive waste, also the reprocessing and the decontamination of facilities and laboratories originating from 45 years of research and development at the Seibersdorf site as well as the operation of the Hot Cell Laboratory [1]. The new Hot Cell Laboratory inside the NHZ consists of the following room areas: - One hot cell, placed in the center, for remote controlled, radiation protected handling of radioactive materials, including an integrated floor storage for the long-term temporary storage of highly radioactive radiation sources; - An anteroom for the loading and unloading of the hot cell; - One control room for the remote controlling of the hot cell equipment; - One floor storage, placed laterally to the hot cell, for burial, interim storage and removal of fissionable radioactive material in leak-proof packed units in 100 l drums. The specific design activity of the hot cell of 1.85 Pbq relating to 1-Me-Radiator including the integrated floor storage influences realization and design of the components used in the cell significantly. (authors)

  18. X-AFm stabilization as a mechanism of bypassing conversion phenomena in calcium aluminate cements

    International Nuclear Information System (INIS)

    2, Department of Civil and Environmental Engineering, University of California, Los Angeles, CA (United States); Department of Materials Science and Engineering, University of California, Los Angeles, CA (United States))" data-affiliation=" (Laboratory for the Chemistry of Construction Materials LC2, Department of Civil and Environmental Engineering, University of California, Los Angeles, CA (United States); Department of Materials Science and Engineering, University of California, Los Angeles, CA (United States))" >Falzone, Gabriel; Balonis, Magdalena; 2, Department of Civil and Environmental Engineering, University of California, Los Angeles, CA (United States); California Nanosystems Institute (CNSI), University of California, Los Angeles, CA (United States))" data-affiliation=" (Laboratory for the Chemistry of Construction Materials LC2, Department of Civil and Environmental Engineering, University of California, Los Angeles, CA (United States); California Nanosystems Institute (CNSI), University of California, Los Angeles, CA (United States))" >Sant, Gaurav

    2015-01-01

    Phase conversion phenomena are often observed in calcium aluminate cements (CACs), when the water-rich hydrates (e.g., CAH 10 , C 2 AH 8 ) formed at early ages, at temperatures ≤ 30 °C, expel water in time to form more compact, less water-rich structures (C 3 AH 6 ). The phase conversions follow a path regulated by the thermodynamic stabilities (solubilities) of phases. Based on this premise, it is proposed that conversion phenomena in CACs can be bypassed by provoking the precipitation of phases more preferred than those typically encountered along the conversion pathway. Therefore, X-AFm formation (where in this case, X = NO 3 − ) triggered by the sequential addition of calcium nitrate (Ca(NO 3 ) 2 = CN) additives is identified as a new means of bypassing conversion. A multi-method approach comprising X-ray diffraction (XRD), thermal analytics, and evaluations of the compressive strength is applied to correlate phase balances and properties of CAC systems cured at 25 °C and 45 °C. The results highlight the absence of the C 3 AH 6 phase across all systems and the curing conditions considered, with enhanced strengths being noted, when sufficient quantities of CN are added. The experimental outcomes are supported by insights gained from thermodynamic calculations which highlight thermodynamic selectivity as a means of regulating and controlling the evolutions of solid phase balances using inorganic salts in CACs, and more generally in cementing material systems

  19. Difference in surface reactions between titanium and zirconium in Hanks' solution to elucidate mechanism of calcium phosphate formation on titanium using XPS and cathodic polarization

    International Nuclear Information System (INIS)

    Tsutsumi, Y.; Nishimura, D.; Doi, H.; Nomura, N.; Hanawa, T.

    2009-01-01

    Titanium and zirconium were immersed in Hanks' solution with and without calcium and phosphate ions, and the surfaces were characterized with X-ray photoelectron spectroscopy (XPS) to determine the mechanism of calcium phosphate formation on titanium in simulated body fluids and in a living body. In addition, they were cathodically polarized in the above solutions. XPS characterization and cathodic polarization revealed differences in the surface properties in the ability of calcium phosphate formation between titanium and zirconium. The surface oxide film on titanium is not completely oxidized and is relatively reactive; that on zirconium is more passive and protective than that on titanium. Neither calcium nor phosphate stably exists alone on titanium, and calcium phosphate is naturally formed on it; calcium phosphate formed on titanium is stable and protective. On the other hand, calcium is never incorporated on zirconium, while zirconium phosphate, which is easily formed on zirconium, is highly stable and protective. Our study presents new information regarding the surface property of titanium and demonstrates that the characteristics of titanium and zirconium may be applied to various medical devices and new surface modification techniques.

  20. Mechanisms of calcium transport in small intestine. Progress report, March 16, 1974--March 1, 1975

    International Nuclear Information System (INIS)

    DeLuca, H.F.

    1975-01-01

    The macromolecular components of rat intestinal mucosal cytosol have been examined for their ability to bind radioactive 1,25-(OH) 2 D 3 and radioactive 25-OH-D 3 . In a variety of media the binding of these metabolites is found only to a 6S macromolecular component. No evidence for the existence of a 3.5S component which has been reported in the chick can be found in this species. The 6S component prefers 25-OH-D 3 to 1,25-(OH) 2 D 3 and furthermore saturation experiments in vivo have shown that the 6S component does not bind 1,25-(OH) 2 D 3 in vivo but instead binds the 25-OH-D 3 . This allowed the conclusion that the 6S macromolecular component does not play a role in the 1,25-(OH) 2 D 3 's function in stimulating intestinal calcium absorption. (U.S.)

  1. Swelling behavior of ion exchange resins incorporated in tri-calcium silicate cement matrix: II. Mechanical analysis

    International Nuclear Information System (INIS)

    Neji, M.; Bary, B.; Le Bescop, P.; Burlion, N.

    2015-01-01

    This paper presents the second part of a study aiming at modelling the mechanical behavior of composites made up of ion exchange resins (IER) solidified in a tri-calcium silicate cement paste (C_3S). Such composites may be subjected to internal pressures due to ion exchange processes between ionic species which are in IER and interstitial solution of the cement paste. The reactive transport model developed in the companion paper is coupled in this study to a multi-scale approach describing the mechanical behavior of the material. It is based on an analogy with thermomechanics for taking in account the IER internal pressures, and on Eshelby-based homogenization techniques to estimate both mechanical and coupling parameters. A laboratory test has been set up to measure the macroscopic strain caused by the swelling phenomenon. The model has been finally implemented in a finite elements software. The simulation of the laboratory tests has been performed and the results have been analyzed and compared to experimental data. - Highlights: • Experimental analysis about mechanical behavior of a composite material. • Chemo-Mechanical-Transport modeling on a composite material made up with IER embedded into cement paste matrix. • Multi-scale modeling.

  2. Effects of Pore Size on the Osteoconductivity and Mechanical Properties of Calcium Phosphate Cement in a Rabbit Model.

    Science.gov (United States)

    Zhao, Yi-Nan; Fan, Jun-Jun; Li, Zhi-Quan; Liu, Yan-Wu; Wu, Yao-Ping; Liu, Jian

    2017-02-01

    Calcium phosphate cement (CPC) porous scaffold is widely used as a suitable bone substitute to repair bone defect, but the optimal pore size is unclear yet. The current study aimed to evaluate the effect of different pore sizes on the processing of bone formation in repairing segmental bone defect of rabbits using CPC porous scaffolds. Three kinds of CPC porous scaffolds with 5 mm diameters and 12 mm length were prepared with the same porosity but different pore sizes (Group A: 200-300 µm, Group B: 300-450 µm, Group C: 450-600 µm, respectively). Twelve millimeter segmental bone defects were created in the middle of the radius bone and filled with different kinds of CPC cylindrical scaffolds. After 4, 12, and 24 weeks, alkaline phosphatase (ALP), histological assessment, and mechanical properties evaluation were performed in all three groups. After 4 weeks, ALP activity increased in all groups but was highest in Group A with smallest pore size. The new bone formation within the scaffolds was not obvious in all groups. After 12 weeks, the new bone formation within the scaffolds was obvious in each group and highest in Group A. At 24 weeks, no significant difference in new bone formation was observed among different groups. Besides the osteoconductive effect, Group A with smallest pore size also had the best mechanical properties in vivo at 12 weeks. We demonstrate that pore size has a significant effect on the osteoconductivity and mechanical properties of calcium phosphate cement porous scaffold in vivo. Small pore size favors the bone formation in the early stage and may be more suitable for repairing segmental bone defect in vivo. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  3. Mechanical properties and ion release from bioactive restorative composites containing glass fillers and calcium phosphate nano-structured particles.

    Science.gov (United States)

    Chiari, Marina D S; Rodrigues, Marcela C; Xavier, Tathy A; de Souza, Eugen M N; Arana-Chavez, Victor E; Braga, Roberto R

    2015-06-01

    To evaluate the effect of the replacement of barium glass by dicalcium phosphate dihydrate (DCPD) particles on the mechanical properties and degree of conversion (DC) of composites. Additionally, calcium and hydrogen phosphate (HPO4(2-)) release were followed for 28 days. Nine composites containing equal parts (in mols) of BisGMA and TEGDMA and 40, 50 or 60 vol% of total filler were manipulated. Filler phase was constituted by silanated barium glass and 0%, 10% or 20% of DCPD particles. DC was determined by near-FTIR. Biaxial flexural strength (BFS) and modulus (E) were tested using the "piston on three balls" method, while fracture toughness (KIc) used the "single edge notched beam" method. Specimens were tested after 24h and 28 days in water. Ion release was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). Data were analyzed by ANOVA/Tukey (DC and ion release) or Kruskal-Wallis/Mann-Whitney (mechanical properties; alpha: 5%). DC was not affected by DCPD. The presence of DCPD reduced BFS for both storage times, while differences in E became evident after 28 days. After 24h, KIc increased with the addition of DCPD; after 28 days, however, KIc decreased only for DCPD-containing composites. Calcium release was similar for both DCPD contents and remained fairly constant during the 28-day period. Overall, HPO4(2-) release was higher at 7 days and did not decrease after 14 days. The composite with the highest filler level and 10% DCPD represented the best compromise between mechanical properties after aging in water and ion release. Copyright © 2015 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  4. Novel adaptations to zinc-silicate glass polyalkenoate cements: the unexpected influences of germanium based glasses on handling characteristics and mechanical properties.

    Science.gov (United States)

    Dickey, B T; Kehoe, S; Boyd, D

    2013-07-01

    Aluminum-free glass polyalkenoate cements (GPC) have been hindered for use as injectable bone cements by their inability to balance handling characteristics with mechanical integrity. Currently, zinc-based, aluminum-free GPCs demonstrate compression strengths in excess of 60MPa, but set in c. 1-2 min. Previous efforts to extend the setting reaction have remained clinically insufficient and are typically accompanied by a significant drop in strength. This work synthesized novel glasses based on a zinc silicate composition with the inclusion of GeO2, ZrO2, and Na2O, and evaluated the setting reaction and mechanical properties of the resultant GPCs. Germanium based GPCs were found to have working times between 5 and 10 min, setting times between 14 and 36 min, and compression strengths in excess of 30 MPa for the first 30 days. The results of this investigation have shown that the inclusion of GeO2, ZrO2, and Na2O into the glass network have produced, for the first time, an aluminum-free GPC that is clinically viable as injectable bone cements with regards to handling characteristics and mechanical properties. Crown Copyright © 2013. Published by Elsevier Ltd. All rights reserved.

  5. Carbon dioxide transport in molten calcium carbonate occurs through an oxo-Grotthuss mechanism via a pyrocarbonate anion.

    Science.gov (United States)

    Corradini, Dario; Coudert, François-Xavier; Vuilleumier, Rodolphe

    2016-05-01

    The reactivity, speciation and solvation structure of CO2 in carbonate melts are relevant for both the fate of carbon in deep geological formations and for its electroreduction to CO (to be used as fuel) when solvated in a molten carbonate electrolyte. In particular, the high solubility of CO2 in carbonate melts has been tentatively attributed to the formation of the pyrocarbonate anion, C2O5(2-). Here we study, by first-principles molecular dynamics simulations, the behaviour of CO2 in molten calcium carbonate. We find that pyrocarbonate forms spontaneously and the identity of the CO2 molecule is quickly lost through O(2-) exchange. The transport of CO2 in this molten carbonate thus occurs in a fashion similar to the Grotthuss mechanism in water, and is three times faster than molecular diffusion. This shows that Grotthuss-like transport is more general than previously thought.

  6. Comparative transcriptome analysis reveals different molecular mechanisms of Bacillus coagulans 2-6 response to sodium lactate and calcium lactate during lactic acid production.

    Directory of Open Access Journals (Sweden)

    Jiayang Qin

    Full Text Available Lactate production is enhanced by adding calcium carbonate or sodium hydroxide during fermentation. However, Bacillus coagulans 2-6 can produce more than 180 g/L L-lactic acid when calcium lactate is accumulated, but less than 120 g/L L-lactic acid when sodium lactate is formed. The molecular mechanisms by which B. coagulans responds to calcium lactate and sodium lactate remain unclear. In this study, comparative transcriptomic methods based on high-throughput RNA sequencing were applied to study gene expression changes in B. coagulans 2-6 cultured in non-stress, sodium lactate stress and calcium lactate stress conditions. Gene expression profiling identified 712 and 1213 significantly regulated genes in response to calcium lactate stress and sodium lactate stress, respectively. Gene ontology assignments of the differentially expressed genes were performed. KEGG pathway enrichment analysis revealed that 'ATP-binding cassette transporters' were significantly affected by calcium lactate stress, and 'amino sugar and nucleotide sugar metabolism' was significantly affected by sodium lactate stress. It was also found that lactate fermentation was less affected by calcium lactate stress than by sodium lactate stress. Sodium lactate stress had negative effect on the expression of 'glycolysis/gluconeogenesis' genes but positive effect on the expression of 'citrate cycle (TCA cycle' genes. However, calcium lactate stress had positive influence on the expression of 'glycolysis/gluconeogenesis' genes and had minor influence on 'citrate cycle (TCA cycle' genes. Thus, our findings offer new insights into the responses of B. coagulans to different lactate stresses. Notably, our RNA-seq dataset constitute a robust database for investigating the functions of genes induced by lactate stress in the future and identify potential targets for genetic engineering to further improve L-lactic acid production by B. coagulans.

  7. Comparative transcriptome analysis reveals different molecular mechanisms of Bacillus coagulans 2-6 response to sodium lactate and calcium lactate during lactic acid production.

    Science.gov (United States)

    Qin, Jiayang; Wang, Xiuwen; Wang, Landong; Zhu, Beibei; Zhang, Xiaohua; Yao, Qingshou; Xu, Ping

    2015-01-01

    Lactate production is enhanced by adding calcium carbonate or sodium hydroxide during fermentation. However, Bacillus coagulans 2-6 can produce more than 180 g/L L-lactic acid when calcium lactate is accumulated, but less than 120 g/L L-lactic acid when sodium lactate is formed. The molecular mechanisms by which B. coagulans responds to calcium lactate and sodium lactate remain unclear. In this study, comparative transcriptomic methods based on high-throughput RNA sequencing were applied to study gene expression changes in B. coagulans 2-6 cultured in non-stress, sodium lactate stress and calcium lactate stress conditions. Gene expression profiling identified 712 and 1213 significantly regulated genes in response to calcium lactate stress and sodium lactate stress, respectively. Gene ontology assignments of the differentially expressed genes were performed. KEGG pathway enrichment analysis revealed that 'ATP-binding cassette transporters' were significantly affected by calcium lactate stress, and 'amino sugar and nucleotide sugar metabolism' was significantly affected by sodium lactate stress. It was also found that lactate fermentation was less affected by calcium lactate stress than by sodium lactate stress. Sodium lactate stress had negative effect on the expression of 'glycolysis/gluconeogenesis' genes but positive effect on the expression of 'citrate cycle (TCA cycle)' genes. However, calcium lactate stress had positive influence on the expression of 'glycolysis/gluconeogenesis' genes and had minor influence on 'citrate cycle (TCA cycle)' genes. Thus, our findings offer new insights into the responses of B. coagulans to different lactate stresses. Notably, our RNA-seq dataset constitute a robust database for investigating the functions of genes induced by lactate stress in the future and identify potential targets for genetic engineering to further improve L-lactic acid production by B. coagulans.

  8. Efficient removal of copper from wastewater by using mechanically activated calcium carbonate.

    Science.gov (United States)

    Hu, Huimin; Li, Xuewei; Huang, Pengwu; Zhang, Qiwu; Yuan, Wenyi

    2017-12-01

    Copper removal from aqueous solution is necessary from the stances of both environmental protection and copper resource recycling. It is important to develop a new chemical precipitation method suitable for removing copper particularly at low concentration as the case of waste mine water, with regards to the various problems related to the current precipitation methods by using strong alkalis or soluble sulfides. In this research, we studied a possible chemical precipitation of copper ions at concentration around 60 mg/L or lower by cogrinding copper sulfate in water with calcium carbonate (CaCO 3 ) using wet stirred ball milling. With the aid of ball milling, copper precipitation as a basic sulfate (posnjakite: Cu 4 (SO 4 ) (OH) 6 ·H 2 O) occurred at a very high copper removal rate of 99.76%, to reduce the residual copper concentration in the solution less than 0.5 mg/L, reaching the discharge limit, even with the addition amount of CaCO 3 as a stoichiometric ratio of CaCO 3 /Cu 2+ at 1:1. It is more interesting to notice that, at the same conditions, other heavy metals such as Ni, Mn, Zn and Cd do not precipitate obviously just with CaCO 3 addition at CaCO 3 /M 2+ at 1:1 so that the precipitate without the impurities can be processed as good source to recover copper. This newly proposed concept can be further developed to treat wastewaters with other metals to serve both purposes of environmental purification and resource recovery in a similar way. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. Calcium carbonate scaling in seawater desalination by ammonia-carbon dioxide forward osmosis: Mechanism and implications

    KAUST Repository

    Li, Zhenyu

    2015-02-07

    Forward osmosis (FO) is an osmotically driven membrane process, where the membrane separates a draw solution (DS) with high salinity from a feed solution (FS) with low salinity. There can be a counter direction flow of salt (i.e., salt leakage) that may interact with the water flux through the FO membrane. For the first time reported, this study describes a new calcium carbonate scaling phenomenon in the seawater FO desalination process using ammonium bicarbonate as the DS. The scaling on the membrane surface at the feed side is caused by the interaction between an anion reversely diffused from the DS and a cation present in the FS, causing a significant decline of the water flux. The composition of the scaling layer is dominated by the solubility (represented as solubility product constant, Ksp) of salt formed by the paired anion and cation. Membrane surface morphology plays a crucial role in the reversibility of the scaling. If the scaling occurs on the active layer of the FO membrane, hydraulic cleaning (increasing crossflow velocity) efficiency to restore the water flux is up to 82%. When scaling occurs on the support layer of the FO membrane, the hydraulic cleaning efficiency is strongly reduced, with only 36% of the water flux recovered. The present study reveals the risk of scaling induced by the interaction of feed solute and draw solute, which is different from the scaling caused by the supersaturation in reverse osmosis and other FO studies reported. The scaling investigated in this study can occur with a very low solute concentration at an early stage of the FO process. This finding provides an important implication for selection of draw solution and development of new membranes in the FO process.

  10. Aluminum-induced dreierketten chain cross-links increase the mechanical properties of nanocrystalline calcium aluminosilicate hydrate

    Science.gov (United States)

    Geng, Guoqing; Myers, Rupert J.; Li, Jiaqi; Maboudian, Roya; Carraro, Carlo; Shapiro, David A.; Monteiro, Paulo J. M.

    2017-03-01

    The incorporation of Al and increased curing temperature promotes the crystallization and cross-linking of calcium (alumino)silicate hydrate (C-(A-)S-H), which is the primary binding phase in most contemporary concrete materials. However, the influence of Al-induced structural changes on the mechanical properties at atomistic scale is not well understood. Herein, synchrotron radiation-based high-pressure X-ray diffraction is used to quantify the influence of dreierketten chain cross-linking on the anisotropic mechanical behavior of C-(A-)S-H. We show that the ab-planar stiffness is independent of dreierketten chain defects, e.g. vacancies in bridging tetrahedra sites and Al for Si substitution. The c-axis of non-cross-linked C-(A-)S-H is more deformable due to the softer interlayer opening but stiffens with decreased spacing and/or increased zeolitic water and Ca2+ of the interlayer. Dreierketten chain cross-links act as ‘columns’ to resist compression, thus increasing the bulk modulus of C-(A-)S-H. We provide the first experimental evidence on the influence of the Al-induced atomistic configurational change on the mechanical properties of C-(A-)S-H. Our work advances the fundamental knowledge of C-(A-)S-H on the lowest level of its hierarchical structure, and thus can impact the way that innovative C-(A-)S-H-based cementitious materials are developed using a ‘bottom-up’ approach.

  11. Remote handling at LAMPF

    International Nuclear Information System (INIS)

    Grisham, D.L.; Lambert, J.E.

    1983-01-01

    Experimental area A at the Clinton P. Anderson Meson Physics Facility (LAMPF) encompasses a large area. Presently there are four experimental target cells along the main proton beam line that have become highly radioactive, thus dictating that all maintenance be performed remotely. The Monitor remote handling system was developed to perform in situ maintenance at any location within area A. Due to the complexity of experimental systems and confined space, conventional remote handling methods based upon hot cell and/or hot bay concepts are not workable. Contrary to conventional remote handling which require special tooling for each specifically planned operation, the Monitor concept is aimed at providing a totally flexible system capable of remotely performing general mechanical and electrical maintenance operations using standard tools. The Monitor system is described

  12. Expression of the calcium-binding proteins MRP8 and MRP14 in monocytes is regulated by a calcium-induced suppressor mechanism.

    OpenAIRE

    Roth, J; Goebeler, M; Wrocklage, V; van den Bos, C; Sorg, C

    1994-01-01

    MRP8 and MRP14 are two calcium-binding proteins of the S-100 family the expression of which is restricted to distinct stages of monocytic differentiation. Heteromeric MRP8/MRP14 complexes have been shown to represent their biologically active forms. However, it is not as yet clear whether biochemical modification of complexes, or regulation on the transcriptional level, are responsible for the control of MRP8/MRP14 expression. Employing Western-blot analysis and metabolic labelling we have de...

  13. Synthesis and mechanical properties of a calcium sulphoaluminate cement made of industrial wastes

    Directory of Open Access Journals (Sweden)

    Gallardo, M.

    2014-09-01

    Full Text Available Environmentally-friendly calcium sulphoaluminate clinkers were obtained from a mixture of aluminium dross, fluorgypsum, fly ash and CaCO₃ at temperatures within the range of 1100 to 1400 °C. After the heat treatments Ca₄Al₆O₁₂SO₄ was the main phase. Three different cements were prepared using the clinkers synthesized at 1250, 1350 and 1400 °C; the clinker powders were mixed with 20 wt% of hemihydrate. Cement pastes were prepared using a water/cement ratio (w/c, 0.4 followed by curing at 20 or 40 °C for periods of time ranging from 1 to 28 days. Most of the samples showed high compression strengths 40–47 MPa after 28 days, which were comparable to the strength of Portland cement. Ettringite was the main hydration product and its morphology consisted of acicular and hexagonal plates, which is typical of this phase.Se fabricaron clinkers de bajo impacto ambiental a base de sulfoaluminato de calcio calcinando mezclas de escoria de aluminio, fluoryeso, ceniza volante y CaCO₃ a diferentes temperaturas dentro de un rango de 1100 a 1400 °C. Se observó la formación de Ca₄Al₆O₁₂SO₄ como fase principal. Para obtener los cementos, los clinkers obtenidos a 1250, 1350 y 1400 °C se mezclaron con 20% en peso de hemihidrato. Se prepararon pastas usando una relación agua/cemento, de 0.4 y se curaron a 20 y 40 °C por diferentes periodos de tiempo desde 1 hasta 28 días. Los valores de resistencia a la compresión a los 28 días de curado de la mayoría de las muestras estuvieron entre 40–47 MPa, equiparables a los de referencia de pastas de cemento Portland. La etringita fue el principal producto de hidratación y su morfología consistió de placas hexagonales y aciculares, típicas de esta fase.

  14. Structural and mechanical characterization of boron doped biphasic calcium phosphate produced by wet chemical method and subsequent thermal treatment

    Energy Technology Data Exchange (ETDEWEB)

    Albayrak, Onder, E-mail: albayrakonder@mersin.edu.tr

    2016-03-15

    In the current study, boron doped biphasic calcium phosphate bioceramics consisting of a mixture of boron doped hydroxyapatite (BHA) and beta tricalcium phosphate (β-TCP) of varying BHA/β-TCP ratios were obtained after sintering stage. The effects of varying boron contents and different sintering temperatures on the BHA/β-TCP ratios and on the sinterability of the final products were investigated. Particle sizes and morphologies of the obtained precipitates were determined using SEM. XRD and FTIR investigation were conducted to detect the boron formation in the structure of HA and quantitative analysis was performed to determine the BHA/β-TCP ratio before and after sintering stage. In order to determine the sinterability of the obtained powders, pellets were prepared and sintered; the rates of densification were calculated and obtained results were correlated by SEM images. Also Vickers microhardness values of the sintered samples were determined. The experimental results verified that boron doped hydroxyapatite powders were obtained after sintering stage and the structure consists of a mixture of BHA and β-TCP. As the boron content used in the precipitation stage increases, β-TCP content of the BHA/β-TCP ratio increases but sinterability, density and microhardness deteriorate. As the sintering temperature increases, β-TCP content, density and microhardness of the samples increase and sinterability improves. - Highlights: • This is the first paper about boron doped biphasic calcium phosphate bioceramics. • Boron doping affects the structural and mechanical properties. • BHA/β-TCP ratio can be adjustable with boron content and sintering temperature.

  15. Carbon monoxide releasing molecule induces endothelial nitric oxide synthase activation through a calcium and phosphatidylinositol 3-kinase/Akt mechanism.

    Science.gov (United States)

    Yang, Po-Min; Huang, Yu-Ting; Zhang, Yu-Qi; Hsieh, Chia-Wen; Wung, Being-Sun

    2016-12-01

    The production of nitric oxide (NO) by endothelial NO synthase (eNOS) plays a major role in maintaining vascular homeostasis. This study elucidated the potential role of carbon monoxide (CO)-releasing molecules (CORMs) in NO production and explored the underlying mechanisms in endothelial cells. We observed that 25μM CORM-2 could increase NO production and stimulate an increase in the intracellular Ca 2+ level. Furthermore, ethylene glycol-bis(β-aminoethyl ether)-N,N,N',N'-tetra acetic acid caused CORM-2-induced NO production, which was abolished by 1,2-bis(2-aminophenoxy) ethane-N,N,N',N'-tetraacetic acid tetraacetoxy-methyl ester (BAPTA-AM), indicating that intracellular Ca 2+ release plays a major role in eNOS activation. The inhibition of the IP3 receptor diminished the CORM-2-induced intracellular Ca 2+ increase and NO production. Furthermore, CORM-2 induced eNOS Ser 1179 phosphorylation and eNOS dimerization, but it did not alter eNOS expression. CORM-2 (25μM) also prolonged Akt phosphorylation, lasting for at least 12h. Pretreatment with phosphatidylinositol 3-kinase inhibitors (wortmannin or LY294002) inhibited the increases in NO production and phosphorylation but did not affect eNOS dimerization. CORM-2-induced eNOS Ser 1179 phosphorylation was intracellularly calcium-dependent, because pretreatment with an intracellular Ca 2+ chelator (BAPTA-AM) inhibited this process. Although CORM-2 increases intracellular reactive oxygen species (ROS), pretreatment with antioxidant enzyme catalase and N-acetyl-cysteine did not abolish the CORM-2-induced eNOS activity or phosphorylation, signifying that ROS is not involved in this activity. Hence, CORM-2 enhances eNOS activation through intracellular calcium release, Akt phosphorylation, and eNOS dimerization. Copyright © 2016 Elsevier Inc. All rights reserved.

  16. An analytical approach to elucidate the mechanism of grain refinement in calcium added Mg-Al alloys

    International Nuclear Information System (INIS)

    Nagasivamuni, B.; Ravi, K.R.

    2015-01-01

    Highlights: • Minor additions of Ca (<0.2%) refines the grain structure in Mg-(3, 6 and 9)Al alloys. • Analytical model elucidate that nucleation potency is enhanced after Ca addition. • Ternary Mg-Al-xCa growth restriction values (Q t ) are computed using Scheil equations. • Grain size predictions elucidate that nucleation events dominate grain refinement. • Growth restriction due to the higher Ca addition on grain refinement is not significant. - Abstract: The present study investigates the grain refinement of Mg-3Al, Mg-6Al and Mg-9Al alloys by calcium addition. The maximum reduction in grain size has been observed at 0.2% Ca addition in Mg-Al alloys, in which any further addition (up to 0.4%) has marginal improvement in grain refinement. The mechanism associated with the grain refinement of Mg-Al alloys by Ca addition is discussed in terms of growth restriction factor (Q) and constitutional undercooling (ΔT CS ) using analytical model. The influence of growth restriction factor (Q) on the final grain size of Ca-added Mg-Al alloys are calculated with the help analytical model by assuming that the number of nucleant particles is not altered through Ca addition. For accurate grain size calculations, the value of Q has been estimated with reliable thermodynamic database using Scheil solidification simulation. The comparison of predicted and experimental grain size results indicate that constitutional undercooling activation of nucleation events plays dominant role in grain refinement in Mg-Al alloys by calcium addition, whereas the increase in growth restriction value has negligible effect

  17. Effects of calcium (Ca(2+)) extrusion mechanisms on electrophysiological properties in a hypoglossal motoneuron: insight from a mathematical model.

    Science.gov (United States)

    Horn, Kyle G; Solomon, Irene C

    2014-01-01

    Spike-frequency dynamics and spike shape can provide insight into the types of ion channels present in any given neuron and give a sense for the precise response any neuron may have to a given input stimulus. Motoneuron firing frequency over time is especially important due to its direct effect on motor output. Of particular interest is intracellular Ca(2+), which exerts a powerful influence on both firing properties over time and spike shape. In order to better understand the cellular mechanisms for the regulation of intracellular Ca(2+) and their effect on spiking behavior, we have modified a computational model of an HM to include a variety of Ca(2+) handling processes. For the current study, a series of HM models that include Ca(2+) pumps, Na(+)/Ca(2+) exchangers, and a generic exponential decay of excess Ca(2+) were generated. Simulations from these models indicate that although each extrusion mechanism exerts a similar effect on voltage, the firing properties change distinctly with the inclusion of additional Ca(2+)-related mechanisms: BK channels, Ca(2+) buffering, and diffusion of [Ca(2+)]i modeled via a linear diffusion partial differential equation. While an exponential decay of Ca(2+) seems to adequately capture short-term changes in firing frequency seen in biological data, internal diffusion of Ca(2+) appears to be necessary for capturing longer term frequency changes. © 2014 Elsevier B.V. All rights reserved.

  18. Effects of graphene plates' adoption on the microstructure, mechanical properties, and in vivo biocompatibility of calcium silicate coating.

    Science.gov (United States)

    Xie, Youtao; Li, Hongqin; Ding, Chuanxian; Zheng, Xuebin; Li, Kai

    2015-01-01

    Calcium silicate (CS) ceramic is a good coating candidate for biomedical implants to improve biocompatibility and accelerate early osseointegration. However, the poor fracture toughness and wear resistance of this ceramic material restricts the long-term performance of implants. In this study, graphene plates (GPs) were used as reinforcement to improve the mechanical properties of CS coating. Composite coating containing 1.5 weight % GPs was prepared by vacuum plasma spraying technology. The good survival of the GPs in the composite coating was demonstrated by Raman analysis, although the defects of the GPs were increased after plasma spraying. Effects of the GPs' adoption on the microstructure of the coating were studied by scanning electron microscopy and transmission electron microscopy. Results showed that the GPs were homogenously distributed in the CS grains interface or enwrapped on the particles, and exhibited good wetting behavior with the CS matrix. The wear properties of the composite coating were obviously enhanced by the reinforcement of GPs. The reinforcement mechanism was attributed to the enhanced micro-hardness and interfacial bonding of the particles in the coating. In vivo experiments demonstrated that the composite coating possessed similarly good biocompatibility compared to pure CS coating. The bone-implant contact ratio reached 84.3%±7.4% for GPs/CS coating and 79.6%±9.4% for CS coating after 3 months' implantation.

  19. Effects of graphene plates’ adoption on the microstructure, mechanical properties, and in vivo biocompatibility of calcium silicate coating

    Science.gov (United States)

    Xie, Youtao; Li, Hongqin; Ding, Chuanxian; Zheng, Xuebin; Li, Kai

    2015-01-01

    Calcium silicate (CS) ceramic is a good coating candidate for biomedical implants to improve biocompatibility and accelerate early osseointegration. However, the poor fracture toughness and wear resistance of this ceramic material restricts the long-term performance of implants. In this study, graphene plates (GPs) were used as reinforcement to improve the mechanical properties of CS coating. Composite coating containing 1.5 weight % GPs was prepared by vacuum plasma spraying technology. The good survival of the GPs in the composite coating was demonstrated by Raman analysis, although the defects of the GPs were increased after plasma spraying. Effects of the GPs’ adoption on the microstructure of the coating were studied by scanning electron microscopy and transmission electron microscopy. Results showed that the GPs were homogenously distributed in the CS grains interface or enwrapped on the particles, and exhibited good wetting behavior with the CS matrix. The wear properties of the composite coating were obviously enhanced by the reinforcement of GPs. The reinforcement mechanism was attributed to the enhanced micro-hardness and interfacial bonding of the particles in the coating. In vivo experiments demonstrated that the composite coating possessed similarly good biocompatibility compared to pure CS coating. The bone-implant contact ratio reached 84.3%±7.4% for GPs/CS coating and 79.6%±9.4% for CS coating after 3 months’ implantation. PMID:26089662

  20. Effect of dietary boron on growth performance, calcium and phosphorus metabolism, and bone mechanical properties in growing barrows.

    Science.gov (United States)

    Armstrong, T A; Spears, J W

    2001-12-01

    An experiment was conducted to evaluate the effects of dietary boron (B) on growth performance, bone mechanical properties, and calcium (Ca) and phosphorus (P) metabolism in pigs. Thirty-six barrows were weaned at approximately 21 d of age and randomly assigned to receive one of three dietary treatments. Treatments consisted of 1) low-B basal diet (control), 2) basal + 5 mg B/kg diet, and 3) basal + 15 mg B/kg diet. Boron was supplemented as sodium borate. Barrows remained on their respective experimental diets throughout the nursery (35 d) and growing (30 d) phases of production. Blood samples were obtained from each barrow at the end of each phase. Following the 30-d growing period, eight barrows per treatment were transferred to stainless steel metabolism crates. Barrows had an adjustment period of 7 d, followed by a 7-d total collection of urine and feces. All barrows were fed at 90% of the previous ad libitum grower intake of the control animals during the adjustment and collection periods. At the end of the 7-d collection period, barrows were killed and femurs and fibulas were harvested for the assessment of bone mechanical properties. During the nursery phase, ADG and ADFI were increased (P 0.05) by dietary B. These data indicate that B supplementation to pigs can increase growth and bone strength without greatly affecting Ca and P metabolism.

  1. Porous calcium polyphosphate bone substitutes: additive manufacturing versus conventional gravity sinter processing-effect on structure and mechanical properties.

    Science.gov (United States)

    Hu, Youxin; Shanjani, Yaser; Toyserkani, Ehsan; Grynpas, Marc; Wang, Rizhi; Pilliar, Robert

    2014-02-01

    Porous calcium polyphosphate (CPP) structures proposed as bone-substitute implants and made by sintering CPP powders to form bending test samples of approximately 35 vol % porosity were machined from preformed blocks made either by additive manufacturing (AM) or conventional gravity sintering (CS) methods and the structure and mechanical characteristics of samples so made were compared. AM-made samples displayed higher bending strengths (≈1.2-1.4 times greater than CS-made samples), whereas elastic constant (i.e., effective elastic modulus of the porous structures) that is determined by material elastic modulus and structural geometry of the samples was ≈1.9-2.3 times greater for AM-made samples. X-ray diffraction analysis showed that samples made by either method displayed the same crystal structure forming β-CPP after sinter annealing. The material elastic modulus, E, determined using nanoindentation tests also showed the same value for both sample types (i.e., E ≈ 64 GPa). Examination of the porous structures indicated that significantly larger sinter necks resulted in the AM-made samples which presumably resulted in the higher mechanical properties. The development of mechanical properties was attributed to the different sinter anneal procedures required to make 35 vol % porous samples by the two methods. A primary objective of the present study, in addition to reporting on bending strength and sample stiffness (elastic constant) characteristics, was to determine why the two processes resulted in the observed mechanical property differences for samples of equivalent volume percentage of porosity. An understanding of the fundamental reason(s) for the observed effect is considered important for developing improved processes for preparation of porous CPP implants as bone substitutes for use in high load-bearing skeletal sites. Copyright © 2013 Wiley Periodicals, Inc.

  2. Morphological and mechanical characterization of chitosan-calcium phosphate composites for potential application as bone-graft substitutes

    Directory of Open Access Journals (Sweden)

    Guilherme Maia Mulder van de Graaf

    Full Text Available Introduction: Bone diseases, aging and traumas can cause bone loss and lead to bone defects. Treatment of bone defects is challenging, requiring chirurgical procedures. Bone grafts are widely used for bone replacement, but they are limited and expensive. Due to bone graft limitations, natural, semi-synthetic, synthetic and composite materials have been studied as potential bone-graft substitutes. Desirable characteristics of bone-graft substitutes are high osteoinductive and angiogenic potentials, biological safety, biodegradability, bone-like mechanical properties, and reasonable cost. Herein, we prepared and characterized potential bone-graft substitutes composed of calcium phosphate (CP - a component of natural bone, and chitosan (CS - a biocompatible biopolymer. Methods CP-CS composites were synthetized, molded, dried and characterized. The effect of drying temperatures (38 and 60 °C on the morphology, porosity and chemical composition of the composites was evaluated. As well, the effects of drying temperature and period of drying (3, 24, 48 and 72 hours on the mechanical properties - compressive strength, modulus of elasticity and relative deformation-of the demolded samples were investigated. Results Scanning electron microscopy and gas adsorption-desorption analyses of the CS-CP composites showed interconnected pores, indicating that the drying temperature played an important role on pores size and distribution. In addition, drying temperature have altered the color (brownish at 60 °C due to Maillard reaction and the chemical composition of the samples, confirmed by FTIR. Conclusion Particularly, prolonged period of drying have improved mechanical properties of the CS-CP composites dried at 38 °C, which can be designed according to the mechanical needs of the replaceable bone.

  3. Glucose stimulates neurotensin secretion from the rat small intestine by mechanisms involving SGLT1 and GLUT2 leading to cell depolarization and calcium influx

    DEFF Research Database (Denmark)

    Kuhre, Rune Ehrenreich; Bechmann, Louise Ellegaard; Hartmann, Bolette

    2015-01-01

    of secretion. Luminal glucose (20% wt/vol) stimulated secretion but vascular glucose (5, 10, or 15 mmol/l) was without effect. The underlying mechanisms depend on membrane depolarization and calcium influx, since the voltage-gated calcium channel inhibitor nifedipine and the KATP channel opener diazoxide......, suggesting that glucose stimulates secretion by initial uptake by this transporter. However, secretion was also sensitive to GLUT2 inhibition (by phloretin) and blockage of oxidative phosphorylation (2-4-dinitrophenol). Direct KATP channel closure by sulfonylureas stimulated secretion. Therefore, glucose...

  4. Calcium supplements

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/007477.htm Calcium supplements To use the sharing features on this page, please enable JavaScript. WHO SHOULD TAKE CALCIUM SUPPLEMENTS? Calcium is an important mineral for the ...

  5. Kinetics and mechanism of heterogeneous oxidation of sulfur dioxide by ozone on surface of calcium carbonate

    Directory of Open Access Journals (Sweden)

    L. Li

    2006-01-01

    Full Text Available Sulfate particles play a key role in the air quality and the global climate, but the heterogeneous formation mechanism of sulfates on surfaces of atmospheric particles is not well established. Carbonates, which act as a reactive component in mineral dust due to their special chemical properties, may contribute significantly to the sulfate formation by heterogeneous processes. This paper presents a study on the oxidation of SO2 by O3 on CaCO3 particles. Using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS, the formation of sulfite and sulfate on the surface was identified, and the roles of O3 and water in oxidation processes were determined. The results showed that in the presence of O3, SO2can be oxidized to sulfate on the surface of CaCO3 particles. The reaction is first order in SO2 and zero order in O3. The reactive uptake coefficient for SO2 [(0.6–9.8×1014 molecule cm-3] oxidation by O3 [(1.2–12×1014 molecule cm-3] was determined to be (1.4±0.3×10-7 using the BET area as the reactive area and (7.7±1.6×10-4 using the geometric area. A two-stage mechanism that involves adsorption of SO2 followed by O3 oxidation is proposed and the adsorption of SO2 on the CaCO3 surface is the rate-determining step. The proposed mechanism can well explain the experiment results. The atmospheric implications were explored based on a box model calculation. It was found that the heterogeneous reaction might be an important pathway for sulfate formation in the atmosphere.

  6. Epinephrine impairs insulin release by a mechanism distal to calcium mobilization. Similarity to lipoxygenase inhibitors

    International Nuclear Information System (INIS)

    Metz, S.A.

    1988-01-01

    The mechanisms that enable epinephrine (EPI) and lipoxygenase inhibitors to impede insulin secretion are unknown. We examined the possibility that EPI inhibits Ca 2+ fluxes as its major mechanism by studying 45 Ca efflux from prelabeled, intact rat islets. EPI (2.5 x 10(-7) to 1 x 10(-5) M) inhibited insulin release induced by the influx of extracellular Ca 2+ (46 mM K+) or the mobilization of intracellular Ca 2+ stores (2 mM Ba 2+ ), but it did not reduce the 45 Ca efflux stimulated by either agonist. EPI also nullified insulin release induced by isobutylmethylxanthine or dibutyryl cAMP, with minimal or no effects on 45 Ca efflux, and blocked the insulinotropic effects of 12-O-tetradecanoylphorbol-13-acetate (a direct activator of protein kinase C), which is believed primarily to sensitize the exocytotic apparatus to Ca 2+ without mobilizing additional Ca 2+ . Previously we reported that similar effects were induced by inhibitors of pancreatic islet lipoxygenase. In this study, however, pretreatment with either the alpha 2-adrenergic antagonist yohimbine or pertussis toxin did not block the effects of lipoxygenase inhibitors, although either agent did block the effects of EPI. Thus, EPI, via an alpha 2-receptor mechanism, is able to reduce exocytosis largely distal to, or independent of, changes in Ca 2+ flux, cAMP formation or its Ca 2+ -mobilizing action, or generation of protein kinase C activators. Therefore, EPI may reduce the sensitivity of the exocytotic apparatus to Ca 2+ . Inhibition of islet lipoxygenase may have a similar effect; however, in this case, the effect would have to be unrelated, or distal, to stimulation of alpha 2-receptors

  7. Mechanisms underlying the cardiac pacemaker: the role of SK4 calcium-activated potassium channels.

    Science.gov (United States)

    Weisbrod, David; Khun, Shiraz Haron; Bueno, Hanna; Peretz, Asher; Attali, Bernard

    2016-01-01

    The proper expression and function of the cardiac pacemaker is a critical feature of heart physiology. The sinoatrial node (SAN) in human right atrium generates an electrical stimulation approximately 70 times per minute, which propagates from a conductive network to the myocardium leading to chamber contractions during the systoles. Although the SAN and other nodal conductive structures were identified more than a century ago, the mechanisms involved in the generation of cardiac automaticity remain highly debated. In this short review, we survey the current data related to the development of the human cardiac conduction system and the various mechanisms that have been proposed to underlie the pacemaker activity. We also present the human embryonic stem cell-derived cardiomyocyte system, which is used as a model for studying the pacemaker. Finally, we describe our latest characterization of the previously unrecognized role of the SK4 Ca(2+)-activated K(+) channel conductance in pacemaker cells. By exquisitely balancing the inward currents during the diastolic depolarization, the SK4 channels appear to play a crucial role in human cardiac automaticity.

  8. The effect of supplementation of calcium, vitamin D, boron, and increased fluoride intake on bone mechanical properties and metabolic hormones in rat.

    Science.gov (United States)

    Ghanizadeh, G; Babaei, M; Naghii, Mohammad Reza; Mofid, M; Torkaman, G; Hedayati, M

    2014-04-01

    Evidence indicates that optimal nutrition plays a role in bone formation and maintenance. Besides major components of mineralization such as calcium, phosphorus, and vitamin D, other nutrients like boron and fluoride have beneficial role, too. In this study, 34 male Wistar rats were divided into five groups: control diet, fluoride, fluoride + boron, fluoride + calcium + vitamin D, and fluoride + boron + calcium + vitamin D. Boron equal to 1.23 mg, calcium and vitamin D equal to 210 mg + 55 IU and fluoride equal to 0.7 mg/rat/day was added to their drinking water for 8 weeks. Plasma blood samples and bones were collected. Findings are evidence that fluoride + boron intake revealed significant positive effects on bone mechanical properties and bone metabolic hormones. These findings suggest that combined intake of these two elements has beneficial effects on bone stiffness and breaking strength comparing to even calcium + vitamin D supplementation. This evidence dealing with health problems related to bone and skeletal system in humans should justify further investigation of the role of boron and fluoride with other elements in relation to bone.

  9. Stochastic Simulation of Cardiac Ventricular Myocyte Calcium Dynamics and Waves

    OpenAIRE

    Tuan, Hoang-Trong Minh; Williams, George S. B.; Chikando, Aristide C.; Sobie, Eric A.; Lederer, W. Jonathan; Jafri, M. Saleet

    2011-01-01

    A three dimensional model of calcium dynamics in the rat ventricular myocyte was developed to study the mechanism of calcium homeostasis and pathological calcium dynamics during calcium overload. The model contains 20,000 calcium release units (CRUs) each containing 49 ryanodine receptors. The model simulates calcium sparks with a realistic spontaneous calcium spark rate. It suggests that in addition to the calcium spark-based leak, there is an invisible calcium leak caused by the stochastic ...

  10. Mechanisms of calcium transport in small intestine. Overall review of the contract, September 1, 1972--March 1, 1976

    Energy Technology Data Exchange (ETDEWEB)

    DeLuca, H.F.

    1976-01-01

    Progress is reported in the following areas of research: role of high molecular weight protein in calcium transport in vitamin D deficient chicks; subcellular localization of 1,25-(OH)/sub 2/D/sub 3/; receptor proteins for 1,25-(OH)/sub 2/D/sub 3/; effects of high calcium diet, strontium diet, EHDP, and parathyroidectomy on intestinal calcium transport in chicks; effects of analogs of 1,25-(OH)/sub 2/D/sub 3/ on intestinal calcium transport; discrimination by chicks against vitamin D/sub 2/ compounds by metabolism; effects of extract of Solanum malacoxylan on intestinal calcium absorption in nephrectomized rats; and role of vitamin D in phosphate transport reactions in the intestine. (HLW)

  11. The mechanism of vapor phase hydration of calcium oxide: implications for CO2 capture.

    Science.gov (United States)

    Kudłacz, Krzysztof; Rodriguez-Navarro, Carlos

    2014-10-21

    Lime-based sorbents are used for fuel- and flue-gas capture, thereby representing an economic and effective way to reduce CO2 emissions. Their use involves cyclic carbonation/calcination which results in a significant conversion reduction with increasing number of cycles. To reactivate spent CaO, vapor phase hydration is typically performed. However, little is known about the ultimate mechanism of such a hydration process. Here, we show that the vapor phase hydration of CaO formed after calcination of calcite (CaCO3) single crystals is a pseudomorphic, topotactic process, which progresses via an intermediate disordered phase prior to the final formation of oriented Ca(OH)2 nanocrystals. The strong structural control during this solid-state phase transition implies that the microstructural features of the CaO parent phase predetermine the final structural and physicochemical (reactivity and attrition) features of the product hydroxide. The higher molar volume of the product can create an impervious shell around unreacted CaO, thereby limiting the efficiency of the reactivation process. However, in the case of compact, sintered CaO structures, volume expansion cannot be accommodated in the reduced pore volume, and stress generation leads to pervasive cracking. This favors complete hydration but also detrimental attrition. Implications of these results in carbon capture and storage (CCS) are discussed.

  12. Atomic-level characterization of the activation mechanism of SERCA by calcium.

    Directory of Open Access Journals (Sweden)

    L Michel Espinoza-Fonseca

    Full Text Available We have performed molecular dynamics (MD simulations to elucidate, in atomic detail, the mechanism by which the sarcoplasmic reticulum Ca(2+-ATPase (SERCA is activated by Ca(2+. Crystal structures suggest that activation of SERCA occurs when the cytoplasmic head-piece, in an open (E1 conformation stabilized by Ca(2+, undergoes a large-scale open-to-closed (E1 to E2 transition that is induced by ATP binding. However, spectroscopic measurements in solution suggest that these structural states (E1 and E2 are not tightly coupled to biochemical states (defined by bound ligands; the closed E2 state predominates even in the absence of ATP, in both the presence and absence of Ca(2+. How is this loose coupling consistent with the high efficiency of energy transduction in the Ca(2+-ATPase? To provide insight into this question, we performed long (500 ns all-atom MD simulations starting from the open crystal structure, including a lipid bilayer and water. In both the presence and absence of Ca(2+, we observed a large-scale open-to-closed conformational transition within 400 ns, supporting the weak coupling between structural and biochemical states. However, upon closer inspection, it is clear that Ca(2+ is necessary and sufficient for SERCA to reach the precise geometrical arrangement necessary for activation of ATP hydrolysis. Contrary to suggestions from crystal structures, but in agreement with solution spectroscopy, the presence of ATP is not required for this activating transition. Principal component analysis showed that Ca(2+ reshapes the free energy landscape of SERCA to create a path between the open conformation and the activated closed conformation. Thus the malleability of the free energy landscape is essential for SERCA efficiency, ensuring that ATP hydrolysis is tightly coupled to Ca(2+ transport. These results demonstrate the importance of real-time dynamics in the formation of catalytically competent conformations of SERCA, with broad

  13. Novel mechanism for the modification of Al2O3-based inclusions in ultra-low carbon Al-killed steel considering the effects of magnesium and calcium

    Science.gov (United States)

    Guo, Jing; Cheng, Shu-sen; Guo, Han-jie; Mei, Ya-guang

    2018-03-01

    Many researchers have explored the inclusion modification mechanism to improve non-metallic inclusion modifications in steelmaking. In this study, two types of industrial trials on inclusion modifications in liquid steel were conducted using ultra-low-carbon Al-killed steel with different Mg and Ca contents to verify the effects of Ca and Mg contents on the modification mechanism of Al2O3-based inclusions during secondary refining. The results showed that Al2O3-based inclusions can be modified into liquid calcium aluminate or a multi-component inclusion with the addition of a suitable amount of Ca. In addition, [Mg] in liquid steel can further reduce CaO in liquid calcium aluminate to drive its evolution into CaO-MgO-Al2O3 multi-component inclusions. Thermodynamic analysis confirmed that the reaction between [Mg] and CaO in liquid calcium aluminate occurs when the MgO content of liquid calcium aluminate is less than 3wt% and the temperature is higher than 1843 K.

  14. Calcium absorption

    International Nuclear Information System (INIS)

    Carlmark, B.; Reizenstein, P.; Dudley, R.A.

    1976-01-01

    The methods most commonly used to measure the absorption and retention of orally administered calcium are reviewed. Nearly all make use of calcium radioisotopes. The magnitude of calcium absorption and retention depends upon the chemical form and amount of calcium administered, and the clinical and nutritional status of the subject; these influences are briefly surveyed. (author)

  15. Cable handling

    International Nuclear Information System (INIS)

    1980-01-01

    In computerized axial tomography scanning, problems arise in exchanging electrical signals between fixed and rotating assemblies. A novel method of overcoming this problem is described in detail for both signal and high voltage cables. Apparatus using a sequence of drums and pulleys is used to maintain the interconnecting cables in a neat arrangement and free from mechanical strain. The apparatus is simple and relatively easy and inexpensive to assemble and maintain. (UK)

  16. Growth Rates and Mechanisms of Magmatic Orbicule Formation: Insights from Calcium Isotopes

    Science.gov (United States)

    Antonelli, M. A.; Watkins, J. M.; DePaolo, D. J.

    2017-12-01

    Orbicular diorites and granites are rare plutonic rock textures that remain enigmatic despite a century of study. Orbicules consist of a rounded core (xenolith, xenocryst, or autolith) surrounded by a variable number of concentric rings defined by different modal mineralogies and textures. Recent work suggests that the alternating layers of mineral growth are a consequence of either changes in external conditions of the magma (e.g. temperature, magma composition due to mixing, changes in volatile abundances), or rapid growth of one mineral phase (e.g plagioclase) creating a depleted boundary layer that then promotes precipitation of an alternative mineral phase (e.g. pyroxene). This process can be repeated to produce multiple layers. The rates at which orbicules grow is also of interest and relates to the mechanisms. Studies of orbicular diorites from the northern Sierra Nevada suggest exceptionally high growth rates (McCarthy et al., 2016). Ca isotopes can offer a unique perspective on orbicule formation, as diffusive isotope fractionation should be substantial when growth rates are high, and they are also sensitive to the nature of the growth medium (silicate liquid or supercritical fluid phase). We present δ44Ca measurements and chemistry for a transect of a dioritic orbicule collected from Emerald Lake, California (Sierra Nevada), where the growth layers are defined by variations in plagioclase/pyroxene ratio, grain size, and texture. Ca concentration varies from 5-13 wt%, and d44Ca values oscillate between -0.5 to 0.0‰ relative to BSE, correlating with changes in mineralogy and texture. Zones of plagioclase comb texture are associated with negative δ44Ca excursions of -0.2 to -0.4‰, consistent with diffusive isotope fractionation during rapid mineral growth. Assuming a 10‰ difference in diffusivity for 44Ca vs. 40Ca in dioritic liquids (Watson et al., 2016), and using the models of Watson and Muller (2009) as a guide, these small fractionations

  17. Protection of cortical cells by equine estrogens against glutamate-induced excitotoxicity is mediated through a calcium independent mechanism

    Directory of Open Access Journals (Sweden)

    Perrella Joel

    2005-05-01

    Full Text Available Abstract Background High concentrations of glutamate can accumulate in the brain and may be involved in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease. This form of neurotoxicity involves changes in the regulation of cellular calcium (Ca2+ and generation of free radicals such as peroxynitrite (ONOO-. Estrogen may protect against glutamate-induced cell death by reducing the excitotoxic Ca2+ influx associated with glutamate excitotoxicity. In this study, the inhibition of N-methyl-D-aspartate (NMDA receptor and nitric oxide synthase (NOS along with the effect of 17β-estradiol (17β-E2 and a more potent antioxidant Δ8, 17β-estradiol (Δ8, 17β-E2 on cell viability and intracellular Ca2+ ([Ca2+]i, following treatment of rat cortical cells with glutamate, was investigated. Results Primary rat cortical cells were cultured for 7–12 days in Neurobasal medium containing B27 supplements. Addition of glutamate (200 μM decreased cell viability to 51.3 ± 0.7% compared to control. Treatment with the noncompetitive NMDAR antagonist, MK-801, and the NOS inhibitor, L-NAME, completely prevented cell death. Pretreatment (24 hrs with 17β-E2 and Δ8, 17β-E2 (0.01 to 10 μM significantly reduced cell death. 17β-E2 was more potent than Δ8, 17β-E2. Glutamate caused a rapid 2.5 fold increase in [Ca2+]i. Treatment with 0.001 to 10 μM MK-801 reduced the initial Ca2+ influx by 14–41% and increased cell viability significantly. Pretreatment with 17β-E2 and Δ8, 17β-E2 had no effect on Ca2+ influx but protected the cortical cells against glutamate-induced cell death. Conclusion Glutamate-induced cell death in cortical cultures can occur through NMDAR and NOS-linked mechanisms by increasing nitric oxide and ONOO-. Equine estrogens: 17β-E2 and Δ8, 17β-E2, significantly protected cortical cells against glutamate-induced excitotoxicity by a mechanism that appears to be independent of Ca2+ influx. To our knowledge, this is a first

  18. Handling uncertainty

    DEFF Research Database (Denmark)

    Jønsson, Jesper Bosse; Fold, Niels

    2009-01-01

    Small-scale mining supports the livelihoods of several hundred thousand rural households in Africa. Nonetheless, the understanding of the organizational dynamics of small-scale miners' activities is modest. The paper outlines the small-scale mining codes in Tanzania and contrasts them to prevalent...... organizational practices in two Tanzanian small-scale mining settlements. It is argued that there is a need to adjust the regulatory mechanisms to well-consolidated practices: If basic practices differ substantially from official prescriptions of the mining codes over an extended period of time, certain elements...... manoeuvring of local small-scale mining operators and the reasons for the variations are essential to understand for policymakers and development practitioners. By incorporating prevalent practices and context-dependent variations in some of the crucial organizational components, it is possible to design...

  19. The Plasma Membrane Calcium Pump

    Science.gov (United States)

    Rasmussen, H.

    1983-01-01

    Three aspect of cellular calcium metabolism in animal cells was discussed including the importance of the plasma membrane in calcium homeostasis, experiments dealing with the actual mechanism of the calcium pump, and the function of the pump in relationship to the mitochondria and to the function of calmodulin in the intact cell.

  20. Mechanism of small-polaron formation in the biferroic YCrO{sub 3} doped with calcium

    Energy Technology Data Exchange (ETDEWEB)

    Duran, A., E-mail: dural@cnyn.unam.mx [Universidad Nacional Autonoma de Mexico, Centro de Nanociencias y Nanotecnologia, Apartado Postal 41, C.P. 22800, Ensenada, B.C. (Mexico); Verdin, E. [Universidad de Sonora, Departamento de Fisica, Apartado Postal 1626, Hermosillo, Sonora C.P. 8300 (Mexico); Escamilla, R.; Morales, F.; Escudero, R. [Universidad Nacional Autonoma de Mexico, Instituto de Investigaciones en Materiales, Apartado Postal 70-360, Mexico D.F. 04510 (Mexico)

    2012-04-16

    Highlights: Black-Right-Pointing-Pointer The Ca doped in the YCrO3 matrix was analyzed by means of complete structural, magnetic and electric properties. Black-Right-Pointing-Pointer E{sub act} deduced by Arrhenius' Law suggests small-polarons as conduction mechanisms in pristine and doped sample. Black-Right-Pointing-Pointer Local non-centrosymmetry in pristine sample is proposed as responsible of small polarons formation. Black-Right-Pointing-Pointer A mechanism of formation of small polarons is proposed supported by experimental evidence. Black-Right-Pointing-Pointer The structural distortion caused by the Ca doped in the YCrO3 matrix is harmful to the Ferroic properties. - Abstract: The effects of Ca substitutions on the structure, magnetism and electrical properties of YCrO{sub 3} ceramics are investigated by X-ray diffraction, magnetic susceptibility and electrical conductivity measurements. The cell volume decrease occurs through the change from Cr(III) to Cr(IV) as a result of the charge compensation of the Ca doping. No changes are observed in the antiferromagnetic transition temperature while strong changes are observed in the transport measurements due to Ca content. The increase of the electrical conductivity as well as the decrease of the activation energy is caused by the formation of the small-polarons localized in the O-Cr-O lattice distortion. The origin of small-polarons in the undoped sample is different in nature from the calcium doped. 'Local non-centrosymmetry' is the source of the small-polaron formation in undoped sample, while the change from Cr(III) to Cr(IV) through the charge compensation of Ca(II) in the Y(III) site is the source of small-polarons formations. The decrease of the average bond length Cr-O as well as effective moments in the paramagnetic state and the increase of the electrical conductivity are clear evidence that the Ca doping induces localized polarons, which in turn, these quasiparticles move from site to

  1. Noradrenergic mechanisms and high blood pressure maintenance in genetic hypertension: The role of Gi proteins and voltage-dependent calcium channels

    Czech Academy of Sciences Publication Activity Database

    Zicha, Josef; Pintérová, Mária; Líšková, Silvia; Dobešová, Zdenka; Kuneš, Jaroslav

    2007-01-01

    Roč. 29, č. 4 (2007), s. 229-229 ISSN 1064-1963. [International symposium on SHR /12./. 20.10.2006-21.10.2006, Kyoto] R&D Projects: GA MZd(CZ) NR7786 Institutional research plan: CEZ:AV0Z50110509 Keywords : genetic hypertension * noradrenergic mechanisms * Gi proteins * voltage-dependent calcium channels Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery

  2. Mechanical strain stimulates vasculogenesis and expression of angiogenesis guidance molecules of embryonic stem cells through elevation of intracellular calcium, reactive oxygen species and nitric oxide generation.

    Science.gov (United States)

    Sharifpanah, Fatemeh; Behr, Sascha; Wartenberg, Maria; Sauer, Heinrich

    2016-12-01

    Differentiation of embryonic stem (ES) cells may be regulated by mechanical strain. Herein, signaling molecules underlying mechanical stimulation of vasculogenesis and expression of angiogenesis guidance cues were investigated in ES cell-derived embryoid bodies. Treatment of embryoid bodies with 10% static mechanical strain using a Flexercell strain system significantly increased CD31-positive vascular structures and the angiogenesis guidance molecules plexinB1, ephrin B2, neuropilin1 (NRP1), semaphorin 4D (sem4D) and robo4 as well as vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2) and platelet-derived growth factor-BB (PDGF-BB) as evaluated by Western blot and real time RT-PCR. In contrast ephrin type 4 receptor B (EphB4) expression was down-regulated upon mechanical strain, indicating an arterial-type differentiation. Robo1 protein expression was modestly increased with no change in mRNA expression. Mechanical strain increased intracellular calcium as well as reactive oxygen species (ROS) and nitric oxide (NO). Mechanical strain-induced vasculogenesis was abolished by the NOS inhibitor L-NAME, the NADPH oxidase inhibitor VAS2870, upon chelation of intracellular calcium by BAPTA as well as upon siRNA inactivation of ephrin B2, NRP1 and robo4. BAPTA blunted the strain-induced expression of angiogenic growth factors, the increase in NO and ROS as well as the expression of NRP1, sem4D and plexinB1, whereas ephrin B2, EphB4 as well as robo1 and robo4 expression were not impaired. Mechanical strain stimulates vasculogenesis of ES cells by the intracellular messengers ROS, NO and calcium as well as by upregulation of angiogenesis guidance molecules and the angiogenic growth factors VEGF, FGF-2 and PDGF-BB. Copyright © 2016 Elsevier B.V. All rights reserved.

  3. [Role of calcium ions in the mechanism of action of acetylcholine on energy metabolism in rat liver mitochondria].

    Science.gov (United States)

    Vatamaniuk, M Z; Artym, V V; Kuka, O B; Doliba, M M; Shostakovs'ka, I V

    1996-01-01

    It is shown that administration of acetylcholine to animals (50 micrograms per 100 g of body weight) leads to the activation of respiration and oxidative phosphorylation in the rat liver mitochondria under oxidation of alpha-ketoglutarate; this effect depends on the concentration of calcium ions in the incubation medium of mitochondria. The rate of ADP-stimulated respiration of mitochondria of experimental animals reaches its maximum level under lower concentrations of Ca2+ than in the control animals. The results of investigation of dependence of acetyl choline effect on respiration of mitochondria on the concentration of alpha-ketoglutarate in calcium and calcium-free incubation medium have shown that the half-maximum effect of acetylcholine is observed in calcium medium at lower concentration of the substrate than in calcium-free medium. The latter indicates to the increase of affinity of alpha-ketoglutarate dehydrogenase to alpha-ketoglutarate under these conditions. It is found out that acetylcholine (1.10(-8) M) increases the rate of ADP- and Ca(2+)-stimulated respiration of mitochondria of isolated perfused rat liver, while mutual effect of verapamyl and niphedipin removes this effect.

  4. The mechanical and biological studies of calcium phosphate cement-fibrin glue for bone reconstruction of rabbit femoral defects

    Directory of Open Access Journals (Sweden)

    Dong J

    2013-03-01

    Full Text Available Jingjing Dong,1,* Geng Cui,2,* Long Bi,1,* Jie Li,3 Wei Lei11Institute of Orthopedics, Xijing Hospital, Fourth Military Medical University, Xi’an, Shaanxi, People’s Republic of China; 2Institute of Orthopedics, General Hospital of PLA, Beijing, People’s Republic of China; 3Institute of Gynecology and Obstetrics, General Hospital of PLA, Beijing, People’s Republic of China*These authors contributed equally to this workAbstract: In order to improve the mechanical and biological properties of calcium phosphate cement (CPC, nanometer-biomaterial for bone reconstruction in the rabbit femoral defect model, fibrin glue (FG, the natural product, purified from the blood was introduced at three different ratios. The CPC powder and the FG solution were mixed, respectively, at the powder/liquid (P/L ratios (g/mL of 1:1, 3:1, and 5:1 (g/mL, and pure CPC was used as a control. After being implanted into the femoral defect in rabbit, the healing process was evaluated by micro-computed tomography scan, biomechanical testing, and histological examination. By micro-computed tomography analysis, the P/L ratio of 1:1 (g/mL group indicated the largest quantity of new bone formation at 4 weeks, 8 weeks, and 12 weeks after implantation, respectively. Bone volume per trabecular volume of the 1:1 group was highest in the four groups, which was 1.45% ± 0.42%, 7.35% ± 1.45%, and 29.10% ± 1.67% at 4 weeks, 8 weeks, and 12 weeks after the operation, respectively. In the biomechanical tests, the compressive strength and the elastic modulus of the three CPC–FG groups were much higher than those of the pure CPC group at the determined time point (P < 0.05. The histological evaluation also showed the best osseointegration in the 1:1 group at 4 weeks, 8 weeks, and 12 weeks after the operation, respectively. In the 1:1 group, the bone grew into the pore of the cement in the laminar arrangement and connected with the cement tightly at the 12th week after the operation

  5. Calcium - ionized

    Science.gov (United States)

    ... diuretics Thrombocytosis (high platelet count) Tumors Vitamin A excess Vitamin D excess Lower-than-normal levels may be due to: Hypoparathyroidism Malabsorption Osteomalacia Pancreatitis Renal failure Rickets Vitamin D deficiency Alternative Names Free calcium; Ionized calcium ...

  6. Calcium Carbonate

    Science.gov (United States)

    ... Calcium is needed by the body for healthy bones, muscles, nervous system, and heart. Calcium carbonate also ... to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in ...

  7. LOW CONCENTRATION MERCURY SORPTION MECHANISMS AND CONTROL BY CALCIUM-BASED SORBENTS; APPLICATION IN COAL-FIRED PROCESSES

    Science.gov (United States)

    The capture of elemental mercury (Hgo) and mercuric chloride (HgCl2) by three types of calcium (Ca)-based sorbents was examined in this bench-scale study under conditions prevalent in coal fired utilities. Ca-based sorbent performances were compared to that of an activated carbon...

  8. Bulk physicochemical, interconnectivity, and mechanical properties of calcium phosphate cements-fibrin glue composites for bone substitute applications

    NARCIS (Netherlands)

    Lopez-Heredia, M.A.; Pattipeilohy, J.; Hsu, S.; Grykien, M.; Weijden, B. van der; Leeuwenburgh, S.C.G.; Salmon, P.; Wolke, J.G.C.; Jansen, J.A.

    2013-01-01

    Calcium phosphate cements (CPCs) and fibrin glue (FG) are used for surgical applications. Their combination is promising to create bone substitutes able to promote cell attachment and bone remodeling. This study proposes a novel approach to create CPC-FG composites by simultaneous CPC setting and FG

  9. Ergonomic material-handling device

    Science.gov (United States)

    Barsnick, Lance E.; Zalk, David M.; Perry, Catherine M.; Biggs, Terry; Tageson, Robert E.

    2004-08-24

    A hand-held ergonomic material-handling device capable of moving heavy objects, such as large waste containers and other large objects requiring mechanical assistance. The ergonomic material-handling device can be used with neutral postures of the back, shoulders, wrists and knees, thereby reducing potential injury to the user. The device involves two key features: 1) gives the user the ability to adjust the height of the handles of the device to ergonomically fit the needs of the user's back, wrists and shoulders; and 2) has a rounded handlebar shape, as well as the size and configuration of the handles which keep the user's wrists in a neutral posture during manipulation of the device.

  10. Specific corrosion product on interior surface of a bronze wine vessel with loop-handle and its growth mechanism, Shang Dynasty, China

    International Nuclear Information System (INIS)

    Li Yang; Bao Zhirong; Wu Taotao; Jiang, Junchun; Chen Guantao; Pan Chunxu

    2012-01-01

    In this paper, a kind of specific stalactitic product was found on the interior surface of a covered bronze wine vessel with loop-handle (Chinese name is you), which was fabricated in Shang Dynasty (1700 B.C.–1100 B.C.) and now is collected in Xiaogan Museum, Hubei province of China. The microstructures of the product were characterized systematically by using optical microscopy, scanning electron microscope, transmission electron microscope, X-ray diffraction, and Raman microscopy. The experimental results revealed that the product belonged to a kind of malachite with high purity and high crystallinity. The growth of the product was considered to be a possible reason that the vessel was overly airtight within a museum display cabinet besides a lid of the vessel, which made the excess of H 2 O and CO 2 gas concentrations inside the vessel during long-term storage. This corrosion product is very harmful to bronze cultural relics, because of a large amount of copper consumption from the matrix which will reduce its life. The growth mechanism of the specific stalactitic product and the suggestions for preservation of the similar bronze relics in museum were proposed. - Highlights: ► The stalactitic product was the high purity and good crystallinity malachite. ► Its growth was related to the excess of H 2 O and CO 2 gas concentrations in museum. ► It is harmful to the bronzes, because copper will be consumed from the matrix. ► The suggestions for preservation of the similar bronzes in museum were proposed.

  11. Specific corrosion product on interior surface of a bronze wine vessel with loop-handle and its growth mechanism, Shang Dynasty, China

    Energy Technology Data Exchange (ETDEWEB)

    Li Yang; Bao Zhirong; Wu Taotao [School of Physics and Technology, Center for Electron Microscopy and MOE Key Laboratory of Artificial Micro- and Nano-structures, Wuhan University, Wuhan 430072 (China); Jiang, Junchun [Xiaogan Museum, Xiaogan 432000 (China); Chen Guantao [Center for Archaeometry, Wuhan University, Wuhan 430072 (China); Pan Chunxu, E-mail: cxpan@whu.edu.cn [School of Physics and Technology, Center for Electron Microscopy and MOE Key Laboratory of Artificial Micro- and Nano-structures, Wuhan University, Wuhan 430072 (China); Center for Archaeometry, Wuhan University, Wuhan 430072 (China)

    2012-06-15

    In this paper, a kind of specific stalactitic product was found on the interior surface of a covered bronze wine vessel with loop-handle (Chinese name is you), which was fabricated in Shang Dynasty (1700 B.C.-1100 B.C.) and now is collected in Xiaogan Museum, Hubei province of China. The microstructures of the product were characterized systematically by using optical microscopy, scanning electron microscope, transmission electron microscope, X-ray diffraction, and Raman microscopy. The experimental results revealed that the product belonged to a kind of malachite with high purity and high crystallinity. The growth of the product was considered to be a possible reason that the vessel was overly airtight within a museum display cabinet besides a lid of the vessel, which made the excess of H{sub 2}O and CO{sub 2} gas concentrations inside the vessel during long-term storage. This corrosion product is very harmful to bronze cultural relics, because of a large amount of copper consumption from the matrix which will reduce its life. The growth mechanism of the specific stalactitic product and the suggestions for preservation of the similar bronze relics in museum were proposed. - Highlights: Black-Right-Pointing-Pointer The stalactitic product was the high purity and good crystallinity malachite. Black-Right-Pointing-Pointer Its growth was related to the excess of H{sub 2}O and CO{sub 2} gas concentrations in museum. Black-Right-Pointing-Pointer It is harmful to the bronzes, because copper will be consumed from the matrix. Black-Right-Pointing-Pointer The suggestions for preservation of the similar bronzes in museum were proposed.

  12. Development of a degradable cement of calcium phosphate and calcium sulfate composite for bone reconstruction

    International Nuclear Information System (INIS)

    Guo, H; Wei, J; Liu, C S

    2006-01-01

    A new type of composite bone cement was prepared and investigated by adding calcium sulfate (CS) to calcium phosphate cement (CPC). This composite cement can be handled as a paste and easily shaped into any contour, which can set within 5-20 min, the setting time largely depending on the liquid-solid (L/S) ratio; adding CS to CPC had little effect on the setting time of the composite cements. No obvious temperature increase and pH change were observed during setting and immersion in simulated body fluid (SBF). The compressive strength of the cement decreased with an increase in the content of CS. The degradation rate of the composite cements increased with time when the CS content was more than 20 wt%. Calcium deficient apatite could form on the surface of the composite cement because the release of calcium into SBF from the dissolution of CS and the apatite of the cement induced the new apatite formation; increasing the content of CS in the composite could improve the bioactivity of the composite cements. The results suggested that composite cement has a reasonable setting time, excellent degradability and suitable mechanical strength and bioactivity, which shows promising prospects for development as a clinical cement

  13. Production and characterization of setting hydraulic cements based on calcium phosphate

    International Nuclear Information System (INIS)

    Oliveira, Luci C. de; Rigo, Eliana C.S.; Santos, Luis A dos; Boschi, Anselmo Ortega; Carrodeguas, Raul G.

    1997-01-01

    Setting hydraulic cements based on calcium phosphate has risen great interest in scientific literature during recent years due to their total bio compatibility and to the fact that they harden 'in situ', providing easy handling and adaptation to the shape and dimensions of the defect which requires correction, differently from the predecessors, the calcium phosphate ceramics (Hydroxy apatite, β-tri calcium phosphate, biphasic, etc) in the shape of dense or porous blocks and grains. In the work, three calcium-phosphate cement compositions were studied. The resulting compositions were characterized according to the following aspects: setting times, pH, mechanical resistance, crystalline phases, microstructure and solubility in SBF (Simulated Body Fluid). The results show a potential use for the compositions. (author)

  14. Molecular mechanisms of oxidative and radiation stress effect to the status of calcium homeostasis of immune system cells

    International Nuclear Information System (INIS)

    Pukhteeva, I.V.; Gerasimovich, N.V.

    2007-01-01

    In some works ability of active forms of oxygen and low doses of irradiation to damage biological molecules and theirs role in the disorganisation of the cellular structures is shown. The dynamics of the change of the ratio of the free and connected calcium in thymocytes of the rats after the influence of peroxide (10-9 - 10-3 M) and the irradiation in low doses and the structural state of plasmatic membrane in the present work was analysed. The peroxide and irradiation brought about the modification of the structured organization of the plasmatic membrane and calcium homeostasis. Thus the results of the influence of the peroxide and low doses of ionizing irradiation on the cells of the immune system are similar.(authors)

  15. Mitochondrial Calcium Dysregulation Contributes to Dendrite Degeneration Mediated by PD/LBD-Associated LRRK2 Mutants.

    Science.gov (United States)

    Verma, Manish; Callio, Jason; Otero, P Anthony; Sekler, Israel; Wills, Zachary P; Chu, Charleen T

    2017-11-15

    Mutations in leucine-rich repeat kinase 2 (LRRK2) contribute to development of late-onset familial Parkinson's disease (PD), with clinical features of motor and cognitive dysfunction indistinguishable from sporadic PD. Calcium dysregulation plays an important role in PD pathogenesis, but the mechanisms of neurodegeneration remain unclear. Recent reports indicate enhanced excitatory neurotransmission in cortical neurons expressing mutant LRRK2, which occurs before the well-characterized phenotype of dendritic shortening. As mitochondria play a major role in the rapid buffering of cytosolic calcium, we hypothesized that altered mitochondrial calcium handling contributes to dendritic retraction elicited by the LRRK2-G2019S and -R1441C mutations. In primary mouse cortical neurons, we observed increased depolarization-induced mitochondrial calcium uptake. We found that expression of mutant LRRK2 elicited transcriptional upregulation of the mitochondrial calcium uniporter (MCU) and the mitochondrial calcium uptake 1 protein (MICU1) with no change in levels of the mitochondrial calcium antiporter NCLX. Elevated MCU and MICU1 were also observed in LRRK2-mutated patient fibroblasts, along with increased mitochondrial calcium uptake, and in postmortem brains of sporadic PD/PDD patients of both sexes. Transcriptional upregulation of MCU and MICU1 was caused by activation of the ERK1/2 (MAPK3/1) pathway. Inhibiting ERK1/2 conferred protection against mutant LRRK2-induced neurite shortening. Pharmacological inhibitors or RNAi knockdown of MCU attenuated mitochondrial calcium uptake and dendritic/neuritic shortening elicited by mutant LRRK2, whereas expression of a constitutively active mutant of NCLX that enhances calcium export from mitochondria was neuroprotective. These data suggest that an increased susceptibility to mitochondrial calcium dysregulation contributes to dendritic injury in mutant LRRK2 pathogenesis. SIGNIFICANCE STATEMENT Cognitive dysfunction and dementia are

  16. Calcium waves.

    Science.gov (United States)

    Jaffe, Lionel F

    2008-04-12

    Waves through living systems are best characterized by their speeds at 20 degrees C. These speeds vary from those of calcium action potentials to those of ultraslow ones which move at 1-10 and/or 10-20 nm s(-1). All such waves are known or inferred to be calcium waves. The two classes of calcium waves which include ones with important morphogenetic effects are slow waves that move at 0.2-2 microm s(-1) and ultraslow ones. Both may be propagated by cycles in which the entry of calcium through the plasma membrane induces subsurface contraction. This contraction opens nearby stretch-sensitive calcium channels. Calcium entry through these channels propagates the calcium wave. Many slow waves are seen as waves of indentation. Some are considered to act via cellular peristalsis; for example, those which seem to drive the germ plasm to the vegetal pole of the Xenopus egg. Other good examples of morphogenetic slow waves are ones through fertilizing maize eggs, through developing barnacle eggs and through axolotl embryos during neural induction. Good examples of ultraslow morphogenetic waves are ones during inversion in developing Volvox embryos and across developing Drosophila eye discs. Morphogenetic waves may be best pursued by imaging their calcium with aequorins.

  17. Deterioration of the mechanical properties of calcium phosphate cements with Poly (γ-glutamic acid) and its strontium salt after in vitro degradation.

    Science.gov (United States)

    Liang, Ting; Gao, Chun-Xia; Yang, Lei; Saijilafu; Yang, Hui-Lin; Luo, Zong-Ping

    2017-11-01

    The mechanical reliability of calcium phosphate cements has restricted their clinical application in load-bearing locations. Although their mechanical strength can be improved using a variety of strategies, their fatigue properties are still unclear, especially after degradation. The evolutions of uniaxial compressive properties and the fatigue behavior of calcium phosphate cements incorporating poly (γ-glutamic acid) and its strontium salt after different in vitro degradation times were investigated in the present study. Compressive strength decreased from the 61.2±5.4MPa of the original specimen, to 51.1±4.4, 42.2±3.8, 36.8±2.4 and 28.9±3.2MPa following degradation for one, two, three and four weeks, respectively. Fatigue life under same loading condition also decreased with increasing degradation time. The original specimens remained intact for one million cycles (run-out) under a maximum stress of 30MPa. After degradation for one to four weeks, the specimens were able to withstand maximum stress of 20, 15, 10 and 10MPa, respectively until run-out. Defect volume fraction within the specimens increased from 0.19±0.021% of the original specimen to 0.60±0.19%, 1.09±0.04%, 2.68±0.64% and 7.18±0.34% at degradation time of one, two, three and four weeks, respectively. Therefore, we can infer that the primary cause of the deterioration of the mechanical properties was an increasing in micro defects induced by degradation, which promoted crack initiation and propagation, accelerating the final mechanical failure of the bone cement. This study provided the data required for enhancing the mechanical reliability of the calcium phosphate cements after different degradation times, which will be significant for the modification of load-bearing biodegradable bone cements to match clinical application. Copyright © 2017 Elsevier Ltd. All rights reserved.

  18. Complex formation ions calcium with macromolecules pectin

    International Nuclear Information System (INIS)

    Khalikova, M.D.; Avloev, Kh.Kh.; Muhiddinov, Z.K.

    2005-01-01

    In clause the mechanism of sorption of ions of calcium by macromolecules of pectin is opened. Is shown, that the linkage of ions of calcium descends on acid bunches of pectin, and process carries cooperative character

  19. Calcium Signaling in Taste Cells

    Science.gov (United States)

    Medler, Kathryn F.

    2014-01-01

    The sense of taste is a common ability shared by all organisms and is used to detect nutrients as well as potentially harmful compounds. Thus taste is critical to survival. Despite its importance, surprisingly little is known about the mechanisms generating and regulating responses to taste stimuli. All taste responses depend on calcium signals to generate appropriate responses which are relayed to the brain. Some taste cells have conventional synapses and rely on calcium influx through voltage-gated calcium channels. Other taste cells lack these synapses and depend on calcium release to formulate an output signal through a hemichannel. Beyond establishing these characteristics, few studies have focused on understanding how these calcium signals are formed. We identified multiple calcium clearance mechanisms that regulate calcium levels in taste cells as well as a calcium influx that contributes to maintaining appropriate calcium homeostasis in these cells. Multiple factors regulate the evoked taste signals with varying roles in different cell populations. Clearly, calcium signaling is a dynamic process in taste cells and is more complex than has previously been appreciated. PMID:25450977

  20. Enhanced removal of humic acid from aqueous solution by novel stabilized nano-amorphous calcium phosphate: Behaviors and mechanisms

    Science.gov (United States)

    Jiang, Ling; Li, Yiming; Shao, Yi; Zhang, Yong; Han, Ruiming; Li, Shiyin; Wei, Wei

    2018-01-01

    Stabilized nano-amorphous calcium phosphate (nACP) was prepared using polyethylene glycol as stabilizer to obtain a nanosized amorphous adsorbent. The produced nACP was evaluated by using XRD, FTIR, SEM and X-ray photoelectron spectroscopy (XPS). The sedimentation test demonstrated that nACP exhibited better stability than crystallized hydroxyapatite. The adsorption efficiency of the nACP material for aqueous humic acid (HA) was evaluated from the point of view of medium pH, adsorption time, temperature, and ionic strength, as well as the presences of metal ions. The results of the study showed very good adsorption performance towards aqueous HA. The Sips modeling results revealed that the stabilized nACP adsorbent had a considerably high adsorption capacity (248.3 mg/g) for HA at 298 K. The adsorption data fitted well into pseudo-second order and Elovich kinetic models. XPS analyses indicated that HA retention on nACP material might be due to the surface complexation reaction between oxygen-containing group and calcium of HA and nACP, respectively. Moreover, the HA adsorption capacity of nACP could still keep more than 86% after four adsorption-desorption cycles. By taking into account all results it was concluded that the nACP adsorbent leveraged its stability in combination with its high uptake capacity to offer a great promise for HA adsorption from water.

  1. Inhibition of T-Type Voltage Sensitive Calcium Channel Reduces Load-Induced OA in Mice and Suppresses the Catabolic Effect of Bone Mechanical Stress on Chondrocytes.

    Directory of Open Access Journals (Sweden)

    Padma P Srinivasan

    Full Text Available Voltage-sensitive calcium channels (VSCC regulate cellular calcium influx, one of the earliest responses to mechanical stimulation in osteoblasts. Here, we postulate that T-type VSCCs play an essential role in bone mechanical response to load and participate in events leading to the pathology of load-induced OA. Repetitive mechanical insult was used to induce OA in Cav3.2 T-VSCC null and wild-type control mouse knees. Osteoblasts (MC3T3-E1 and chondrocytes were treated with a selective T-VSCC inhibitor and subjected to fluid shear stress to determine how blocking of T-VSCCs alters the expression profile of each cell type upon mechanical stimulation. Conditioned-media (CM obtained from static and sheared MC3T3-E1 was used to assess the effect of osteoblast-derived factors on the chondrocyte phenotype. T-VSCC null knees exhibited significantly lower focal articular cartilage damage than age-matched controls. In vitro inhibition of T-VSCC significantly reduced the expression of both early and late mechanoresponsive genes in osteoblasts but had no effect on gene expression in chondrocytes. Furthermore, treatment of chondrocytes with CM obtained from sheared osteoblasts induced expression of markers of hypertrophy in chondrocytes and this was nearly abolished when osteoblasts were pre-treated with the T-VSCC-specific inhibitor. These results indicate that T-VSCC plays a role in signaling events associated with induction of OA and is essential to the release of osteoblast-derived factors that promote an early OA phenotype in chondrocytes. Further, these findings suggest that local inhibition of T-VSCC may serve as a therapy for blocking load-induced bone formation that results in cartilage degeneration.

  2. Peeping into human renal calcium oxalate stone matrix: characterization of novel proteins involved in the intricate mechanism of urolithiasis.

    Directory of Open Access Journals (Sweden)

    Kanu Priya Aggarwal

    Full Text Available BACKGROUND: The increasing number of patients suffering from urolithiasis represents one of the major challenges which nephrologists face worldwide today. For enhancing therapeutic outcomes of this disease, the pathogenic basis for the formation of renal stones is the need of hour. Proteins are found as major component in human renal stone matrix and are considered to have a potential role in crystal-membrane interaction, crystal growth and stone formation but their role in urolithiasis still remains obscure. METHODS: Proteins were isolated from the matrix of human CaOx containing kidney stones. Proteins having MW>3 kDa were subjected to anion exchange chromatography followed by molecular-sieve chromatography. The effect of these purified proteins was tested against CaOx nucleation and growth and on oxalate injured Madin-Darby Canine Kidney (MDCK renal epithelial cells for their activity. Proteins were identified by Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF MS followed by database search with MASCOT server. In silico molecular interaction studies with CaOx crystals were also investigated. RESULTS: Five proteins were identified from the matrix of calcium oxalate kidney stones by MALDI-TOF MS followed by database search with MASCOT server with the competence to control the stone formation process. Out of which two proteins were promoters, two were inhibitors and one protein had a dual activity of both inhibition and promotion towards CaOx nucleation and growth. Further molecular modelling calculations revealed the mode of interaction of these proteins with CaOx at the molecular level. CONCLUSIONS: We identified and characterized Ethanolamine-phosphate cytidylyltransferase, Ras GTPase-activating-like protein, UDP-glucose:glycoprotein glucosyltransferase 2, RIMS-binding protein 3A, Macrophage-capping protein as novel proteins from the matrix of human calcium oxalate stone which play a critical role in kidney stone

  3. A novel and easy-to-prepare strontium(II) modified calcium phosphate bone cement with enhanced mechanical properties.

    Science.gov (United States)

    Schumacher, M; Henß, A; Rohnke, M; Gelinsky, M

    2013-07-01

    The aim of this study was to evaluate two different approaches to obtaining strontium-modified calcium phosphate bone cements (SrCPCs) without elaborate synthesis of Sr-containing calcium phosphate species as cement precursors that could release biologically effective doses of Sr(2+) and thus could improve the healing of osteoporotic bone defects. Using strontium carbonate as a strontium(II) source, it was introduced into a hydroxyapatite-forming cement either by the addition of SrCO3 to an α-tricalcium phosphate-based cement precursor mixture (A-type) or by substitution of CaCO3 by SrCO3 during precursor composition (S-type). The cements, obtained after setting in a water-saturated atmosphere, contained up to 2.2at.% strontium in different distribution patterns as determined by time-of-flight secondary ion mass spectrometry and energy-dispersive X-ray spectroscopy. The setting time of CPC and A-type cements was in the range of 6.5-7.5min and increased for substitution-type cements (12.5-13.0min). Set cements had an open porosity between 26 and 42%. Compressive strength was found to increase from 29MPa up to 90% in substituted S-type cements (58MPa). SrCPC samples released between 0.45 and 1.53mgg(-1) Sr(2+) within 21days and showed increased radiopacity. Based on these findings, the SrCPC developed in this study could be beneficial for the treatment of defects of systemically impaired (e.g. osteoporotic) bone. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  4. FGF-23 dysregulates calcium homeostasis and electrophysiological properties in HL-1 atrial cells.

    Science.gov (United States)

    Kao, Yu-Hsun; Chen, Yao-Chang; Lin, Yung-Kuo; Shiu, Rong-Jie; Chao, Tze-Fan; Chen, Shih-Ann; Chen, Yi-Jen

    2014-08-01

    Fibroblast growth factor (FGF)-23 is a key regulator of phosphate homeostasis. Higher FGF-23 levels are correlated with poor outcomes in cardiovascular diseases. FGF-23 can produce cardiac hypertrophy and increase intracellular calcium, which can change cardiac electrical activity. However, it is not clear whether FGF-23 possesses arrhythmogenic potential through calcium dysregulation. Therefore, the purposes of this study were to evaluate the electrophysiological effects of FGF-23 and identify the underlying mechanisms. Patch clamp, confocal microscope with Fluo-4 fluorescence, and Western blot analyses were used to evaluate the electrophysiological characteristics, calcium homeostasis and calcium regulatory proteins in HL-1 atrial myocytes with and without FGF-23 (10 and 25 ng/mL) incubation for 24 h. FGF-23 (25 ng/mL) increased L-type calcium currents, calcium transient and sarcoplasmic reticulum Ca(2+) contents in HL-1 cells. FGF-23 (25 ng/mL)-treated cells (n = 14) had greater incidences (57%, 17% and 15%, P calcium/calmodulin-dependent protein kinase IIδ and phospholamban (PLB) at threonine 17 but had similar phosphorylation extents of PLB at serine 16, total PLB and sarcoplasmic reticulum Ca(2+) -ATPase protein. Moreover, the FGF receptor inhibitor (PD173074, 10 nM), calmodulin inhibitor (W7, 5 μM) and phospholipase C inhibitor (U73122, 1 μM) attenuated the effects of FGF-23 on calcium/calmodulin-dependent protein kinase II phosphorylation. FGF-23 increases HL-1 cells arrhythmogenesis with calcium dysregulation through modulating calcium-handling proteins. © 2014 Stichting European Society for Clinical Investigation Journal Foundation.

  5. Structural and nano-mechanical properties of Calcium Silicate Hydrate (C-S-H) formed from alite hydration in the presence of sodium and potassium hydroxide

    Energy Technology Data Exchange (ETDEWEB)

    Mendoza, Oscar, E-mail: oamendoz@unal.edu.co [Grupo del Cemento y Materiales de Construcción (CEMATCO). Universidad Nacional de Colombia, Facultad de Minas, Medellín (Colombia); Giraldo, Carolina [Cementos Argos S.A., Medellín (Colombia); Camargo, Sergio S. [Engenharia Metalúrgica e de Materiais, Universidade Federal do Rio de Janeiro/COPPE, Rio de Janeiro (Brazil); Tobón, Jorge I. [Grupo del Cemento y Materiales de Construcción (CEMATCO). Universidad Nacional de Colombia, Facultad de Minas, Medellín (Colombia)

    2015-08-15

    This research evaluates the effect of sodium and potassium hydroxide on the structure and nano-mechanical properties of Calcium Silicate Hydrate (C-S-H) formed from the hydration of pure alite. Monoclinic (MIII) alite was synthesized and hydrated, using water-to-alite ratios of 0.5 and 0.6 and additions of 10% NaOH and KOH by weight of alite. Based on results of X-ray diffraction, isothermal calorimetry, thermogravimetric analysis, Nuclear Magnetic Resonance and nanoindentation, two different effects of the alkaline hydroxides on the hydration reaction of alite, both at early and later ages, can be identified: (i) a differentiated hydration process, attributed to an enhancement in calcium hydroxide (CH) precipitation and a stimulation of the C-S-H nuclei; and (ii) an increase in the elastic modulus of the C-S-H aggregations, attributed to an electrostatic attraction between positive charges from the alkaline cations and negative charges from the C-S-H structure.

  6. Structural and nano-mechanical properties of Calcium Silicate Hydrate (C-S-H) formed from alite hydration in the presence of sodium and potassium hydroxide

    International Nuclear Information System (INIS)

    Mendoza, Oscar; Giraldo, Carolina; Camargo, Sergio S.; Tobón, Jorge I.

    2015-01-01

    This research evaluates the effect of sodium and potassium hydroxide on the structure and nano-mechanical properties of Calcium Silicate Hydrate (C-S-H) formed from the hydration of pure alite. Monoclinic (MIII) alite was synthesized and hydrated, using water-to-alite ratios of 0.5 and 0.6 and additions of 10% NaOH and KOH by weight of alite. Based on results of X-ray diffraction, isothermal calorimetry, thermogravimetric analysis, Nuclear Magnetic Resonance and nanoindentation, two different effects of the alkaline hydroxides on the hydration reaction of alite, both at early and later ages, can be identified: (i) a differentiated hydration process, attributed to an enhancement in calcium hydroxide (CH) precipitation and a stimulation of the C-S-H nuclei; and (ii) an increase in the elastic modulus of the C-S-H aggregations, attributed to an electrostatic attraction between positive charges from the alkaline cations and negative charges from the C-S-H structure

  7. Calcium oxalate stone and gout.

    Science.gov (United States)

    Marickar, Y M Fazil

    2009-12-01

    Gout is well known to be produced by increased uric acid level in blood. The objective of this paper is to assess the relationship between gout and calcium oxalate stone formation in the humans. 48 patients with combination of gout and calcium oxalate stone problem were included. The biochemical values of this group were compared with 38 randomly selected uric acid stone patients with gout, 43 stone patients with gout alone, 100 calcium oxalate stone patients without gout and 30 controls, making a total of 259 patients. Various biochemical parameters, namely serum calcium, phosphorus and uric acid and 24-h urine calcium, phosphorus, uric acid, oxalate, citrate and magnesium were analysed. ANOVA and Duncan's multiple-range tests were performed to assess statistical significance of the variations. The promoters of stone formation, namely serum calcium (P stone patients and gouty calcium oxalate stone patients compared to the non-gouty patients and controls. Urine oxalate (P stones patients. The inhibitor urine citrate (P stone gouty patients, followed by the gouty uric acid stone formers and gouty calcium oxalate stone patients. The high values of promoters, namely uric acid and calcium in the gouty stone patients indicate the tendency for urinary stone formation in the gouty stone patients. There is probably a correlation between gout and calcium oxalate urinary stone. We presume this mechanism is achieved through the uric acid metabolism. The findings point to the summation effect of metabolic changes in development of stone disease.

  8. Calcium Electroporation

    DEFF Research Database (Denmark)

    Frandsen, Stine Krog; Gibot, Laure; Madi, Moinecha

    2015-01-01

    BACKGROUND: Calcium electroporation describes the use of high voltage electric pulses to introduce supraphysiological calcium concentrations into cells. This promising method is currently in clinical trial as an anti-cancer treatment. One very important issue is the relation between tumor cell kill...... efficacy-and normal cell sensitivity. METHODS: Using a 3D spheroid cell culture model we have tested the effect of calcium electroporation and electrochemotherapy using bleomycin on three different human cancer cell lines: a colorectal adenocarcinoma (HT29), a bladder transitional cell carcinoma (SW780......), and a breast adenocarcinoma (MDA-MB231), as well as on primary normal human dermal fibroblasts (HDF-n). RESULTS: The results showed a clear reduction in spheroid size in all three cancer cell spheroids three days after treatment with respectively calcium electroporation (p

  9. Nuclear fuel handling apparatus

    International Nuclear Information System (INIS)

    Andrea, C.; Dupen, C.F.G.; Noyes, R.C.

    1977-01-01

    A fuel handling machine for a liquid metal cooled nuclear reactor in which a retractable handling tube and gripper are lowered into the reactor to withdraw a spent fuel assembly into the handling tube. The handling tube containing the fuel assembly immersed in liquid sodium is then withdrawn completely from the reactor into the outer barrel of the handling machine. The machine is then used to transport the spent fuel assembly directly to a remotely located decay tank. The fuel handling machine includes a decay heat removal system which continuously removes heat from the interior of the handling tube and which is capable of operating at its full cooling capacity at all times. The handling tube is supported in the machine from an articulated joint which enables it to readily align itself with the correct position in the core. An emergency sodium supply is carried directly by the machine to provide make up in the event of a loss of sodium from the handling tube during transport to the decay tank. 5 claims, 32 drawing figures

  10. Effects of the addition of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on mechanical properties of luting and lining glass ionomer cement

    Science.gov (United States)

    Heravi, Farzin; Bagheri, Hossein; Rangrazi, Abdolrasoul; Mojtaba Zebarjad, Seyed

    2016-07-01

    Recently, the addition of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) into glass ionomer cements (GICs) has attracted interest due to its remineralization of teeth and its antibacterial effects. However, it should be investigated to ensure that the incorporation of CPP-ACP does not have significant adverse effects on its mechanical properties. The purpose of this study was to evaluate the effects of the addition of CPP-ACP on the mechanical properties of luting and lining GIC. The first step was to synthesize the CPP-ACP. Then the CPP-ACP at concentrations of 1%, 1.56% and 2% of CPP-ACP was added into a luting and lining GIC. GIC without CPP-ACP was used as a control group. The results revealed that the incorporation of CPP-ACP up to 1.56%(w/w) increased the flexural strength (29%), diametral tensile strength (36%) and microhardness (18%), followed by a reduction in these mechanical properties at 2%(w/w) CPP-ACP. The wear rate was significantly decreased (23%) in 1.56%(w/w) concentration of CPP-ACP and it was increased in 2%(w/w). Accordingly, the addition of 1.56%(w/w) CPP-ACP into luting and lining GIC had no adverse effect on the mechanical properties of luting and lining GIC and could be used in clinical practice.

  11. Calcium-Magnesium-Alumino-Silicates (CMAS) Reaction Mechanisms and Resistance of Advanced Turbine Environmental Barrier Coatings for SiC/SiC Ceramic Matrix Composites

    Science.gov (United States)

    Zhu, Dongming; Costa, Gustavo; Harder, Bryan J.; Wiesner, Valerie L.; Hurst, Janet B.; Puleo, Bernadette J.

    2017-01-01

    Environmental barrier coatings (EBCs) and SiC/SiC ceramic matrix composites (CMCs) systems will play a crucial role in future turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is an essential requirement to enable the applications of the 2700-3000 F EBC - CMC systems. This presentation primarily focuses on the reaction mechanisms of advanced NASA environmental barrier coating systems, when in contact with Calcium-Magnesium Alumino-Silicates (CMAS) at high temperatures. Advanced oxide-silicate defect cluster environmental barrier coatings are being designed for ultimate balanced controls of the EBC temperature capability and CMAS reactivity, thus improving the CMAS resistance. Further CMAS mitigation strategies are also discussed.

  12. Effects of nanosilver and nanozinc incorporated mesoporous calcium-silicate nanoparticles on the mechanical properties of dentin.

    Directory of Open Access Journals (Sweden)

    Jie Zhu

    Full Text Available Mesoporous calcium-silicate nanoparticles (MCSNs are advanced biomaterials for drug delivery and mineralization induction. They can load silver and exhibit significantly antibacterial effects. However, the effects of MCSNs and silver-loaded MCSNs on dentin are unknown. The silver (Ag and/or zinc (Zn incorporated MCSNs (Ag-Zn-MCSNs were prepared by a template method, and their characterizations were tested. Then the nanoparticles were filled into root canals and their effects on the dentin were investigated. Ag-Zn-MCSNs showed characteristics of mesoporous materials and sustained release of ions over time. Ag-Zn-MCSNs adhered well to the root canal walls and infiltrated into the dentinal tubules after ultrasound activation. Ag-Zn-MCSNs showed no significantly negative effects on either the flexural strength or the modulus of elasticity of dentin, while CH decreased the flexural strength of dentin significantly (P<0.05. These findings suggested that Ag and Zn can be incorporated into MCSNs using a template method, and the Ag-Zn-MCSNs may be developed into a new disinfectant for the root canal and dentinal tubules.

  13. Parathyroid Hormone Induces Bone Cell Motility and Loss of Mature Osteocyte Phenotype through L-Calcium Channel Dependent and Independent Mechanisms.

    Directory of Open Access Journals (Sweden)

    Matthew Prideaux

    Full Text Available Parathyroid Hormone (PTH can exert both anabolic and catabolic effects on the skeleton, potentially through expression of the PTH type1 receptor (PTH1R, which is highly expressed in osteocytes. To determine the cellular and molecular mechanisms responsible, we examined the effects of PTH on osteoblast to osteocyte differentiation using primary osteocytes and the IDG-SW3 murine cell line, which differentiate from osteoblast to osteocyte-like cells in vitro and express GFP under control of the dentin matrix 1 (Dmp1 promoter. PTH treatment resulted in an increase in some osteoblast and early osteocyte markers and a decrease in mature osteocyte marker expression. The gene expression profile of PTH-treated Day 28 IDG-SW3 cells was similar to PTH treated primary osteocytes. PTH treatment induced striking changes in the morphology of the Dmp1-GFP positive cells in IDG-SW3 cultures and primary cells from Dmp1-GFP transgenic mice. The cells changed from a more dendritic to an elongated morphology and showed increased cell motility. E11/gp38 has been shown to be important for cell migration, however, deletion of the E11/gp38/podoplanin gene had no effect on PTH-induced motility. The effects of PTH on motility were reproduced using cAMP, but not with protein kinase A (PKA, exchange proteins activated by cAMP (Epac, protein kinase C (PKC or phosphatidylinositol-4,5-bisphosphonate 3-kinase (Pi3K agonists nor were they blocked by their antagonists. However, the effects of PTH were mediated through calcium signaling, specifically through L-type channels normally expressed in osteoblasts but decreased in osteocytes. PTH was shown to increase expression of this channel, but decrease the T-type channel that is normally more highly expressed in osteocytes. Inhibition of L-type calcium channel activity attenuated the effects of PTH on cell morphology and motility but did not prevent the downregulation of mature osteocyte marker expression. Taken together, these

  14. Experimental study on the mechanism of SO2 emission and calcium-based desulfurization in the coal oxygen-enriched combustion

    International Nuclear Information System (INIS)

    Tian, Luning; Chen, Hanping; Yang, Haiping; Wang, Xianhua; Zhang, Shihong

    2010-01-01

    Full text: The emission of SO 2 , CO 2 brings serious harm to the ecological environment, human health and the global climate change. The largest source of SO 2 , CO 2 is the combustion of fossil fuels for power generation. So developing the new technology for controlling pollutants emissions from coal combustion was imperative. Oxygen-enriched combustion technology is such a new technology which can realize CO 2 zero emission, enhance the combustion efficiency and reduce pollutants emission. Due to the high concentration of CO 2 , it has many different aspects in the SO 2 emission and calcium-based desulfurization compare with the conventional combustion. In this article, experiments have been done to investigate the behavior and mechanism of SO 2 emissions and removal in oxygen-enriched combustion. First, in TGA and fixed bed reactor, the SO 2 emission characteristics were investigated under various bed temperature, particle size and O 2 / CO 2 concentration. It was observed that SO 2 released faster and the emission peak was higher than air atmosphere. SO 2 emission concentration increased with the reaction temperature increasing. Simultaneously, the mechanism of SO 2 emission was obtained by analyzing the sulfur compounds in the gas products and solid products in different reaction times. Then, the impacts of reaction temperature, particle size, O 2 / CO 2 concentration and SO 2 concentration etc. on the efficiency of SO 2 removal were analyzed. The phase analysis, pore diameter distribution and microstructure of the solid product were investigated. The experimental results showed that the sulphur capture takes place by direct sulphation reaction at high CO 2 concentration which attributes to light sinter, better porous structure, higher optimal desulfurization temperature and high desulfurization efficiency of calcium-based sorbent. (author)

  15. Human interleukin 1. beta. stimulates islet insulin release by a mechanism not dependent on changes in phospholipase C and protein kinase C activities or Ca sup 2+ handling

    Energy Technology Data Exchange (ETDEWEB)

    Welsh, N.; Nilsson, T.; Hallberg, A.; Arkhammar, P.; Berggren, P.-O.; Sandler, S.

    1989-01-01

    Isolated islets from adult rats or obese hyperglycemic (ob/ob) mice were incubated with human recombinant interleukin 1{beta} in order to study whether the acute effects of the cytokine on islet insulin release are associated with changes in islet phospholipase C activity, Ca{sup 2+} handling or protein phosphorylation. The cytokine stimulated insulin release both at low and high glucose concentrations during one hour incubations. In shortterm incubations (<1 min) interleukin 1{beta} did not affect the production of inositoltrisphosphate. Addition of interleukin 1{beta} affected neither the cytoplasmic free Ca{sup 2+} concentration at rest nor that observed subsequent to stimulation with a high concentration of glucose. Furthermore, the endogenous protein kinase C activity, as visualized by immunoprecipitation of a {sup 32}P-labelled substrate for this enzyme, was not altered by interleukin 1{beta}. Separation of {sup 32}P-labelled proteins by means of 2-dimensional gel electrophoresis failed to reveal any specific effects of the cytokine on the total protein phosphorylation activity. These results suggest that the stimulatory effects on insulin release exerted by interleukin 1{beta} are not caused by acute activation of phospholipase C and protein kinase C or by an alternation of islet Ca{sup 2+} handling of the B-cells. (author).

  16. Human interleukin 1β stimulates islet insulin release by a mechanism not dependent on changes in phospholipase C and protein kinase C activities or Ca2+ handling

    International Nuclear Information System (INIS)

    Welsh, N.; Nilsson, T.; Hallberg, A.; Arkhammar, P.; Berggren, P.-O.; Sandler, S.

    1989-01-01

    Isolated islets from adult rats or obese hyperglycemic (ob/ob) mice were incubated with human recombinant interleukin 1β in order to study whether the acute effects of the cytokine on islet insulin release are associated with changes in islet phospholipase C activity, Ca 2+ handling or protein phosphorylation. The cytokine stimulated insulin release both at low and high glucose concentrations during one hour incubations. In shortterm incubations ( 2+ concentration at rest nor that observed subsequent to stimulation with a high concentration of glucose. Furthermore, the endogenous protein kinase C activity, as visualized by immunoprecipitation of a 32 P-labelled substrate for this enzyme, was not altered by interleukin 1β. Separation of 32 P-labelled proteins by means of 2-dimensional gel electrophoresis failed to reveal any specific effects of the cytokine on the total protein phosphorylation activity. These results suggest that the stimulatory effects on insulin release exerted by interleukin 1β are not caused by acute activation of phospholipase C and protein kinase C or by an alternation of islet Ca 2+ handling of the B-cells. (author)

  17. Calcium dynamics in vascular smooth muscle

    OpenAIRE

    Amberg, Gregory C.; Navedo, Manuel F.

    2013-01-01

    Smooth muscle cells are ultimately responsible for determining vascular luminal diameter and blood flow. Dynamic changes in intracellular calcium are a critical mechanism regulating vascular smooth muscle contractility. Processes influencing intracellular calcium are therefore important regulators of vascular function with physiological and pathophysiological consequences. In this review we discuss the major dynamic calcium signals identified and characterized in vascular smooth muscle cells....

  18. How to Handle Abuse

    Science.gov (United States)

    ... Handle Abuse KidsHealth / For Kids / How to Handle Abuse What's in this article? Tell Right Away How Do You Know Something Is Abuse? ... babysitter, teacher, coach, or a bigger kid. Child abuse can happen anywhere — at ... building. Tell Right Away A kid who is being seriously hurt ...

  19. Grain Handling and Storage.

    Science.gov (United States)

    Harris, Troy G.; Minor, John

    This text for a secondary- or postecondary-level course in grain handling and storage contains ten chapters. Chapter titles are (1) Introduction to Grain Handling and Storage, (2) Elevator Safety, (3) Grain Grading and Seed Identification, (4) Moisture Control, (5) Insect and Rodent Control, (6) Grain Inventory Control, (7) Elevator Maintenance,…

  20. Fuel handling machine and auxiliary systems for a fuel handling cell

    International Nuclear Information System (INIS)

    Suikki, M.

    2013-10-01

    This working report is an update for as well as a supplement to an earlier fuel handling machine design (Kukkola and Roennqvist 2006). A focus in the earlier design proposal was primarily on the selection of a mechanical structure and operating principle for the fuel handling machine. This report introduces not only a fuel handling machine design but also auxiliary fuel handling cell equipment and its operation. An objective of the design work was to verify the operating principles of and space allocations for fuel handling cell equipment. The fuel handling machine is a remote controlled apparatus capable of handling intensely radiating fuel assemblies in the fuel handling cell of an encapsulation plant. The fuel handling cell is air tight space radiation-shielded with massive concrete walls. The fuel handling machine is based on a bridge crane capable of traveling in the handling cell along wall tracks. The bridge crane has its carriage provided with a carousel type turntable having mounted thereon both fixed and telescopic masts. The fixed mast has a gripper movable on linear guides for the transfer of fuel assemblies. The telescopic mast has a manipulator arm capable of maneuvering equipment present in the fuel handling cell, as well as conducting necessary maintenance and cleaning operations or rectifying possible fault conditions. The auxiliary fuel handling cell systems consist of several subsystems. The subsystems include a service manipulator, a tool carrier for manipulators, a material hatch, assisting winches, a vacuum cleaner, as well as a hose reel. With the exception of the vacuum cleaner, the devices included in the fuel handling cell's auxiliary system are only used when the actual encapsulation process is not ongoing. The malfunctions of mechanisms or actuators responsible for the motion actions of a fuel handling machine preclude in a worst case scenario the bringing of the fuel handling cell and related systems to a condition appropriate for

  1. Fuel handling machine and auxiliary systems for a fuel handling cell

    Energy Technology Data Exchange (ETDEWEB)

    Suikki, M. [Optimik Oy, Turku (Finland)

    2013-10-15

    This working report is an update for as well as a supplement to an earlier fuel handling machine design (Kukkola and Roennqvist 2006). A focus in the earlier design proposal was primarily on the selection of a mechanical structure and operating principle for the fuel handling machine. This report introduces not only a fuel handling machine design but also auxiliary fuel handling cell equipment and its operation. An objective of the design work was to verify the operating principles of and space allocations for fuel handling cell equipment. The fuel handling machine is a remote controlled apparatus capable of handling intensely radiating fuel assemblies in the fuel handling cell of an encapsulation plant. The fuel handling cell is air tight space radiation-shielded with massive concrete walls. The fuel handling machine is based on a bridge crane capable of traveling in the handling cell along wall tracks. The bridge crane has its carriage provided with a carousel type turntable having mounted thereon both fixed and telescopic masts. The fixed mast has a gripper movable on linear guides for the transfer of fuel assemblies. The telescopic mast has a manipulator arm capable of maneuvering equipment present in the fuel handling cell, as well as conducting necessary maintenance and cleaning operations or rectifying possible fault conditions. The auxiliary fuel handling cell systems consist of several subsystems. The subsystems include a service manipulator, a tool carrier for manipulators, a material hatch, assisting winches, a vacuum cleaner, as well as a hose reel. With the exception of the vacuum cleaner, the devices included in the fuel handling cell's auxiliary system are only used when the actual encapsulation process is not ongoing. The malfunctions of mechanisms or actuators responsible for the motion actions of a fuel handling machine preclude in a worst case scenario the bringing of the fuel handling cell and related systems to a condition appropriate for

  2. Development of standard components for remote handling

    International Nuclear Information System (INIS)

    Taguchi, Kou; Kakudate, Satoshi; Nakahira, Masataka; Ito, Akira

    1998-01-01

    The core of Fusion Experimental Reactor consists of various components such as superconducting magnets and forced-cooled in-vessel components, which are remotely maintained due to intense of gamma radiation. Mechanical connectors such as cooling pipe connections, insulation joints and electrical connectors are commonly used for maintenance of these components and have to be standardized in terms of remote handling. This paper describes these mechanical connectors developed as the standard component compatible with remote handling and tolerable for radiation. (author)

  3. Development of standard components for remote handling

    Energy Technology Data Exchange (ETDEWEB)

    Taguchi, Kou; Kakudate, Satoshi; Nakahira, Masataka; Ito, Akira [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-04-01

    The core of Fusion Experimental Reactor consists of various components such as superconducting magnets and forced-cooled in-vessel components, which are remotely maintained due to intense of gamma radiation. Mechanical connectors such as cooling pipe connections, insulation joints and electrical connectors are commonly used for maintenance of these components and have to be standardized in terms of remote handling. This paper describes these mechanical connectors developed as the standard component compatible with remote handling and tolerable for radiation. (author)

  4. The mechanism underlying calcium phosphate precipitation on titanium via ultraviolet, visible, and near infrared laser-assisted biomimetic process

    International Nuclear Information System (INIS)

    Mahanti, Moumita; Nakamura, Maki; Pyatenko, Alexander; Sakamaki, Ikuko; Koga, Kenji; Oyane, Ayako

    2016-01-01

    We recently developed a rapid single-step calcium phosphate (CaP) precipitation technique on several substrates using a laser-assisted biomimetic process (LAB process). In this process, ultraviolet (UV, λ   =  355 nm) pulsed laser irradiation has been applied to a substrate that is immersed in a supersaturated CaP solution. In the present study, the LAB process for CaP precipitation on a titanium substrate was successfully expanded to include not only UV but also visible (VIS, λ   =  532 nm) and near infrared (NIR, λ   =  1064 nm) lasers. Surface heating and plasma-mediated surface reactions (micro-deformation, oxidization, photoexcitation, and wetting) generated by UV, VIS, or NIR lasers are considered to be involved in the CaP precipitation on the titanium surface in the LAB process. The kinetics of these reactions and consequently of CaP precipitation were dependent on the laser wavelength and fluence. The higher laser fluence did not always accelerate CaP precipitation on the substrate; rather, it was found that an optimal range of fluence exists for each laser wavelength. These results suggest that for efficient CaP precipitation, a suitable laser wavelength should be selected according to the optical absorption properties of the substrate material and the laser fluence should also be adjusted to induce surface heating and plasma-mediated surface reactions that are favorable for CaP precipitation. (paper)

  5. Balancing mechanical strength with bioactivity in chitosan-calcium phosphate 3D microsphere scaffolds for bone tissue engineering: air- vs. freeze-drying processes.

    Science.gov (United States)

    Nguyen, D T; McCanless, J D; Mecwan, M M; Noblett, A P; Haggard, W O; Smith, R A; Bumgardner, J D

    2013-01-01

    The objective of this study was to evaluate the potential benefit of 3D composite scaffolds composed of chitosan and calcium phosphate for bone tissue engineering. Additionally, incorporation of mechanically weak lyophilized microspheres within those air-dried (AD) was considered for enhanced bioactivity. AD microsphere, alone, and air- and freeze-dried microsphere (FDAD) 3D scaffolds were evaluated in vitro using a 28-day osteogenic culture model with the Saos-2 cell line. Mechanical testing, quantitative microscopy, and lysozyme-driven enzymatic degradation of the scaffolds were also studied. FDAD scaffold showed a higher concentration (p < 0.01) in cells per scaffold mass vs. AD constructs. Collagen was ∼31% greater (p < 0.01) on FDAD compared to AD scaffolds not evident in microscopy of microsphere surfaces. Alternatively, AD scaffolds demonstrated a superior threefold increase in compressive strength over FDAD (12 vs. 4 MPa) with minimal degradation. Inclusion of FD spheres within the FDAD scaffolds allowed increased cellular activity through improved seeding, proliferation, and extracellular matrix production (as collagen), although mechanical strength was sacrificed through introduction of the less stiff, porous FD spheres.

  6. Addition of 1, 2 and 3% in mass of sodium alginate in calcium phosphate cement

    International Nuclear Information System (INIS)

    Coelho, W.T.; Fernandes, J.M.; Vieira, R.S.; Thurmer, M.B.; Santos, L.A.

    2011-01-01

    The calcium phosphate cement (CFC) are bone substitutes with great potential for use in orthopedics, traumatology and dentistry because of their biocompatibility, bioactivity, osteoconductivity and osteotransdutivity, and a paste that can be easily molded and placed into the surgical site. However, CFCs have low mechanical strength, which equals the maximum mechanical strength of trabecular bone. Aiming to evaluate the strength and time to handle a CFC phase composed mainly of alpha were added to sodium alginate (1%, 2% and 3% wt) and an accelerator handle in an aqueous medium. The cement powder was mixed with liquid takes 2 minutes and resigned in specimens and assessed for apparent density and porosity by the Archimedes method, X-ray diffraction and mechanical strength. We noticed a significant increase in mechanical properties of cement added sodium alginate. (author)

  7. Carbonation as a binding mechanism for coal/calcium hydroxide pellets. Final technical report, 1 September, 1992--31 August, 1993

    Energy Technology Data Exchange (ETDEWEB)

    Rapp, D.; Lytle, J.; Hackley, K.; Dagamac, M. [Illinois State Geological Survey, Champaign, IL (United States); Berger, R. [Univ. of Illinois, Urbana, IL (United States); Schanche, G. [Army Construction Engineering Research Lab., Champaign, IL (United States)

    1993-12-31

    This research was an investigation of calcium hydroxide, a sulfur-capturing sorbent, as a binder for coal fines. The reaction of carbon dioxide with calcium hydroxide, referred to as carbonation, was studied as a method for improving pellet quality. Carbonation forms a cementitious matrix of calcium carbonate. Research has demonstrated that calcium hydroxide is a viable binder for coal fines and that a roller-and-die pellet mill is an effective method of pellet formation. From a minus 28 mesh preparation plant fine coal sample, a roller-and-die pellet mill produced strong pellets when 5 and 10% calcium hydroxide was used as a binder. The pellets containing 10% calcium hydroxide strengthened considerably when air cured. This increase in strength was attributed to carbonation via atmospheric carbon dioxide. Pellets containing 10 wt% calcium hydroxide were produced using an extruder but pellets formed in this manner were much weaker than pellets produced with the roller-and-die mill. In tests performed using a laboratory hydraulic press, the effect of particle size and compaction pressure on pellet strength was studied. Particle distributions with mean sizes of 200, 90 and 40 microns were tested. The results indicate that pellet strength increased with decreasing particle size and increasing compaction pressure when calcium hydroxide was used as a binder. Pellets containing 10 wt% calcium hydroxide increased in strength by approximately 40% when air dried for one day. As above, this increase in strength was attributed to carbonation of the calcium hydroxide via atmospheric carbon dioxide.

  8. Cardiovascular Effects of Calcium Supplements

    Directory of Open Access Journals (Sweden)

    Ian R. Reid

    2013-07-01

    Full Text Available Calcium supplements reduce bone turnover and slow the rate of bone loss. However, few studies have demonstrated reduced fracture incidence with calcium supplements, and meta-analyses show only a 10% decrease in fractures, which is of borderline statistical and clinical significance. Trials in normal older women and in patients with renal impairment suggest that calcium supplements increase the risk of cardiovascular disease. To further assess their safety, we recently conducted a meta-analysis of trials of calcium supplements, and found a 27%–31% increase in risk of myocardial infarction, and a 12%–20% increase in risk of stroke. These findings are robust because they are based on pre-specified analyses of randomized, placebo-controlled trials and are consistent across the trials. Co-administration of vitamin D with calcium does not lessen these adverse effects. The increased cardiovascular risk with calcium supplements is consistent with epidemiological data relating higher circulating calcium concentrations to cardiovascular disease in normal populations. There are several possible pathophysiological mechanisms for these effects, including effects on vascular calcification, vascular cells, blood coagulation and calcium-sensing receptors. Thus, the non-skeletal risks of calcium supplements appear to outweigh any skeletal benefits, and are they appear to be unnecessary for the efficacy of other osteoporosis treatments.

  9. Calcium in plant cells

    Directory of Open Access Journals (Sweden)

    V. V. Schwartau

    2014-04-01

    connect ion conformationally rearranged, thus passing the signal through the chain of intermediaries. The most important function of calcium is its participation in many cell signaling pathways. Channels, pumps, gene expression, synthesis of alkaloids, protective molecules, NO etc. respond to changes in [Ca2+]cyt, while transductors are represented by a number of proteins. The universality of calcium is evident in the study in connection with other signaling systems, such as NO, which is involved in the immune response and is able to control the feedback activity of protein activators channels, producing nitric oxide. Simulation of calcium responses can determine the impact of key level and their regulation, and also depends on the type of stimulus and the effector protein that specifically causes certain changes. Using spatiotemporal modeling, scientists showed that the key components for the formation of Ca2+ bursts are the internal and external surfaces of the nucleus membrane. The research was aimed at understanding of the mechanisms of influence of Ca2+-binding components on Ca2+ oscillations. The simulation suggests the existence of a calcium depot EPR with conjugated lumen of the nucleus which releases its contents to nucleoplasm. With these assumptions, the mathematical model was created and confirmed experimentally. It describes the oscillation of nuclear calcium in root hairs of Medicago truncatula at symbiotic relationship of plants and fungi (rhizobia. Calcium oscillations are present in symbiotic relationships of the cortical layer of plant root cells. Before penetration of bacteria into the cells, slow oscillations of Ca2+ are observed, but with their penetration into the cells the oscillation frequency increases. These processes take place by changing buffer characteristics of the cytoplasm caused by signals from microbes, such as Nod-factor available after penetration of bacteria through the cell wall. Thus, the basic known molecular mechanisms for

  10. Protective effect of calcium dobesilate combined with benazepril therapy on renal injury in patients with early diabetic nephropathy and the possible molecular mechanisms

    Directory of Open Access Journals (Sweden)

    Ling Zhang

    2017-06-01

    Full Text Available Objective: To explore the protective effect of calcium dobesilate combined with benazepril therapy on renal injury in patients with early diabetic nephropathy and the possible molecular mechanisms. Methods: A total of 50 patients with early diabetic nephropathy treated in our hospital between May 2012 and January 2016 were collected, and according to the random number table, the patients were divided into observation group (n=25 and control group (n=25. On the basis of conventional treatment, control group of patients received benazepril therapy, observation group of patients received calcium dobesilate combined with benazepril therapy, and the treatment lasted for 3 months. Before and after treatment, automatic biochemical analyzer was used to detect the levels of renal injury indexes in peripheral blood, RIA method was used to detect the levels of renal injury indexes in urine, ELISA method was used to detect the levels of renal fibrosis indexes and Western-blot method was used to detect the protein expression of TGF-β1/BMP-7 and Smad signaling pathway molecules in renal tissue. Results: Before treatment, differences in renal injury index levels, renal fibrosis index levels and signaling pathway molecule protein expression were not statistically significant between two groups of patients. After treatment, BUN, SCr and β-TP levels in the peripheral blood as well as KIM-1 level in urine of observation group were lower than those of control group; renal fibrosis indexes TGF-β1, CTGF, TIMP-1, LN and HA levels in serum of observation group were lower than those of control group; TGF-β1 and Smad2/3 protein expression in renal tissue of observation group were lower than those of control group while Smad7 and BMP-7 protein expression were higher than those of control group. Conclusion: Calcium dobesilate combined with benazepril therapy can reduce the renal injury and inhibit the fibrosis process in patients with early diabetic nephropathy, and it

  11. Handling Pyrophoric Reagents

    Energy Technology Data Exchange (ETDEWEB)

    Alnajjar, Mikhail S.; Haynie, Todd O.

    2009-08-14

    Pyrophoric reagents are extremely hazardous. Special handling techniques are required to prevent contact with air and the resulting fire. This document provides several methods for working with pyrophoric reagents outside of an inert atmosphere.

  12. Remote handling equipment

    International Nuclear Information System (INIS)

    Clement, G.

    1984-01-01

    After a definition of intervention, problems encountered for working in an adverse environment are briefly analyzed for development of various remote handling equipments. Some examples of existing equipments are given [fr

  13. Ergonomics and patient handling.

    Science.gov (United States)

    McCoskey, Kelsey L

    2007-11-01

    This study aimed to describe patient-handling demands in inpatient units during a 24-hour period at a military health care facility. A 1-day total population survey described the diverse nature and impact of patient-handling tasks relative to a variety of nursing care units, patient characteristics, and transfer equipment. Productivity baselines were established based on patient dependency, physical exertion, type of transfer, and time spent performing the transfer. Descriptions of the physiological effect of transfers on staff based on patient, transfer, and staff characteristics were developed. Nursing staff response to surveys demonstrated how patient-handling demands are impacted by the staff's physical exertion and level of patient dependency. The findings of this study describe the types of transfers occurring in these inpatient units and the physical exertion and time requirements for these transfers. This description may guide selection of the most appropriate and cost-effective patient-handling equipment required for specific units and patients.

  14. Calcium homeostasis in diabetes mellitus.

    Science.gov (United States)

    Ahn, Changhwan; Kang, Ji-Houn; Jeung, Eui-Bae

    2017-09-30

    Diabetes mellitus (DM) is becoming a lifestyle-related pandemic disease. Diabetic patients frequently develop electrolyte disorders, especially diabetic ketoacidosis or nonketotic hyperglycemic hyperosmolar syndrome. Such patients show characteristic potassium, magnesium, phosphate, and calcium depletion. In this review, we discuss a homeostatic mechanism that links calcium and DM. We also provide a synthesis of the evidence in favor or against this linking mechanism by presenting recent clinical indications, mainly from veterinary research. There are consistent results supporting the use of calcium and vitamin D supplementation to reduce the risk of DM. Clinical trials support a marginal reduction in circulating lipids, and some meta-analyses support an increase in insulin sensitivity, following vitamin D supplementation. This review provides an overview of the calcium and vitamin D disturbances occurring in DM and describes the underlying mechanisms. Such elucidation will help indicate potential pathophysiology-based precautionary and therapeutic approaches and contribute to lowering the incidence of DM.

  15. Get Enough Calcium

    Science.gov (United States)

    ... Calcium Print This Topic En español Get Enough Calcium Browse Sections The Basics Overview Foods and Vitamins ... women, don't get enough calcium. How much calcium do I need every day? Women: If you ...

  16. Calcium - urine

    Science.gov (United States)

    ... Female urinary tract Male urinary tract Calcium urine test References Bringhurst FR, Demay MB, Kronenberg HM. Hormones and disorders of mineral metabolism. In: Melmed S, Polonsky KS, Larsen PR, Kronenberg HM, eds. Williams Textbook of Endocrinology . 13th ed. Philadelphia, PA: Elsevier; ...

  17. Materials Handling. Module SH-01. Safety and Health.

    Science.gov (United States)

    Center for Occupational Research and Development, Inc., Waco, TX.

    This student module on materials handling is one of 50 modules concerned with job safety and health. It presents the procedures for safe materials handling. Discussed are manual handling methods (lifting and carrying by hand) and mechanical lifting (lifting by powered trucks, cranes or conveyors). Following the introduction, 15 objectives (each…

  18. Bone Mineral Density, Mechanical, Microstructural Properties and Mineral Content of the Femur in Growing Rats Fed with Cactus Opuntia ficus indica (L.) Mill. (Cactaceae) Cladodes as Calcium Source in Diet.

    Science.gov (United States)

    Hernández-Becerra, Ezequiel; Gutiérrez-Cortez, Elsa; Del Real, Alicia; Rojas-Molina, Alejandra; Rodríguez-García, Mario; Rubio, Efraín; Quintero-García, Michelle; Rojas-Molina, Isela

    2017-02-04

    Mechanical, microstructural properties, mineral content and bone mineral density (BMD) of the femur were evaluated in growing rats fed with Opuntia ficus indica (L.) Mill. (Cactaceae) cladodes at different maturity stages as calcium source. Male weanling rats were fed with cladodes at early maturity stage (25 and 60 days of age, belonging to groups N-60 and N-200, respectively) and cladodes at late maturity stage (100 and 135 days of age, belonging to groups N-400 and N-600, respectively) for 6 weeks. Additionally, a control group fed with calcium carbonate as calcium source was included for comparative purposes. All diets were fitted to the same calcium content (5 g/kg diet). The failure load of femurs was significantly lower ( p ≤ 0.05) in groups N-60 and N-200 in comparison to N-400, N-600 and control groups. The cortical width (Ct.Wi) and trabecular thickness (Tb.Th) of the femurs in control and N-600 groups were significantly higher ( p ≤ 0.05) than Ct.Wi and Tb.Th of femurs in groups N-60 and N-200. Trabecular separation of the femurs in N-60 and N-200 groups showed the highest values compared with all experimental groups. The highest calcium content in the femurs were observed in control, N-600 and N-400 groups; whereas the lowest phosphorus content in the bones were detected in N-200, N-600 and N-400 groups. Finally, the BMD in all experimental groups increased with age; nevertheless, the highest values were observed in N-600 and control groups during pubertal and adolescence stages. The results derived from this research demonstrate, for the first time, that the calcium found in Opuntia ficus indica cladodes is actually bioavailable and capable of improving mineral density and mechanical and microstructural properties of the bones. These findings suggest that the consumption of cladodes at late maturity stage within the diet might have a beneficial impact on bone health.

  19. Mechanism of a strong rise of Tc due to the calcium doping in Y1-xCaxBa2Cu2.8Zn0.2Oy

    International Nuclear Information System (INIS)

    Martynova, O.A.; Potapov, D.V.; Gasumyants, V.E.; Vladimirskaya, E.V.

    2011-01-01

    Highlights: → Calcium is observed to restore superconductivity in Y 1-x Ca x Ba 2 Cu 2.8 Zn 0.2 O y . → Parameters of the band spectrum and charge-carrier system are determined. → The calcium doping is shown to give a noticeable contribution to the DOS function. → The mechanism of calcium effect on T c in doped YBa 2 Cu 3 O y is discussed. - Abstract: The normal-state transport properties and the critical temperature, T c , for three series of Y 1-x Ca x Ba 2 Cu 2.8 Zn 0.2 O y (x = 0-0.2) samples with different oxygen content have been investigated and discussed in comparison with results for other calcium-doped YBa 2 Cu 3 O y . We have observed the calcium doping to restore the superconductivity in the YBa 2 Cu 3 O y system even in case of the preliminary T c suppression by the direct destruction of the CuO 2 planes due to a preliminary doping by zinc. The T c value rises strongly with increasing calcium content and this rise becomes faster for the oxygen-reduced series. Based on a narrow-band model, the parameters of the band spectrum structure and the charge-carrier system in the normal state were determined from the analysis of the thermopower temperature dependences in order to reveal the mechanism of the T c rise under the Ca influence. It is shown that the T c increase in Y 1-x Ca x Ba 2 Cu 2.8 Zn 0.2 O y is related to the direct Ca ions effect. The mechanism of the calcium influence on the T c value is discussed with respect to the Ca-induced conduction band modification. The calcium doping in Y 1-x Ca x Ba 2 Cu 2.8 Zn 0.2 O y is shown to give a noticeable contribution to the density-of-states function leading to a strong rise in its value at the Fermi level that results in a restoration of the superconducting properties.

  20. A Comparison in Mechanical Properties of Cermets of Calcium Silicate with Ti-55Ni and Ti-6Al-4V Alloys for Hard Tissues Replacement

    Science.gov (United States)

    Pramanik, Sumit; Shirazi, Seyed Farid Seyed; Mehrali, Mehdi; Yau, Yat-Huang; Abu Osman, Noor Azuan

    2014-01-01

    This study investigated the impact of calcium silicate (CS) content on composition, compressive mechanical properties, and hardness of CS cermets with Ti-55Ni and Ti-6Al-4V alloys sintered at 1200°C. The powder metallurgy route was exploited to prepare the cermets. New phases of materials of Ni16Ti6Si7, CaTiO3, and Ni31Si12 appeared in cermet of Ti-55Ni with CS and in cermet of Ti-6Al-4V with CS, the new phases Ti5Si3, Ti2O, and CaTiO3, which were emerged during sintering at different CS content (wt%). The minimum shrinkage and density were observed in both groups of cermets for the 50 and 100 wt% CS content, respectively. The cermets with 40 wt% of CS had minimum compressive Young's modulus. The minimum of compressive strength and strain percentage at maximum load were revealed in cermets with 50 and 40 wt% of CS with Ti-55Ni and Ti-6Al-4V cermets, respectively. The cermets with 80 and 90 wt% of CS showed more plasticity than the pure CS. It concluded that the composition and mechanical properties of sintered cermets of Ti-55Ni and Ti-6Al-4V with CS significantly depend on the CS content in raw cermet materials. Thus, the different mechanical properties of the cermets can be used as potential materials for different hard tissues replacements. PMID:25538954

  1. A Comparison in Mechanical Properties of Cermets of Calcium Silicate with Ti-55Ni and Ti-6Al-4V Alloys for Hard Tissues Replacement

    Directory of Open Access Journals (Sweden)

    Azim Ataollahi Oshkour

    2014-01-01

    Full Text Available This study investigated the impact of calcium silicate (CS content on composition, compressive mechanical properties, and hardness of CS cermets with Ti-55Ni and Ti-6Al-4V alloys sintered at 1200°C. The powder metallurgy route was exploited to prepare the cermets. New phases of materials of Ni16Ti6Si7, CaTiO3, and Ni31Si12 appeared in cermet of Ti-55Ni with CS and in cermet of Ti-6Al-4V with CS, the new phases Ti5Si3, Ti2O, and CaTiO3, which were emerged during sintering at different CS content (wt%. The minimum shrinkage and density were observed in both groups of cermets for the 50 and 100 wt% CS content, respectively. The cermets with 40 wt% of CS had minimum compressive Young’s modulus. The minimum of compressive strength and strain percentage at maximum load were revealed in cermets with 50 and 40 wt% of CS with Ti-55Ni and Ti-6Al-4V cermets, respectively. The cermets with 80 and 90 wt% of CS showed more plasticity than the pure CS. It concluded that the composition and mechanical properties of sintered cermets of Ti-55Ni and Ti-6Al-4V with CS significantly depend on the CS content in raw cermet materials. Thus, the different mechanical properties of the cermets can be used as potential materials for different hard tissues replacements.

  2. Reaction Mechanism of Calcium Hydroxide with Gaseous Hydrogen Chloride Mécanisme de réaction de l'hydroxyde de calcium avec de l'acide chlorhydrique gazeux

    Directory of Open Access Journals (Sweden)

    Allal K. M.

    2006-12-01

    Full Text Available The reduction of acid gas content in combustion or incineration flue gases can be carried out by reaction with dry, fine alkaline sorbents such as calcium oxide or calcium hydroxide. In the present work, in addition to the thermodynamic study of the different reactions involved in the dechlorination process, an experimental study to identify the reaction products by means of X-ray diffraction, electron microscopy and thermogravimetry has been carried out. It has been shown that the reaction of hydrochloric acid with hydrated lime leads to the formation of not only calcium chloride but calcium hydroxichloride. La diminution de la teneur en gaz acides dans les effluents provenant des unités de combustion ou d'incinération peut être accomplie en faisant réagir ces gaz polluants avec des absorbants alcalins tels que l'oxyde ou l'hydroxyde de calcium. Dans cet article, à l'étude thermodynamique des différentes réactions mises en jeu durant le processus de déchloruration, s'ajoute une étude expérimentale menant à l'identification des produits finaux en utilisant la diffraction X, la microscopie électronique ainsi que la thermogravimétrie. A l'issue de cette étude, il a été montré que la réaction de Ca(OH2 avec HCl entraîne la formation non seulement de CaCI2 mais aussi CaCIOH.

  3. Production and characterization of setting hydraulic cements based on calcium phosphate; Obtencao e caracterizacao de cimentos de fosfato de calcio de pega hidraulica

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Luci C. de; Rigo, Eliana C.S.; Santos, Luis A dos; Boschi, Anselmo Ortega [Sao Carlos Univ., SP (Brazil). Dept. de Engenharia de Materiais; Carrodeguas, Raul G. [Universidad de La Habana, Habana (Cuba). Centro de Biomateriales

    1997-12-31

    Setting hydraulic cements based on calcium phosphate has risen great interest in scientific literature during recent years due to their total bio compatibility and to the fact that they harden `in situ`, providing easy handling and adaptation to the shape and dimensions of the defect which requires correction, differently from the predecessors, the calcium phosphate ceramics (Hydroxy apatite, {beta}-tri calcium phosphate, biphasic, etc) in the shape of dense or porous blocks and grains. In the work, three calcium-phosphate cement compositions were studied. The resulting compositions were characterized according to the following aspects: setting times, pH, mechanical resistance, crystalline phases, microstructure and solubility in SBF (Simulated Body Fluid). The results show a potential use for the compositions. (author) 6 figs., 4 tabs.

  4. INFLUENCE OF CURING TEMPERATURE ON THE PHYSICO-MECHANICAL, CHARACTERISTICS OF CALCIUM ALUMINATE CEMENT WITH AIR-COOLED SLAG OR WATER-COOLED SLAG

    Directory of Open Access Journals (Sweden)

    M. Heikal

    2004-12-01

    Full Text Available The nature, sequence, crystallinity and microstructure of hydrated phases were analyzed using differential scanning calorimetry (DSC, X-ray diffraction (XRD and scanning electron microscopy (SEM. The results showed that the formation of different hydrated phases was temperature dependence. The physico-mechanical and microstructural characteristics were investigated after curing at 20, 40 and 60° C. The results indicated that for the substitution of calcium aluminate cement (CAC by air-cooled slag (AS or water-cooled slag (WS at 20° C, the compressive strength increases with slag content up to 10 wt.%, then followed by a decrease with further slag substitution up to 25 wt.%; but the values are still higher than those of the neat CAC pastes at different curing ages up to 60 days. After 28 days of hydration at 40-60° C, the compressive strength increases with the slag content. This is attributed to the prevention of the conversion reaction, which was confirmed by XRD, DSC and SEM techniques, and the preferential formation of stratlingite (gehleinte-like phase. The SEM micrographs showed a close texture of hydrated CAC/slag blends made with AS or WS at 40°C due to the formation of C2ASH8 and C-S-H phases.

  5. Non-classical mechanisms of transcriptional regulation by the vitamin D receptor: insights into calcium homeostasis, immune system regulation and cancer chemoprevention.

    Science.gov (United States)

    Dimitrov, Vassil; Salehi-Tabar, Reyhaneh; An, Beum-Soo; White, John H

    2014-10-01

    Hormonal 1,25-dihydroxyvitamin D [1,25(OH)2D] signals through the nuclear vitamin D receptor (VDR), a ligand-regulated transcription factor. Gene expression profiling studies have revealed that 1,25(OH)2D signaling through the VDR can lead to activation or repression of target gene transcription in roughly equal proportions. Classically, transcriptional regulation by the VDR, similar to other nuclear receptors, has been characterized by its capacity to recognize high affinity cognate vitamin D response elements (VDREs), located in the regulatory regions of target genes. Several biochemical studies revealed that the VDRE-bound receptor recruits a series of coregulatory proteins, leading to transactivation of adjacent target genes. However, genome-wide and other analyses of VDR binding have revealed that a subset of VDR binding sites does not contain VDREs, and that VDREs are not associated with transcriptionally repressed VDR target genes. Work over the last ∼20 years and in particular recent findings have revealed a diverse array of mechanisms by which VDR can form complexes with several other classes of transcriptional activators, leading to repression of gene transcription. Moreover, these efforts have led to several insights into the molecular basis for the physiological regulation of calcium homeostasis, immune system function and cancer chemoprevention by 1,25(OH)2D/VDR signaling. This article is part of a Special Issue entitled '16th Vitamin D Workshop'. Copyright © 2013 Elsevier Ltd. All rights reserved.

  6. Normal pregnancy: mechanisms underlying the paradox of a ouabain-resistant state with elevated endogenous ouabain, suppressed arterial sodium calcium exchange, and low blood pressure

    Science.gov (United States)

    Jacobs, Brandiese E.; Liu, Yong; Pulina, Maria V.; Golovina, Vera A.

    2012-01-01

    Endogenous cardiotonic steroids (CTS) raise blood pressure (BP) via vascular sodium calcium exchange (NCX1.3) and transient receptor-operated channels (TRPCs). Circulating CTS are superelevated in pregnancy-induced hypertension and preeclampsia. However, their significance in normal pregnancy, where BP is low, is paradoxical. Here we test the hypothesis that vascular resistance to endogenous ouabain (EO) develops in normal pregnancy and is mediated by reduced expression of NCX1.3 and TRPCs. We determined plasma and adrenal levels of EO and the impact of exogenous ouabain in pregnancy on arterial expression of Na+ pumps, NCX1.3, TRPC3, and TRPC6 and BP. Pregnant (embryonic day 4) and nonpregnant rats received infusions of ouabain or vehicle. At 14–16 days, tissues and plasma were collected for blotting and EO assay by radioimmunoassay (RIA), liquid chromatography (LC)-RIA, and LC-multidimensional mass spectrometry (MS3). BP (−8 mmHg; P vs. nonpregnant (0.6 ± 0.08 nM; P endogenous and exogenous ouabain is mediated by suppressed NCX1.3 and reduced sensitivity of events downstream of Ca2+ entry. The mechanisms of EO resistance and the impaired fetal and placental growth due to elevated ouabain may be important in pregnancy-induced hypertension (PIH) and preeclampsia (PE). PMID:22245773

  7. Calcium paradox and calcium entry blockers

    NARCIS (Netherlands)

    Ruigrok, T.J.C.; Slade, A.M.; Nayler, W.G.; Meijler, F.L.

    1984-01-01

    Reperfusion of isolated hearts with calcium-containing solution after a short period of calcium-free perfusion results in irreversible cell damage (calcium paradox). This phenomenon is characterized by an excessive influx of calcium into the cells, the rapid onset of myocardial contracture,

  8. Remote handling machines

    International Nuclear Information System (INIS)

    Sato, Shinri

    1985-01-01

    In nuclear power facilities, the management of radioactive wastes is made with its technology plus the automatic techniques. Under the radiation field, the maintenance or aid of such systems is important. To cope with this situation, MF-2 system, MF-3 system and a manipulator system as remote handling machines are described. MF-2 system consists of an MF-2 carrier truck, a control unit and a command trailer. It is capable of handling heavy-weight objects. The system is not by hydraulic but by electrical means. MF-3 system consists of a four-crawler truck and a manipulator. The truck is versatile in its posture by means of the four independent crawlers. The manipulator system is bilateral in operation, so that the delicate handling is made possible. (Mori, K.)

  9. Practices of Handling

    DEFF Research Database (Denmark)

    Ræbild, Ulla

    to touch, pick up, carry, or feel with the hands. Figuratively it is to manage, deal with, direct, train, or control. Additionally, as a noun, a handle is something by which we grasp or open up something. Lastly, handle also has a Nordic root, here meaning to trade, bargain or deal. Together all four...... meanings seem to merge in the fashion design process, thus opening up for an embodied engagement with matter that entails direction giving, organizational management and negotiation. By seeing processes of handling as a key fashion methodological practice, it is possible to divert the discourse away from...... introduces four ways whereby fashion designers apply their own bodies as tools for design; a) re-activating past garment-design experiences, b) testing present garment-design experiences c) probing for new garment-design experiences and d) design of future garment experiences by body proxy. The paper...

  10. TRANSPORT/HANDLING REQUESTS

    CERN Multimedia

    Groupe ST/HM

    2002-01-01

    A new EDH document entitled 'Transport/Handling Request' will be in operation as of Monday, 11th February 2002, when the corresponding icon will be accessible from the EDH desktop, together with the application instructions. This EDH form will replace the paper-format transport/handling request form for all activities involving the transport of equipment and materials. However, the paper form will still be used for all vehicle-hire requests. The introduction of the EDH transport/handling request form is accompanied by the establishment of the following time limits for the various services concerned: 24 hours for the removal of office items, 48 hours for the transport of heavy items (of up to 6 metric tons and of standard road width), 5 working days for a crane operation, extra-heavy transport operation or complete removal, 5 working days for all transport operations relating to LHC installation. ST/HM Group, Logistics Section Tel: 72672 - 72202

  11. Effect of Cr on the passive film formation mechanism of steel rebar in saturated calcium hydroxide solution

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Ming; Cheng, Xuequn [Corrosion and Protection Center, University of Science and Technology Beijing, Beijing, 100083 (China); Li, Xiaogang, E-mail: lixiaogang@ustb.edu.cn [Corrosion and Protection Center, University of Science and Technology Beijing, Beijing, 100083 (China); Ningbo Institute of Material Technology & Engineering, Chinese Academy of Sciences, Ningbo, 315201, Zhejiang (China); Pan, Yue; Li, Jun [Corrosion and Protection Center, University of Science and Technology Beijing, Beijing, 100083 (China)

    2016-12-15

    Highlights: • Cr inhibits the formation of passive film at the beginning of its formation. • Cr promotes the formation of a denser and more compact passive film. • The passive film thickness presents a slight increase as the content of Cr goes up. - Abstract: Passive films grow on the surface of Cr-modified steels subjected to saturated Ca(OH){sub 2} solution. Electrochemical techniques, such as measurement of open circuit potentials, polarization curves, and electrochemical impedance spectroscopy combined with X-ray photoelectron spectrometer and auger electron spectroscopy, were applied to study the influence of low Cr content on the passive film formation mechanism of steel rebar in saturated Ca(OH){sub 2} solution. Results show that Cr inhibits the formation of passive film at the beginning of its formation. Corrosion current density decreases and polarization resistance increases with the extension of the immersion time. A stable passive film takes at least three days to form. The passive film resistance of HRB400 carbon steel is higher than that of Cr-modified steels in the early stage of immersion (<72 h). The polarization resistance of Cr-modified steel is larger after a stable passive film is formed (>72 h), and Cr promotes the formation of a denser and more compact passive film. The stable passive film is primarily made up of iron oxides with a thickness of 5–6 nm. Cr are involved in the formation of passive films, thereby resulting in a film that consists of an inner layer that contains Cr–Fe oxides and an outer layer that contains Fe oxides, whose thickness presents a slight increase as the content of Cr increases.

  12. On the Mechanism of Human Red Blood Cell Longevity: Roles of Calcium, the Sodium Pump, PIEZO1, and Gardos Channels

    Directory of Open Access Journals (Sweden)

    Virgilio L. Lew

    2017-12-01

    Full Text Available In a healthy adult, the transport of O2 and CO2 between lungs and tissues is performed by about 2 · 1013 red blood cells, of which around 1.7 · 1011 are renewed every day, a turnover resulting from an average circulatory lifespan of about 120 days. Cellular lifespan is the result of an evolutionary balance between the energy costs of maintaining cells in a fit functional state versus cell renewal. In this Review we examine how the set of passive and active membrane transporters of the mature red blood cells interact to maximize their circulatory longevity thus minimizing costs on expensive cell turnover. Red blood cell deformability is critical for optimal rheology and gas exchange functionality during capillary flow, best fulfilled when the volume of each human red blood cell is kept at a fraction of about 0.55–0.60 of the maximal spherical volume allowed by its membrane area, the optimal-volume-ratio range. The extent to which red blood cell volumes can be preserved within or near these narrow optimal-volume-ratio margins determines the potential for circulatory longevity. We show that the low cation permeability of red blood cells allows volume stability to be achieved with extraordinary cost-efficiency, favouring cell longevity over cell turnover. We suggest a mechanism by which the interplay of a declining sodium pump and two passive membrane transporters, the mechanosensitive PIEZO1 channel, a candidate mediator of Psickle in sickle cells, and the Ca2+-sensitive, K+-selective Gardos channel, can implement red blood cell volume stability around the optimal-volume-ratio range, as required for extended circulatory longevity.

  13. LACIE data-handling techniques

    Science.gov (United States)

    Waits, G. H. (Principal Investigator)

    1979-01-01

    Techniques implemented to facilitate processing of LANDSAT multispectral data between 1975 and 1978 are described. The data that were handled during the large area crop inventory experiment and the storage mechanisms used for the various types of data are defined. The overall data flow, from the placing of the LANDSAT orders through the actual analysis of the data set, is discussed. An overview is provided of the status and tracking system that was developed and of the data base maintenance and operational task. The archiving of the LACIE data is explained.

  14. The effect of powder properties on sintering, microstructure, mechanical strength and degradability of beta-tricalcium phosphate/calcium silicate composite bioceramics

    Energy Technology Data Exchange (ETDEWEB)

    Lin Kaili; Chang Jiang; Shen Ruxiang, E-mail: jchang@mail.sic.ac.c [State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050 (China)

    2009-12-15

    The effect of powder properties on sintering, microstructure, mechanical strength and degradability of beta-tricalcium phosphate/Calcium silicate (beta-Ca{sub 3}(PO{sub 4}){sub 2}/CaSiO{sub 3}, beta-TCP/CS) composite bioceramics was investigated. beta-TCP/CS composite powders with a weight ratio of 50:50 were prepared by three different methods: mechanical milling method (TW-A), two-step chemical precipitation method (TW-B) and in situ chemical co-precipitation method (TW-C), and then the three composite powders were uniaxially compacted at 30 MPa, followed by cold isostatic pressing into rectangular-prism-shaped specimens under a pressure of 200 MPa for 15 min, and then sintered at 1150 deg. C for 5 h. The TW-B powders with less agglomerative morphologies and uniform nano-size particles attained 96.14% relative density (RD). A uniform microstructure with about 120 nm grains was observed. Whereas, the samples obtained from TW-A and TW-C powders only reached a RD of 63.08% and 78.86%, respectively. The bending strength of the samples fabricated from TW-B reached 125 MPa, which was more than 3.7 and 1.5 times higher as compared with that of samples obtained from TW-A and TW-C powders, respectively. Furthermore, the degradability of the samples fabricated from TW-B powders was obviously lower than that of the samples fabricated from TW-A and TW-C powders.

  15. Exploring the mechanism of action of the sperm-triggered calcium-wave pacemaker in ascidian zygotes.

    Science.gov (United States)

    Carroll, Michael; Levasseur, Mark; Wood, Chris; Whitaker, Michael; Jones, Keith T; McDougall, Alex

    2003-12-15

    In ascidians, as in mammals, sperm trigger repetitive Ca2+-waves that originate from cortical pacemakers situated in the vegetal hemisphere of the zygotes. In ascidians, a vegetal protrusion termed the contraction pole (CP) acts as the Ca2+-wave pacemaker, but the mechanism that underlies the generation of a Ca2+-wave pacemaker is not known. Here, we tested four hypotheses to determine which factors at the CP are involved in setting the pace of the ascidian Ca2+-wave pacemaker: (1) localized Ca2+ influx; (2) accumulation of phosphatidylinositol (4,5)bisphosphate [PtdIns(4,5)P2]; (3) accumulation of cortical endoplasmic reticulum (cER); and (4) enrichment of the sperm activating factor. We developed a method of dynamically monitoring the location of the CP during fertilization using a plekstrin homology (PH) domain from phospholipase Cdelta1 coupled to green fluorescent protein (GFP) that binds PtdIns(4,5)P2. We found that eggs in Ca2+-free sea water displayed Ca2+ waves that originated from the CP, showing that enhanced CP Ca2+ influx does not determine the origin of the pacemaker. Also, disruption of the PH::GFP-labelled CP once it had formed did not dislodge the Ca2+-wave pacemaker from that site. Next, when we prevented the accumulation of cER at the CP, all of the Ca2+ waves came from the site of sperm-egg fusion and the frequency of Ca2+ oscillations was unaltered. These data show that local Ca2+ influx, the accumulation of PtdIns(4,5)P2 and cER at the CP are not required for Ca2+-wave pacemaker function and instead suggest that a factor associated with the sperm determines the site of the Ca2+-wave pacemaker. Finally, when we injected ascidian sperm extract into the centre of unfertilized ascidian eggs that had been treated with microfilament- and microtubule-disrupting drugs, all the Ca2+ waves still originated from near the plasma membrane, showing that the sperm factor does not require an intact cortex if it is enriched near the plasma membrane (PM). We

  16. Anticonvulsant mechanism of saponins fraction from adventitious roots of Ficus religiosa: possible modulation of GABAergic, calcium and sodium channel functions

    Directory of Open Access Journals (Sweden)

    Damanpreet Singh

    Full Text Available ABSTRACT In our previous studies, quantified saponins-rich fraction from adventitious root extract of Ficus religiosa L., Moraceae, showed anticonvulsant effect in acute, as well as chronic mice models of epilepsy. The present study was designed to reveal putative anticonvulsant mechanism of quantified saponins-rich fraction using target specific animal models. The anticonvulsant effect of quantified saponins-rich fraction was initially studied in maximal electroshock and pentylenetetrazol test at 1, 2 and 4 mg/kg; i.p. doses. Based on the results of initial anticonvulsant testing, different groups of mice were injected with vehicle or quantified saponins-rich fraction (4 mg/kg; i.p., 30 min prior to an injection of N-methyl-D-aspartic acid (100 mg/kg; s.c., bicuculline (5 mg/kg; i.p., strychnine hydrochloride (2 mg/kg; i.p., BAY k-8644 (37.5 µg; i.c.v., veratridine (500 µg/kg; i.p. and the convulsive episodes were studied. Treatment with the extract (1, 2 and 4 mg/kg showed significant protection in maximal electroshock and pentylenetetrazol-induced convulsion tests, in a dose-dependent manner. Moreover, quantified saponins-rich fraction at 4 mg/kg dose showed significant increase in latency to clonic convulsions, decrease in seizure severity and increase in average wave amplitude in bicuculline, BAY k-8644 and veratridine tests, respectively, as compared to vehicle control. However, SRF treatment failed to abolish N-methyl-D-aspartic acid and strychnine-induced convulsions, indicated by insignificant change in the appearance of turning behavior and onset of tonic extension, respectively, as compared to vehicle control. From the results of present study, it is concluded that quantified saponins-rich fraction suppress maximal electroshock, pentylenetetrazol, bicuculline, BAY k-8644 and veratridine-induced convulsions, indicating its GABAergic, Na+ and Ca2+ channel modulatory effects. Further it can be correlated that quantified saponins

  17. Essential oil from Xylopia frutescens Aubl. reduces cytosolic calcium levels on guinea pig ileum: mechanism underlying its spasmolytic potential.

    Science.gov (United States)

    Souza, Iara Leão Luna de; Correia, Ana Carolina de Carvalho; Araujo, Layanne Cabral da Cunha; Vasconcelos, Luiz Henrique César; Silva, Maria da Conceição Correia; Costa, Vicente Carlos de Oliveira; Tavares, Josean Fechine; Paredes-Gamero, Edgar Julian; Cavalcante, Fabiana de Andrade; Silva, Bagnólia Araújo da

    2015-09-16

    not altered in the presence of XF-OE and the Fluo-4-associated fluorescence intensity in these intestinal myocytes stimulated by histamine was reduced by the essential oil, indicating a [Ca(2+)]c reduction. Spasmolytic action mechanism of XF-EO on guinea pig ileum can involve histaminergic receptor antagonism and Ca(2+) influx blockade, which results in [Ca(2+)]c reduction leading to smooth muscle relaxation.

  18. Calcium Balance in Chronic Kidney Disease.

    Science.gov (United States)

    Hill Gallant, Kathleen M; Spiegel, David M

    2017-06-01

    The kidneys play a critical role in the balance between the internal milieu and external environment. Kidney failure is known to disrupt a number of homeostatic mechanisms that control serum calcium and normal bone metabolism. However, our understanding of calcium balance throughout the stages of chronic kidney disease is limited and the concept of balance itself, especially with a cation as complex as calcium, is often misunderstood. Both negative and positive calcium balance have important implications in patients with chronic kidney disease, where negative balance may increase risk of osteoporosis and fracture and positive balance may increase risk of vascular calcification and cardiovascular events. Here, we examine the state of current knowledge about calcium balance in adults throughout the stages of chronic kidney disease and discuss recommendations for clinical strategies to maintain balance as well as future research needs in this area. Recent calcium balance studies in adult patients with chronic kidney disease show that neutral calcium balance is achieved with calcium intake near the recommended daily allowance. Increases in calcium through diet or supplements cause high positive calcium balance, which may put patients at risk for vascular calcification. However, heterogeneity in calcium balance exists among these patients. Given the available calcium balance data in this population, it appears clinically prudent to aim for recommended calcium intakes around 1000 mg/day to achieve neutral calcium balance and avoid adverse effects of either negative or positive calcium balance. Assessment of patients' dietary calcium intake could further equip clinicians to make individualized recommendations for meeting recommended intakes.

  19. Effect of calcium supplements on osteoporosis by using nuclear analytical techniques

    International Nuclear Information System (INIS)

    Sumin Hu; Xueying Mao; Hong Ouyang

    2004-01-01

    Neutron activation analysis (NAA) and dual energy X-ray absorptiometry (DEXA) have been used to study the effects of different calcium supplements on osteoporosis, including calcium carbonate, calcium threonate, calcium gluconate, calcium lactate, calcium acetate and a traditional Chinese medicine. Animal test results showed that calcium carbonate, calcium gluconate, calcium acetate and the Chinese medicine notably increased osteoporotic rat's femoral bone mineral density (BMD). Also, calcium carbonate, calcium acetate and the Chinese medicine significantly increased osteoporotic rat's vertebral BMD. But calcium L-threonate and calcium lactate had no such effects. Calcium gluconate, calcium acetate and the Chinese medicine improved the bone mechanical intensity of osteoporotic rats. The results of NAA showed that the loss of elements in spongy bones was more seriously than that in compact bone and was difficult to be improved. (author)

  20. BDE-47 and 6-OH-BDE-47 modulate calcium homeostasis in primary fetal human neural progenitor cells via ryanodine receptor-independent mechanisms

    NARCIS (Netherlands)

    Gassmann, Kathrin; Schreiber, Timm; Dingemans, Milou M L; Krause, Guido; Roderigo, Claudia; Giersiefer, Susanne; Schuwald, Janette; Moors, Michaela; Unfried, Klaus; Bergman, Åke; Westerink, Remco H S; Rose, Christine R.; Fritsche, Ellen

    2014-01-01

    Polybrominated diphenyl ethers (PBDEs) are bioaccumulating flame retardants found in rising concentrations in human tissue. Epidemiological and animal studies have raised concern for their potential to induce developmental neurotoxicity (DNT). Considering the essential role of calcium homeostasis in

  1. Safe handling of tritium

    International Nuclear Information System (INIS)

    1991-01-01

    The main objective of this publication is to provide practical guidance and recommendations on operational radiation protection aspects related to the safe handling of tritium in laboratories, industrial-scale nuclear facilities such as heavy-water reactors, tritium removal plants and fission fuel reprocessing plants, and facilities for manufacturing commercial tritium-containing devices and radiochemicals. The requirements of nuclear fusion reactors are not addressed specifically, since there is as yet no tritium handling experience with them. However, much of the material covered is expected to be relevant to them as well. Annex III briefly addresses problems in the comparatively small-scale use of tritium at universities, medical research centres and similar establishments. However, the main subject of this publication is the handling of larger quantities of tritium. Operational aspects include designing for tritium safety, safe handling practice, the selection of tritium-compatible materials and equipment, exposure assessment, monitoring, contamination control and the design and use of personal protective equipment. This publication does not address the technologies involved in tritium control and cleanup of effluents, tritium removal, or immobilization and disposal of tritium wastes, nor does it address the environmental behaviour of tritium. Refs, figs and tabs

  2. Grain Grading and Handling.

    Science.gov (United States)

    Rendleman, Matt; Legacy, James

    This publication provides an introduction to grain grading and handling for adult students in vocational and technical education programs. Organized in five chapters, the booklet provides a brief overview of the jobs performed at a grain elevator and of the techniques used to grade grain. The first chapter introduces the grain industry and…

  3. Mars Sample Handling Functionality

    Science.gov (United States)

    Meyer, M. A.; Mattingly, R. L.

    2018-04-01

    The final leg of a Mars Sample Return campaign would be an entity that we have referred to as Mars Returned Sample Handling (MRSH.) This talk will address our current view of the functional requirements on MRSH, focused on the Sample Receiving Facility (SRF).

  4. Handling wood shavings

    Energy Technology Data Exchange (ETDEWEB)

    1974-09-18

    Details of bulk handling equipment suitable for collection and compressing wood waste from commercial joinery works are discussed. The Redler Bin Discharger ensures free flow of chips from storage silo discharge prior to compression into briquettes for use as fuel or processing into chipboard.

  5. Seasonal Variations in Mercury's Dayside Calcium Exosphere

    Science.gov (United States)

    Burger, Matthew H.; Killen, Rosemary M.; McClintock, William E.; Merkel, Aimee W.; Vervack, Ronald J., Jr.; Cassidy, Timothy A.; Sarantos, Menelaos

    2014-01-01

    The Mercury Atmospheric and Surface Composition Spectrometer on the MESSENGER spacecraft has observed calcium emission in Mercury's exosphere on a near-daily basis since March 2011. During MESSENGER's primary and first extended missions (March 2011 - March 2013) the dayside calcium exosphere was measured over eight Mercury years. We have simulated these data with a Monte Carlo model of exospheric source processes to show that (a) there is a persistent source of energetic calcium located in the dawn equatorial region, (b) there is a seasonal dependence in the calcium source rate, and (c) there are no obvious year-to-year variations in the near-surface dayside calcium exosphere. Although the precise mechanism responsible for ejecting the calcium has not yet been determined, the most likely process is the dissociation of Ca-bearing molecules produced in micrometeoroid impact plumes to form energetic, escaping calcium atoms.

  6. Magnesium implant alloy with low levels of strontium and calcium: The third element effect and phase selection improve bio-corrosion resistance and mechanical performance

    Energy Technology Data Exchange (ETDEWEB)

    Bornapour, M., E-mail: mandana.bornapour@mail.mcgill.ca [Light Metals and Advanced Magnesium Materials, Mining and Materials Engineering, McGill University, Montreal, QC H3A 2B2 (Canada); Biointerface Lab, Mining and Materials Engineering, McGill University, Montreal, QC H3A 2B2 (Canada); Celikin, M. [Light Metals and Advanced Magnesium Materials, Mining and Materials Engineering, McGill University, Montreal, QC H3A 2B2 (Canada); Cerruti, M. [Biointerface Lab, Mining and Materials Engineering, McGill University, Montreal, QC H3A 2B2 (Canada); Pekguleryuz, M. [Light Metals and Advanced Magnesium Materials, Mining and Materials Engineering, McGill University, Montreal, QC H3A 2B2 (Canada)

    2014-02-01

    Low density, non-toxicity, biodegradability and mechanical properties similar to human tissues such as bone make magnesium (Mg) alloys attractive for biomedical applications ranging from bone to cardiovascular implants. The most important challenge that still prevents the widespread use of Mg implants is their rapid degradation rate. In this study we investigate the combined effect of calcium (Ca) and strontium (Sr) on the corrosion behavior of Mg via in vitro immersion and electrochemical tests in simulated body fluid (SBF), and analyze changes in mechanical properties. We show that the combined addition of 0.3 wt.% Sr and 0.4 wt.% Ca decreases the corrosion rate of Mg both in terms of mass loss and hydrogen evolution more effectively than the single addition of either alloying element. We investigate the microstructure of as-cast specimens and the morphology of the corrosion products using optical microscopy, scanning electron microscopy, electron probe micro-analysis, X-ray diffraction, and X-ray photoelectron spectroscopy. Tensile and three point bending tests reveal that the ternary alloy Mg–0.3Sr–0.3Ca has a good combination of mechanical properties and corrosion resistance with hydrogen evolution rates of 0.01 mL/cm{sup 2}/h in SBF. Higher concentrations of Sr and Ca alter the resulting microstructure leading to increased corrosion rates in SBF by promoting the micro-galvanic corrosion between the α-Mg matrix and intermetallic phases of Mg{sub 17}Sr{sub 2} and Mg{sub 2}Ca along the grain boundaries. These results indicate that the combined addition of optimal amounts of Ca and Sr is a promising approach to decrease the high degradation rate of Mg implants in physiological conditions, as well as attaining high ductility in the alloy. The better properties of the Mg–0.3Sr–0.3Ca alloy are related to the new intermetallic phases found in this sample. The optimum composition is attributed to the “third element effect”, as seen in the corrosion

  7. A short introduction to the new principle of binding ration calcium with sodium zeolite

    DEFF Research Database (Denmark)

    Jørgensen, R J; Bjerrum, M J; Classen, H

    2003-01-01

    This paper summarise the development of the new principle of preventing parturient hypocalcaemia by reducing the bioavailability of ration calcium with calcium binders, based on the idea that a negative calcium balance would stimulate natural defence mechanisms against threatening hypocalcaemia...

  8. Calcium phosphates for biomedical applications

    Directory of Open Access Journals (Sweden)

    Maria Canillas

    2017-05-01

    Full Text Available The history of calcium phosphates in the medicine field starts in 1769 when the first evidence of its existence in the bone tissue is discovered. Since then, the interest for calcium phosphates has increased among the scientific community. Their study has been developed in parallel with new advances in materials sciences, medicine or tissue engineering areas. Bone tissue engineering is the field where calcium phosphates have had a great importance. While the first bioceramics are selected according to bioinert, biocompatibility and mechanical properties with the aim to replace bone tissue damaged, calcium phosphates open the way to the bone tissue regeneration challenge. Nowadays, they are present in the majority of commercial products directed to repair or regenerate damaged bone tissue. Finally, in the last few decades, they have been suggested and studied as drug delivering devices and as vehicles of DNA and RNA for the future generation therapies.

  9. Calcium phosphates for biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Canillas, M.; Pena, P.; Aza, A.H. de; Rodriguez, M.A.

    2017-07-01

    The history of calcium phosphates in the medicine field starts in 1769 when the first evidence of its existence in the bone tissue is discovered. Since then, the interest for calcium phosphates has increased among the scientific community. Their study has been developed in parallel with new advances in materials sciences, medicine or tissue engineering areas. Bone tissue engineering is the field where calcium phosphates have had a great importance. While the first bioceramics are selected according to bioinert, biocompatibility and mechanical properties with the aim to replace bone tissue damaged, calcium phosphates open the way to the bone tissue regeneration challenge. Nowadays, they are present in the majority of commercial products directed to repair or regenerate damaged bone tissue. Finally, in the last few decades, they have been suggested and studied as drug delivering devices and as vehicles of DNA and RNA for the future generation therapies. (Author)

  10. Calcium blood test

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/003477.htm Calcium blood test To use the sharing features on this page, please enable JavaScript. The calcium blood test measures the level of calcium in the blood. ...

  11. Calcium source (image)

    Science.gov (United States)

    Getting enough calcium to keep bones from thinning throughout a person's life may be made more difficult if that person has ... as a tendency toward kidney stones, for avoiding calcium-rich food sources. Calcium deficiency also effects the ...

  12. Calcium Pyrophosphate Deposition (CPPD)

    Science.gov (United States)

    ... Patient / Caregiver Diseases & Conditions Calcium Pyrophosphate Deposition (CPPD) Calcium Pyrophosphate Deposition (CPPD) Fast Facts The risk of ... young people, too. Proper diagnosis depends on detecting calcium pyrophosphate crystals in the fluid of an affected ...

  13. Calcium carbonate overdose

    Science.gov (United States)

    Tums overdose; Calcium overdose ... Calcium carbonate can be dangerous in large amounts. ... Products that contain calcium carbonate are certain: Antacids (Tums, Chooz) Mineral supplements Hand lotions Vitamin and mineral supplements Other products may also contain ...

  14. Calcium and bones (image)

    Science.gov (United States)

    Calcium is one of the most important minerals for the growth, maintenance, and reproduction of the human ... body, are continually being re-formed and incorporate calcium into their structure. Calcium is essential for the ...

  15. Calcium hydroxide poisoning

    Science.gov (United States)

    Hydrate - calcium; Lime milk; Slaked lime ... Calcium hydroxide ... These products contain calcium hydroxide: Cement Limewater Many industrial solvents and cleaners (hundreds to thousands of construction products, flooring strippers, brick cleaners, cement ...

  16. Test sample handling apparatus

    International Nuclear Information System (INIS)

    1981-01-01

    A test sample handling apparatus using automatic scintillation counting for gamma detection, for use in such fields as radioimmunoassay, is described. The apparatus automatically and continuously counts large numbers of samples rapidly and efficiently by the simultaneous counting of two samples. By means of sequential ordering of non-sequential counting data, it is possible to obtain precisely ordered data while utilizing sample carrier holders having a minimum length. (U.K.)

  17. Handling and Transport Problems

    Energy Technology Data Exchange (ETDEWEB)

    Pomarola, J. [Head of Technical Section, Atomic Energy Commission, Saclay (France); Savouyaud, J. [Head of Electro-Mechanical Sub-Division, Atomic Energy Commission, Saclay (France)

    1960-07-01

    Arrangements for special or dangerous transport operations by road arising out of the activities of the Atomic Energy Commission are made by the Works and Installations Division which acts in concert with the Monitoring and Protection Division (MPD) whenever radioactive substances or appliances are involved. In view of the risk of irradiation and contamination entailed in handling and transporting radioactive substances, including waste, a specialized transport and storage team has been formed as a complement to the emergency and decontamination teams.

  18. Solid waste handling

    International Nuclear Information System (INIS)

    Parazin, R.J.

    1995-01-01

    This study presents estimates of the solid radioactive waste quantities that will be generated in the Separations, Low-Level Waste Vitrification and High-Level Waste Vitrification facilities, collectively called the Tank Waste Remediation System Treatment Complex, over the life of these facilities. This study then considers previous estimates from other 200 Area generators and compares alternative methods of handling (segregation, packaging, assaying, shipping, etc.)

  19. Handling of radioactive waste

    International Nuclear Information System (INIS)

    Sanhueza Mir, Azucena

    1998-01-01

    Based on characteristics and quantities of different types of radioactive waste produced in the country, achievements in infrastructure and the way to solve problems related with radioactive waste handling and management, are presented in this paper. Objectives of maintaining facilities and capacities for controlling, processing and storing radioactive waste in a conditioned form, are attained, within a great range of legal framework, so defined to contribute with safety to people and environment (au)

  20. Renal phosphate handling: Physiology

    Directory of Open Access Journals (Sweden)

    Narayan Prasad

    2013-01-01

    Full Text Available Phosphorus is a common anion. It plays an important role in energy generation. Renal phosphate handling is regulated by three organs parathyroid, kidney and bone through feedback loops. These counter regulatory loops also regulate intestinal absorption and thus maintain serum phosphorus concentration in physiologic range. The parathyroid hormone, vitamin D, Fibrogenic growth factor 23 (FGF23 and klotho coreceptor are the key regulators of phosphorus balance in body.

  1. Uranium hexafluoride handling

    International Nuclear Information System (INIS)

    1991-01-01

    The United States Department of Energy, Oak Ridge Field Office, and Martin Marietta Energy Systems, Inc., are co-sponsoring this Second International Conference on Uranium Hexafluoride Handling. The conference is offered as a forum for the exchange of information and concepts regarding the technical and regulatory issues and the safety aspects which relate to the handling of uranium hexafluoride. Through the papers presented here, we attempt not only to share technological advances and lessons learned, but also to demonstrate that we are concerned about the health and safety of our workers and the public, and are good stewards of the environment in which we all work and live. These proceedings are a compilation of the work of many experts in that phase of world-wide industry which comprises the nuclear fuel cycle. Their experience spans the entire range over which uranium hexafluoride is involved in the fuel cycle, from the production of UF 6 from the naturally-occurring oxide to its re-conversion to oxide for reactor fuels. The papers furnish insights into the chemical, physical, and nuclear properties of uranium hexafluoride as they influence its transport, storage, and the design and operation of plant-scale facilities for production, processing, and conversion to oxide. The papers demonstrate, in an industry often cited for its excellent safety record, continuing efforts to further improve safety in all areas of handling uranium hexafluoride

  2. Uranium hexafluoride handling. Proceedings

    Energy Technology Data Exchange (ETDEWEB)

    1991-12-31

    The United States Department of Energy, Oak Ridge Field Office, and Martin Marietta Energy Systems, Inc., are co-sponsoring this Second International Conference on Uranium Hexafluoride Handling. The conference is offered as a forum for the exchange of information and concepts regarding the technical and regulatory issues and the safety aspects which relate to the handling of uranium hexafluoride. Through the papers presented here, we attempt not only to share technological advances and lessons learned, but also to demonstrate that we are concerned about the health and safety of our workers and the public, and are good stewards of the environment in which we all work and live. These proceedings are a compilation of the work of many experts in that phase of world-wide industry which comprises the nuclear fuel cycle. Their experience spans the entire range over which uranium hexafluoride is involved in the fuel cycle, from the production of UF{sub 6} from the naturally-occurring oxide to its re-conversion to oxide for reactor fuels. The papers furnish insights into the chemical, physical, and nuclear properties of uranium hexafluoride as they influence its transport, storage, and the design and operation of plant-scale facilities for production, processing, and conversion to oxide. The papers demonstrate, in an industry often cited for its excellent safety record, continuing efforts to further improve safety in all areas of handling uranium hexafluoride. Selected papers were processed separately for inclusion in the Energy Science and Technology Database.

  3. Torus sector handling system

    International Nuclear Information System (INIS)

    Grisham, D.L.

    1981-01-01

    A remote handling system is proposed for moving a torus sector of the accelerator from under the cryostat to a point where it can be handled by a crane and for the reverse process for a new sector. Equipment recommendations are presented, as well as possible alignment schemes. Some general comments about future remote-handling methods and the present capabilities of existing systems will also be included. The specific task to be addressed is the removal and replacement of a 425 to 450 ton torus sector. This requires a horizontal movement of approx. 10 m from a normal operating position to a point where its further transport can be accomplished by more conventional means (crane or floor transporter). The same horizontal movement is required for reinstallation, but a positional tolerance of 2 cm is required to allow reasonable fit-up for the vacuum seal from the radial frames to the torus sector. Since the sectors are not only heavy but rather tall and narrow, the transport system must provide a safe, stable, and repeatable method fo sector movement. This limited study indicates that the LAMPF-based method of transporting torus sectors offers a proven method of moving heavy items. In addition, the present state of the art in remote equipment is adequate for FED maintenance

  4. Handling of Solid Residues

    International Nuclear Information System (INIS)

    Medina Bermudez, Clara Ines

    1999-01-01

    The topic of solid residues is specifically of great interest and concern for the authorities, institutions and community that identify in them a true threat against the human health and the atmosphere in the related with the aesthetic deterioration of the urban centers and of the natural landscape; in the proliferation of vectorial transmitters of illnesses and the effect on the biodiversity. Inside the wide spectrum of topics that they keep relationship with the environmental protection, the inadequate handling of solid residues and residues dangerous squatter an important line in the definition of political and practical environmentally sustainable. The industrial development and the population's growth have originated a continuous increase in the production of solid residues; of equal it forms, their composition day after day is more heterogeneous. The base for the good handling includes the appropriate intervention of the different stages of an integral administration of residues, which include the separation in the source, the gathering, the handling, the use, treatment, final disposition and the institutional organization of the administration. The topic of the dangerous residues generates more expectation. These residues understand from those of pathogen type that are generated in the establishments of health that of hospital attention, until those of combustible, inflammable type, explosive, radio-active, volatile, corrosive, reagent or toxic, associated to numerous industrial processes, common in our countries in development

  5. ERROR HANDLING IN INTEGRATION WORKFLOWS

    Directory of Open Access Journals (Sweden)

    Alexey M. Nazarenko

    2017-01-01

    Full Text Available Simulation experiments performed while solving multidisciplinary engineering and scientific problems require joint usage of multiple software tools. Further, when following a preset plan of experiment or searching for optimum solu- tions, the same sequence of calculations is run multiple times with various simulation parameters, input data, or conditions while overall workflow does not change. Automation of simulations like these requires implementing of a workflow where tool execution and data exchange is usually controlled by a special type of software, an integration environment or plat- form. The result is an integration workflow (a platform-dependent implementation of some computing workflow which, in the context of automation, is a composition of weakly coupled (in terms of communication intensity typical subtasks. These compositions can then be decomposed back into a few workflow patterns (types of subtasks interaction. The pat- terns, in their turn, can be interpreted as higher level subtasks.This paper considers execution control and data exchange rules that should be imposed by the integration envi- ronment in the case of an error encountered by some integrated software tool. An error is defined as any abnormal behavior of a tool that invalidates its result data thus disrupting the data flow within the integration workflow. The main requirementto the error handling mechanism implemented by the integration environment is to prevent abnormal termination of theentire workflow in case of missing intermediate results data. Error handling rules are formulated on the basic pattern level and on the level of a composite task that can combine several basic patterns as next level subtasks. The cases where workflow behavior may be different, depending on user's purposes, when an error takes place, and possible error handling op- tions that can be specified by the user are also noted in the work.

  6. Calcium in Urine Test

    Science.gov (United States)

    ... K. Brunner & Suddarth's Handbook of Laboratory and Diagnostic Tests. 2 nd Ed, Kindle. Philadelphia: Wolters Kluwer Health, Lippincott Williams & Wilkins; c2014. Calcium, Serum; Calcium and Phosphates, Urine; ...

  7. Pharmacological modulation of mitochondrial calcium homeostasis.

    Science.gov (United States)

    Arduino, Daniela M; Perocchi, Fabiana

    2018-01-10

    Mitochondria are pivotal organelles in calcium (Ca 2+ ) handling and signalling, constituting intracellular checkpoints for numerous processes that are vital for cell life. Alterations in mitochondrial Ca 2+ homeostasis have been linked to a variety of pathological conditions and are critical in the aetiology of several human diseases. Efforts have been taken to harness mitochondrial Ca 2+ transport mechanisms for therapeutic intervention, but pharmacological compounds that direct and selectively modulate mitochondrial Ca 2+ homeostasis are currently lacking. New avenues have, however, emerged with the breakthrough discoveries on the genetic identification of the main players involved in mitochondrial Ca 2+ influx and efflux pathways and with recent hints towards a deep understanding of the function of these molecular systems. Here, we review the current advances in the understanding of the mechanisms and regulation of mitochondrial Ca 2+ homeostasis and its contribution to physiology and human disease. We also introduce and comment on the recent progress towards a systems-level pharmacological targeting of mitochondrial Ca 2+ homeostasis. © 2018 The Authors. The Journal of Physiology © 2018 The Physiological Society.

  8. β-Microseminoprotein endows post coital seminal plasma with potent candidacidal activity by a calcium- and pH-dependent mechanism

    DEFF Research Database (Denmark)

    Edström Hägerwall, Anneli; Rydengård, Victoria; Fernlund, Per

    2012-01-01

    is very rare. This prompted us to investigate whether the post coital vaginal milieu contained factors active against C. albicans. By CFU assays, we found prominent candidacidal activity of post coital seminal plasma at both neutral and the acid vaginal pH. In contrast, normal seminal plasma did...... not display candidacidal activity prior to acidification. By antifungal gel overlay assay, one clearing zone corresponding to a protein band was found in both post coital and normal seminal plasma, which was subsequently identified as β-microseminoprotein. At neutral pH, the fungicidal activity of β......-microseminoprotein and seminal plasma was inhibited by calcium. By NMR spectroscopy, amino acid residue E(71) was shown to be critical for the calcium coordination. The acidic vaginal milieu unleashed the fungicidal activity by decreasing the inhibitory effect of calcium. The candidacidal activity of β...

  9. Remote handling prospects. Computer aided remote handling

    International Nuclear Information System (INIS)

    Vertut, J.

    1984-01-01

    Mechanical manipulators, electrical control manipulators and computer aided manipulators were successively developed. The aim of computer aided manipulators is the realization of complex or tricky job in adverse environment but man is required for non routine work or for situation in evolution. French effort is developed in the frame of the project automation and advanced robotics and new problems have to be solved particularly at the interface man/machine [fr

  10. Excessive dietary calcium in the disruption of structural and functional status of adult male reproductive system in rat with possible mechanism.

    Science.gov (United States)

    K Chandra, Amar; Sengupta, Pallav; Goswami, Haimanti; Sarkar, Mahitosh

    2012-05-01

    Calcium is essential for functioning of different systems including male reproduction. However, it has also been reported as chemo-castrative agent. The study has been undertaken to elucidate the effect of excessive dietary calcium on male reproductive system in animals with possible action. Adult male healthy rats fed CaCl(2) at different doses (0.5, 1.0 and 1.5 g%) in diet for 13 and 26 days to investigate reproductive parameters as well as the markers of oxidative stress. Significant alteration was found (P male reproduction.

  11. Models of calcium signalling

    CERN Document Server

    Dupont, Geneviève; Kirk, Vivien; Sneyd, James

    2016-01-01

    This book discusses the ways in which mathematical, computational, and modelling methods can be used to help understand the dynamics of intracellular calcium. The concentration of free intracellular calcium is vital for controlling a wide range of cellular processes, and is thus of great physiological importance. However, because of the complex ways in which the calcium concentration varies, it is also of great mathematical interest.This book presents the general modelling theory as well as a large number of specific case examples, to show how mathematical modelling can interact with experimental approaches, in an interdisciplinary and multifaceted approach to the study of an important physiological control mechanism. Geneviève Dupont is FNRS Research Director at the Unit of Theoretical Chronobiology of the Université Libre de Bruxelles;Martin Falcke is head of the Mathematical Cell Physiology group at the Max Delbrück Center for Molecular Medicine, Berlin;Vivien Kirk is an Associate Professor in the Depar...

  12. Study of mechanical properties of calcium phosphate cement with addition of sodium alginate and dispersant; Estudo das propriedades mecanicas de cimento de fosfato de calcio com adicao de alginato de sodio e defloculante

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, J.M.; Coelho, W.T.; Thurmer, M.B.; Vieira, P.S.; Santos, L.A., E-mail: julianafernandes2@yahoo.com.br [Universidade Federal do Rio Grande do Sul (UFRS), RS (Brazil)

    2011-07-01

    Several studies in literature have shown that the addition of polymer additives and deflocculant has a strong influence on the mechanical properties of cements in general.The low mechanical strength is the main impediment to wider use of bone cement of calcium phosphate (CFCs) as the implant material, since they have mechanical strength which equals the maximum of trabecular bone.In order to evaluate the strength of a CFC compound alpha-tricalcium phosphate, sodium alginate were added (1%, 2% and 3% by weight) and dispersant ammonium polyacrylate (3%) in aqueous solution.Specimens were made and evaluated for density, porosity, crystalline phases and mechanical strength.The results show the increase of the mechanical properties of cement when added sodium alginate and dispersant. (author)

  13. Bone Mineral Density, Mechanical, Microstructural Properties and Mineral Content of the Femur in Growing Rats Fed with Cactus Opuntia ficus indica (L. Mill. (Cactaceae Cladodes as Calcium Source in Diet

    Directory of Open Access Journals (Sweden)

    Ezequiel Hernández-Becerra

    2017-02-01

    Full Text Available Mechanical, microstructural properties, mineral content and bone mineral density (BMD of the femur were evaluated in growing rats fed with Opuntia ficus indica (L. Mill. (Cactaceae cladodes at different maturity stages as calcium source. Male weanling rats were fed with cladodes at early maturity stage (25 and 60 days of age, belonging to groups N-60 and N-200, respectively and cladodes at late maturity stage (100 and 135 days of age, belonging to groups N-400 and N-600, respectively for 6 weeks. Additionally, a control group fed with calcium carbonate as calcium source was included for comparative purposes. All diets were fitted to the same calcium content (5 g/kg diet. The failure load of femurs was significantly lower (p ≤ 0.05 in groups N-60 and N-200 in comparison to N-400, N-600 and control groups. The cortical width (Ct.Wi and trabecular thickness (Tb.Th of the femurs in control and N-600 groups were significantly higher (p ≤ 0.05 than Ct.Wi and Tb.Th of femurs in groups N-60 and N-200. Trabecular separation of the femurs in N-60 and N-200 groups showed the highest values compared with all experimental groups. The highest calcium content in the femurs were observed in control, N-600 and N-400 groups; whereas the lowest phosphorus content in the bones were detected in N-200, N-600 and N-400 groups. Finally, the BMD in all experimental groups increased with age; nevertheless, the highest values were observed in N-600 and control groups during pubertal and adolescence stages. The results derived from this research demonstrate, for the first time, that the calcium found in Opuntia ficus indica cladodes is actually bioavailable and capable of improving mineral density and mechanical and microstructural properties of the bones. These findings suggest that the consumption of cladodes at late maturity stage within the diet might have a beneficial impact on bone health.

  14. Preference Handling for Artificial Intelligence

    OpenAIRE

    Goldsmith, Judy; University of Kentucky; Junker, Ulrich; ILOG

    2009-01-01

    This article explains the benefits of preferences for AI systems and draws a picture of current AI research on preference handling. It thus provides an introduction to the topics covered by this special issue on preference handling.

  15. Recommendations for cask features for robotic handling from the Advanced Handling Technology Project

    International Nuclear Information System (INIS)

    Drotning, W.

    1991-02-01

    This report describes the current status and recent progress in the Advanced Handling Technology Project (AHTP) initiated to explore the use of advanced robotic systems and handling technologies to perform automated cask handling operations at radioactive waste handling facilities, and to provide guidance to cask designers on the impact of robotic handling on cask design. Current AHTP tasks have developed system mock-ups to investigate robotic manipulation of impact limiters and cask tiedowns. In addition, cask uprighting and transport, using computer control of a bridge crane and robot, were performed to demonstrate the high speed cask transport operation possible under computer control. All of the current AHTP tasks involving manipulation of impact limiters and tiedowns require robotic operations using a torque wrench. To perform these operations, a pneumatic torque wrench and control system were integrated into the tool suite and control architecture of the gantry robot. The use of captured fasteners is briefly discussed as an area where alternative cask design preferences have resulted from the influence of guidance for robotic handling vs traditional operations experience. Specific robotic handling experiences with these system mock-ups highlight a number of continually recurring design principles: (1) robotic handling feasibility is improved by mechanical designs which emphasize operation with limited dexterity in constrained workspaces; (2) clearances, tolerances, and chamfers must allow for operations under actual conditions with consideration for misalignment and imprecise fixturing; (3) successful robotic handling is enhanced by including design detail in representations for model-based control; (4) robotic handling and overall quality assurance are improved by designs which eliminate the use of loose, disassembled parts. 8 refs., 15 figs

  16. Crud handling circuit

    International Nuclear Information System (INIS)

    Smith, J.C.; Manuel, R.J.; McAllister, J.E.

    1981-01-01

    A process for handling the problems of crud formation during the solvent extraction of wet-process phosphoric acid, e.g. for uranium and rare earth removal, is described. It involves clarification of the crud-solvent mixture, settling, water washing the residue and treatment of the crud with a caustic wash to remove and regenerate the solvent. Applicable to synergistic mixtures of dialkylphosphoric acids and trialkylphosphine oxides dissolved in inert diluents and more preferably to the reductive stripping technique. (U.K.)

  17. Handling of potassium

    International Nuclear Information System (INIS)

    Schwarz, N.; Komurka, M.

    1983-03-01

    As a result for the Fast Breeder Development extensive experience is available worldwide with respect to Sodium technology. Due to the extension of the research program to topping cycles with Potassium as the working medium, test facilities with Potassium have been designed and operated in the Institute of Reactor Safety. The different chemical properties of Sodium and Potassium give rise in new safety concepts and operating procedures. The handling problems of Potassium are described in the light of theoretical properties and own experiences. Selected literature on main safety and operating problems complete this report. (Author) [de

  18. Extreme coal handling

    Energy Technology Data Exchange (ETDEWEB)

    Bradbury, S; Homleid, D. [Air Control Science Inc. (United States)

    2004-04-01

    Within the journals 'Focus on O & M' is a short article describing modifications to coal handling systems at Eielson Air Force Base near Fairbanks, Alaska, which is supplied with power and heat from a subbituminous coal-fired central plant. Measures to reduce dust include addition of an enclosed recirculation chamber at each transfer point and new chute designs to reduce coal velocity, turbulence, and induced air. The modifications were developed by Air Control Science (ACS). 7 figs., 1 tab.

  19. Handling large variations in mechanics: Some applications

    Indian Academy of Sciences (India)

    become a simple random walk wherein most jumps occur to the left-and right- ..... region 1 spans from the start of the test to the occurrence of the 1st event .... analysis would help in engineering design decision making. 4. ... Colombo I S, Forde M C, Main I G and Halliday J 2003a AE monitoring of concrete bridge beams in.

  20. Regulation of cardiomyocyte autophagy by calcium.

    Science.gov (United States)

    Shaikh, Soni; Troncoso, Rodrigo; Criollo, Alfredo; Bravo-Sagua, Roberto; García, Lorena; Morselli, Eugenia; Cifuentes, Mariana; Quest, Andrew F G; Hill, Joseph A; Lavandero, Sergio

    2016-04-15

    Calcium signaling plays a crucial role in a multitude of events within the cardiomyocyte, including cell cycle control, growth, apoptosis, and autophagy. With respect to calcium-dependent regulation of autophagy, ion channels and exchangers, receptors, and intracellular mediators play fundamental roles. In this review, we discuss calcium-dependent regulation of cardiomyocyte autophagy, a lysosomal mechanism that is often cytoprotective, serving to defend against disease-related stress and nutrient insufficiency. We also highlight the importance of the subcellular distribution of calcium and related proteins, interorganelle communication, and other key signaling events that govern cardiomyocyte autophagy. Copyright © 2016 the American Physiological Society.

  1. Pathophysiologic Changes in Extracellular pH Modulate Parathyroid Calcium-Sensing Receptor Activity and Secretion via a Histidine-Independent Mechanism.

    Science.gov (United States)

    Campion, Katherine L; McCormick, Wanda D; Warwicker, Jim; Khayat, Mohd Ezuan Bin; Atkinson-Dell, Rebecca; Steward, Martin C; Delbridge, Leigh W; Mun, Hee-Chang; Conigrave, Arthur D; Ward, Donald T

    2015-09-01

    The calcium-sensing receptor (CaR) modulates renal calcium reabsorption and parathyroid hormone (PTH) secretion and is involved in the etiology of secondary hyperparathyroidism in CKD. Supraphysiologic changes in extracellular pH (pHo) modulate CaR responsiveness in HEK-293 (CaR-HEK) cells. Therefore, because acidosis and alkalosis are associated with altered PTH secretion in vivo, we examined whether pathophysiologic changes in pHo can significantly alter CaR responsiveness in both heterologous and endogenous expression systems and whether this affects PTH secretion. In both CaR-HEK and isolated bovine parathyroid cells, decreasing pHo from 7.4 to 7.2 rapidly inhibited CaR-induced intracellular calcium (Ca(2+)i) mobilization, whereas raising pHo to 7.6 potentiated responsiveness to extracellular calcium (Ca(2+)o). Similar pHo effects were observed for Ca(2+)o-induced extracellular signal-regulated kinase phosphorylation and actin polymerization and for L-Phe-induced Ca(2+)i mobilization. Intracellular pH was unaffected by acute 0.4-unit pHo changes, and the presence of physiologic albumin concentrations failed to attenuate the pHo-mediated effects. None of the individual point mutations created at histidine or cysteine residues in the extracellular domain of CaR attenuated pHo sensitivity. Finally, pathophysiologic pHo elevation reversibly suppressed PTH secretion from perifused human parathyroid cells, and acidosis transiently increased PTH secretion. Therefore, pathophysiologic pHo changes can modulate CaR responsiveness in HEK-293 and parathyroid cells independently of extracellular histidine residues. Specifically, pathophysiologic acidification inhibits CaR activity, thus permitting PTH secretion, whereas alkalinization potentiates CaR activity to suppress PTH secretion. These findings suggest that acid-base disturbances may affect the CaR-mediated control of parathyroid function and calcium metabolism in vivo. Copyright © 2015 by the American Society of

  2. Calcium sensing in exocytosis

    DEFF Research Database (Denmark)

    Gustavsson, Natalia; Wu, Bingbing; Han, Weiping

    2012-01-01

    an increase in intracellular calcium levels. Besides the triggering role, calcium signaling modulates the precise amount and kinetics of vesicle release. Thus, it is a central question to understand the molecular machineries responsible for calcium sensing in exocytosis. Here we provide an overview of our...... current understanding of calcium sensing in neurotransmitter release and hormone secretion....

  3. Calcium fluoride

    International Nuclear Information System (INIS)

    King, C.W.; Nestor, O.H.

    1989-01-01

    A new process for producing large, single, oriented crystals of calcium fluoride (CaF 2 ) has been developed which overcomes the limitations of current growing methods. This process has been reduced to practice and has yielded oriented crystals 17.5 x 17.5 x 5 cm 3 . Currently nearing completion is a system for producing 35 x 35 x 7.5 cm 3 single crystals. A scale up to one-meter-square is considered feasible. This crystal growing process makes possible the fabrication of very large CaF 2 windows. Suitability for very high power lasers, however, requires attention to properties beyond mere size. A process to generate higher purity growth stock (starting material) was also developed. The additional purification of the growth stock contributes to lower bulk absorption, the absence of color centers and increased radiation hardness. Also identified were several specific impurities which correlate with radiation hardness. A correlation was found between color centers induced by laser radiation and ionizing radiation. Other CaF 2 crystal properties such as tensile strength, absorption and laser damage thresholds were studied and are discussed

  4. Voltage-gated calcium flux mediates Escherichia coli mechanosensation.

    Science.gov (United States)

    Bruni, Giancarlo N; Weekley, R Andrew; Dodd, Benjamin J T; Kralj, Joel M

    2017-08-29

    Electrically excitable cells harness voltage-coupled calcium influx to transmit intracellular signals, typically studied in neurons and cardiomyocytes. Despite intense study in higher organisms, investigations of voltage and calcium signaling in bacteria have lagged due to their small size and a lack of sensitive tools. Only recently were bacteria shown to modulate their membrane potential on the timescale of seconds, and little is known about the downstream effects from this modulation. In this paper, we report on the effects of electrophysiology in individual bacteria. A genetically encoded calcium sensor expressed in Escherichia coli revealed calcium transients in single cells. A fusion sensor that simultaneously reports voltage and calcium indicated that calcium influx is induced by voltage depolarizations, similar to metazoan action potentials. Cytoplasmic calcium levels and transients increased upon mechanical stimulation with a hydrogel, and single cells altered protein concentrations dependent on the mechanical environment. Blocking voltage and calcium flux altered mechanically induced changes in protein concentration, while inducing calcium flux reproduced these changes. Thus, voltage and calcium relay a bacterial sense of touch and alter cellular lifestyle. Although the calcium effectors remain unknown, these data open a host of new questions about E. coli , including the identity of the underlying molecular players, as well as other signals conveyed by voltage and calcium. These data also provide evidence that dynamic voltage and calcium exists as a signaling modality in the oldest domain of life, and therefore studying electrophysiology beyond canonical electrically excitable cells could yield exciting new findings.

  5. Radiological safety aspects of handling plutonium

    International Nuclear Information System (INIS)

    Sundararajan, A.R.

    2016-01-01

    Department of Atomic Energy in its scheme of harnessing the nuclear energy for electrical power generation and strategic applications has given a huge role to utilization of plutonium. In the power production programme, fast reactors with plutonium as fuel are expected to play a major role. This would require establishing fuel reprocessing plants to handle both thermal and fast reactor fuels. So in the nuclear fuel cycle facilities variety of chemical, metallurgical, mechanical operations have to be carried out involving significant inventories of "2"3"9 Pu and associated radionuclides. Plutonium is the most radiotoxic radionuclide and therefore any facility handling it has to be designed and operated with utmost care. Two problems of major concern in the protection of persons working in plutonium handling facilities are the internal exposure to the operating personnel from uptake of plutonium and transplutonic nuclides as they are highly radiotoxic and the radiation exposure of hands and eye lens during fuel fabrication operations especially while handling recycled high burn up plutonium. In view of the fact that annual limit for intake is very small for "2"3"9Pu and its radiation emission characteristics are such that it is a huge challenge for the health physicists to detect Pu in air and in workers. This paper discusses the principles and practices followed in providing radiological surveillance to workers in plutonium handling areas. The challenges in protecting the workers from receiving exposures to hands and eye lens in handling high burn up plutonium are also discussed. The sites having Pu fuel cycle facilities should have trained medical staff to handle cases involving excessive intake of plutonium. (author)

  6. Calcium movements and the cellular basis of gravitropism

    Science.gov (United States)

    Roux, S. J.; Biro, R. L.; Hale, C. C.

    An early gravity-transduction event in oat coleoptiles which precedes any noticeable bending is the accumulation of calcium on their prospective slower-growing side. Sub-cellular calcium localization studies indicate that the gravity-stimulated redistribution of calcium results in an increased concentration of calcium in the walls of responding cells. Since calcium can inhibit the extension growth of plant cell walls, this selective accumulation of calcium in walls may play a role in inducing the asymmetry of growth which characterizes gravitropism. The active transport of calcium from cells into walls is performed by a calcium-dependent ATPase localized in the plasma membrane. Evidence is presented in support of the hypothesis that this calcium pump is regulated by a feed-back mechanism which includes the participation of calmodulin.

  7. Chemical alteration of calcium silicate hydrates in saline groundwater. Mechanism of sorption of Na on C-S-H and effect of NaCl on leaching of Ca from C-S-H

    International Nuclear Information System (INIS)

    Sugiyama, Daisuke; Fujita, Tomonari

    2004-01-01

    In the concept for TRU waste disposal in Japan, cement is a potential waste packaging and backfilling material and is expected to provide chemical containment. In the presence of some reactive ions in a saline groundwater, the chemical properties of cement materials should be affected. In this study, the mechanism of sorption of sodium (Na) on C-S-H and the effect of sodium chloride (NaCl) concentration on dissolution of Calcium Silicate Hydrate (C-S-H) are discussed by measuring the sorption isotherm of sodium onto C-S-H gel (Ca/Si = 0.65-1.2). Based on the experimental results, it is showed that sodium sorbs by substitution for Ca in C-S-H phases and leaching of Ca from C-S-H is enhanced in NaCl solution ( -1 mol dm -3 ). The results of sorption experiments are reasonably well modelled by the ion-exchange model assuming some calcium sites with different ion-exchange log K values. It is also suggested that the dissolution of C-S-H can be modelled reasonably well by considering the effect of ionic strength on activity coefficients of aqueous species for high Ca/Si ratio of C-S-H, and the effect of exchange of sodium with calcium of C-S-H on leaching of Ca becomes obvious for lower Ca/Si ratio of C-S-H. (author)

  8. Remote handling in ZEPHYR

    International Nuclear Information System (INIS)

    Andelfinger, C.; Lackner, E.; Ulrich, M.; Weber, G.; Schilling, H.B.

    1982-04-01

    A conceptual design of the ZEPHYR building is described. The listed radiation data show that remote handling devices will be necessary in most areas of the building. For difficult repair and maintenance works it is intended to transfer complete units from the experimental hall to a hot cell which provides better working conditions. The necessary crane systems and other transport means are summarized as well as suitable commercially available manipulators and observation devices. The conept of automatic devices for cutting and welding and other operations inside the vacuum vessel and the belonging position control system is sketched. Guidelines for the design of passive components are set up in order to facilitate remote operation. (orig.)

  9. Handling hunger strikers.

    Science.gov (United States)

    1992-04-01

    Hunger strikes are being used increasingly and not only by those with a political point to make. Whereas in the past, hunger strikes in the United Kingdom seemed mainly to be started by terrorist prisoners for political purposes, the most recent was begun by a Tamil convicted of murder, to protest his innocence. In the later stages of his strike, before calling it off, he was looked after at the Hammersmith Hospital. So it is not only prison doctors who need to know how to handle a hunger strike. The following guidelines, adopted by the 43rd World Medical Assembly in Malta in November 1991, are therefore a timely reminder of the doctor's duties during a hunger strike.

  10. MFTF exception handling system

    International Nuclear Information System (INIS)

    Nowell, D.M.; Bridgeman, G.D.

    1979-01-01

    In the design of large experimental control systems, a major concern is ensuring that operators are quickly alerted to emergency or other exceptional conditions and that they are provided with sufficient information to respond adequately. This paper describes how the MFTF exception handling system satisfies these requirements. Conceptually exceptions are divided into one of two classes. Those which affect command status by producing an abort or suspend condition and those which fall into a softer notification category of report only or operator acknowledgement requirement. Additionally, an operator may choose to accept an exception condition as operational, or turn off monitoring for sensors determined to be malfunctioning. Control panels and displays used in operator response to exceptions are described

  11. Plutonium safe handling

    International Nuclear Information System (INIS)

    Tvehlov, Yu.

    2000-01-01

    The abstract, prepared on the basis of materials of the IAEA new leadership on the plutonium safe handling and its storage (the publication no. 9 in the Safety Reports Series), aimed at presenting internationally acknowledged criteria on the radiation danger evaluation and summarizing the experience in the safe management of great quantities of plutonium, accumulated in the nuclear states, is presented. The data on the weapon-class and civil plutonium, the degree of its danger, the measures for provision of its safety, including the data on accident radiation consequences with the fission number 10 18 , are presented. The recommendations, making it possible to eliminate the super- criticality danger, as well as ignition and explosion, to maintain the tightness of the facility, aimed at excluding the radioactive contamination and the possibility of internal irradiation, to provide for the plutonium security, physical protection and to reduce irradiation are given [ru

  12. Handle with care

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1965-03-15

    Full text: A film dealing with transport of radioactive materials by everyday means - rail, road, sea and air transport - has been made for IAEA. It illustrates in broad terms some of the simple precautions which should be followed by persons dealing with such materials during shipment. Throughout, the picture stresses the transport regulations drawn up and recommended by the Agency, and in particular the need to carry out carefully the instructions based on these regulations in order to ensure that there is no hazard to the public nor to those who handle radioactive materials in transit and storage. In straightforward language, the film addresses the porter of a goods wagon, an airline cargo clerk, a dockside crane operator, a truck driver and others who load and ship freight. It shows the various types of package used to contain different categories of radioactive substances according to the intensity of the radiation emitted. It also illustrates their robustness by a series of tests involving drops, fires, impact, crushing, etc. Clear instructions are conveyed on what to do in the event of an unlikely accident with any type of package. The film is entitled, 'The Safe Transport of Radioactive Materials', and is No. 3 in the series entitled, 'Handle with Care'. It was made for IAEA through the United Kingdom Atomic Energy Authority by the Film Producers' Guild in the United Kingdom. It is in 16 mm colour, optical sound, with a running time of 20 minutes. It is available for order at $50 either direct from IAEA or through any of its Member Governments. Prints can be supplied in English, French, Russian or Spanish. Copies are also available for adaptation for commentaries in other languages. (author)

  13. Application of Calcium Phosphate Materials in Dentistry

    Directory of Open Access Journals (Sweden)

    Jabr S. Al-Sanabani

    2013-01-01

    Full Text Available Calcium phosphate materials are similar to bone in composition and in having bioactive and osteoconductive properties. Calcium phosphate materials in different forms, as cements, composites, and coatings, are used in many medical and dental applications. This paper reviews the applications of these materials in dentistry. It presents a brief history, dental applications, and methods for improving their mechanical properties. Notable research is highlighted regarding (1 application of calcium phosphate into various fields in dentistry; (2 improving mechanical properties of calcium phosphate; (3 biomimetic process and functionally graded materials. This paper deals with most common types of the calcium phosphate materials such as hydroxyapatite and tricalcium phosphate which are currently used in dental and medical fields.

  14. Testis-specific isoform of Na/K-ATPase (ATP1A4) regulates sperm function and fertility in dairy bulls through potential mechanisms involving reactive oxygen species, calcium and actin polymerization.

    Science.gov (United States)

    Rajamanickam, G D; Kroetsch, T; Kastelic, J P; Thundathil, J C

    2017-07-01

    Traditional bull breeding soundness evaluation (BBSE) eliminates bulls that are grossly abnormal; however, bulls classified as satisfactory potential breeders still vary in field fertility, implying submicroscopic differences in sperm characteristics. The testis-specific isoform of Na/K-ATPase (ATP1A4) is involved in regulation of sperm motility and capacitation in bulls through well-established enzyme activity and signaling functions. The objective was to determine ATP1A4 content, activity and their relationship to post-thaw sperm function and field fertility, using semen samples from low-fertility (LF) and high-fertility (HF) Holstein bulls (n = 20 each) with known FERTSOL rates (measure of field fertility, based on non-return rate). Frozen-thawed sperm from HF bulls had increased ATP1A4 content and activity compared to LF bulls. Furthermore, post-thaw sperm from HF bulls had increased tyrosine phosphorylation, ROS, F-actin content, and low intracellular calcium compared to LF bulls. Subsequent incubation of HF bull sperm with ouabain (a specific ligand of Na/K-ATPase) further augmented the post-thaw increase in tyrosine phosphorylation, ROS production, and F-actin content, whereas the increase in intracellular calcium was still low compared to LF bull sperm. ATP1A4 content and activity, ROS, F-actin and calcium were significantly correlated with fertility. In conclusion, we inferred that ATP1A4 content and activity differed among dairy bulls with satisfactory semen characteristics and that ATP1A4 may regulate sperm function through mechanisms involving ROS, F-actin and calcium in frozen-thawed sperm of HF and LF dairy bulls. © 2017 American Society of Andrology and European Academy of Andrology.

  15. β-Microseminoprotein Endows Post Coital Seminal Plasma with Potent Candidacidal Activity by a Calcium- and pH-Dependent Mechanism

    Science.gov (United States)

    Edström Hägerwall, Anneli M. L.; Rydengård, Victoria; Fernlund, Per; Mörgelin, Matthias; Baumgarten, Maria; Cole, Alexander M.; Malmsten, Martin; Kragelund, Birthe B.; Sørensen, Ole E.

    2012-01-01

    The innate immune factors controlling Candida albicans are mostly unknown. Vulvovaginal candidiasis is common in women and affects approximately 70–75% of all women at least once. Despite the propensity of Candida to colonize the vagina, transmission of Candida albicans following sexual intercourse is very rare. This prompted us to investigate whether the post coital vaginal milieu contained factors active against C. albicans. By CFU assays, we found prominent candidacidal activity of post coital seminal plasma at both neutral and the acid vaginal pH. In contrast, normal seminal plasma did not display candidacidal activity prior to acidification. By antifungal gel overlay assay, one clearing zone corresponding to a protein band was found in both post coital and normal seminal plasma, which was subsequently identified as β-microseminoprotein. At neutral pH, the fungicidal activity of β-microseminoprotein and seminal plasma was inhibited by calcium. By NMR spectroscopy, amino acid residue E71 was shown to be critical for the calcium coordination. The acidic vaginal milieu unleashed the fungicidal activity by decreasing the inhibitory effect of calcium. The candidacidal activity of β-microseminoprotein was mapped to a fragment of the C-terminal domain with no structural similarity to other known proteins. A homologous fragment from porcine β-microseminoprotein demonstrated calcium-dependent fungicidal activity in a CFU assay, suggesting this may be a common feature for members of the β-microseminoprotein family. By electron microscopy, β-microseminoprotein was found to cause lysis of Candida. Liposome experiments demonstrated that β-microseminoprotein was active towards ergosterol-containing liposomes that mimic fungal membranes, offering an explanation for the selectivity against fungi. These data identify β-microseminoprotein as an important innate immune factor active against C. albicans and may help explain the low sexual transmission rate of Candida

  16. Effect of Calcium Chloride and Cooling on Post-Harvest Brussels Cabbage (Brassica Oleracea L.

    Directory of Open Access Journals (Sweden)

    Alfonso Rincón Pérez

    2014-11-01

    Full Text Available In recent years, the demand of crucifers has increased and particularly of Brussels sprouts (Brassica genus, species Brassica oleracea L.; mainly due to their functional properties; however, this vegetable is perishable and with inadequate techniques in postharvest handling, considerable losses are generated. The objective of this research was to determine the effect of calcium chloride and cooling on postharvest behavior of Brussels sprouts. A completely randomized design was performed, treatments corresponded to three storage temperatures (4°C, 8°C and temperature (18°C and three concentrations of calcium chloride (0%, 2% and 4% were used. Sprouts were harvested at commercial maturity on a farm irrigation district in Usochicamocha, Boyacá Department; of uniform size, excellent plant health and free from mechanical damage conditions. For 19 days of storage, weight loss, respiratory rate and total chlorophyll were measured. Sprouts stored at room temperature lasted 11days postharvest, while cooled lasted for 19 days. A significant effect in reducing weight loss between those sprouts which were stored at 4°C and 8°C and treated with calcium chloride solution at 4% was observed. For the respiratory rate was observed a significant reduction insprouts stored at 4°C. Therefore the most favorable temperature for the storage of Brussels sprouts is 4°C and calcium chloride solution 4%,useful information for producers and marketers.

  17. Calcium signals can freely cross the nuclear envelope in hippocampal neurons: somatic calcium increases generate nuclear calcium transients

    Directory of Open Access Journals (Sweden)

    Bading Hilmar

    2007-07-01

    Full Text Available Abstract Background In hippocampal neurons, nuclear calcium signaling is important for learning- and neuronal survival-associated gene expression. However, it is unknown whether calcium signals generated by neuronal activity at the cell membrane and propagated to the soma can unrestrictedly cross the nuclear envelope to invade the nucleus. The nuclear envelope, which allows ion transit via the nuclear pore complex, may represent a barrier for calcium and has been suggested to insulate the nucleus from activity-induced cytoplasmic calcium transients in some cell types. Results Using laser-assisted uncaging of caged calcium compounds in defined sub-cellular domains, we show here that the nuclear compartment border does not represent a barrier for calcium signals in hippocampal neurons. Although passive diffusion of molecules between the cytosol and the nucleoplasm may be modulated through changes in conformational state of the nuclear pore complex, we found no evidence for a gating mechanism for calcium movement across the nuclear border. Conclusion Thus, the nuclear envelope does not spatially restrict calcium transients to the somatic cytosol but allows calcium signals to freely enter the cell nucleus to trigger genomic events.

  18. Unvented Drum Handling Plan

    International Nuclear Information System (INIS)

    MCDONALD, K.M.

    2000-01-01

    This drum-handling plan proposes a method to deal with unvented transuranic drums encountered during retrieval of drums. Finding unvented drums during retrieval activities was expected, as identified in the Transuranic (TRU) Phase I Retrieval Plan (HNF-4781). However, significant numbers of unvented drums were not expected until excavation of buried drums began. This plan represents accelerated planning for management of unvented drums. A plan is proposed that manages unvented drums differently based on three categories. The first category of drums is any that visually appear to be pressurized. These will be vented immediately, using either the Hanford Fire Department Hazardous Materials (Haz. Mat.) team, if such are encountered before the facilities' capabilities are established, or using internal capabilities, once established. To date, no drums have been retrieved that showed signs of pressurization. The second category consists of drums that contain a minimal amount of Pu isotopes. This minimal amount is typically less than 1 gram of Pu, but may be waste-stream dependent. Drums in this category are assayed to determine if they are low-level waste (LLW). LLW drums are typically disposed of without venting. Any unvented drums that assay as TRU will be staged for a future venting campaign, using appropriate safety precautions in their handling. The third category of drums is those for which records show larger amounts of Pu isotopes (typically greater than or equal to 1 gram of Pu). These are assumed to be TRU and are not assayed at this point, but are staged for a future venting campaign. Any of these drums that do not have a visible venting device will be staged awaiting venting, and will be managed under appropriate controls, including covering the drums to protect from direct solar exposure, minimizing of container movement, and placement of a barrier to restrict vehicle access. There are a number of equipment options available to perform the venting. The

  19. New transport and handling contract

    CERN Multimedia

    SC Department

    2008-01-01

    A new transport and handling contract entered into force on 1.10.2008. As with the previous contract, the user interface is the internal transport/handling request form on EDH: https://edh.cern.ch/Document/TransportRequest/ To ensure that you receive the best possible service, we invite you to complete the various fields as accurately as possible and to include a mobile telephone number on which we can reach you. You can follow the progress of your request (schedule, completion) in the EDH request routing information. We remind you that the following deadlines apply: 48 hours for the transport of heavy goods (up to 8 tonnes) or simple handling operations 5 working days for crane operations, transport of extra-heavy goods, complex handling operations and combined transport and handling operations in the tunnel. For all enquiries, the number to contact remains unchanged: 72202. Heavy Handling Section TS-HE-HH 72672 - 160319

  20. An Exploration of the Calcium-Binding Mode of Egg White Peptide, Asp-His-Thr-Lys-Glu, and In Vitro Calcium Absorption Studies of Peptide-Calcium Complex.

    Science.gov (United States)

    Sun, Na; Jin, Ziqi; Li, Dongmei; Yin, Hongjie; Lin, Songyi

    2017-11-08

    The binding mode between the pentapeptide (DHTKE) from egg white hydrolysates and calcium ions was elucidated upon its structural and thermodynamics characteristics. The present study demonstrated that the DHTKE peptide could spontaneously bind calcium with a 1:1 stoichiometry, and that the calcium-binding site corresponded to the carboxyl oxygen, amino nitrogen, and imidazole nitrogen atoms of the DHTKE peptide. Moreover, the effect of the DHTKE-calcium complex on improving the calcium absorption was investigated in vitro using Caco-2 cells. Results showed that the DHTKE-calcium complex could facilitate the calcium influx into the cytosol and further improve calcium absorption across Caco-2 cell monolayers by more than 7 times when compared to calcium-free control. This study facilitates the understanding about the binding mechanism between peptides and calcium ions as well as suggests a potential application of egg white peptides as nutraceuticals to improve calcium absorption.

  1. Remote handling and accelerators

    International Nuclear Information System (INIS)

    Wilson, M.T.

    1983-01-01

    The high-current levels of contemporary and proposed accelerator facilities induce radiation levels into components, requiring consideration be given to maintenance techniques that reduce personnel exposure. Typical components involved include beamstops, targets, collimators, windows, and instrumentation that intercepts the direct beam. Also included are beam extraction, injection, splitting, and kicking regions, as well as purposeful spill areas where beam tails are trimmed and neutral particles are deposited. Scattered beam and secondary particles activate components all along a beamline such as vacuum pipes, magnets, and shielding. Maintenance techniques vary from hands-on to TV-viewed operation using state-of-the-art servomanipulators. Bottom- or side-entry casks are used with thimble-type target and diagnostic assemblies. Long-handled tools are operated from behind shadow shields. Swinging shield doors, unstacking block, and horizontally rolling shield roofs are all used to provide access. Common to all techniques is the need to make operations simple and to provide a means of seeing and reaching the area

  2. TFTR tritium handling concepts

    International Nuclear Information System (INIS)

    Garber, H.J.

    1976-01-01

    The Tokamak Fusion Test Reactor, to be located on the Princeton Forrestal Campus, is expected to operate with 1 to 2.5 MA tritium--deuterium plasmas, with the pulses involving injection of 50 to 150 Ci (5 to 16 mg) of tritium. Attainment of fusion conditions is based on generation of an approximately 1 keV tritium plasma by ohmic heating and conversion to a moderately hot tritium--deuterium ion plasma by injection of a ''preheating'' deuterium neutral beam (40 to 80 keV), followed by injection of a ''reacting'' beam of high energy neutral deuterium (120 to 150 keV). Additionally, compressions accompany the beam injections. Environmental, safety and cost considerations led to the decision to limit the amount of tritium gas on-site to that required for an experiment, maintaining all other tritium in ''solidified'' form. The form of the tritium supply is as uranium tritide, while the spent tritium and other hydrogen isotopes are getter-trapped by zirconium--aluminum alloy. The issues treated include: (1) design concepts for the tritium generator and its purification, dispensing, replenishment, containment, and containment--cleanup systems; (2) features of the spent plasma trapping system, particularly the regenerable absorption cartridges, their integration into the vacuum system, and the handling of non-getterables; (3) tritium permeation through the equipment and the anticipated releases to the environment; (4) overview of the tritium related ventilation systems; and (5) design bases for the facility's tritium clean-up systems

  3. Safe Handling of Radioisotopes

    International Nuclear Information System (INIS)

    1958-01-01

    Under its Statute the International Atomic Energy Agency is empowered to provide for the application of standards of safety for protection against radiation to its own operations and to operations making use of assistance provided by it or with which it is otherwise directly associated. To this end authorities receiving such assistance are required to observe relevant health and safety measures prescribed by the Agency. As a first step, it has been considered an urgent task to provide users of radioisotopes with a manual of practice for the safe handling of these substances. Such a manual is presented here and represents the first of a series of manuals and codes to be issued by the Agency. It has been prepared after careful consideration of existing national and international codes of radiation safety, by a group of international experts and in consultation with other international bodies. At the same time it is recommended that the manual be taken into account as a basic reference document by Member States of the Agency in the preparation of national health and safety documents covering the use of radioisotopes.

  4. Radioactive wastes handling facility

    International Nuclear Information System (INIS)

    Hirose, Emiko; Inaguma, Masahiko; Ozaki, Shigeru; Matsumoto, Kaname.

    1997-01-01

    There are disposed an area where a conveyor is disposed for separating miscellaneous radioactive solid wastes such as metals, on area for operators which is disposed in the direction vertical to the transferring direction of the conveyor, an area for receiving the radioactive wastes and placing them on the conveyor and an area for collecting the radioactive wastes transferred by the conveyor. Since an operator can conduct handling while wearing a working cloth attached to a partition wall as he wears his ordinary cloth, the operation condition can be improved and the efficiency for the separating work can be improved. When the area for settling conveyors and the area for the operators is depressurized, cruds on the surface of the wastes are not released to the outside and the working clothes can be prevented from being involved. Since the wastes are transferred by the conveyor, the operator's moving range is reduced, poisonous materials are fallen and moved through a sliding way to an area for collecting materials to be separated. Accordingly, the materials to be removed can be accumulated easily. (N.H.)

  5. Calcium and magnesium determination

    International Nuclear Information System (INIS)

    Bhattacharya, S.K.

    1982-01-01

    The roles of calcium and magnesium in human health and disease have been extensively studied. Calcium and magnesium have been determined in biological specimens by atomic absorption spectroscopy using stiochiometric nitrous oxide-acetylene flame

  6. Fenoprofen calcium overdose

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/002649.htm Fenoprofen calcium overdose To use the sharing features on this page, please enable JavaScript. Fenoprofen calcium is a type of medicine called a nonsteroidal ...

  7. Calcium channel blocker overdose

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/002580.htm Calcium-channel blocker overdose To use the sharing features on this page, please enable JavaScript. Calcium-channel blockers are a type of medicine used ...

  8. Safety measuring for sodium handling

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Ji Young; Jeong, K C; Kim, T J; Kim, B H; Choi, J H

    2001-09-01

    This is the report for the safety measures of sodium handling. These contents are prerequisites for the development of sodium technology and thus the workers participate in sodium handling and experiments have to know them perfectly. As an appendix, the relating parts of the laws are presented.

  9. Comparative proteomic and metabolomic analyses reveal mechanisms of improved cold stress tolerance in bermudagrass (Cynodon dactylon (L.) Pers.) by exogenous calcium.

    Science.gov (United States)

    Shi, Haitao; Ye, Tiantian; Zhong, Bao; Liu, Xun; Chan, Zhulong

    2014-11-01

    As an important second messenger, calcium is involved in plant cold stress response, including chilling (Cynodon dactylon (L.) Pers.). Physiological analyses showed that CaCl2 treatment alleviated the reactive oxygen species (ROS) burst and cell damage triggered by chilling stress, via activating antioxidant enzymes, non-enzymatic glutathione antioxidant pool, while EGTA treatment had the opposite effects. Additionally, comparative proteomic analysis identified 51 differentially expressed proteins that were enriched in redox, tricarboxylicacid cycle, glycolysis, photosynthesis, oxidative pentose phosphate pathway, and amino acid metabolisms. Consistently, 42 metabolites including amino acids, organic acids, sugars, and sugar alcohols were regulated by CaCl2 treatment under control and cold stress conditions, further confirming the common modulation of CaCl2 treatment in carbon metabolites and amino acid metabolism. Taken together, this study reported first evidence of the essential and protective roles of endogenous and exogenous calcium in bermudagrass response to cold stress, partially via activation of the antioxidants and modulation of several differentially expressed proteins and metabolic homeostasis in the process of cold acclimation. © 2014 Institute of Botany, Chinese Academy of Sciences.

  10. Development of spent fuel remote handling technology

    Energy Technology Data Exchange (ETDEWEB)

    Yoon, Ji Sup; Park, B S; Park, Y S; Oh, S C; Kim, S H; Cho, M W; Hong, D H

    1997-12-01

    Since the nation`s policy on spent fuel management is not finalized, the technical items commonly required for safe management and recycling of spent fuel - remote technologies of transportation, inspection, maintenance, and disassembly of spent fuel - are selected and pursued. In this regards, the following R and D activities are carried out : collision free transportation of spent fuel assembly, mechanical disassembly of spent nuclear fuel and graphical simulation of fuel handling / disassembly process. (author). 36 refs., 16 tabs., 77 figs

  11. Development of spent fuel remote handling technology

    International Nuclear Information System (INIS)

    Yoon, Ji Sup; Park, B. S.; Park, Y. S.; Oh, S. C.; Kim, S. H.; Cho, M. W.; Hong, D. H.

    1997-12-01

    Since the nation's policy on spent fuel management is not finalized, the technical items commonly required for safe management and recycling of spent fuel - remote technologies of transportation, inspection, maintenance, and disassembly of spent fuel - are selected and pursued. In this regards, the following R and D activities are carried out : collision free transportation of spent fuel assembly, mechanical disassembly of spent nuclear fuel and graphical simulation of fuel handling / disassembly process. (author). 36 refs., 16 tabs., 77 figs

  12. Waste Handling Building Conceptual Study

    International Nuclear Information System (INIS)

    G.W. Rowe

    2000-01-01

    The objective of the ''Waste Handling Building Conceptual Study'' is to develop proposed design requirements for the repository Waste Handling System in sufficient detail to allow the surface facility design to proceed to the License Application effort if the proposed requirements are approved by DOE. Proposed requirements were developed to further refine waste handling facility performance characteristics and design constraints with an emphasis on supporting modular construction, minimizing fuel inventory, and optimizing facility maintainability and dry handling operations. To meet this objective, this study attempts to provide an alternative design to the Site Recommendation design that is flexible, simple, reliable, and can be constructed in phases. The design concept will be input to the ''Modular Design/Construction and Operation Options Report'', which will address the overall program objectives and direction, including options and issues associated with transportation, the subsurface facility, and Total System Life Cycle Cost. This study (herein) is limited to the Waste Handling System and associated fuel staging system

  13. Quantitative proteomics reveals new insights into calcium-mediated resistance mechanisms in Aspergillus flavus against the antifungal protein PgAFP in cheese.

    Science.gov (United States)

    Delgado, Josué; Owens, Rebecca A; Doyle, Sean; Núñez, Félix; Asensio, Miguel A

    2017-09-01

    The ability of Aspergillus flavus to produce aflatoxins in dairy products presents a potential hazard. The antifungal protein PgAFP from Penicillium chrysogenum inhibits various foodborne toxigenic fungi, including Aspergillus flavus. However, PgAFP did not inhibit A. flavus growth in cheese, which was related to the associated cation content. CaCl 2 increased A. flavus permeability and prevented PgAFP-mediated inhibition in potato dextrose broth (PDB). PgAFP did not elicit any additional increase in permeability of CaCl 2 -incubated A. flavus. Furthermore, PgAFP did not alter metabolic capability, chitin deposition, or hyphal viability of A. flavus grown with CaCl 2 . Comparative proteomic analysis after PgAFP treatment of A. flavus in calcium-enriched PDB revealed increased abundance of 125 proteins, including oxidative stress-related proteins, as determined by label-free mass spectrometry (MS)-based proteomics. Seventy proteins were found at lower abundance, with most involved in metabolic pathways and biosynthesis of secondary metabolites. These changes do not support the blockage of potential PgAFP receptors in A. flavus by calcium as the main cause of the protective role. A. flavus resistance appears to be mediated by calcineurin, G-protein, and γ-glutamyltranspeptidase that combat oxidative stress and impede apoptosis. These findings could serve to design strategies to improve PgAFP activity against aflatoxigenic moulds in dairy products. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Calcium and Bone Metabolism Indices.

    Science.gov (United States)

    Song, Lu

    2017-01-01

    Calcium and inorganic phosphate are of critical importance for many body functions, thus the regulations of their plasma concentrations are tightly controlled by the concerted actions of reabsorption/excretion in the kidney, absorption in the intestines, and exchange from bone, the major reservoir for calcium and phosphate in the body. Parathyroid hormone (PTH) and 1,25-dihydroxyvitamin D (1,25(OH) 2 D) control calcium homeostasis, whereas PTH, 1,25(OH) 2 D, and bone-derived fibroblast growth factor 23 (FGF 23) control phosphate homeostasis. Hypoparathyroidism can cause hypocalcemia and hyperphosphatemia, whereas deficient vitamin D actions can cause osteomalacia in adults and rickets in children. Hyperparathyroidism, alternatively, can cause hypercalcemia and hypophosphatemia. Laboratory tests of calcium, phosphate, PTH, and 25-hydroxyvitamin D are very useful in the diagnosis of abnormalities associated with calcium and/or phosphate metabolisms. Bone is constantly remodeled throughout life in response to mechanical stress and a need for calcium in extracellular fluids. Metabolic bone diseases such as osteoporosis, osteomalacia in adults or rickets in children, and renal osteodystrophy develop when bone resorption exceeds bone formation. Bone turnover markers (BTM) such as serum N-terminal propeptide of type I procollagen (P1NP) and C-terminal collagen cross-link (CTX) may be useful in predicting future fracture risk or monitoring the response to anti-resorptive therapy. There is a need to standardize sample collection protocols because certain BTMs exhibit large circadian variations and tend to be influenced by food intakes. In the United States, a project to standardize BTM sample collection protocols and to establish the reference intervals for serum P1NP and serum CTX is ongoing. We anticipate the outcome of this project to shine lights on the standardization of BTM assays, sample collection protocols, reference intervals in relation to age, sex, and ethnic

  15. Sophisticated fuel handling system evolved

    International Nuclear Information System (INIS)

    Ross, D.A.

    1988-01-01

    The control systems at Sellafield fuel handling plant are described. The requirements called for built-in diagnostic features as well as the ability to handle a large sequencing application. Speed was also important; responses better than 50ms were required. The control systems are used to automate operations within each of the three main process caves - two Magnox fuel decanners and an advanced gas-cooled reactor fuel dismantler. The fuel route within the fuel handling plant is illustrated and described. ASPIC (Automated Sequence Package for Industrial Control) which was developed as a controller for the plant processes is described. (U.K.)

  16. Production management of window handles

    Directory of Open Access Journals (Sweden)

    Manuela Ingaldi

    2014-12-01

    Full Text Available In the chapter a company involved in the production of aluminum window and door handles was presented. The main customers of the company are primarily companies which produce PCV joinery and wholesalers supplying these companies. One chosen product from the research company - a single-arm pin-lift window handle - was described and its production process depicted technologically. The chapter also includes SWOT analysis conducted in the research company and the value stream of the single-arm pin-lift window handle.

  17. Colonic potassium handling

    DEFF Research Database (Denmark)

    Sørensen, Mads Vaarby; Matos, Joana E.; Prætorius, Helle

    2010-01-01

    , intestinal K+ losses caused by activated ion secretion may become life threatening. This topical review provides an update of the molecular mechanisms and the regulation of mammalian colonic K+ absorption and secretion. It is motivated by recent results, which have identified the K+ secretory ion channel...... regulated by hormones and adapts readily to changes in dietary K+ intake, aldosterone and multiple local paracrine agonists. In chronic renal insufficiency, colonic K+ secretion is greatly enhanced and becomes an important accessory K+ excretory pathway. During severe diarrheal diseases of different causes...

  18. Substitution of strontium for calcium in glass ionomer cements (Part ...

    African Journals Online (AJOL)

    Substitution of strontium for calcium in glass ionomer cements (Part 1): Glass synthesis and characterisation, and the effects on the cement handling variables and ... acid to form glass ionomer cements, whose properties were investigated at different time points: working and setting times were determined by rheometry; and, ...

  19. Safe handling of radiation sources

    International Nuclear Information System (INIS)

    Abd Nasir Ibrahim; Azali Muhammad; Ab Razak Hamzah; Abd Aziz Mohamed; Mohammad Pauzi Ismail

    2004-01-01

    This chapter discussed the subjects related to the safe handling of radiation sources: type of radiation sources, method of use: transport within premises, transport outside premises; Disposal of Gamma Sources

  20. How Retailers Handle Complaint Management

    DEFF Research Database (Denmark)

    Hansen, Torben; Wilke, Ricky; Zaichkowsky, Judy

    2009-01-01

    This article fills a gap in the literature by providing insight about the handling of complaint management (CM) across a large cross section of retailers in the grocery, furniture, electronic and auto sectors. Determinants of retailers’ CM handling are investigated and insight is gained as to the......This article fills a gap in the literature by providing insight about the handling of complaint management (CM) across a large cross section of retailers in the grocery, furniture, electronic and auto sectors. Determinants of retailers’ CM handling are investigated and insight is gained...... as to the links between CM and redress of consumers’ complaints. The results suggest that retailers who attach large negative consequences to consumer dissatisfaction are more likely than other retailers to develop a positive strategic view on customer complaining, but at the same time an increase in perceived...

  1. [Pharmacotherapy for preventing calcium containing stone formation].

    Science.gov (United States)

    Nagata, Masao; Takayama, Tatsuya; Mugiya, Souichi; Ohzono, Seiichiro

    2011-10-01

    Many urinary tract stones consist of calcium, and has high relapse rate. Accordingly, it is very important to prevent calcium-containing stone formation. This paper describes about effects and mechanisms for Xanthine oxidase inhibitor, citrate formulation, magnesium formulation, thiazides, vitamin B(6), extract of Quercus salicina Blume and chorei-to (medical herb) . Recent new drugs and the elucidation of new metabolic pathways may lead to the development of prevention of urolithiasis.

  2. Calcium absorption and achlorhydria

    International Nuclear Information System (INIS)

    Recker, R.R.

    1985-01-01

    Defective absorption of calcium has been thought to exist in patients with achlorhydria. The author compared absorption of calcium in its carbonate form with that in a pH-adjusted citrate form in a group of 11 fasting patients with achlorhydria and in 9 fasting normal subjects. Fractional calcium absorption was measured by a modified double-isotope procedure with 0.25 g of calcium used as the carrier. Mean calcium absorption (+/- S.D.) in the patients with achlorhydria was 0.452 +/- 0.125 for citrate and 0.042 +/- 0.021 for carbonate (P less than 0.0001). Fractional calcium absorption in the normal subjects was 0.243 +/- 0.049 for citrate and 0.225 +/- 0.108 for carbonate (not significant). Absorption of calcium from carbonate in patients with achlorhydria was significantly lower than in the normal subjects and was lower than absorption from citrate in either group; absorption from citrate in those with achlorhydria was significantly higher than in the normal subjects, as well as higher than absorption from carbonate in either group. Administration of calcium carbonate as part of a normal breakfast resulted in completely normal absorption in the achlorhydric subjects. These results indicate that calcium absorption from carbonate is impaired in achlorhydria under fasting conditions. Since achlorhydria is common in older persons, calcium carbonate may not be the ideal dietary supplement

  3. Adaptive control of manipulators handling hazardous waste

    International Nuclear Information System (INIS)

    Colbaugh, R.; Glass, K.

    1994-01-01

    This article focuses on developing a robot control system capable of meeting hazardous waste handling application requirements, and presents as a solution an adaptive strategy for controlling the mechanical impedance of kinematically redundant manipulators. The proposed controller is capable of accurate end-effector impedance control and effective redundancy utilization, does not require knowledge of the complex robot dynamic model or parameter values for the robot or the environment, and is implemented without calculation of the robot inverse transformation. Computer simulation results are given for a four degree of freedom redundant robot under adaptive impedance control. These results indicate that the proposed controller is capable of successfully performing important tasks in robotic waste handling applications. (author) 3 figs., 39 refs

  4. The technique on handling radiation

    International Nuclear Information System (INIS)

    1997-11-01

    This book describes measurement of radiation and handling radiation. The first part deals with measurement of radiation. The contents of this part are characteristic on measurement technique of radiation, radiation detector, measurement of energy spectrum, measurement of radioactivity, measurement for a level of radiation and county's statistics on radiation. The second parts explains handling radiation with treating of sealed radioisotope, treating unsealed source and radiation shield.

  5. Civilsamfundets ABC: H for Handling

    DEFF Research Database (Denmark)

    Lund, Anker Brink; Meyer, Gitte

    2015-01-01

    Hvad er civilsamfundet? Anker Brink Lund og Gitte Meyer fra CBS Center for Civil Society Studies gennemgår civilsamfundet bogstav for bogstav. Vi er nået til H for Handling.......Hvad er civilsamfundet? Anker Brink Lund og Gitte Meyer fra CBS Center for Civil Society Studies gennemgår civilsamfundet bogstav for bogstav. Vi er nået til H for Handling....

  6. Calcium channel blocker poisoning

    Directory of Open Access Journals (Sweden)

    Miran Brvar

    2005-04-01

    Full Text Available Background: Calcium channel blockers act at L-type calcium channels in cardiac and vascular smooth muscles by preventing calcium influx into cells with resultant decrease in vascular tone and cardiac inotropy, chronotropy and dromotropy. Poisoning with calcium channel blockers results in reduced cardiac output, bradycardia, atrioventricular block, hypotension and shock. The findings of hypotension and bradycardia should suggest poisoning with calcium channel blockers.Conclusions: Treatment includes immediate gastric lavage and whole-bowel irrigation in case of ingestion of sustainedrelease products. All patients should receive an activated charcoal orally. Specific treatment includes calcium, glucagone and insulin, which proved especially useful in shocked patients. Supportive care including the use of catecholamines is not always effective. In the setting of failure of pharmacological therapy transvenous pacing, balloon pump and cardiopulmonary by-pass may be necessary.

  7. Modifications on the properties of a calcium phosphate cement by additions of sodium alginate

    International Nuclear Information System (INIS)

    Coelho, W.T.; Fernandes, J.M.; Vieira, R.S.; Thurmer, M.B.; Santos, L.A.

    2012-01-01

    The Calcium Phosphate Cement (CPC) are bone substitutes with great potential for use in orthopedics, traumatology and dentistry due to its biocompatibility, bioactivity and osteoconductivity, and form a paste that can be easily shaped and placed into the surgical site. However, CPCs have low mechanical strength, which equals the maximum mechanical strength of trabecular bone. In order to assess the strength and time to handle a CPC composed primarily of alpha phase, were added sodium alginate (1%, 2% and 3% wt) and an accelerator in an aqueous solution. The cement powder was mixed with liquid of setting, shaped into specimens and evaluated for apparent density and porosity by Archimedes method, X-ray diffraction and compressive strength. A significant increase in compressive strength by adding sodium alginate was verified. (author)

  8. Short-range intercellular calcium signaling in bone

    DEFF Research Database (Denmark)

    Jørgensen, Niklas Rye

    2005-01-01

    into biological effects in bone. Intercellular calcium waves are increases in intracellular calcium concentration in single cells, subsequently propagating to adjacent cells, and can be a possible mechanism for the coupling of bone formation to bone resorption. The aim of the present studies was to investigate...... whether bone cells are capable of communicating via intercellular calcium signals, and determine by which mechanisms the cells propagate the signals. First, we found that osteoblastic cells can propagate intercellular calcium transients upon mechanical stimulation, and that there are two principally...... different mechanisms for this propagation. One mechanism involves the secretion of a nucleotide, possibly ATP, acting in an autocrine action to purinergic P2Y2 receptors on the neighboring cells, leading to intracellular IP3 generation and subsequent release of calcium from intracellular stores. The other...

  9. Dengue and Calcium

    OpenAIRE

    Shivanthan, Mitrakrishnan C; Rajapakse, Senaka

    2014-01-01

    Dengue is potentially fatal unless managed appropriately. No specific treatment is available and the mainstay of treatment is fluid management with careful monitoring, organ support, and correction of metabolic derangement. Evidence with regards to the role of calcium homeostasis in dengue is limited. Low blood calcium levels have been demonstrated in dengue infection and hypocalcemia maybe more pronounced in more severe forms. The cause of hypocalcemia is likely to be multifactorial. Calcium...

  10. Safety issues in robotic handling of nuclear weapon parts

    International Nuclear Information System (INIS)

    Drotning, W.; Wapman, W.; Fahrenholtz, J.

    1993-01-01

    Robotic systems are being developed by the Intelligent Systems and Robotics Center at Sandia National Laboratories to perform automated handling tasks with radioactive weapon parts. These systems will reduce the occupational radiation exposure to workers by automating operations that are currently performed manually. The robotic systems at Sandia incorporate several levels of mechanical, electrical, and software safety for handling hazardous materials. For example, tooling used by the robot to handle radioactive parts has been designed with mechanical features that allow the robot to release its payload only at designated locations in the robotic workspace. In addition, software processes check for expected and unexpected situations throughout the operations. Incorporation of features such as these provides multiple levels of safety for handling hazardous or valuable payloads with automated intelligent systems

  11. Calcium Channel Blockers

    Science.gov (United States)

    ... Certain calcium channel blockers interact with grapefruit products. Kaplan NM, et al. Treatment of hypertension: Drug therapy. In: Kaplan's Clinical Hypertension. 11th ed. Philadelphia, Pa.: Wolters Kluwer ...

  12. The Function of the Mitochondrial Calcium Uniporter in Neurodegenerative Disorders

    Directory of Open Access Journals (Sweden)

    Yajin Liao

    2017-02-01

    Full Text Available The mitochondrial calcium uniporter (MCU—a calcium uniporter on the inner membrane of mitochondria—controls the mitochondrial calcium uptake in normal and abnormal situations. Mitochondrial calcium is essential for the production of adenosine triphosphate (ATP; however, excessive calcium will induce mitochondrial dysfunction. Calcium homeostasis disruption and mitochondrial dysfunction is observed in many neurodegenerative disorders. However, the role and regulatory mechanism of the MCU in the development of these diseases are obscure. In this review, we summarize the role of the MCU in controlling oxidative stress-elevated mitochondrial calcium and its function in neurodegenerative disorders. Inhibition of the MCU signaling pathway might be a new target for the treatment of neurodegenerative disorders.

  13. The prevention and handling of the missing data

    OpenAIRE

    Kang, Hyun

    2013-01-01

    Even in a well-designed and controlled study, missing data occurs in almost all research. Missing data can reduce the statistical power of a study and can produce biased estimates, leading to invalid conclusions. This manuscript reviews the problems and types of missing data, along with the techniques for handling missing data. The mechanisms by which missing data occurs are illustrated, and the methods for handling the missing data are discussed. The paper concludes with recommendations for ...

  14. Asthma, guides for diagnostic and handling

    International Nuclear Information System (INIS)

    Salgado, Carlos E; Caballero A, Andres S; Garcia G, Elizabeth

    1999-01-01

    The paper defines the asthma, includes topics as diagnostic, handling of the asthma, special situations as asthma and pregnancy, handling of the asthmatic patient's perioperatory and occupational asthma

  15. SRV-automatic handling device

    International Nuclear Information System (INIS)

    Yamada, Koji

    1987-01-01

    Automatic handling device for the steam relief valves (SRV's) is developed in order to achieve a decrease in exposure of workers, increase in availability factor, improvement in reliability, improvement in safety of operation, and labor saving. A survey is made during a periodical inspection to examine the actual SVR handling operation. An SRV automatic handling device consists of four components: conveyor, armed conveyor, lifting machine, and control/monitoring system. The conveyor is so designed that the existing I-rail installed in the containment vessel can be used without any modification. This is employed for conveying an SRV along the rail. The armed conveyor, designed for a box rail, is used for an SRV installed away from the rail. By using the lifting machine, an SRV installed away from the I-rail is brought to a spot just below the rail so that the SRV can be transferred by the conveyor. The control/monitoring system consists of a control computer, operation panel, TV monitor and annunciator. The SRV handling device is operated by remote control from a control room. A trial equipment is constructed and performance/function testing is carried out using actual SRV's. As a result, is it shown that the SRV handling device requires only two operators to serve satisfactorily. The required time for removal and replacement of one SRV is about 10 minutes. (Nogami, K.)

  16. Handling of waste in ports

    International Nuclear Information System (INIS)

    Olson, P.H.

    1994-01-01

    The regulations governing the handling of port-generated waste are often national and/or local legislation, whereas the handling of ship-generated waste is governed by the MARPOL Convention in most parts of the world. The handling of waste consists of two main phases -collection and treatment. Waste has to be collected in every port and on board every ship, whereas generally only some wastes are treated and to a certain degree in ports and on board ships. This paper considers the different kinds of waste generated in both ports and on board ships, where and how it is generated, how it could be collected and treated. The two sources are treated together to show how some ship-generated waste may be treated in port installations primarily constructed for the treatment of the port-generated waste, making integrated use of the available treatment facilities. (author)

  17. WASTE HANDLING BUILDING SHIELD WALL ANALYSIS

    International Nuclear Information System (INIS)

    Padula, D.

    2000-01-01

    The scope of this analysis is to estimate the shielding wall, ceiling or equivalent door thicknesses that will be required in the Waste Handling Building to maintain the radiation doses to personnel within acceptable limits. The shielding thickness calculated is the minimum required to meet administrative limits, and not necessarily what will be recommended for the final design. The preliminary evaluations will identify the areas which have the greatest impact on mechanical and facility design concepts. The objective is to provide the design teams with the necessary information to assure an efficient and effective design

  18. Acidosis and Urinary Calcium Excretion

    DEFF Research Database (Denmark)

    Alexander, R Todd; Cordat, Emmanuelle; Chambrey, Régine

    2016-01-01

    Metabolic acidosis is associated with increased urinary calcium excretion and related sequelae, including nephrocalcinosis and nephrolithiasis. The increased urinary calcium excretion induced by metabolic acidosis predominantly results from increased mobilization of calcium out of bone and inhibi...

  19. Calcium D-saccharate

    DEFF Research Database (Denmark)

    Garcia, André Castilho; Hedegaard, Martina Vavrusova; Skibsted, Leif Horsfelt

    2016-01-01

    Molar conductivity of saturated aqueous solutions of calcium d-saccharate, used as a stabilizer of beverages fortified with calcium d-gluconate, increases strongly upon dilution, indicating complex formation between calcium and d-saccharate ions, for which, at 25 °C, Kassoc = 1032 ± 80, ΔHassoc......° = -34 ± 6 kJ mol-1, and ΔSassoc° = -55 ± 9 J mol-1 K-1, were determined electrochemically. Calcium d-saccharate is sparingly soluble, with a solubility product, Ksp, of (6.17 ± 0.32) × 10-7 at 25 °C, only moderately increasing with the temperature: ΔHsol° = 48 ± 2 kJ mol-1, and ΔSassoc° = 42 ± 7 J mol-1...... K-1. Equilibria in supersaturated solutions of calcium d-saccharate seem only to adjust slowly, as seen from calcium activity measurements in calcium d-saccharate solutions made supersaturated by cooling. Solutions formed by isothermal dissolution of calcium d-gluconate in aqueous potassium d...

  20. Analysis of Spontaneous and Nerve-Evoked Calcium Transients in Intact Extraocular Muscles in Vitro

    Science.gov (United States)

    Feng, Cheng-Yuan; Hennig, Grant W.; Corrigan, Robert D.; Smith, Terence K.; von Bartheld, Christopher S.

    2012-01-01

    Extraocular muscles (EOMs) have unique calcium handling properties, yet little is known about the dynamics of calcium events underlying ultrafast and tonic contractions in myofibers of intact EOMs. Superior oblique EOMs of juvenile chickens were dissected with their nerve attached, maintained in oxygenated Krebs buffer, and loaded with fluo-4. Spontaneous and nerve stimulation-evoked calcium transients were recorded and, following calcium imaging, some EOMs were double-labeled with rhodamine-conjugated alpha-bungarotoxin (rhBTX) to identify EOM myofiber types. EOMs showed two main types of spontaneous calcium transients, one slow type (calcium waves with 1/2max duration of 2–12 s, velocity of 25–50 μm/s) and two fast “flash-like” types (Type 1, 30–90 ms; Type 2, 90–150 ms 1/2max duration). Single pulse nerve stimulation evoked fast calcium transients identical to the fast (Type 1) calcium transients. Calcium waves were accompanied by a local myofiber contraction that followed the calcium transient wavefront. The magnitude of calcium-wave induced myofiber contraction far exceeded those of movement induced by nerve stimulation and associated fast calcium transients. Tetrodotoxin eliminated nerve-evoked transients, but not spontaneous transients. Alpha-bungarotoxin eliminated both spontaneous and nerve-evoked fast calcium transients, but not calcium waves, and caffeine increased wave activity. Calcium waves were observed in myofibers lacking spontaneous or evoked fast transients, suggestive of multiply-innervated myofibers, and this was confirmed by double-labeling with rhBTX. We propose that the abundant spontaneous calcium transients and calcium waves with localized contractions that do not depend on innervation may contribute to intrinsic generation of tonic functions of EOMs. PMID:22579493

  1. Calcium metabolism in birds.

    Science.gov (United States)

    de Matos, Ricardo

    2008-01-01

    Calcium is one of the most important plasma constituents in mammals and birds. It provides structural strength and support (bones and eggshell) and plays vital roles in many of the biochemical reactions in the body. The control of calcium metabolism in birds is highly efficient and closely regulated in a number of tissues, primarily parathyroid gland, intestine, kidney, and bone. The hormones with the greatest involvement in calcium regulation in birds are parathyroid hormone, 1,25-dihydroxyvitamin D(3) (calcitriol), and estrogen, with calcitonin playing a minor and uncertain role. The special characteristics of calcium metabolism in birds, mainly associated with egg production, are discussed, along with common clinical disorders secondary to derangements in calcium homeostasis.

  2. Effect of oral calcium and calcium + fluoride treatments on mouse bone properties during suspension

    Science.gov (United States)

    Simske, S. J.; Luttges, M. W.; Allen, K. A.; Spooner, B. S. (Principal Investigator)

    1992-01-01

    The bone effects of oral dosages of calcium chloride with or without supplementary sodium fluoride were assessed in antiorthostatically suspended mice. Two calcium dosages were used to replace half (3.1 mM) or all(6.3 mM) of the dietary calcium lost due to reduced food intake by the suspended mice. Two groups of 6.3 mM CaCl2-treated mice were additionally treated with 0.25 or 2.5 mM NaF. The results indicate that supplementation of the mouse drinking water with calcium salts prevents bone changes induced by short-term suspension, while calcium salts in combination with fluoride are less effective as fluoride dosage increases. However, the calcium supplements change the relationship between the femur mechanical properties and the mineral composition of the bone. Because of this, it appears that oral calcium supplements are effective through a mechanism other than simple dietary supplementation and may indicate a dependence of bone consistency on systemic and local fluid conditions.

  3. Conceptual design of CFETR divertor remote handling compatible structure

    International Nuclear Information System (INIS)

    Dai, Huaichu; Yao, Damao; Cao, Lei; Zhou, Zibo; Li, Lei

    2016-01-01

    Highlights: • Conceptual design for the CFETR divertor have been proposed, especially the divertor remote handling compatible structure. • The degrees of freedom of the divertor are analyzed in order to validate the design the divertor supports structure. • Besides the ITER-like scheme, a new scheme for the divertor remote handling compatible supports is proposed, that is the rack and pinion mechanism. • The installation/removel process is verified through simulation in Delmia in order to check design quality for remote handling requirements. - Abstract: Divertor is one of key components of tokamak fusion reactor. The CFETR is China Fusion Engineering Test Reactor. Its divertor will expose to tritium environment and neutron radiation. Materials of the divertor will be radioactived, and cannot be handled by personnel directly. To develop structure which compatible with robots handle for installation, maintenance and removing is required. This paper introduces a conceptual design of CFETR divertor module which compatible with remote handling end-effectors. The divertor module is confined by inner and outer support. The inner support is only confined divertor module radial, toroidal and vertical moving freedom degrees, but not confined rotating freedom degrees. The outer support is the structure that can confine rotating freedom degrees and should also be compatible with remote handling end-effectors.

  4. Conceptual design of CFETR divertor remote handling compatible structure

    Energy Technology Data Exchange (ETDEWEB)

    Dai, Huaichu, E-mail: yaodm@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China); University of Science and Technology of China, Hefei (China); Yao, Damao; Cao, Lei; Zhou, Zibo; Li, Lei [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031 (China)

    2016-11-15

    Highlights: • Conceptual design for the CFETR divertor have been proposed, especially the divertor remote handling compatible structure. • The degrees of freedom of the divertor are analyzed in order to validate the design the divertor supports structure. • Besides the ITER-like scheme, a new scheme for the divertor remote handling compatible supports is proposed, that is the rack and pinion mechanism. • The installation/removel process is verified through simulation in Delmia in order to check design quality for remote handling requirements. - Abstract: Divertor is one of key components of tokamak fusion reactor. The CFETR is China Fusion Engineering Test Reactor. Its divertor will expose to tritium environment and neutron radiation. Materials of the divertor will be radioactived, and cannot be handled by personnel directly. To develop structure which compatible with robots handle for installation, maintenance and removing is required. This paper introduces a conceptual design of CFETR divertor module which compatible with remote handling end-effectors. The divertor module is confined by inner and outer support. The inner support is only confined divertor module radial, toroidal and vertical moving freedom degrees, but not confined rotating freedom degrees. The outer support is the structure that can confine rotating freedom degrees and should also be compatible with remote handling end-effectors.

  5. HYPERTHERMIA, INTRACELLULAR FREE CALCIUM AND CALCIUM IONOPHORES

    NARCIS (Netherlands)

    STEGE, GJJ; WIERENGA, PK; KAMPINGA, HH; KONINGS, AWT

    1993-01-01

    It is shown that heat-induced increase of intracellular calcium does not correlate with hyperthermic cell killing. Six different cell lines were investigated; in four (EAT, HeLa S3, L5178Y-R and L5178Y-S) heat treatments killing 90% of the cells did not affect the levels of intracellular free

  6. Effects of extracellular calcium on calcium transport during hyperthermia of tumor cells.

    Science.gov (United States)

    Anghileri, L J; Marcha, C; Crone-Escanyé, M C; Robert, J

    1985-08-01

    The effects of different concentrations of extracellular ion calcium on the transport of calcium by tumor cells have been studied by means of the uptake of radiocalcium. Tumor cells incubated at 45 degrees C take up 4-10 times the amount of radioactivity incorporated by cells incubated at 37 degrees C. The difference is still greater (up to 100 times) for the intracellular incorporation as assessed by elimination of the membrane-bound calcium by EGTA treatment. The possible mechanisms involved in this differential behavior are discussed.

  7. Software for handling MFME1

    International Nuclear Information System (INIS)

    Van der Merwe, W.G.

    1984-01-01

    The report deals with SEMFIP, a computer code for determining magnetic field measurements. The program is written in FORTRAN and ASSEMBLER. The preparations for establishing SEMFIP, the actual measurements, data handling and the problems that were experienced are discussed. Details on the computer code are supplied in an appendix

  8. Welding method by remote handling

    International Nuclear Information System (INIS)

    Hashinokuchi, Minoru.

    1994-01-01

    Water is charged into a pit (or a water reservoir) and an article to be welded is placed on a support in the pit by remote handling. A steel plate is disposed so as to cover the article to be welded by remote handling. The welding device is positioned to the portion to be welded and fixed in a state where the article to be welded is shielded from radiation by water and the steel plate. Water in the pit is drained till the portion to be welded is exposed to the atmosphere. Then, welding is conducted. After completion of the welding, water is charged again to the pit and the welding device and fixing jigs are decomposed in a state where the article to be welded is shielded again from radiation by water and the steel plate. Subsequently, the steel plate is removed by remote handling. Then, the article to be welded is returned from the pit to a temporary placing pool by remote handling. This can reduce operator's exposure. Further, since the amount of the shielding materials can be minimized, the amount of radioactive wastes can be decreased. (I.N.)

  9. Glass-water interphase reactivity with calcium rich solutions

    International Nuclear Information System (INIS)

    Chave, T.; Frugier, P.; Gin, S.; Chave, T.; Ayral, A.

    2011-01-01

    The effect of calcium on synthetic glass alteration mechanisms has been studied. It is known that the higher the calcium content in the glass, the higher the forward rate. However, in a confined medium reaching apparent saturation state and a pH (90 degrees C) around 9, synthetic calcium-bearing glasses are those with the lowest alteration rates. This work brings new and fundamental evidence toward understanding the alteration mechanisms: the rate-decreasing effect of calcium exists even if the calcium comes from the solution. Calcium from solution reacts with silica network in the hydrated layer at the glass surface. The calcium effect on the alteration kinetics is explained by the condensation of a passivating reactive interphase (PRI) whose passivating properties are strongly enhanced when calcium participates in its construction. These experiments provide new evidence of the role of condensation mechanisms in glass alteration. This better understanding of the calcium effect on glass long-term behavior will be useful both for improving glass formulations and for understanding the influence of the water composition. (authors)

  10. Calcium signaling in liver.

    Science.gov (United States)

    Gaspers, Lawrence D; Thomas, Andrew P

    2005-01-01

    In hepatocytes, hormones linked to the formation of the second messenger inositol 1,4,5-trisphosphate (InsP3) evoke transient increases or spikes in cytosolic free calcium ([Ca2+]i), that increase in frequency with the agonist concentration. These oscillatory Ca2+ signals are thought to transmit the information encoded in the extracellular stimulus to down-stream Ca2+-sensitive metabolic processes. We have utilized both confocal and wide field fluorescence microscopy techniques to study the InsP3-dependent signaling pathway at the cellular and subcellular levels in the intact perfused liver. Typically InsP3-dependent [Ca2+]i spikes manifest as Ca2+ waves that propagate throughout the entire cytoplasm and nucleus, and in the intact liver these [Ca2+]i increases are conveyed through gap junctions to encompass entire lobular units. The translobular movement of Ca2+ provides a means to coordinate the function of metabolic zones of the lobule and thus, liver function. In this article, we describe the characteristics of agonist-evoked [Ca2+]i signals in the liver and discuss possible mechanisms to explain the propagation of intercellular Ca2+ waves in the intact organ.

  11. The impact of calcium carbonate as pore forming agent and drug entrapment method towards drug dissolution mechanism of amoxicillin trihydrate encapsulated by chitosan-methyl cellulose semi-IPN hydrogel for floating drug delivery system

    Science.gov (United States)

    Dewantara, Fauzi; Budianto, Emil

    2018-04-01

    Chitosan-methyl cellulose semi-IPN hydrogel is used as floating drug delivery system, and calcium carbonate also added as pore forming agent. The hydrogel network arranged by not only using biopolymer chitosan and methyl cellulose, but also the crosslink agent that is glutaraldehyde. Amoxicillin trihydrate entrapped into the polymer network with two different method, in situ loading and post loading. Furthermore both method has been tested for drug entrapment efficiency along with drug dissolution test, and the result for drug entrapment efficiency is in situ loading method has highest value of 100%, compared to post loading method which has value only 71%. Moreover, at the final time of drug dissolution test shows in situ loading method has value of 96% for total accumulative of drug dissolution, meanwhile post loading method has 72%. The value of drug dissolution test from both method is used for analyzing drug dissolution mechanism of amoxicillin trihydrate from hydrogel network with four mathematical drug mechanism models as parameter. The polymer network encounter destructive degradation causes by acid solution which used as dissolution medium, and the level of degradation is observed with optical microscope. However the result shows that degradation of the polymer network doesn't affect drug dissolution mechanism directly. Although the pore forming agent causes the pore inside the hydrogel network create interconnection and it was quite influential to drug dissolution mechanism. Interconnected pore is observed with Scanning Electron Microscope (SEM) and shows that the amount and area of interconnected pore inside the hydrogel network is increasing as drug dissolution goes on.

  12. Calcium binding properties of calcium dependent protein kinase 1 (CaCDPK1) from Cicer arietinum.

    Science.gov (United States)

    Dixit, Ajay Kumar; Jayabaskaran, Chelliah

    2015-05-01

    Calcium plays a crucial role as a secondary messenger in all aspects of plant growth, development and survival. Calcium dependent protein kinases (CDPKs) are the major calcium decoders, which couple the changes in calcium level to an appropriate physiological response. The mechanism by which calcium regulates CDPK protein is not well understood. In this study, we investigated the interactions of Ca(2+) ions with the CDPK1 isoform of Cicer arietinum (CaCDPK1) using a combination of biophysical tools. CaCDPK1 has four different EF hands as predicted by protein sequence analysis. The fluorescence emission spectrum of CaCDPK1 showed quenching with a 5 nm red shift upon addition of calcium, indicating conformational changes in the tertiary structure. The plot of changes in intensity against calcium concentrations showed a biphasic curve with binding constants of 1.29 μM and 120 μM indicating two kinds of binding sites. Isothermal calorimetric (ITC) titration with CaCl2 also showed a biphasic curve with two binding constants of 0.027 μM and 1.7 μM. Circular dichroism (CD) spectra showed two prominent peaks at 208 and 222 nm indicating that CaCDPK1 is a α-helical rich protein. Calcium binding further increased the α-helical content of CaCDPK1 from 75 to 81%. Addition of calcium to CaCDPK1 also increased fluorescence of 8-anilinonaphthalene-1-sulfonic acid (ANS) indicating exposure of hydrophobic surfaces. Thus, on the whole this study provides evidence for calcium induced conformational changes, exposure of hydrophobic surfaces and heterogeneity of EF hands in CaCDPK1. Copyright © 2015 Elsevier GmbH. All rights reserved.

  13. Calcium-Induced calcium release during action potential firing in developing inner hair cells.

    Science.gov (United States)

    Iosub, Radu; Avitabile, Daniele; Grant, Lisa; Tsaneva-Atanasova, Krasimira; Kennedy, Helen J

    2015-03-10

    into the calcium signaling mechanisms involved in early developmental processes. Copyright © 2015 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  14. Calcium and Egg Activation in Drosophila

    Science.gov (United States)

    Sartain, Caroline V.; Wolfner, Mariana F.

    2012-01-01

    Summary In many animals, a rise in intracellular calcium levels is the trigger for egg activation, the process by which an arrested mature oocyte transitions to prepare for embryogenesis. In nearly all animals studied to date, this calcium rise, and thus egg activation, is triggered by the fertilizing sperm. However in the insects that have been examined, fertilization is not necessary to activate their oocytes. Rather, these insects’ eggs activate as they transit through the female’s reproductive tract, regardless of male contribution. Recent studies in Drosophila have shown that egg activation nevertheless requires calcium and that the downstream events and molecules of egg activation are also conserved, despite the difference in initial trigger. Genetic studies have uncovered essential roles for the calcium-dependent enzyme calcineurin and its regulator calcipressin, and have hinted at roles for calmodulin, in Drosophila egg activation. Physiological and in vitro studies have led to a model in which mechanical forces that impact the Drosophila oocyte as it moves through the reproductive tract triggers the influx of calcium from the external environment, thereby initiating egg activation. Future research will aim to test this model, as well as to determine the spatiotemporal dynamics of cytoplasmic calcium flux and mode of signal propagation in this unique system. PMID:23218670

  15. Aromatase deficiency causes altered expression of molecules critical for calcium reabsorption in the kidneys of female mice *.

    NARCIS (Netherlands)

    Oz, O.K.; Hajibeigi, A.; Howard, K.; Cummins, C.L.; Abel, M. van; Bindels, R.J.M.; Word, R.A.; Kuro-o, M.; Pak, C.Y.; Zerwekh, J.E.

    2007-01-01

    Kidney stones increase after menopause, suggesting a role for estrogen deficiency. ArKO mice have hypercalciuria and lower levels of calcium transport proteins, whereas levels of the klotho protein are elevated. Thus, estrogen deficiency is sufficient to cause altered renal calcium handling.

  16. Computational Material Modeling of Hydrated Cement Paste Calcium Silicate Hydrate (C-S-H) Chemistry Structure - Influence of Magnesium Exchange on Mechanical Stiffness: C-S-H Jennite

    Science.gov (United States)

    2015-04-27

    MODELING OF C-S-H Material chemistry level modeling following the principles and techniques commonly grouped under Computational Material Science is...Henmi, C. and Kusachi, I. Monoclinic tobermorite from fuka, bitchu-cho, Okoyama Perfecture. Japan J. Min. Petr. Econ . Geol. (1989)84:374-379. [22...31] Liu, Y. et al. First principles study of the stability and mechanical properties of MC (M=Ti, V, Zr, Nb, Hf and Ta) compounds. Journal of Alloys and Compounds. (2014) 582:500-504. 10

  17. Calcium Biofortification: Three Pronged Molecular Approaches for Dissecting Complex Trait of Calcium Nutrition in Finger Millet (Eleusine coracana) for Devising Strategies of Enrichment of Food Crops.

    Science.gov (United States)

    Sharma, Divya; Jamra, Gautam; Singh, Uma M; Sood, Salej; Kumar, Anil

    2016-01-01

    Calcium is an essential macronutrient for plants and animals and plays an indispensable role in structure and signaling. Low dietary intake of calcium in humans has been epidemiologically linked to various diseases which can have serious health consequences over time. Major staple food-grains are poor source of calcium, however, finger millet [ Eleusine coracana (L.) Gaertn.], an orphan crop has an immense potential as a nutritional security crop due to its exceptionally high calcium content. Understanding the existing genetic variation as well as molecular mechanisms underlying the uptake, transport, accumulation of calcium ions (Ca 2+ ) in grains is of utmost importance for development of calcium bio-fortified crops. In this review, we have discussed molecular mechanisms involved in calcium accumulation and transport thoroughly, emphasized the role of molecular breeding, functional genomics and transgenic approaches to understand the intricate mechanism of calcium nutrition in finger millet. The objective is to provide a comprehensive up to date account of molecular mechanisms regulating calcium nutrition and highlight the significance of bio-fortification through identification of potential candidate genes and regulatory elements from finger millet to alleviate calcium malnutrition. Hence, finger millet could be used as a model system for explaining the mechanism of elevated calcium (Ca 2+ ) accumulation in its grains and could pave way for development of nutraceuticals or designer crops.

  18. Interaction of calcium oxide with molten alkali metal chlorides

    International Nuclear Information System (INIS)

    Volkovich, A.V.; Zhuravlev, V.I.; Ermakov, D.S.; Magurina, M.V.

    1999-01-01

    Calcium oxide solubility in molten lithium, sodium, potassium, cesium chlorides and their binary mixtures is determined in a temperature range of 973-1173 K by the method of isothermal saturation. Mechanisms of calcium oxide interaction with molten alkali metal chlorides are proposed

  19. The effect of calcium on auxin depletion-induced tomato ...

    African Journals Online (AJOL)

    Indole-3-acetic acid (IAA) and calcium are the most important factors that instigate plant organ abscission. This study aimed to elucidate the mechanisms that underlie the effects of IAA and calcium on delayed abscission in tomato. The results showed a clear trend towards reduced abscission rates with increased ...

  20. Multiparameter imaging of calcium and abscisic acid and high-resolution quantitative calcium measurements using R-GECO1-mTurquoise in Arabidopsis.

    Science.gov (United States)

    Waadt, Rainer; Krebs, Melanie; Kudla, Jörg; Schumacher, Karin

    2017-10-01

    Calcium signals occur in specific spatio-temporal patterns in response to various stimuli and are coordinated with, for example, hormonal signals, for physiological and developmental adaptations. Quantification of calcium together with other signalling molecules is required for correlative analyses and to decipher downstream calcium-decoding mechanisms. Simultaneous in vivo imaging of calcium and abscisic acid has been performed here to investigate the interdependence of the respective signalling processes in Arabidopsis thaliana roots. Advanced ratiometric genetically encoded calcium indicators have been generated and in vivo calcium calibration protocols were established to determine absolute calcium concentration changes in response to auxin and ATP. In roots, abscisic acid induced long-term basal calcium concentration increases, while auxin triggered rapid signals in the elongation zone. The advanced ratiometric calcium indicator R-GECO1-mTurquoise exhibited an increased calcium signal resolution compared to commonly used Förster resonance energy transfer-based indicators. Quantitative calcium measurements in Arabidopsis root tips using R-GECO1-mTurquoise revealed detailed maps of absolute calcium concentration changes in response to auxin and ATP. Calcium calibration protocols using R-GECO1-mTurquoise enabled high-resolution quantitative imaging of resting cytosolic calcium concentrations and their dynamic changes that revealed distinct hormonal and ATP responses in roots. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  1. Effect of cadmium on myocardial contractility and calcium fluxes

    International Nuclear Information System (INIS)

    Pilati, C.F.

    1979-01-01

    The effect of cadmium on myocardial mechanical performance and calcium fluxes was studied in kitten isometric papillary muscles and in isovolumic Langendorff-perfused rabbit hearts. Therefore, it is concluded that cadmium-induced decreases in contractility are not primarily the result of cadmium interference with ATP metabolic processes. Furthermore, these results imply that cadmium causes no structural alterations of the contractile proteins. These data suggest that cadmium may be competing with the calcium needed for excitation-contraction coupling. During experiments using radioisotopic calcium, a statistically significant cellular influx of calcium was observed following the onset of 100 μM Cd ++ perfusion of isolated, Langendorff-prepared rabbit hearts

  2. Effect of various additives on microstructure, mechanical properties, and in vitro bioactivity of sodium oxide-calcium oxide-silica-phosphorus pentoxide glass-ceramics.

    Science.gov (United States)

    Li, H C; Wang, D G; Hu, J H; Chen, C Z

    2013-09-01

    The partial substitution of MgO, TiO2, or CaF2 for CaO in the Na2O-CaO-SiO2-P2O5 (45S5) system was conducted by the sol-gel method and a comparative study on structural, mechanical properties, and bioactivity of the glasses was reported. Based on thermogravimetric and differential thermal analysis, the gels were sintered with a suitable heat treatment procedure. The glass-ceramic properties were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and so on, and the bioactivity of the glass-ceramic was evaluated by in vitro assays in simulated body fluid (SBF). Results indicate that with the partial substitution of MgO, TiO2, CaF2 for CaO in glass composition, the mechanical properties of the glass-ceramics have been significantly improved. Furthermore, CaF2 promotes glass crystallization and the crystallization does not inhibit the glass-ceramic bioactivity. All samples possess bioactivity; however, the bioactivity of these glass-ceramics is quite different. Compared with 45S5, the introduction of MgO decreases the ability of apatite induction. The addition of TiO2 does not significantly improve the bioactivity, and the replacement of CaO by CaF2 shows a higher bioactivity. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Calcium supplementation and cardiovascular risk: A rising concern.

    Science.gov (United States)

    Tankeu, Aurel T; Ndip Agbor, Valirie; Noubiap, Jean Jacques

    2017-06-01

    Over the past decade, the number of individuals taking calcium supplementation worldwide has been on the rise, especially with the emergence of new pharmaceutical companies specialized in the marketing of dietary supplements; with calcium supplementation being their main business axis. This is mostly because of the established role of calcium in the prevention and treatment of osteoporosis and, to a lesser extent, its role in the prevention of fractures. Recently, a rising body of evidence on the adverse effect of calcium supplementation on nonskeletal, especially cardiovascular, health has been a cause for concern. In fact, a significant number of studies have reported an association between calcium supplementation and adverse cardiovascular events, even though high dietary calcium intake was shown to have a protective effect. The mechanism by which calcium supplementation could cause a cardiovascular event was still unclear until a recent study published in the Journal of the American Heart Association. Combining this recent finding with available data associating calcium supplementation with cardiovascular mortality and all-cause mortality, we call on the need for an evidence-based approach to calcium supplementation, while stressing on the safety of dietary calcium intake over the former on cardiovascular health. ©2017 Wiley Periodicals, Inc.

  4. A Perspective on Equipment Design for Fusion Remote Handling

    International Nuclear Information System (INIS)

    Mills, S.; Haist, B.; Hamilton, D.

    2006-01-01

    For 8 years, JET remote operations have become more capable and confident. Many tasks have been successfully completed, even those never intended to be remote maintenance activities. The general approach to the provision of remote handling equipment at JET has been the preferred use of commercially-off-the-shelf equipment. In the areas of electrical, electronic, software and control this approach has been generally achievable. However, in the area of mechanical equipment it has been more difficult. In particular the RH tooling has been almost entirely bespoke as its requirements are highly sensitive to the design of the JET component being handled and there are many design variations. Hence, JET has required the design and manufacture of over 700 types of bespoke RH equipment. This paper will discuss the experience of introducing and developing remote handling mechanical equipment for JET. The paper will cover the relationship between the remote handling equipment and the JET component design and the potential for improving the design function. A major lesson from the introduction of remote handling to JET has been demonstration of the very close interdependency of the design of JET components with design of remote handling tooling. The JET remote handling manual was originally introduced as the vehicle to ensure remote handling compatibility by the introduction of standards. Experience has shown that in general the remote handling manual approach has been insufficient. Future fusion machines will be much more complex than JET and will demand even greater remote handling compatibility. This paper will discuss possible methods for improving this process. Equipment operating in a high radiation environment must be dependable It may spend part of its time in areas that would be extremely difficult to recover from in the case of failure. The equipment may also have a high duty cycle to minimise shutdown times and probably cannot be manually inspected on a frequent

  5. DIHYDROPYRIDINE CALCIUM- CHANNELBLOCKERSFOR ...

    African Journals Online (AJOL)

    Furthermore, the controversy over the role of calci~-channel blockers as first-line ..... group trials while fully accounting for placebo effects as well as interindividual ..... Reducing calcium overload in the ischemic brain. N Engl JMed. 1999; 341 ...

  6. Calcium and Your Child

    Science.gov (United States)

    ... calcium-set tofu edamame (soybeans) broccoli, collard greens, kale, chard, Chinese cabbage, and other leafy greens almonds ... more dark green, leafy vegetables (such as broccoli, kale, collard greens, or Chinese cabbage) with meals. Kids ...

  7. Experience in handling concentrated tritium

    International Nuclear Information System (INIS)

    Holtslander, W.J.

    1985-12-01

    The notes describe the experience in handling concentrated tritium in the hydrogen form accumulated in the Chalk River Nuclear Laboratories Tritium Laboratory. The techniques of box operation, pumping systems, hydriding and dehydriding operations, and analysis of tritium are discussed. Information on the Chalk River Tritium Extraction Plant is included as a collection of reprints of papers presented at the Dayton Meeting on Tritium Technology, 1985 April 30 - May 2

  8. International handling of fissionable material

    International Nuclear Information System (INIS)

    1975-01-01

    The opinion of the ministry for foreign affairs on international handling of fissionable materials is given. As an introduction a survey is given of the possibilities to produce nuclear weapons from materials used in or produced by power reactors. Principles for international control of fissionable materials are given. International agreements against proliferation of nuclear weapons are surveyed and methods to improve them are proposed. (K.K.)

  9. Confinement facilities for handling plutonium

    International Nuclear Information System (INIS)

    Maraman, W.J.; McNeese, W.D.; Stafford, R.G.

    1975-01-01

    Plutonium handling on a multigram scale began in 1944. Early criteria, equipment, and techniques for confining contamination have been superseded by more stringent criteria and vastly improved equipment and techniques for in-process contamination control, effluent air cleaning and treatment of liquid wastes. This paper describes the evolution of equipment and practices to minimize exposure of workers and escape of contamination into work areas and into the environment. Early and current contamination controls are compared. (author)

  10. Remote handling equipment for SNS

    International Nuclear Information System (INIS)

    Poulten, B.H.

    1983-01-01

    This report gives information on the areas of the SNS, facility which become highly radioactive preventing hands-on maintenance. Levels of activity are sufficiently high in the Target Station Area of the SNS, especially under fault conditions, to warrant reactor technology to be used in the design of the water, drainage and ventilation systems. These problems, together with the type of remote handling equipment required in the SNS, are discussed

  11. Remote handling in reprocessing plants

    International Nuclear Information System (INIS)

    Streiff, G.

    1984-01-01

    Remote control will be the rule for maintenance in hot cells of future spent fuel reprocessing plants because of the radioactivity level. New handling equipments will be developed and intervention principles defined. Existing materials, recommendations for use and new manipulators are found in the PMDS' documentation. It is also a help in the choice and use of intervention means and a guide for the user [fr

  12. Equipment for the handling of thorium materials

    International Nuclear Information System (INIS)

    Heisler, S.W. Jr.; Mihalovich, G.S.

    1988-01-01

    The Feed Materials Production Center (FMPC) is the United States Department of Energy's storage facility for thorium. FMPC thorium handling and overpacking projects ensure the continued safe handling and storage of the thorium inventory until final disposition of the materials is determined and implemented. The handling and overpacking of the thorium materials requires the design of a system that utilizes remote handling and overpacking equipment not currently utilized at the FMPC in the handling of uranium materials. The use of remote equipment significantly reduces radiation exposure to personnel during the handling and overpacking efforts. The design system combines existing technologies from the nuclear industry, the materials processing and handling industry and the mining industry. The designed system consists of a modified fork lift truck for the transport of thorium containers, automated equipment for material identification and inventory control, and remote handling and overpacking equipment for material identification and inventory control, and remote handling and overpacking equipment for repackaging of the thorium materials

  13. Enteral Feeding Set Handling Techniques.

    Science.gov (United States)

    Lyman, Beth; Williams, Maria; Sollazzo, Janet; Hayden, Ashley; Hensley, Pam; Dai, Hongying; Roberts, Cristine

    2017-04-01

    Enteral nutrition therapy is common practice in pediatric clinical settings. Often patients will receive a pump-assisted bolus feeding over 30 minutes several times per day using the same enteral feeding set (EFS). This study aims to determine the safest and most efficacious way to handle the EFS between feedings. Three EFS handling techniques were compared through simulation for bacterial growth, nursing time, and supply costs: (1) rinsing the EFS with sterile water after each feeding, (2) refrigerating the EFS between feedings, and (3) using a ready-to-hang (RTH) product maintained at room temperature. Cultures were obtained at baseline, hour 12, and hour 21 of the 24-hour cycle. A time-in-motion analysis was conducted and reported in average number of seconds to complete each procedure. Supply costs were inventoried for 1 month comparing the actual usage to our estimated usage. Of 1080 cultures obtained, the overall bacterial growth rate was 8.7%. The rinse and refrigeration techniques displayed similar bacterial growth (11.4% vs 10.3%, P = .63). The RTH technique displayed the least bacterial growth of any method (4.4%, P = .002). The time analysis in minutes showed the rinse method was the most time-consuming (44.8 ± 2.7) vs refrigeration (35.8 ± 2.6) and RTH (31.08 ± 0.6) ( P refrigerating the EFS between uses is the next most efficacious method for handling the EFS between bolus feeds.

  14. Calcium and bone disorders in pregnancy

    Directory of Open Access Journals (Sweden)

    Shriraam Mahadevan

    2012-01-01

    Full Text Available Significant transplacental calcium transfer occurs during pregnancy, especially during the last trimester, to meet the demands of the rapidly mineralizing fetal skeleton. Similarly, there is an obligate loss of calcium in the breast milk during lactation. Both these result in considerable stress on the bone mineral homeostasis in the mother. The maternal adaptive mechanisms to conserve calcium are different in pregnancy and lactation. During pregnancy, increased intestinal absorption of calcium from the gut mainly due to higher generation of calcitriol (1,25 dihydroxy vitamin D helps in maintaining maternal calcium levels. On the other hand, during lactation, the main compensatory mechanism is skeletal resorption due to increased generation of parathormone related peptide (PTHrP from the breast. Previous studies suggest that in spite of considerable changes in bone mineral metabolism during pregnancy, parity and lactation are not significantly associated with future risk for osteoporosis. However, in India, the situation may not be the same as a significant proportion of pregnancies occur in the early twenties when peak bone mass is not yet achieved. Further, malnutrition, anemia and vitamin D deficiency are commonly encountered in this age group. This may have an impact on future bone health of the mother. It may also probably provide an opportunity for health care providers for prevention. Other metabolic bone diseases like hypoparathyroidism, hyperparathyroidism and pseudohypoparathyroidism are rarely encountered in pregnancy. Their clinical implications and management are also discussed.

  15. Calcium binding by dietary fibre

    International Nuclear Information System (INIS)

    James, W.P.T.; Branch, W.J.; Southgate, D.A.T.

    1978-01-01

    Dietary fibre from plants low in phytate bound calcium in proportion to its uronic-acid content. This binding by the non-cellulosic fraction of fibre reduces the availability of calcium for small-intestinal absorption, but the colonic microbial digestion of uronic acids liberates the calcium. Thus the ability to maintain calcium balance on high-fibre diets may depend on the adaptive capacity on the colon for calcium. (author)

  16. Superphenix 1 primary handling system fabrication and testing

    International Nuclear Information System (INIS)

    Branchu, J.; Ebbinghaus, K.; Gigarel, C.

    1985-01-01

    Primary handling covers the operations performed for spent fuel removal, new fuel insertion, and the insodium storage outside the new or spent fuel vessel. This equipment typifies many of the difficulties encountered with the project as a whole: fabrication coordination when several countries are involved and design and construction of very large, relatively complex components. Detailed design studies were mainly influenced by thermal and seismic requirements, as applicable to sodium-immersed structures. Where possible, well-tried mechanical solutions were used, but widely differing techniques were involved, ranging from the high precision fabrication of structures and mechanisms comprising numerous component parts, implying complex machining operations. No particular problems were encountered during the sodium testing of the primary handling equipment. Trends for the 1500-MW (electric) breeder include investigation of the advisability of fuel storage in the core lattice and the possibility of handling system simplification

  17. A comparative study on Ca content and distribution in two Gesneriaceae species reveals distinctive mechanisms to cope with high rhizospheric soluble calcium

    Directory of Open Access Journals (Sweden)

    Wenlong eLi

    2014-11-01

    Full Text Available Excessive Ca is toxic to plants thus significantly affects plant growth and species distribution in Ca-rich karst areas. To understand how plants survive high Ca soil, laboratory experiments were established to compare the physiological responses and internal Ca distribution in organ, tissue, cell and intracellular levels under different Ca levels for Lysionotus pauciflorus and Boea hygrometrica, two karst habitant Gesneriaceae species in Southwest China. In the controlled condition, L. pauciflorus could survive as high as 200 mM rhizospheric soluble Ca, attributed to a series of physiological responses and preferential storage that limited Ca accumulation in chloroplasts of palisade cells. In contrast, B. hygrometrica could survive only 20 mM rhizospheric soluble Ca, but accumulated a high level of internal Ca in both palisade and spongy cells without disturbance on photosynthetic activity. By phenotype screening of transgenic plants expressing high Ca-inducible genes from B. hygrometrica, the expression of BhDNAJC2 in A. thaliana was found to enhance plant growth and photosynthesis under high soluble Ca stress. BhDNAJC2 encodes a recently reported heat shock protein (HSP 40 family DnaJ-domain protein. The Ca-resistant phenotype of BhDNAJC2 highlights the important role of chaperone-mediated protein quality control in Ca tolerance in B. hygrometrica. Taken together, our results revealed that distinctive mechanisms were employed in the two Gesneriaceae karst habitants to cope with a high Ca environment.

  18. [Calcium suppletion for patients who use gastric acid inhibitors: calcium citrate or calcium carbonate?].

    NARCIS (Netherlands)

    Jonge, H.J. de; Gans, R.O.; Huls, G.A.

    2012-01-01

    Various calcium supplements are available for patients who have an indication for calcium suppletion. American guidelines and UpToDate recommend prescribing calcium citrate to patients who use antacids The rationale for this advice is that water-insoluble calcium carbonate needs acid for adequate

  19. Effect of diuretics on renal tubular transport of calcium and magnesium.

    Science.gov (United States)

    Alexander, R Todd; Dimke, Henrik

    2017-06-01

    Calcium (Ca 2+ ) and Magnesium (Mg 2+ ) reabsorption along the renal tubule is dependent on distinct trans- and paracellular pathways. Our understanding of the molecular machinery involved is increasing. Ca 2+ and Mg 2+ reclamation in kidney is dependent on a diverse array of proteins, which are important for both forming divalent cation-permeable pores and channels, but also for generating the necessary driving forces for Ca 2+ and Mg 2+ transport. Alterations in these molecular constituents can have profound effects on tubular Ca 2+ and Mg 2+ handling. Diuretics are used to treat a large range of clinical conditions, but most commonly for the management of blood pressure and fluid balance. The pharmacological targets of diuretics generally directly facilitate sodium (Na + ) transport, but also indirectly affect renal Ca 2+ and Mg 2+ handling, i.e., by establishing a prerequisite electrochemical gradient. It is therefore not surprising that substantial alterations in divalent cation handling can be observed following diuretic treatment. The effects of diuretics on renal Ca 2+ and Mg 2+ handling are reviewed in the context of the present understanding of basal molecular mechanisms of Ca 2+ and Mg 2+ transport. Acetazolamide, osmotic diuretics, Na + /H + exchanger (NHE3) inhibitors, and antidiabetic Na + /glucose cotransporter type 2 (SGLT) blocking compounds, target the proximal tubule, where paracellular Ca 2+ transport predominates. Loop diuretics and renal outer medullary K + (ROMK) inhibitors block thick ascending limb transport, a segment with significant paracellular Ca 2+ and Mg 2+ transport. Thiazides target the distal convoluted tubule; however, their effect on divalent cation transport is not limited to that segment. Finally, potassium-sparing diuretics, which inhibit electrogenic Na + transport at distal sites, can also affect divalent cation transport. Copyright © 2017 the American Physiological Society.

  20. Decontamination manual of RI handling laboratory

    International Nuclear Information System (INIS)

    Wadachi, Yoshiki

    2004-01-01

    Based on experiences in Japan Atomic Energy Research Institute (JAERI), the essential and practical knowledge of radioactive contamination and its decontamination, and the method and procedure of floor decontamination are described for researcher and managing person in charge of handling radioisotopes (RI) in RI handling laboratories. Essential knowledge concerns the uniqueness of solid surface contamination derived from RI half lives and quantities, surface contamination density limit, and mode/mechanism of contamination. The principle of decontamination is a single conduct with recognition of chemical form of the RI under use. As the practical knowledge, there are physical and chemical methods of solid surface decontamination. The latter involves use of inorganic acids, chelaters and surfactants. Removal and replacement of contaminated solid like floor material are often effective. Distribution mapping of surface contamination can be done by measuring the radioactivity in possibly contaminated areas, and is useful for planning of effective decontamination. Floor surface decontamination is for the partial and spread areas of the floor. It is essential to conduct the decontamination with reagent from the highly to less contaminated areas. Skin decontamination with either neutral detergent or titanium oxide is also described. (N.I.)

  1. 7 CFR 926.9 - Handle.

    Science.gov (United States)

    2010-01-01

    ... the Department of Agriculture (Continued) AGRICULTURAL MARKETING SERVICE (Marketing Agreements and Orders; Fruits, Vegetables, Nuts), DEPARTMENT OF AGRICULTURE DATA COLLECTION, REPORTING AND RECORDKEEPING REQUIREMENTS APPLICABLE TO CRANBERRIES NOT SUBJECT TO THE CRANBERRY MARKETING ORDER § 926.9 Handle. Handle...

  2. HMSRP Hawaiian Monk Seal Handling Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains records for all handling and measurement of Hawaiian monk seals since 1981. Live seals are handled and measured during a variety of events...

  3. Care and handling of container plants from storage to outplanting

    Science.gov (United States)

    Thomas D. Landis; R. Kasten Dumroese

    2011-01-01

    Nursery plants are in a period of high risk from the time they leave the protected environment of the nursery to when they are outplanted. During handling and shipping, nursery stock may be exposed to many damaging stresses, including extreme temperatures, desiccation, mechanical injuries, and storage molds. This is also the period of greatest financial risk, because...

  4. Controlling fugitive dust emissions in material handling operations

    Energy Technology Data Exchange (ETDEWEB)

    Tooker, G E

    1992-05-01

    The primary mechanism of fugitive dust generation in bulk material handling transfer operations is by dispersion of dust in turbulent air induced to flow with falling or projected material streams. This paper returns to basic theories of particle dynamics and fluid mechanics to quantify the dust generating mechanism by rational analysis. Calculations involving fluid mechanisms are made easier by the availability of the personal computer and the many math manipulating programs. Rational analysis is much more cost effective when estimating collection air volumes to control fugitive emissions; especially in enclosed material handling transfers transporting large volumes of dusty material. Example calculations, using a typical enclosed conveyor-to-conveyor transfer operation are presented to illustrate and highlight the key parameters that determine the magnitude of induced air flow that must be controlled. The methods presented in this paper for estimating collection air volumes apply only enclosed material handling transfers, exhausted to a dust collector. Since some assistance to the control of dust emissions must be given by the material handling transfer chute design, a discussion of good transfer chute design practice is presented. 4 refs., 2 figs., 2 tabs.

  5. The handling of radiation accidents

    International Nuclear Information System (INIS)

    Macdonald, H.F.; Orchard, H.C.; Walker, C.W.

    1977-04-01

    Some of the more interesting and important contributions to a recent International Symposium on the Handling of Radiation Accidents are discussed and personal comments on many of the papers presented are included. The principal conclusion of the Symposium was that although the nuclear industry has an excellent safety record, there is no room for complacency. Continuing attention to emergency planning and exercising are essential in order to maintain this position. A full list of the papers presented at the Symposium is included as an Appendix. (author)

  6. Short-range intercellular calcium signaling in bone

    DEFF Research Database (Denmark)

    Jørgensen, Niklas R

    2005-01-01

    The regulation of bone turnover is a complex and finely tuned process. Many factors regulate bone remodeling, including hormones, growth factors, cytokines etc. However, little is known about the signals coupling bone formation to bone resorption, and how mechanical forces are translated...... into biological effects in bone. Intercellular calcium waves are increases in intracellular calcium concentration in single cells, subsequently propagating to adjacent cells, and can be a possible mechanism for the coupling of bone formation to bone resorption. The aim of the present studies was to investigate...... whether bone cells are capable of communicating via intercellular calcium signals, and determine by which mechanisms the cells propagate the signals. First, we found that osteoblastic cells can propagate intercellular calcium transients upon mechanical stimulation, and that there are two principally...

  7. 7 CFR 58.443 - Whey handling.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 3 2010-01-01 2010-01-01 false Whey handling. 58.443 Section 58.443 Agriculture... Procedures § 58.443 Whey handling. (a) Adequate sanitary facilities shall be provided for the handling of whey. If outside, necessary precautions shall be taken to minimize flies, insects and development of...

  8. Mechanics

    CERN Document Server

    Hartog, J P Den

    1961-01-01

    First published over 40 years ago, this work has achieved the status of a classic among introductory texts on mechanics. Den Hartog is known for his lively, discursive and often witty presentations of all the fundamental material of both statics and dynamics (and considerable more advanced material) in new, original ways that provide students with insights into mechanical relationships that other books do not always succeed in conveying. On the other hand, the work is so replete with engineering applications and actual design problems that it is as valuable as a reference to the practicing e

  9. ITER - TVPS remote handling critical design issues

    International Nuclear Information System (INIS)

    1990-09-01

    This report describes critical design issues concerning remote maintenance of the ITER Torus Vacuum Pumping System (TVPS). The key issues under investigation are the regeneration/isolation valve seal and seal mechanism replacement; impact of inert gas operation; impact of remote handling (RH) on the building configuration and RH equipment requirements. Seal exchange concepts are developed and their impact on the valve design identified. Concerns regarding the design and operation of RH equipment in an inert gas atmosphere are also explored. The report compares preliminary RH equipment options, pumping equipment maintenance frequency and their impact on the building design, and makes recommendations where a conflict exists between pumping equipment and the building layout. (51 figs., 11 refs.)

  10. Antagonist effects of calcium on borosilicate glass alteration

    Energy Technology Data Exchange (ETDEWEB)

    Mercado-Depierre, S. [CEA Marcoule, DTCD SPDE LCLT, 30207 Bagnols sur Cèze (France); Angeli, F., E-mail: frederic.angeli@cea.fr [CEA Marcoule, DTCD SPDE LCLT, 30207 Bagnols sur Cèze (France); Frizon, F. [CEA Marcoule, DTCD SECM LP2C, 30207 Bagnols sur Cèze (France); Gin, S. [CEA Marcoule, DTCD SPDE LCLT, 30207 Bagnols sur Cèze (France)

    2013-10-15

    Graphical abstract: Display Omitted -- Highlights: •Kinetic study of glass alteration is investigated in calcium-enriched solutions. •New insights into silicon–calcium interactions in glass/cement systems are proposed. •Glass alteration is controlled by pH, Ca concentration and reaction progress. •Evidence of antagonist effects according to the importance of these parameters. -- Abstract: Numerous studies have been conducted on glass and cement durability in contact with water, but very little work to date has focused directly on interactions between the two materials. These interactions are mostly controlled by silicon–calcium reactivity. However, the physical and chemical processes involved remain insufficiently understood to predict the evolution of coupled glass–cement systems used in several industrial applications. Results are reported from borosilicate glass alteration in calcium-rich solutions. Our data show that four distinct behaviors can be expected according to the relative importance of three key parameters: the pH, the reaction progress (short- or long-term alteration) and the calcium concentration. Glass alteration is thus controlled by specific mechanisms depending on the solution chemistry: calcium complexation at the glass surface, precipitation of calcium silicate hydrates (C–S–H) or calcium incorporation in the altered layer. These findings highlight the impact of silicon–calcium interactions on glass durability and open the way for a better understanding of glass–cement mixing in civil engineering applications as well as in nuclear waste storage.

  11. Antagonist effects of calcium on borosilicate glass alteration

    International Nuclear Information System (INIS)

    Mercado-Depierre, S.; Angeli, F.; Frizon, F.; Gin, S.

    2013-01-01

    Graphical abstract: Display Omitted -- Highlights: •Kinetic study of glass alteration is investigated in calcium-enriched solutions. •New insights into silicon–calcium interactions in glass/cement systems are proposed. •Glass alteration is controlled by pH, Ca concentration and reaction progress. •Evidence of antagonist effects according to the importance of these parameters. -- Abstract: Numerous studies have been conducted on glass and cement durability in contact with water, but very little work to date has focused directly on interactions between the two materials. These interactions are mostly controlled by silicon–calcium reactivity. However, the physical and chemical processes involved remain insufficiently understood to predict the evolution of coupled glass–cement systems used in several industrial applications. Results are reported from borosilicate glass alteration in calcium-rich solutions. Our data show that four distinct behaviors can be expected according to the relative importance of three key parameters: the pH, the reaction progress (short- or long-term alteration) and the calcium concentration. Glass alteration is thus controlled by specific mechanisms depending on the solution chemistry: calcium complexation at the glass surface, precipitation of calcium silicate hydrates (C–S–H) or calcium incorporation in the altered layer. These findings highlight the impact of silicon–calcium interactions on glass durability and open the way for a better understanding of glass–cement mixing in civil engineering applications as well as in nuclear waste storage

  12. Sandia National Laboratories Small-Scale Sensitivity Testing (SSST) Report: Calcium Nitrate Mixtures with Various Fuels.

    Energy Technology Data Exchange (ETDEWEB)

    Phillips, Jason Joe [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2014-07-01

    Based upon the presented sensitivity data for the examined calcium nitrate mixtures using sugar and sawdust, contact handling/mixing of these materials does not present hazards greater than those occurring during handling of dry PETN powder. The aluminized calcium nitrate mixtures present a known ESD fire hazard due to the fine aluminum powder fuel. These mixtures may yet present an ESD explosion hazard, though this has not been investigated at this time. The detonability of these mixtures will be investigated during Phase III testing.

  13. Renal Control of Calcium, Phosphate, and Magnesium Homeostasis

    Science.gov (United States)

    Chonchol, Michel; Levi, Moshe

    2015-01-01

    Calcium, phosphate, and magnesium are multivalent cations that are important for many biologic and cellular functions. The kidneys play a central role in the homeostasis of these ions. Gastrointestinal absorption is balanced by renal excretion. When body stores of these ions decline significantly, gastrointestinal absorption, bone resorption, and renal tubular reabsorption increase to normalize their levels. Renal regulation of these ions occurs through glomerular filtration and tubular reabsorption and/or secretion and is therefore an important determinant of plasma ion concentration. Under physiologic conditions, the whole body balance of calcium, phosphate, and magnesium is maintained by fine adjustments of urinary excretion to equal the net intake. This review discusses how calcium, phosphate, and magnesium are handled by the kidneys. PMID:25287933

  14. Safety of Cargo Aircraft Handling Procedure

    Directory of Open Access Journals (Sweden)

    Daniel Hlavatý

    2017-07-01

    Full Text Available The aim of this paper is to get acquainted with the ways how to improve the safety management system during cargo aircraft handling. The first chapter is dedicated to general information about air cargo transportation. This includes the history or types of cargo aircraft handling, but also the means of handling. The second part is focused on detailed description of cargo aircraft handling, including a description of activities that are performed before and after handling. The following part of this paper covers a theoretical interpretation of safety, safety indicators and legislative provisions related to the safety of cargo aircraft handling. The fourth part of this paper analyzes the fault trees of events which might occur during handling. The factors found by this analysis are compared with safety reports of FedEx. Based on the comparison, there is a proposal on how to improve the safety management in this transportation company.

  15. Calcium ferrite formation from the thermolysis of calcium tris (maleato)

    Indian Academy of Sciences (India)

    For preparing calcium ferrite, calcium tris (maleato) ferrate(III) precursor was prepared by mixing aqueous solutions of iron(III) maleate, calcium maleate and maleic acid. Various physico-chemical techniques i.e. TG, DTG, DTA, Mössbauer, XRD, IR etc have been used to study the decomposition behaviour from ambient to ...

  16. Flexible Electrostatic Technologies for Capture and Handling, Phase 1

    Science.gov (United States)

    Bryan, Thomas

    2015-01-01

    Fundamental to many of NASA's in-space transportation missions is the capture and handling of various objects and vehicles in various orbits for servicing, debris disposal, sample retrieval, and assembly without the benefit of sufficient grapple fixtures and docking ports. To perform similar material handling tasks on Earth, pincher grippers, suction grippers, or magnetic chucks are used, but are unable to reliably grip aluminum and composite spacecraft, insulation, radiators, solar arrays, or extra-terrestrial objects in the vacuum of outer space without dedicated handles in the right places. The electronic Flexible Electrostatic Technologies for space Capture and Handling (FETCH) will enable reliable and compliant gripping (soft dock) of practically any object in various orbits or surfaces without dedicated mechanical features, very low impact capture, and built-in proximity sensing without any conventional actuators. Originally developed to handle semiconductor and glass wafers during vacuum chamber processing without contamination, the normal rigid wafer handling chucks are replaced with thin metal foil segments laminated in flexible insulation driven by commercial off-the-shelf solid state, high-voltage power supplies. Preliminary testing in NASA Marshall Space Flight Center's (MSFC's) Flat Floor Robotics Lab demonstrated compliant alignment and gripping with a full-sized, 150-lb microsat mockup and translation before a clean release with a flip of a switch. The flexible electrostatic gripper pads can be adapted to various space applications with different sizes, shapes, and foil electrode layouts even with openings through the gripper pads for addition of guidance sensors or injection of permanent adhesives. With gripping forces estimated between 0.5 and 2.5 lb/in2 or 70-300 lb/ft2 of surface contact, the FETCH can turn on and off rapidly and repeatedly to enable sample handling, soft docking, in-space assembly, precision relocation, and surface translation

  17. Principles for the Safe Moving and Handling of Patients

    Directory of Open Access Journals (Sweden)

    Wanless Stephen

    2016-12-01

    Full Text Available Human movement when walking or running is a widely researched area. However, there is an increased incidence of musculoskeletal injury from poor positioning when moving and handling patients amongst healthcare professionals and is one of the main causes of long term musculoskeletal health problems. In the clinical area, an individual’s musculoskeletal health system is subjected to mechanical loading, increasing the body’s stress and strain limits, and once these are exceeded injury occurs. The risk of pain and injury has a direct relation from the over use of poor posture from poor moving and handling, which in turn can cause loss of strength and reduce musculoskeletal function. This can be changed through healthcare workers adopting safe biomechanical body movements during patient handling tasks.

  18. A sensor for calcium uptake

    Science.gov (United States)

    Collins, Sean; Meyer, Tobias

    2011-01-01

    Mitochondria — the cell’s power plants — increase their energy production in response to calcium signals in the cytoplasm. A regulator of the elusive mitochondrial calcium channel has now been identified. PMID:20844529

  19. Children's Bone Health and Calcium

    Science.gov (United States)

    ... Twitter Pinterest Email Print Children's Bone Health and Calcium: Condition Information What is bone health and how ... straight, walk, run, and lead an active life. Calcium is one of the key dietary building blocks ...

  20. Calcium – how and why?

    Indian Academy of Sciences (India)

    Unknown

    biological processes because of its unusual physical and chemical properties. 1. History of calcium ... cellular roles of calcium has established the importance of this ion ..... Ca2+ ion, for example in regulating enzyme activity (Price. 1975 ...

  1. CANISTER HANDLING FACILITY DESCRIPTION DOCUMENT

    Energy Technology Data Exchange (ETDEWEB)

    J.F. Beesley

    2005-04-21

    The purpose of this facility description document (FDD) is to establish requirements and associated bases that drive the design of the Canister Handling Facility (CHF), which will allow the design effort to proceed to license application. This FDD will be revised at strategic points as the design matures. This FDD identifies the requirements and describes the facility design, as it currently exists, with emphasis on attributes of the design provided to meet the requirements. This FDD is an engineering tool for design control; accordingly, the primary audience and users are design engineers. This FDD is part of an iterative design process. It leads the design process with regard to the flowdown of upper tier requirements onto the facility. Knowledge of these requirements is essential in performing the design process. The FDD follows the design with regard to the description of the facility. The description provided in this FDD reflects the current results of the design process.

  2. Bulk handling benefits from ICT

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-11-15

    The efficiency and accuracy of bulk handling is being improved by the range of management information systems and services available today. As part of the program to extend Richards Bay Coal Terminal, Siemens is installing a manufacturing execution system which coordinates and monitors all movements of raw materials. The article also reports recent developments by AXSMarine, SunGuard Energy, Fuelworx and Railworx in providing integrated tools for tracking, managing and optimising solid/liquid fuels and rail car maintenance activities. QMASTOR Ltd. has secured a contract with Anglo Coal Australia to provide its Pit to Port.net{reg_sign} and iFuse{reg_sign} software systems across all their Australians sites, to include pit-to-product stockpile management. 2 figs.

  3. Handling and transport problems (1960)

    International Nuclear Information System (INIS)

    Pomarola, J.; Savouyaud, J.

    1960-01-01

    I. The handling and transport of radioactive wastes involves the danger of irradiation and contamination. It is indispensable: - to lay down a special set of rules governing the removal and transport of wastes within centres or from one centre to another; - to give charge of this transportation to a group containing teams of specialists. The organisation, equipment and output of these teams is being examined. II. Certain materials are particularly dangerous to transport, and for these special vehicles and fixed installations are necessary. This is the case especially for the evacuation of very active liquids. A transport vehicle is described, consisting of a trailer tractor and a recipient holding 500 litres of liquid of which the activity can reach 1000 C/l; the decanting operation, the route to be followed by the vehicle, and the precautions taken are also described. (author) [fr

  4. CANISTER HANDLING FACILITY DESCRIPTION DOCUMENT

    International Nuclear Information System (INIS)

    Beesley. J.F.

    2005-01-01

    The purpose of this facility description document (FDD) is to establish requirements and associated bases that drive the design of the Canister Handling Facility (CHF), which will allow the design effort to proceed to license application. This FDD will be revised at strategic points as the design matures. This FDD identifies the requirements and describes the facility design, as it currently exists, with emphasis on attributes of the design provided to meet the requirements. This FDD is an engineering tool for design control; accordingly, the primary audience and users are design engineers. This FDD is part of an iterative design process. It leads the design process with regard to the flowdown of upper tier requirements onto the facility. Knowledge of these requirements is essential in performing the design process. The FDD follows the design with regard to the description of the facility. The description provided in this FDD reflects the current results of the design process

  5. Fuel Handling Facility Description Document

    International Nuclear Information System (INIS)

    M.A. LaFountain

    2005-01-01

    The purpose of the facility description document (FDD) is to establish the requirements and their bases that drive the design of the Fuel Handling Facility (FHF) to allow the design effort to proceed to license application. This FDD is a living document that will be revised at strategic points as the design matures. It identifies the requirements and describes the facility design as it currently exists, with emphasis on design attributes provided to meet the requirements. This FDD was developed as an engineering tool for design control. Accordingly, the primary audience and users are design engineers. It leads the design process with regard to the flow down of upper tier requirements onto the facility. Knowledge of these requirements is essential to performing the design process. It trails the design with regard to the description of the facility. This description is a reflection of the results of the design process to date

  6. Data Handling and Parameter Estimation

    DEFF Research Database (Denmark)

    Sin, Gürkan; Gernaey, Krist

    2016-01-01

    ,engineers, and professionals. However, it is also expected that they will be useful both for graduate teaching as well as a stepping stone for academic researchers who wish to expand their theoretical interest in the subject. For the models selected to interpret the experimental data, this chapter uses available models from...... literature that are mostly based on the ActivatedSludge Model (ASM) framework and their appropriate extensions (Henze et al., 2000).The chapter presents an overview of the most commonly used methods in the estimation of parameters from experimental batch data, namely: (i) data handling and validation, (ii......Modelling is one of the key tools at the disposal of modern wastewater treatment professionals, researchers and engineers. It enables them to study and understand complex phenomena underlying the physical, chemical and biological performance of wastewater treatment plants at different temporal...

  7. Solar Imagery - Chromosphere - Calcium

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This dataset consists of full-disk images of the sun in Calcium (Ca) II K wavelength (393.4 nm). Ca II K imagery reveal magnetic structures of the sun from about 500...

  8. The training for nuclear fuel handling at EDF

    International Nuclear Information System (INIS)

    Marion, J.P.

    1999-01-01

    The handling of fuel assemblies in a nuclear power plant presents 3 types of work: the taking delivery of fresh fuel, the refueling and the disposal of spent fuel. These operations are realized by teams made up of 3 handling operators and a supervisor. The refueling is made by 3*8-hour teams. These handling operations are important for the nuclear safety, a mishandling can damage the fuel cladding which is the first containment barrier, so a training center (CETIC) has been created. This center was founded in 1986 by EDF and Framatome, the purpose was to validate maintenance procedures, to test handling equipment and to train the teams which work on site. Various training programmes have been set up and a system of qualification degrees has been organized. The CETIC is fitted up with equipment that are full-sized mockups of real installations. Fuel assemblies don't react in a similar way to the different mechanical and neutronic stresses they undergo while they are in the core, they get deformed and the handling operations become more delicate. The mockup fuel assemblies are quite deformed to train the teams and prepare them to face any real situation. (A.C.)

  9. Musculoskeletal injuries resulting from patient handling tasks among hospital workers.

    Science.gov (United States)

    Pompeii, Lisa A; Lipscomb, Hester J; Schoenfisch, Ashley L; Dement, John M

    2009-07-01

    The purpose of this study was to evaluate musculoskeletal injuries and disorders resulting from patient handling prior to the implementation of a "minimal manual lift" policy at a large tertiary care medical center. We sought to define the circumstances surrounding patient handling injuries and to identify potential preventive measures. Human resources data were used to define the cohort and their time at work. Workers' compensation records (1997-2003) were utilized to identify work-related musculoskeletal claims, while the workers' description of injury was used to identify those that resulted from patient handling. Adjusted rate ratios were generated using Poisson regression. One-third (n = 876) of all musculoskeletal injuries resulted from patient handling activities. Most (83%) of the injury burden was incurred by inpatient nurses, nurses' aides and radiology technicians, while injury rates were highest for nurses' aides (8.8/100 full-time equivalent, FTEs) and smaller workgroups including emergency medical technicians (10.3/100 FTEs), patient transporters (4.3/100 FTEs), operating room technicians (3.1/100 FTEs), and morgue technicians (2.2/100 FTEs). Forty percent of injuries due to lifting/transferring patients may have been prevented through the use of mechanical lift equipment, while 32% of injuries resulting from repositioning/turning patients, pulling patients up in bed, or catching falling patients may not have been prevented by the use of lift equipment. The use of mechanical lift equipment could significantly reduce the risk of some patient handling injuries but additional interventions need to be considered that address other patient handling tasks. Smaller high-risk workgroups should not be neglected in prevention efforts.

  10. Antenatal calcium intake in Malaysia.

    Science.gov (United States)

    Mahdy, Zaleha Abdullah; Basri, Hashimah; Md Isa, Zaleha; Ahmad, Shuhaila; Shamsuddin, Khadijah; Mohd Amin, Rahmah

    2014-04-01

    To determine the adequacy of antenatal calcium intake in Malaysia, and the influencing factors. A cross-sectional study was conducted among postnatal women who delivered in two tertiary hospitals. Data were collected from antenatal cards, hospital documents and diet recall on daily milk and calcium intake during pregnancy. SPSS version 19.0 was used for statistical analyses. A total of 150 women were studied. The total daily calcium intake was 834 ± 43 mg (mean ± standard error of the mean), but the calcium intake distribution curve was skewed to the right with a median intake of 725 mg daily. When calcium intake from milk and calcium supplements was excluded, the daily dietary calcium intake was only 478 ± 25 mg. Even with inclusion of milk and calcium supplements, more than a third (n=55 or 36.7%) of the women consumed less than 600 mg calcium in their daily diet. The adequacy of daily calcium intake was not influenced by maternal age, ethnicity, income or maternal job or educational status as well as parity. The daily dietary calcium intake of the Malaysian antenatal population is far from adequate without the addition of calcium supplements and milk. © 2013 The Authors. Journal of Obstetrics and Gynaecology Research © 2013 Japan Society of Obstetrics and Gynecology.

  11. C2-domain containing calcium sensors in neuroendocrine secretion

    DEFF Research Database (Denmark)

    Pinheiro, Paulo S; Houy, Sébastien; Sørensen, Jakob B

    2016-01-01

    The molecular mechanisms for calcium-triggered membrane fusion have long been sought for, and detailed models now exist that account for at least some of the functions of the many proteins involved in the process. Key players in the fusion reaction are a group of proteins that, upon binding...... to calcium, trigger the merger of cargo-filled vesicles with the plasma membrane. Low-affinity, fast-kinetics calcium sensors of the synaptotagmin family - especially synaptotagmin-1 and synaptotagmin-2 - are the main calcium sensors for fast exocytosis triggering in many cell types. Their functions extend...... beyond fusion triggering itself, having been implicated in the calcium-dependent vesicle recruitment during activity, docking of vesicles to the plasma membrane and priming, and even in post-fusion steps, such as fusion pore expansion and endocytosis. Furthermore, synaptotagmin diversity imparts distinct...

  12. Calcium mobilization in HeLa cells induced by nitric oxide.

    Science.gov (United States)

    Huang, Yimei; Zheng, Liqin; Yang, Hongqin; Chen, Jiangxu; Wang, Yuhua; Li, Hui; Xie, Shusen

    2014-01-01

    Nitric oxide (NO) has been proposed to be involved in tumor growth and metastasis. However, the mechanism by which nitric oxide modulates cancer cell growth and metastasis on cellular and molecular level is still not fully understood. This work utilized confocal microscopy and fluorescence microplate reader to investigate the effects of exogenous NO on the mobilization of calcium, which is one of the regulators of cell migration, in HeLa cells. The results show that NO elevates calcium in concentration-dependent manner in HeLa cells. And the elevation of calcium induced by NO is due to calcium influx and calcium release from intracellular calcium stores. Moreover, calcium release from intracellular stores is dominant. Furthermore, calcium release from mitochondria is one of the modulation pathways of NO. These findings would contribute to recognizing the significance of NO in cancer cell proliferation and metastasis. © Wiley Periodicals, Inc.

  13. Regulation of intracellular calcium in resting and stimulated rat basophilic leukemia cells

    International Nuclear Information System (INIS)

    Mohr, F.C.

    1988-01-01

    Intracellular calcium regulation was studied in a cell line of mast cells, the rat basophilic leukemia (RBL) cells with the purpose of determining (1) The properties of the plasma membrane calcium permeability pathway and (2) The role of intracellular calcium stores. The first set of experiments showed that depolarization did not induce calcium entry or secretion in resting cells and did inhibit antigen-stimulated calcium uptake and secretion. In the second set of experiments the ionic basis of antigen-induced depolarization was studied using the fluorescent potential-sensitive probe bis-oxonol. The properties of the calcium entry pathway were more consistent with a calcium channel than a calcium transport mechanism such as Na:Ca exchange. The third set of experiments examined the effects of the proton ionophore carbonyl cyanide m-chlorophenylhydrazone (CCCP) on RBL cells. CCCP inhibited antigen-stimulated 45 Ca uptake and secretion by depolarizing the plasma membrane

  14. Preparation, physical-chemical characterisation and cytocompatibility of calcium carbonate cements.

    Science.gov (United States)

    Combes, C; Miao, Baoji; Bareille, Reine; Rey, Christian

    2006-03-01

    The feasibility of calcium carbonate cements involving the recrystallisation of metastable calcium carbonate varieties has been demonstrated. Calcium carbonate cement compositions presented in this paper can be prepared straightforwardly by simply mixing water (liquid phase) with two calcium carbonate phases (solid phase) which can be easily obtained by precipitation. An original cement composition was obtained by mixing amorphous calcium carbonate and vaterite with an aqueous medium. The cement set and hardened within 2h at 37 degrees C in an atmosphere saturated with water and the final composition of the cement consisted mostly of aragonite. The hardened cement was microporous and showed poor mechanical properties. Cytotoxicity tests revealed excellent cytocompatibility of calcium carbonate cement compositions. Calcium carbonates with a higher solubility than the apatite formed for most of the marketed calcium phosphate cements might be of interest to increase biomedical cement resorption rates and to favour its replacement by bone tissue.

  15. Comparison of Two Educational Methods on Nurses' Adoption of Safe Patient Handling Techniques

    Science.gov (United States)

    Folami, Florence

    2010-01-01

    Musculoskeletal injuries caused by patient lifting and transfers are a concern to health care workers. The Safe Patient Handling Act calls for all health care organizations to move to mechanical assistance from previous manual methods of transfers. This research analyzed two different educational programs that addressed safe patient handling for…

  16. Discovery and Development of Calcium Channel Blockers

    Directory of Open Access Journals (Sweden)

    Théophile Godfraind

    2017-05-01

    Full Text Available In the mid 1960s, experimental work on molecules under screening as coronary dilators allowed the discovery of the mechanism of calcium entry blockade by drugs later named calcium channel blockers. This paper summarizes scientific research on these small molecules interacting directly with L-type voltage-operated calcium channels. It also reports on experimental approaches translated into understanding of their therapeutic actions. The importance of calcium in muscle contraction was discovered by Sidney Ringer who reported this fact in 1883. Interest in the intracellular role of calcium arose 60 years later out of Kamada (Japan and Heibrunn (USA experiments in the early 1940s. Studies on pharmacology of calcium function were initiated in the mid 1960s and their therapeutic applications globally occurred in the the 1980s. The first part of this report deals with basic pharmacology in the cardiovascular system particularly in isolated arteries. In the section entitled from calcium antagonists to calcium channel blockers, it is recalled that drugs of a series of diphenylpiperazines screened in vivo on coronary bed precontracted by angiotensin were initially named calcium antagonists on the basis of their effect in depolarized arteries contracted by calcium. Studies on arteries contracted by catecholamines showed that the vasorelaxation resulted from blockade of calcium entry. Radiochemical and electrophysiological studies performed with dihydropyridines allowed their cellular targets to be identified with L-type voltage-operated calcium channels. The modulated receptor theory helped the understanding of their variation in affinity dependent on arterial cell membrane potential and promoted the terminology calcium channel blocker (CCB of which the various chemical families are introduced in the paper. In the section entitled tissue selectivity of CCBs, it is shown that characteristics of the drug, properties of the tissue, and of the stimuli are

  17. Remote Handling behind port plug in ITER

    International Nuclear Information System (INIS)

    Bede, O.; Neuberger, H.

    2006-01-01

    Different Test Blanket Modules (TBM) will be used in succession in the same equatorial ports of ITER. The remote handling operations for connection/disconnection of an interface between the port plug of the EU-HCPB-TBM and the port cell equipment are investigated with the goal to reach a quick and simple TBM exchange procedure. This paper describes the operations and systems which are required for connection of the TBM to its supply lines at this interface. The interface is located inside the free space of the port plug flange between the port plug shield and the bioshield of the port cell behind. The approach of the operation place is only available through a narrow gate in the bioshield opened temporarily during maintenance periods. This gate limits the dimensions of the whole system and its tools. The current design of the EU-HCPB-TBM foresees up to 9 supply lines which have to be connected inside the free space of one half of the port plug flange. The connection operations require positioning and adjustment of the tools for each pipe separately. Despite the strict circumstances it is still possible to find such an industrial jointed-arm robot with sufficient payload, which can penetrate into the working area. A mechanical system is necessary to move the robot from its storing place in the hot cell to the port plug on 6 m distance. Each operation requires different end-of-arm tools. The most special one is a pipe positioner tool, which can position and pull the pipe ends to each other and align the tool before welding and hold them in proper position during the welding process. Weld seams can be made by orbital welding tool. The pipe positioner tool has to provide place for welding tool. Using of inbore tool is impossible because pipes have no open ends where the tool could leave it. Orbital tool must be modified to meet requirements of remote handling because it is designed for human handling. The coolant is helium, so for eliminating the leak of helium it is

  18. Cask system design guidance for robotic handling

    International Nuclear Information System (INIS)

    Griesmeyer, J.M.; Drotning, W.D.; Morimoto, A.K.; Bennett, P.C.

    1990-10-01

    Remote automated cask handling has the potential to reduce both the occupational exposure and the time required to process a nuclear waste transport cask at a handling facility. The ongoing Advanced Handling Technologies Project (AHTP) at Sandia National Laboratories is described. AHTP was initiated to explore the use of advanced robotic systems to perform cask handling operations at handling facilities for radioactive waste, and to provide guidance to cask designers regarding the impact of robotic handling on cask design. The proof-of-concept robotic systems developed in AHTP are intended to extrapolate from currently available commercial systems to the systems that will be available by the time that a repository would be open for operation. The project investigates those cask handling operations that would be performed at a nuclear waste repository facility during cask receiving and handling. The ongoing AHTP indicates that design guidance, rather than design specification, is appropriate, since the requirements for robotic handling do not place severe restrictions on cask design but rather focus on attention to detail and design for limited dexterity. The cask system design features that facilitate robotic handling operations are discussed, and results obtained from AHTP design and operation experience are summarized. The application of these design considerations is illustrated by discussion of the robot systems and their operation on cask feature mock-ups used in the AHTP project. 11 refs., 11 figs

  19. Activation of L-type calcium channels is required for gap junction-mediated intercellular calcium signaling in osteoblastic cells

    DEFF Research Database (Denmark)

    Jørgensen, Niklas Rye; Teilmann, Stefan Cuoni; Henriksen, Zanne

    2003-01-01

    The propagation of mechanically induced intercellular calcium waves (ICW) among osteoblastic cells occurs both by activation of P2Y (purinergic) receptors by extracellular nucleotides, resulting in "fast" ICW, and by gap junctional communication in cells that express connexin43 (Cx43), resulting...... in "slow" ICW. Human osteoblastic cells transmit intercellular calcium signals by both of these mechanisms. In the current studies we have examined the mechanism of slow gap junction-dependent ICW in osteoblastic cells. In ROS rat osteoblastic cells, gap junction-dependent ICW were inhibited by removal...... of extracellular calcium, plasma membrane depolarization by high extracellular potassium, and the L-type voltage-operated calcium channel inhibitor, nifedipine. In contrast, all these treatments enhanced the spread of P2 receptor-mediated ICW in UMR rat osteoblastic cells. Using UMR cells transfected to express Cx...

  20. Survey of technology for decommissioning of nuclear fuel cycle facilities. 8. Remote handling and cutting techniques

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, Ryuichiro; Ishijima, Noboru [Japan Nuclear Cycle Development Inst., Oarai, Ibaraki (Japan). Oarai Engineering Center

    1999-03-01

    In nuclear fuel cycle facility decommissioning and refurbishment, the remote handling techniques such as dismantling, waste handling and decontamination are needed to reduce personnel radiation exposure. The survey research for the status of R and D activities on remote handling tools suitable for nuclear facilities in the world and domestic existing commercial cutting tools applicable to decommissioning of the facilities was conducted. In addition, the drive mechanism, sensing element and control system applicable to the remote handling devices were also surveyed. This report presents brief surveyed summaries. (H. Itami)

  1. L-Type Calcium Channels Modulation by Estradiol.

    Science.gov (United States)

    Vega-Vela, Nelson E; Osorio, Daniel; Avila-Rodriguez, Marco; Gonzalez, Janneth; García-Segura, Luis Miguel; Echeverria, Valentina; Barreto, George E

    2017-09-01

    Voltage-gated calcium channels are key regulators of brain function, and their dysfunction has been associated with multiple conditions and neurodegenerative diseases because they couple membrane depolarization to the influx of calcium-and other processes such as gene expression-in excitable cells. L-type calcium channels, one of the three major classes and probably the best characterized of the voltage-gated calcium channels, act as an essential calcium binding proteins with a significant biological relevance. It is well known that estradiol can activate rapidly brain signaling pathways and modulatory/regulatory proteins through non-genomic (or non-transcriptional) mechanisms, which lead to an increase of intracellular calcium that activate multiple kinases and signaling cascades, in the same way as L-type calcium channels responses. In this context, estrogens-L-type calcium channels signaling raises intracellular calcium levels and activates the same signaling cascades in the brain probably through estrogen receptor-independent modulatory mechanisms. In this review, we discuss the available literature on this area, which seems to suggest that estradiol exerts dual effects/modulation on these channels in a concentration-dependent manner (as a potentiator of these channels in pM concentrations and as an inhibitor in nM concentrations). Indeed, estradiol may orchestrate multiple neurotrophic responses, which open a new avenue for the development of novel estrogen-based therapies to alleviate different neuropathologies. We also highlight that it is essential to determine through computational and/or experimental approaches the interaction between estradiol and L-type calcium channels to assist these developments, which is an interesting area of research that deserves a closer look in future biomedical research.

  2. Hot Laboratories and Remote Handling

    International Nuclear Information System (INIS)

    Bart, G.; Blanc, J.Y.; Duwe, R.

    2003-01-01

    The European Working Group on ' Hot Laboratories and Remote Handling' is firmly established as the major contact forum for the nuclear R and D facilities at the European scale. The yearly plenary meetings intend to: - Exchange experience on analytical methods, their implementation in hot cells, the methodologies used and their application in nuclear research; - Share experience on common infrastructure exploitation matters such as remote handling techniques, safety features, QA-certification, waste handling; - Promote normalization and co-operation, e.g., by looking at mutual complementarities; - Prospect present and future demands from the nuclear industry and to draw strategic conclusions regarding further needs. The 41. plenary meeting was held in CEA Saclay from September 22 to 24, 2003 in the premises and with the technical support of the INSTN (National Institute for Nuclear Science and Technology). The Nuclear Energy Division of CEA sponsored it. The Saclay meeting was divided in three topical oral sessions covering: - Post irradiation examination: new analysis methods and methodologies, small specimen technology, programmes and results; - Hot laboratory infrastructure: decommissioning, refurbishment, waste, safety, nuclear transports; - Prospective research on materials for future applications: innovative fuels (Generation IV, HTR, transmutation, ADS), spallation source materials, and candidate materials for fusion reactor. A poster session was opened to transport companies and laboratory suppliers. The meeting addressed in three sessions the following items: Session 1 - Post Irradiation Examinations. Out of 12 papers (including 1 poster) 7 dealt with surface and solid state micro analysis, another one with an equally complex wet chemical instrumental analytical technique, while the other four papers (including the poster) presented new concepts for digital x-ray image analysis; Session 2 - Hot laboratory infrastructure (including waste theme) which was

  3. Calcium phosphate cement scaffolds with PLGA fibers.

    Science.gov (United States)

    Vasconcellos, Letícia Araújo; dos Santos, Luís Alberto

    2013-04-01

    The use of calcium phosphate-based biomaterials has revolutionized current orthopedics and dentistry in repairing damaged parts of the skeletal system. Among those biomaterials, the cement made of hydraulic grip calcium phosphate has attracted great interest due to its biocompatibility and hardening "in situ". However, these cements have low mechanical strength compared with the bones of the human body. In the present work, we have studied the attainment of calcium phosphate cement powders and their addition to poly (co-glycolide) (PLGA) fibers to increase mechanical properties of those cements. We have used a new method that obtains fibers by dripping different reagents. PLGA fibers were frozen after lyophilized. With this new method, which was patented, it was possible to obtain fibers and reinforcing matrix which furthered the increase of mechanical properties, thus allowing the attainment of more resistant materials. The obtained materials were used in the construction of composites and scaffolds for tissue growth, keeping a higher mechanical integrity. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Voltage-Gated Calcium Channels

    Science.gov (United States)

    Zamponi, Gerald Werner

    Voltage Gated Calcium Channels is the first comprehensive book in the calcium channel field, encompassing over thirty years of progress towards our understanding of calcium channel structure, function, regulation, physiology, pharmacology, and genetics. This book balances contributions from many of the leading authorities in the calcium channel field with fresh perspectives from risings stars in the area, taking into account the most recent literature and concepts. This is the only all-encompassing calcium channel book currently available, and is an essential resource for academic researchers at all levels in the areas neuroscience, biophysics, and cardiovascular sciences, as well as to researchers in the drug discovery area.

  5. Probabilistic encoding of stimulus strength in astrocyte global calcium signals.

    Science.gov (United States)

    Croft, Wayne; Reusch, Katharina; Tilunaite, Agne; Russell, Noah A; Thul, Rüdiger; Bellamy, Tomas C

    2016-04-01

    Astrocyte calcium signals can range in size from subcellular microdomains to waves that spread through the whole cell (and into connected cells). The differential roles of such local or global calcium signaling are under intense investigation, but the mechanisms by which local signals evolve into global signals in astrocytes are not well understood, nor are the computational rules by which physiological stimuli are transduced into a global signal. To investigate these questions, we transiently applied receptor agonists linked to calcium signaling to primary cultures of cerebellar astrocytes. Astrocytes repetitively tested with the same stimulus responded with global signals intermittently, indicating that each stimulus had a defined probability for triggering a response. The response probability varied between agonists, increased with agonist concentration, and could be positively and negatively modulated by crosstalk with other signaling pathways. To better understand the processes determining the evolution of a global signal, we recorded subcellular calcium "puffs" throughout the whole cell during stimulation. The key requirement for puffs to trigger a global calcium wave following receptor activation appeared to be the synchronous release of calcium from three or more sites, rather than an increasing calcium load accumulating in the cytosol due to increased puff size, amplitude, or frequency. These results suggest that the concentration of transient stimuli will be encoded into a probability of generating a global calcium response, determined by the likelihood of synchronous release from multiple subcellular sites. © 2015 Wiley Periodicals, Inc.

  6. Calcium as a cardiovascular toxin in CKD-MBD.

    Science.gov (United States)

    Moe, Sharon M

    2017-07-01

    Disordered calcium balance and homeostasis are common in patients with chronic kidney disease. Such alterations are commonly associated with abnormal bone remodeling, directly and indirectly. Similarly, positive calcium balance may also be a factor in the pathogenesis of extra skeletal soft tissue and arterial calcification. Calcium may directly affect cardiac structure and function through direct effects to alter cell signaling due to abnormal intracellular calcium homeostasis 2) extra-skeletal deposition of calcium and phosphate in the myocardium and small cardiac arterioles, 3) inducing cardiomyocyte hypertrophy through calcium and hormone activation of NFAT signaling mechanisms, and 4) increased aorta calcification resulting in chronic increased afterload leading to hypertrophy. Similarly, calcium may alter vascular smooth muscle cell function and affect cell signaling which may predispose to a proliferative phenotype important in arteriosclerosis and arterial calcification. Thus, disorders of calcium balance and homeostasis due to CKD-MBD may play a role in the high cardiovascular burden observed in patients with CKD. Published by Elsevier Inc.

  7. Interaction of H2S with Calcium Permeable Channels and Transporters

    Directory of Open Access Journals (Sweden)

    Weihua Zhang

    2015-01-01

    Full Text Available A growing amount of evidence has suggested that hydrogen sulfide (H2S, as a gasotransmitter, is involved in intensive physiological and pathological processes. More and more research groups have found that H2S mediates diverse cellular biological functions related to regulating intracellular calcium concentration. These groups have demonstrated the reciprocal interaction between H2S and calcium ion channels and transporters, such as L-type calcium channels (LTCC, T-type calcium channels (TTCC, sodium/calcium exchangers (NCX, transient receptor potential (TRP channels, β-adrenergic receptors, and N-methyl-D-aspartate receptors (NMDAR in different cells. However, the understanding of the molecular targets and mechanisms is incomplete. Recently, some research groups demonstrated that H2S modulates the activity of calcium ion channels through protein S-sulfhydration and polysulfide reactions. In this review, we elucidate that H2S controls intracellular calcium homeostasis and the underlying mechanisms.

  8. Development of commercial robots for radwaste handling

    International Nuclear Information System (INIS)

    Colborn, K.A.

    1988-01-01

    The cost and dose burden associated with low level radwaste handling activities is a matter of increasing concern to the commercial nuclear power industry. This concern is evidenced by the fact that many utilities have begun to revaluate waste generation, handling, and disposal activities at their plants in an effort to improve their overall radwaste handling operations. This paper reports on the project Robots for Radwaste Handling, to identify the potential of robots to improve radwaste handling operations. The project has focussed on the potential of remote or automated technology to improve well defined, recognizable radwaste operations. The project focussed on repetitive, low skill level radwaste handling and decontamination tasks which involve significant radiation exposure

  9. Mechanics

    CERN Document Server

    Chester, W

    1979-01-01

    When I began to write this book, I originally had in mind the needs of university students in their first year. May aim was to keep the mathematics simple. No advanced techniques are used and there are no complicated applications. The emphasis is on an understanding of the basic ideas and problems which require expertise but do not contribute to this understanding are not discussed. How­ ever, the presentation is more sophisticated than might be considered appropri­ ate for someone with no previous knowledge of the subject so that, although it is developed from the beginning, some previous acquaintance with the elements of the subject would be an advantage. In addition, some familiarity with element­ ary calculus is assumed but not with the elementary theory of differential equations, although knowledge of the latter would again be an advantage. It is my opinion that mechanics is best introduced through the motion of a particle, with rigid body problems left until the subject is more fully developed. Howev...

  10. Sequence trajectory generation for garment handling systems

    OpenAIRE

    Liu, Honghai; Lin, Hua

    2008-01-01

    This paper presents a novel generic approach to the planning strategy of garment handling systems. An assumption is proposed to separate the components of such systems into a component for intelligent gripper techniques and a component for handling planning strategies. Researchers can concentrate on one of the two components first, then merge the two problems together. An algorithm is addressed to generate the trajectory position and a clothes handling sequence of clothes partitions, which ar...

  11. Enclosure for handling high activity materials

    International Nuclear Information System (INIS)

    Jimeno de Osso, F.

    1977-01-01

    One of the most important problems that are met at the laboratories producing and handling radioisotopes is that of designing, building and operating enclosures suitable for the safe handling of active substances. With this purpose in mind, an enclosure has been designed and built for handling moderately high activities under a shielding made of 150 mm thick lead. In this report a description is given of those aspects that may be of interest to people working in this field. (Author)

  12. Enclosure for handling high activity materials abstract

    International Nuclear Information System (INIS)

    Jimeno de Osso, F.; Dominguez Rodriguez, G.; Cruz Castillo, F. de la; Rodriguez Esteban, A.

    1977-01-01

    One of the most important problems that are met at the laboratories producing and handling radioisotopes is that of designing, building and operating enclosures suitable for the safe handling of active substances. With that purpose in mind, an enclosure has been designed and built for handling moderately high activities under a shielding made of 150 mm thick lead. A description is given of those aspects that may be of interest to people working in this field. (author) [es

  13. Scheduling of outbound luggage handling at airports

    DEFF Research Database (Denmark)

    Barth, Torben C.; Pisinger, David

    2012-01-01

    This article considers the outbound luggage handling problem at airports. The problem is to assign handling facilities to outbound flights and decide about the handling start time. This dynamic, near real-time assignment problem is part of the daily airport operations. Quality, efficiency......). Another solution method is a decomposition approach. The problem is divided into different subproblems and solved in iterative steps. The different solution approaches are tested on real world data from Frankfurt Airport....

  14. ATA diagnostic data handling system: an overview

    International Nuclear Information System (INIS)

    Chambers, F.W.; Kallman, J.; McDonald, J.; Slominski, M.

    1984-01-01

    The functions to be performed by the ATA diagnostic data handling system are discussed. The capabilities of the present data acquisition system (System 0) are presented. The goals for the next generation acquisition system (System 1), currently under design, are discussed. Facilities on the Octopus system for data handling are reviewed. Finally, we discuss what has been learned about diagnostics and computer based data handling during the past year

  15. Enclosure for handling high activity materials

    Energy Technology Data Exchange (ETDEWEB)

    Jimeno de Osso, F

    1977-07-01

    One of the most important problems that are met at the laboratories producing and handling radioisotopes is that of designing, building and operating enclosures suitable for the safe handling of active substances. With this purpose in mind, an enclosure has been designed and built for handling moderately high activities under a shielding made of 150 mm thick lead. In this report a description is given of those aspects that may be of interest to people working in this field. (Author)

  16. Calcium signalling silencing in atrial fibrillation.

    Science.gov (United States)

    Greiser, Maura

    2017-06-15

    Subcellular calcium signalling silencing is a novel and distinct cellular and molecular adaptive response to rapid cardiac activation. Calcium signalling silencing develops during short-term sustained rapid atrial activation as seen clinically during paroxysmal atrial fibrillation (AF). It is the first 'anti-arrhythmic' adaptive response in the setting of AF and appears to counteract the maladaptive changes that lead to intracellular Ca 2+ signalling instability and Ca 2+ -based arrhythmogenicity. Calcium signalling silencing results in a failed propagation of the [Ca 2+ ] i signal to the myocyte centre both in patients with AF and in a rabbit model. This adaptive mechanism leads to a substantial reduction in the expression levels of calcium release channels (ryanodine receptors, RyR2) in the sarcoplasmic reticulum, and the frequency of Ca 2+ sparks and arrhythmogenic Ca 2+ waves remains low. Less Ca 2+ release per [Ca 2+ ] i transient, increased fast Ca 2+ buffering strength, shortened action potentials and reduced L-type Ca 2+ current contribute to a substantial reduction of intracellular [Na + ]. These features of Ca 2+ signalling silencing are distinct and in contrast to the changes attributed to Ca 2+ -based arrhythmogenicity. Some features of Ca 2+ signalling silencing prevail in human AF suggesting that the Ca 2+ signalling 'phenotype' in AF is a sum of Ca 2+ stabilizing (Ca 2+ signalling silencing) and Ca 2+ destabilizing (arrhythmogenic unstable Ca 2+ signalling) factors. Calcium signalling silencing is a part of the mechanisms that contribute to the natural progression of AF and may limit the role of Ca 2+ -based arrhythmogenicity after the onset of AF. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

  17. Interaction of alkali metal nitrates with calcium carbonate and kyanite

    International Nuclear Information System (INIS)

    Protsyuk, A.P.; Malakhov, A.I.; Karabanov, V.P.; Lebedeva, L.P.

    1978-01-01

    Thermographic, thermodynamic and X-ray phase studies have been made into the interaction of alkali metal nitrates with calcium carbonate and kyanite. Examined among other things was the effect of water vapor and carbon dioxide on the interaction between alkali metal nitrates and kyanite. The chemical mechanism of the occurring processes has been established. The interaction with calcium carbonates results in the formation of alkali metal carbonates and calcium oxide with liberation of nitrogen oxide and oxygen. The products of the interaction with kyanite are shown to be identical with the compounds forming when alkali metal carbonates are used

  18. Synthesis of calcium aluminates on the big solar furnace

    International Nuclear Information System (INIS)

    Abdurakhmanov, A. A.; Paizullakhanov, M. S.; Akhadov, Zh.

    2012-01-01

    The processes of synthesizing calcium aluminate in the flow of concentrated solar radiation on Large Solar Furnace are studied. It is shown that the synthesis of calcium aluminate takes place through a process of melting of a mixture of aluminum oxides and calcium (Al 2 O 3 + CaO). At values of power of the concentrated flow of 200 W/cm 2 , thermodynamic conditions for melting of the materials studied were implemented. Full fusion penetration is achieved at a power flow of 400 W/cm 2 . The resulting material exhibits high mechanical properties (the modulus of rupture upon bending is 40 MPa). (author)

  19. Automation and remote handling activities in BARC: an overview

    International Nuclear Information System (INIS)

    Badodkar, D.N.

    2016-01-01

    Division of Remote Handling and Robotics, BARC has been working on design and development of various application specific remote handling and automation systems for nuclear front-end and back-end fuel cycle technologies. Division is also engaged in preservice and in-service inspection of coolant channels for Pressurized Heavy Water Reactors in India. Design and development of Reactor Control Mechanisms for Nuclear Research and Power Reactors (PHWRs and Compact LWRs) is another important activity carried out in this division. Robotic systems for Indoor and Outdoor surveillance in and around nuclear installations have also been developed. A line scan camera based system has been developed for measuring individual PHWR fuel pellet lengths as well as stack length. An industrial robot is used for autonomous exchange of pellets to achieve desired stack length. The system can be extended for active fuel pellets also. An automation system has been conceptualized for remote handling and transfer of spent fuel bundles from storage pool directly to the chopper unit of reprocessing plant. In case of Advanced Heavy Water Reactor which uses mixed oxides of (Th-Pu) and (Th-"2"3"3U ) as fuel, automation system for front-end fuel cycle has been designed, which includes Powder processing and pressing; Pellet handling and inspection; Pin handling and inspection; and Cluster assembly and dis-assembly in shielded facilities. System demonstration through fullscale mock-up facility is nearing completion. Above talk is presented on behalf of all the officers and staff of DRHR. The talk is mainly focused on development of an automated fuel fabrication facility for mixed oxides of (Th- Pu)/(Th-"2"3"3U ) fuel pins. An overview of divisional ongoing activities in the field of remote handling and automation are also covered. (author)

  20. Calcium, essential for health

    Science.gov (United States)

    Martínez de Victoria, Emilio

    2016-07-12

    Calcium (Ca) is the most abundant mineral element in our body. It accounts for about 2% of body weight. The functions of calcium are: a) functions skeletal and b) regulatory functions. Bone consists of a protein matrix that mineralizes mainly with calcium (the most abundant), phosphate and magnesium, for it is essential an adequate dietary intake of Ca, phosphorus and vitamin D. The ionic Ca (Ca2+) is essential to maintain and / or perform different specialized functions of, virtually, all body cells cellular. Because of its important functions Ca2+ must be closely regulated, keeping plasma concentrations within narrow ranges. For this reason there is an accurate response against hypocalcemia or hypercalcemia in which the parathormone, calcitriol, calcitonin and vitamin K are involved. Ca intakes in the Spanish population are low in a significant percentage of the older adult’s population, especially in women. The main source of Ca in the diet is milk and milk derivatives. Green leafy vegetables, fruits and legumes can be important sources of Ca in a Mediterranean dietary pattern. The bioavailability of dietary Ca depends on physiological and dietary factors. Physiological include age, physiological status (gestation and lactation) Ca and vitamin D status and disease. Several studies relate Ca intake in the diet and various diseases, such as osteoporosis, cancer, cardiovascular disease and obesity.

  1. Calcium and Nuclear Signaling in Prostate Cancer

    Directory of Open Access Journals (Sweden)

    Ivan V. Maly

    2018-04-01

    Full Text Available Recently, there have been a number of developments in the fields of calcium and nuclear signaling that point to new avenues for a more effective diagnosis and treatment of prostate cancer. An example is the discovery of new classes of molecules involved in calcium-regulated nuclear import and nuclear calcium signaling, from the G protein-coupled receptor (GPCR and myosin families. This review surveys the new state of the calcium and nuclear signaling fields with the aim of identifying the unifying themes that hold out promise in the context of the problems presented by prostate cancer. Genomic perturbations, kinase cascades, developmental pathways, and channels and transporters are covered, with an emphasis on nuclear transport and functions. Special attention is paid to the molecular mechanisms behind prostate cancer progression to the malignant forms and the unfavorable response to anti-androgen treatment. The survey leads to some new hypotheses that connect heretofore disparate results and may present a translational interest.

  2. Hot Laboratories and Remote Handling

    International Nuclear Information System (INIS)

    2007-01-01

    The Opening talk of the workshop 'Hot Laboratories and Remote Handling' was given by Marin Ciocanescu with the communication 'Overview of R and D Program in Romanian Institute for Nuclear Research'. The works of the meeting were structured into three sections addressing the following items: Session 1. Hot cell facilities: Infrastructure, Refurbishment, Decommissioning; Session 2. Waste, transport, safety and remote handling issues; Session 3. Post-Irradiation examination techniques. In the frame of Section 1 the communication 'Overview of hot cell facilities in South Africa' by Wouter Klopper, Willie van Greunen et al, was presented. In the framework of the second session there were given the following four communications: 'The irradiated elements cell at PHENIX' by Laurent Breton et al., 'Development of remote equipment for DUPIC fuel fabrication at KAERI', by Jung Won Lee et al., 'Aspects of working with manipulators and small samples in an αβγ-box, by Robert Zubler et al., and 'The GIOCONDA experience of the Joint Research Centre Ispra: analysis of the experimental assemblies finalized to their safe recovery and dismantling', by Roberto Covini. Finally, in the framework of the third section the following five communications were presented: 'PIE of a CANDU fuel element irradiated for a load following test in the INR TRIGA reactor' by Marcel Parvan et al., 'Adaptation of the pole figure measurement to the irradiated items from zirconium alloys' by Yury Goncharenko et al., 'Fuel rod profilometry with a laser scan micrometer' by Daniel Kuster et al., 'Raman spectroscopy, a new facility at LECI laboratory to investigate neutron damage in irradiated materials' by Lionel Gosmain et al., and 'Analysis of complex nuclear materials with the PSI shielded analytical instruments' by Didier Gavillet. In addition, eleven more presentations were given as posters. Their titles were: 'Presentation of CETAMA activities (CEA analytic group)' by Alain Hanssens et al. 'Analysis of

  3. Fuel handling problems at KANUPP

    Energy Technology Data Exchange (ETDEWEB)

    Ahmed, I; Mazhar Hasan, S; Mugtadir, A [Karachi Nuclear Power Plant (KANUPP), Karachi (Pakistan)

    1991-04-01

    KANUPP experienced two abnormal fuel and fuel handling related problems during the year 1990. One of these had arisen due to development of end plate to end plate coupling between the two bundles at the leading end of the fuel string in channel HO2-S. The incident occurred when attempts were being made to fuel this channel. Due to pulling of sticking bundles into the acceptor fuelling machine (north) magazine, which was not designed to accommodate two bundles, a magazine rotary stop occurred. The forward motion of the charge tube was simultaneously discovered to be restricted. The incident led to stalling of fuelling machine locked on to the channel HO2, necessitating a reactor shut down. Removal of the fuelling machine was accomplished sometime later after draining of the channel. The second incident which made the fuelling of channel KO5-N temporarily inexecutable, occurred during attempts to remove its north end shield plug when this channel came up for fuelling. The incident resulted due to breaking of the lugs of the shield plug, making its withdrawal impossible. The Plant however kept operating with suspended fuelling of channel KO5, until it could no longer sustain a further increase in fuel burnup at the maximum rating position. Resolving both these problems necessitated draining of the respective channels, leaving the resident fuel uncovered for the duration of the associated operation. Due to substantial difference in the oxidation temperatures Of UO{sub 2} and Zircaloy and its influence as such on the cooling requirement, it was necessary either to determine explicitly that the respective channels did not contain defective fuel bundles or wait for time long enough to allow the decay heat to reduce to manageable proportions. This had a significant bearing on the Plant down time necessary for the rectification of the problems. This paper describes the two incidents in detail and dwells upon the measures adopted to resolve the related problems. (author)

  4. Fuel handling problems at KANUPP

    International Nuclear Information System (INIS)

    Ahmed, I.; Mazhar Hasan, S.; Mugtadir, A.

    1991-01-01

    KANUPP experienced two abnormal fuel and fuel handling related problems during the year 1990. One of these had arisen due to development of end plate to end plate coupling between the two bundles at the leading end of the fuel string in channel HO2-S. The incident occurred when attempts were being made to fuel this channel. Due to pulling of sticking bundles into the acceptor fuelling machine (north) magazine, which was not designed to accommodate two bundles, a magazine rotary stop occurred. The forward motion of the charge tube was simultaneously discovered to be restricted. The incident led to stalling of fuelling machine locked on to the channel HO2, necessitating a reactor shut down. Removal of the fuelling machine was accomplished sometime later after draining of the channel. The second incident which made the fuelling of channel KO5-N temporarily inexecutable, occurred during attempts to remove its north end shield plug when this channel came up for fuelling. The incident resulted due to breaking of the lugs of the shield plug, making its withdrawal impossible. The Plant however kept operating with suspended fuelling of channel KO5, until it could no longer sustain a further increase in fuel burnup at the maximum rating position. Resolving both these problems necessitated draining of the respective channels, leaving the resident fuel uncovered for the duration of the associated operation. Due to substantial difference in the oxidation temperatures Of UO 2 and Zircaloy and its influence as such on the cooling requirement, it was necessary either to determine explicitly that the respective channels did not contain defective fuel bundles or wait for time long enough to allow the decay heat to reduce to manageable proportions. This had a significant bearing on the Plant down time necessary for the rectification of the problems. This paper describes the two incidents in detail and dwells upon the measures adopted to resolve the related problems. (author)

  5. Handling of final storage of unreprocessed spent nuclear fuel

    International Nuclear Information System (INIS)

    1978-01-01

    In this report the various facilities incorporated in the proposed handling chain for spent fuel from the power stations to the final repository are discribed. Thus the geological conditions which are essential for a final repository is discussed as well as the buffer and canister materials and how they contribute towards a long-term isolation of the spent fuel. Furthermore one chapter deals with leaching of the deposited fuel in the event that the canister is penetrated as well as the transport mechanisms which determine the migration of the radioactive substances through the buffer material. The dispersal processes in the geosphere and the biosphere are also described together with the transfer mechanisms to the ecological systems as well as radiation doses. Finally a summary is given of the safety analysis of the proposed method for the handling and final storage of the spent fuel. (E.R.)

  6. Determination of percent calcium carbonate in calcium chromate

    International Nuclear Information System (INIS)

    Middleton, H.W.

    1979-01-01

    The precision, accuracy and reliability of the macro-combustion method is superior to the Knorr alkalimetric method, and it is faster. It also significantly reduces the calcium chromate waste accrual problem. The macro-combustion method has been adopted as the official method for determination of percent calcium carbonate in thermal battery grade anhydrous calcium chromate and percent calcium carbonate in quicklime used in the production of calcium chromate. The apparatus and procedure can be used to measure the percent carbonate in inorganic materials other than calcium chromate. With simple modifications in the basic apparatus and procedure, the percent carbon and hydrogen can be measured in many organic material, including polymers and polymeric formulations. 5 figures, 5 tables

  7. Use of technical biochemical in combination for the detection of proteins of union to calcium in Plasmodium falciparum

    International Nuclear Information System (INIS)

    Cabrera, Rodrigo; Wasserman, Moises

    2003-01-01

    Calcium plays a fundamental role in the development of Plasmodium falciparum, the intracellular parasite that causes malaria. With the purpose of understanding the mechanism by which calcium acts in this parasite, calcium-binding proteins were detected in this organism the combined use of the metachromatic dye Stains-all and the 4 5 C a overlay assay allowed the identification, in mature parasites. Of 9 calcium - binding proteins. 6 of which seem to be different from any reported calcium-binding protein. Additionally, it was determined that the combined use of these techniques can be useful for the detection and purification of calcium-binding proteins

  8. 9 CFR 3.118 - Handling.

    Science.gov (United States)

    2010-01-01

    ... 9 Animals and Animal Products 1 2010-01-01 2010-01-01 false Handling. 3.118 Section 3.118 Animals and Animal Products ANIMAL AND PLANT HEALTH INSPECTION SERVICE, DEPARTMENT OF AGRICULTURE ANIMAL WELFARE STANDARDS Specifications for the Humane Handling, Care, Treatment, and Transportation of Marine...

  9. How to Handle Impasses in Bargaining.

    Science.gov (United States)

    Durrant, Robert E.

    Guidelines in an outline format are presented to school board members and administrators on how to handle impasses in bargaining. The following two rules are given: there sometimes may be strikes, but there always will be settlements; and on the way to settlements, there always will be impasses. Suggestions for handling impasses are listed under…

  10. Handling uncertainty through adaptiveness in planning approaches

    NARCIS (Netherlands)

    Zandvoort, M.; Vlist, van der M.J.; Brink, van den A.

    2018-01-01

    Planners and water managers seek to be adaptive to handle uncertainty through the use of planning approaches. In this paper, we study what type of adaptiveness is proposed and how this may be operationalized in planning approaches to adequately handle different uncertainties. We took a

  11. Survey of postharvest handling, preservation and processing ...

    African Journals Online (AJOL)

    Survey of postharvest handling, preservation and processing practices along the camel milk chain in Isiolo district, Kenya. ... Despite the important contribution of camel milk to food security for pastoralists in Kenya, little is known about the postharvest handling, preservation and processing practices. In this study, existing ...

  12. PND fuel handling decontamination: facilities and techniques

    International Nuclear Information System (INIS)

    Pan, R.Y.

    1996-01-01

    The use of various decontamination techniques and equipment has become a critical part of Fuel Handling maintenance work at Ontario Hydro's Pickering Nuclear Division. This paper presents an overview of the set up and techniques used for decontamination in the PND Fuel Handling Maintenance Facility and the effectiveness of each. (author). 1 tab., 9 figs

  13. Handling Kids in Crisis with Care

    Science.gov (United States)

    Bushinski, Cari

    2018-01-01

    The Handle with Care program helps schools help students who experience trauma. While at the scene of an event like a domestic violence call, drug raid, or car accident, law enforcement personnel determine the names and school of any children present. They notify that child's school to "handle ___ with care" the next day, and the school…

  14. PND fuel handling decontamination: facilities and techniques

    Energy Technology Data Exchange (ETDEWEB)

    Pan, R Y [Ontario Hydro, Toronto, ON (Canada)

    1997-12-31

    The use of various decontamination techniques and equipment has become a critical part of Fuel Handling maintenance work at Ontario Hydro`s Pickering Nuclear Division. This paper presents an overview of the set up and techniques used for decontamination in the PND Fuel Handling Maintenance Facility and the effectiveness of each. (author). 1 tab., 9 figs.

  15. Handling knowledge on osteoporosis - a qualitative study

    DEFF Research Database (Denmark)

    Nielsen, Dorthe; Huniche, Lotte; Brixen, Kim

    2013-01-01

    Scand J Caring Sci; 2012 Handling knowledge on osteoporosis - a qualitative study The aim of this qualitative study was to increase understanding of the importance of osteoporosis information and knowledge for patients' ways of handling osteoporosis in their everyday lives. Interviews were...

  16. Calcium-deficiency assessment and biomarker identification by an integrated urinary metabonomics analysis

    Science.gov (United States)

    2013-01-01

    Background Calcium deficiency is a global public-health problem. Although the initial stage of calcium deficiency can lead to metabolic alterations or potential pathological changes, calcium deficiency is difficult to diagnose accurately. Moreover, the details of the molecular mechanism of calcium deficiency remain somewhat elusive. To accurately assess and provide appropriate nutritional intervention, we carried out a global analysis of metabolic alterations in response to calcium deficiency. Methods The metabolic alterations associated with calcium deficiency were first investigated in a rat model, using urinary metabonomics based on ultra-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry and multivariate statistical analysis. Correlations between dietary calcium intake and the biomarkers identified from the rat model were further analyzed to confirm the potential application of these biomarkers in humans. Results Urinary metabolic-profiling analysis could preliminarily distinguish between calcium-deficient and non-deficient rats after a 2-week low-calcium diet. We established an integrated metabonomics strategy for identifying reliable biomarkers of calcium deficiency using a time-course analysis of discriminating metabolites in a low-calcium diet experiment, repeating the low-calcium diet experiment and performing a calcium-supplement experiment. In total, 27 biomarkers were identified, including glycine, oxoglutaric acid, pyrophosphoric acid, sebacic acid, pseudouridine, indoxyl sulfate, taurine, and phenylacetylglycine. The integrated urinary metabonomics analysis, which combined biomarkers with regular trends of change (types A, B, and C), could accurately assess calcium-deficient rats at different stages and clarify the dynamic pathophysiological changes and molecular mechanism of calcium deficiency in detail. Significant correlations between calcium intake and two biomarkers, pseudouridine (Pearson

  17. MRI of meniscal bucket-handle tears

    Energy Technology Data Exchange (ETDEWEB)

    Magee, T.H.; Hinson, G.W. [Menorah Medical Center, Overland Park, KS (United States). Dept. of Radiology

    1998-09-01

    A meniscal bucket-handle tear is a tear with an attached fragment displaced from the meniscus of the knee joint. Low sensitivity of MRI for detection of bucket-handle tears (64% as compared with arthroscopy) has been reported previously. We report increased sensitivity for detecting bucket-handle tears with the use of coronal short tau inversion recovery (STIR) images. Results. By using four criteria for diagnosis of meniscal bucket-handle tears, our overall sensitivity compared with arthroscopy was 93% (28 of 30 meniscal bucket-handle tears seen at arthroscopy were detected by MRI). The meniscal fragment was well visualized in all 28 cases on coronal STIR images. The double posterior cruciate ligament sign was seen in 8 of 30 cases, the flipped meniscus was seen in 10 of 30 cases and a fragment in the intercondylar notch was seen in 18 of 30 cases. (orig.)

  18. Handling Procedures of Vegetable Crops

    Science.gov (United States)

    Perchonok, Michele; French, Stephen J.

    2004-01-01

    The National Aeronautics and Space Administration (NASA) is working towards future long duration manned space flights beyond low earth orbit. The duration of these missions may be as long as 2.5 years and will likely include a stay on a lunar or planetary surface. The primary goal of the Advanced Food System in these long duration exploratory missions is to provide the crew with a palatable, nutritious, and safe food system while minimizing volume, mass, and waste. Vegetable crops can provide the crew with added nutrition and variety. These crops do not require any cooking or food processing prior to consumption. The vegetable crops, unlike prepackaged foods, will provide bright colors, textures (crispy), and fresh aromas. Ten vegetable crops have been identified for possible use in long duration missions. They are lettuce, spinach, carrot, tomato, green onion, radish, bell pepper, strawberries, fresh herbs, and cabbage. Whether these crops are grown on a transit vehicle (e.g., International Space Station) or on the lunar or planetary surface, it will be necessary to determine how to safely handle the vegetables while maintaining acceptability. Since hydrogen peroxide degrades into water and oxygen and is generally recognized as safe (GRAS), hydrogen peroxide has been recommended as the sanitizer. The objective of th is research is to determine the required effective concentration of hydrogen peroxide. In addition, it will be determined whether the use of hydrogen peroxide, although a viable sanitizer, adversely affects the quality of the vegetables. Vegetables will be dipped in 1 % hydrogen peroxide, 3% hydrogen peroxide, or 5% hydrogen peroxide. Treated produce and controls will be stored in plastic bags at 5 C for up to 14 days. Sensory, color, texture, and total plate count will be measured. The effect on several vegetables including lettuce, radish, tomato and strawberries has been completed. Although each vegetable reacts to hydrogen peroxide differently, the

  19. The handling of radiation accidents

    International Nuclear Information System (INIS)

    1977-01-01

    The symposium was attended by 204 participants from 39 countries and 5 international organizations. Forty-two papers were presented in 8 sessions. The purpose of the meeting was to foster an exchange of experiences gained in establishing and exercising plans for mitigating the effects of radiation accidents and in the handling of actual accident situations. Only a small number of accidents were reported at the symposium, and this reflects the very high standards of safety that has been achieved by the nuclear industry. No accidents of radiological significance were reported to have occurred at commercial nuclear power plants. Of the accidents reported, industrial radiography continues to be the area in which most of the radiation accidents occur. The experience gained in the reported accident situations served to confirm the crucial importance of the prompt availability of medical and radiological services, particularly in the case of uptake of radioactive material, and emphasized the importance of detailed investigation into the causes of the accident in order to improve preventative measures. One of the principal themes of the symposium involved emergency procedures related to nuclear power plant accidents, and several papers defining the scope, progression and consequences of design base accidents for both thermal and fast reactor systems were presented. These were complemented by papers defining the resultant protection requirements that should be satisfied in the establishment of plans designed to mitigate the effects of the postulated accident situations. Several papers were presented describing existing emergency organizational arrangements relating both to specific nuclear power plants and to comprehensive national schemes, and a particularly informative session was devoted to the topic of training of personnel in the practical conduct of emergency arrangements. The general feeling of the participants was one of studied confidence in the competence and

  20. Decrease in sarcoplasmic reticulum calcium content, not myofilament function, contributes to muscle twitch force decline in isolated cardiac trabeculae

    Science.gov (United States)

    Milani-Nejad, Nima; Brunello, Lucia; Gyorke, Sándor; Janssen, Paul M.L.

    2014-01-01

    We set out to determine the factors responsible for twitch force decline in isolated intact rat cardiac trabeculae. The contractile force of trabeculae declined over extended periods of isometric twitch contractions. The force-frequency relationship within the frequency range of 4–8 Hz, at 37 °C, became more positive and the frequency optimum shifted to higher rates with this decline in baseline twitch tensions. The post-rest potentiation (37 °C), a phenomenon highly dependent on calcium handling mechanisms, became more pronounced with decrease in twitch tensions. We show that the main abnormality during muscle run-down was not due to a deficit in the myofilaments; maximal tension achieved using a K+ contracture protocol was either unaffected or only slightly decreased. Conversely, the sarcoplasmic reticulum (SR) calcium content, as assessed by rapid cooling contractures (from 27 °C to 0 °C), decreased, and had a close association with the declining twitch tensions (R2 ~ 0.76). SR Ca2+-ATPase, relative to Na+/Ca2+ exchanger activity, was not altered as there was no significant change in paired rapid cooling contracture ratios. Furthermore, confocal microscopy detected no abnormalities in the overall structure of the cardiomyocytes and t-tubules in the cardiac trabeculae (~23 °C). Overall, the data indicates that the primary mechanism responsible for force run-down in multi-cellular cardiac preparations is a decline in the SR calcium content and not the maximal tension generation capability of the myofilaments. PMID:25056841