WorldWideScience

Sample records for aggregates by treatment

  1. Reducing drying shrinkage of concrete by treatment of aggregate

    OpenAIRE

    Kwan, AKH; Fung, WWS; Wong, HHC

    2010-01-01

    Drying shrinkage of concrete has been found to cause cracking, water leakage and other serviceability problems and is thus an important research topic. In early studies, it has been found that the shrinkage of concrete varies with the rock aggregate used. This is partly because the aggregate also shrinks and the shrinkage of aggregate is dependent on the type of rock from which the aggregate is derived. However, there have been few studies on the shrinkage of rock and how the shrinkage of agg...

  2. Microbial aggregates in anaerobic wastewater treatment.

    Science.gov (United States)

    Kosaric, N; Blaszczyk, R

    1990-01-01

    sludge. Methanogenic bacterial aggregates have been successfully applied in many full scale installations, especially for sugar beet, potato, pulp and paper mill, and other soluble wastes. The UASB reactors used for these treatments are simple in construction and handling which result in rather low total costs. A further and wider application of UASB reactors and methanogenic aggregates for various industrial wastewaters is expected. PMID:2291438

  3. Inhibition of platelet aggregation and 5-HT release by extracts of Australian plants used traditionally as headache treatments.

    Science.gov (United States)

    Rogers, K L; Grice, I D; Griffiths, L R

    2000-02-01

    To identify potential migraine therapeutics, extracts of eighteen plants were screened to detect plant constituents affecting ADP induced platelet aggregation and [14C]5-hydroxytryptamine (5-HT) release. Extracts of the seven plants exhibiting significant inhibition of platelet function were reanalysed in the presence of polyvinyl pyrrolidone (PVP) to remove polyphenolic tannins that precipitate proteins. Two of these extracts no longer exhibited inhibition of platelet activity after removal of tannins. However, extracts of Crataegus monogyna, Ipomoea pes-caprae, Eremophila freelingii, Eremophila longifolia, and Asteromyrtus symphyocarpa still potently inhibited ADP induced human platelet [14C]5-HT release in vitro, with levels ranging from 62 to 95% inhibition. I. pes-caprae, and C. monogyna also caused significant inhibition of ADP induced platelet aggregation. All of these plants have been previously used as traditional headache treatments, except for C. monogyna which is used primarily for protective effects on the cardiovascular system. Further studies elucidating the compounds that are responsible for these anti-platelet effects are needed to determine their exact mechanism of action. PMID:10664475

  4. Water-based preparation of highly oleophobic thin films through aggregation of nanoparticles using layer-by-layer treatment

    Science.gov (United States)

    Nishizawa, Shingo; Shiratori, Seimei

    2012-12-01

    The layer-by-layer (LBL) adsorption technique has potential for controlling the surface wettability. In this study, we controlled surface wettability between "superhydrophobic and oleophobic" and "hydrophobic and oleophilic" by LBL process on TiO2 nanoparticle with hydrophobic polymer and hydrophilic polymer. From the cast coating with LBL process on TiO2 nanoparticle, the surface showed "superhydophobic and oleophobic" when the top surface was hydrophobic polymer, on the other hand, the surface showed "hydrophobic and oleophilic" when the top surface was hydrophilic polymer. The LBL process also affected to the structure of TiO2 nanoparticle/polymer composite, and TiO2 nanoparticle were aggregated with polymers in LBL process. In the condition of the aggregated diameter of TiO2 nanoparticle/polymer composite around 10 μm in solution, the oleohobicity of spray coated film was enhanced with its hierarchical structure (static contact angles of rapeseed oil of 150° and hexadecane of 145°) "Superhydrophobic and high oleophobic" surfaces generated from all water-based dispersions are expected for application in technologies that need to avoid organic solvents.

  5. Platelet aggregation values in patients with cardiovascular risk factors are reduced by verbascoside treatment. A randomized study.

    Science.gov (United States)

    Campo, Gianluca; Pavasini, Rita; Biscaglia, Simone; Ferri, Alessandra; Andrenacci, Elisa; Tebaldi, Matteo; Ferrari, Roberto

    2015-07-01

    Verbascoside, a phenolic compound, showed several favorable biological activities, including an antiplatelet activity. No in vivo studies tested its efficacy and safety in subjects with cardiovascular (CV) factors. The aim of this randomized, single-center, double-blind, phase II study was to assess the efficacy and tolerability of verbascoside intake for the modulation of platelet aggregation (PA) values in subjects with cardiovascular (CV) risk factors. One-hundred subjects with at least one CV risk factor (age >65 years, diabetes mellitus, hypertension, current cigarettes use, hyperlidemia, waist circumference >102 cm in male or >88 cm in female) were enrolled and randomly assigned to receive placebo or verbascoside 50mg or verbascoside 100mg. PA was measured at baseline and after 2 weeks of study drug assumption, with light transmittance aggregometry (arachidonic acid, AA, 1 μM and adenosine diphosphate, ADP, 5 μM). Two weeks of treatment with placebo or verbascoside 50mg did not modify PA values (both after AA and ADP stimuli). On the contrary, after 2 weeks of verbascoside 100mg, PA values decreased significantly (from 51 ± 13% to 39 ± 15%, p<0.01 after AA; from 60 ± 12% to 49 ± 15%, p = 0.01 after ADP). No serious adverse events were reported during the study, and no subjects discontinued the study because of adverse events. We conclude that long-term intake of verbascoside 100mg significantly reduces PA values in subjects with CV risk factors. PMID:25846253

  6. Estimation of line efficiency by aggregation

    OpenAIRE

    Koster, de, MBM René

    1987-01-01

    textabstractPresents a multi-stage flow lines with intermediate buffers approximated by two-stage lines using repeated aggregation. Characteristics of the aggregation method; Problems associated with the analysis and design of production lines.

  7. Estimation of Line Efficiency by Aggregation

    NARCIS (Netherlands)

    M.B.M. de Koster (René)

    1987-01-01

    textabstractPresents a multi-stage flow lines with intermediate buffers approximated by two-stage lines using repeated aggregation. Characteristics of the aggregation method; Problems associated with the analysis and design of production lines.

  8. Aggregate Formed by a Cationic Fluorescence Probe

    Institute of Scientific and Technical Information of China (English)

    TIAN, Juan; SANG, Da-Yong; JI, Guo-Zhen

    2007-01-01

    The aggregation behavior of a cationic fluorescence probe 10-(4,7,10,13,16-pentaoxa-1-azacyclooctadecyl-methyl)anthracen-9-ylmethyl dodecanoate (1) was observed and studied by a fluorescence methodology in acidic and neutral conditions. By using the Py scale, differences between simple aggregates and micelles have been discussed. The stability of simple aggregates was discussed in terms of hydrophobic interaction and electrostatic repulsion. The absence of excimer emission of the anthrancene moiety of probe 1 in neutral condition was attributed to the photoinduced electron transfer mechanism instead of photodimerization.

  9. Aggregating judgments by the majority method

    OpenAIRE

    García Bermejo, Juan Carlos

    2006-01-01

    “Judgement aggregation has been receiving increasing attention over recent years. Some typical impossibility results have been proved, about majority and other similar aggregation methods. Those results depend essentially on certain logical constraints borrowed from standard two- valued deductive logic. Nevertheless, the adequacy of these constraints is doubtful. In this paper, we show that by weakening the consistency conditions in a plausible way, such impossibility theorems can be reversed...

  10. Control of aggregation-induced emission by DNA hybridization

    OpenAIRE

    Li, Shaoguang; Langenegger, Simon Matthias; Häner, Robert

    2013-01-01

    Aggregation-induced emission (AIE) was studied by hybridization of dialkynyl-tetraphenylethylene (DATPE) modified DNA strands. Molecular aggregation and fluorescence of DATPEs are controlled by duplex formation.

  11. Extracellular polymeric substances (EPS) of microbial aggregates in biological wastewater treatment systems: a review.

    Science.gov (United States)

    Sheng, Guo-Ping; Yu, Han-Qing; Li, Xiao-Yan

    2010-01-01

    A review concerning the definition, extraction, characterization, production and functions of extracellular polymeric substances (EPS) of microbial aggregates in biological wastewater treatment reactors is given in this paper. EPS are a complex high-molecular-weight mixture of polymers excreted by microorganisms, produced from cell lysis and adsorbed organic matter from wastewater. They are a major component in microbial aggregates for keeping them together in a three-dimensional matrix. Their characteristics (e.g., adsorption abilities, biodegradability and hydrophilicity/hydrophobicity) and the contents of the main components (e.g., carbohydrates, proteins, humic substances and nucleic acids) in EPS are found to crucially affect the properties of microbial aggregates, such as mass transfer, surface characteristics, adsorption ability, stability, the formation of microbial aggregates etc. However, as EPS are very complex, the knowledge regarding EPS is far from complete and much work is still required to fully understand their precise roles in the biological treatment process. PMID:20705128

  12. Environmental Sustainability by Use of Recycled Aggregates - An Overview

    OpenAIRE

    D. K. Gandhi; A. A. Gudadhe

    2014-01-01

    Optimum utilization of available natural resources is the major component to achieve the environmental sustainability. Development in urban infrastructure demands for large quantity of aggregates for construction. Infrastructural waste in the form of demolished aggregates is one of the major components of solid waste. By efficient use of these demolished aggregates in the form of recycled aggregates along with fresh aggregates can achieve a better solid waste management and al...

  13. Aggregation of metallochlorophylls - Examination by spectroscopy

    Science.gov (United States)

    Boucher, L. J.; Katz, J. J.

    1969-01-01

    Nuclear magnetic resonance measurements determine which metallochlorophylls, besides magnesium-containing chlorophylls, possess coordination aggregation properties. Infrared spectroscopy reveals that only zinc pheophytin and zinc methyl pheophorbide showed significant coordination aggregation, whereas divalent nickel and copper did not.

  14. Reinforcement of rubber by fractal aggregates

    Science.gov (United States)

    Witten, T. A.; Rubinstein, M.; Colby, R. H.

    1993-03-01

    Rubber is commonly reinforced with colloidal aggregates of carbon or silica, whose structure has the scale invariance of a fractal object. Reinforced rubbers support large stresses, which often grow faster than linearly with the strain. We argue that under strong elongation the stress arises through lateral compression of the aggregates, driven by the large bulk modulus of the rubber. We derive a power-law relationship between stress and elongation λ when λgg 1. The predicted power p depends on the fractal dimension D and a second structural scaling exponent C. For diffusion-controlled aggregates this power p should lie beween 0.9 and 1.1 ; for reaction-controlled aggregates p should lie between 1.8 and 2.4. For uniaxial compression the analogous powers lie near 4. Practical rubbers filled with fractal aggregates should approach the conditions of validity for these scaling laws. On renforce souvent le caoutchouc avec des agrégats de carbone ou de silice dont la structure a l'invariance par dilatation d'un objet fractal. Les caoutchoucs ainsi renforcés supportent de grandes contraintes qui croissent souvent plus vite que l'élongation. Nous prétendons que, sous élongation forte, cette contrainte apparaît à cause d'une compression latérale des agrégats induite par le module volumique important du caoutchouc. Nous établissons une loi de puissance reliant la contrainte et l'élongation λ quand λgg 1. Cet exposant p dépend de la dimension fractale D et d'un deuxième exposant structural C. Pour des agrégats dont la cinétique de formation est limitée par diffusion, p vaut entre 0,9 et 1,1. Si la cinétique est limitée par le soudage local des particules, p vaut entre 1,8 et 2,4. Sous compression uniaxiale, les puissances homologues valent environ 4. Des caoutchoucs pratiques chargés de tels agrégats devraient approcher des conditions où ces lois d'échelle sont valables.

  15. Composition and aggregation of extracellular polymeric substances (EPS) in hyperhaline and municipal wastewater treatment plants

    Science.gov (United States)

    Zeng, Jie; Gao, Jun-Min; Chen, You-Peng; Yan, Peng; Dong, Yang; Shen, Yu; Guo, Jin-Song; Zeng, Ni; Zhang, Peng

    2016-01-01

    As important constituents of activated sludge flocs, extracellular polymeric substances (EPS) play significant roles in pollutants adsorption, the formation and maintenance of microbial aggregates, and the protection of microbes from external environmental stresses. In this work, EPS in activated sludge from a municipal wastewater treatment plant (M-WWTP) with anaerobic/anoxic/oxic (A2/O) process and a hyperhaline wastewater treatment plant (H-WWTP) with anaerobic/oxic (A/O) process were extracted by ultrasound method. The proteins and polysaccharides contents in EPS were determined by using a modified Lowry method and anthrone colorimetry respectively to analyze the detail differences in two types of WWTPs. Fourier transform-infrared spectroscopy and three-dimensional excitation-emission matrix fluorescence spectroscopy demonstrated proteins and polysaccharides were the dominant components of the two types of EPS, and the aromatic protein-like substances accounted for a larger proportion in EPS proteins. The results of the aggregation test indicated that EPS were good for the sludge aggregation, and the EPS in oxic sludge were more beneficial to sludge aggregation than that in anoxic sludge. Anoxic sludge EPS in H-WWTP showed a negligible effect on sludge aggregation. Comparative study on EPS of different tanks in the M-WWTP and H-WWTP was valuable for understanding the characteristics of EPS isolated from two typical wastewater treatment processes. PMID:27220287

  16. A Novel Method to Quantify Soil Aggregate Stability by Measuring Aggregate Bond Energies

    Science.gov (United States)

    Efrat, Rachel; Rawlins, Barry G.; Quinton, John N.; Watts, Chris W.; Whitmore, Andy P.

    2016-04-01

    Soil aggregate stability is a key indicator of soil quality because it controls physical, biological and chemical functions important in cultivated soils. Micro-aggregates are responsible for the long term sequestration of carbon in soil, therefore determine soils role in the carbon cycle. It is thus vital that techniques to measure aggregate stability are accurate, consistent and reliable, in order to appropriately manage and monitor soil quality, and to develop our understanding and estimates of soil as a carbon store to appropriately incorporate in carbon cycle models. Practices used to assess the stability of aggregates vary in sample preparation, operational technique and unit of results. They use proxies and lack quantification. Conflicting results are therefore drawn between projects that do not provide methodological or resultant comparability. Typical modern stability tests suspend aggregates in water and monitor fragmentation upon exposure to an un-quantified amount of ultrasonic energy, utilising a laser granulometer to measure the change in mean weight diameter. In this project a novel approach has been developed based on that of Zhu et al., (2009), to accurately quantify the stability of aggregates by specifically measuring their bond energies. The bond energies are measured operating a combination of calorimetry and a high powered ultrasonic probe, with computable output function. Temperature change during sonication is monitored by an array of probes which enables calculation of the energy spent heating the system (Ph). Our novel technique suspends aggregates in heavy liquid lithium heteropolytungstate, as opposed to water, to avoid exposing aggregates to an immeasurable disruptive energy source, due to cavitation, collisions and clay swelling. Mean weight diameter is measured by a laser granulometer to monitor aggregate breakdown after successive periods of calculated ultrasonic energy input (Pi), until complete dispersion is achieved and bond

  17. Environmental Sustainability by Use of Recycled Aggregates - An Overview

    Directory of Open Access Journals (Sweden)

    D. K. Gandhi

    2014-05-01

    Full Text Available Optimum utilization of available natural resources is the major component to achieve the environmental sustainability. Development in urban infrastructure demands for large quantity of aggregates for construction. Infrastructural waste in the form of demolished aggregates is one of the major components of solid waste. By efficient use of these demolished aggregates in the form of recycled aggregates along with fresh aggregates can achieve a better solid waste management and also cope up with the rising demands of aggregates leading to economy. Present study is an attempt to increase the awareness about economical viability and technical feasibility for the use of recycled aggregates as a construction material in concrete and to show that the use of recycled aggregates is also an efficient measure to reduce the intensity of environmental impact.

  18. The aggregation behavior and interactions of yak milk protein under thermal treatment.

    Science.gov (United States)

    Wang, T T; Guo, Z W; Liu, Z P; Feng, Q Y; Wang, X L; Tian, Q; Ren, F Z; Mao, X Y

    2016-08-01

    The aggregation behavior and interactions of yak milk protein were investigated after heat treatments. Skim yak milk was heated at temperatures in the range of 65 to 95°C for 10 min. The results showed that the whey proteins in yak milk were denatured after heat treatment, especially at temperatures higher than 85°C. Sodium dodecyl sulfate-PAGE analysis indicated that heat treatment induced milk protein denaturation accompanied with aggregation to a certain extent. When the heating temperature was 75 and 85°C, the aggregation behavior of yak milk proteins was almost completely due to the formation of disulfide bonds, whereas denatured α-lactalbumin and β-lactoglobulin interacted with κ-casein. When yak milk was heated at 85 and 95°C, other noncovalent interactions were found between proteins including hydrophobic interactions. The particle size distributions and microstructures demonstrated that the heat stability of yak milk proteins was significantly lowered by heat treatment. When yak milk was heated at 65 and 75°C, no obvious changes were found in the particle size distribution and microstructures in yak milk. When the temperature was 85 and 95°C, the particle size distribution shifted to larger size trend and aggregates were visible in the heated yak milk. PMID:27209140

  19. DNA binding and aggregation by carbon nanoparticles

    International Nuclear Information System (INIS)

    Significant environmental and health risks due to the increasing applications of engineered nanoparticles in medical and industrial activities have been concerned by many communities. The interactions between nanomaterials and genomes have been poorly studied so far. This study examined interactions of DNA with carbon nanoparticles (CNP) using atomic force microscopy (AFM). We experimentally assessed how CNP affect DNA molecule and bacterial growth of Escherichia coli. We found that CNP were bound to the DNA molecules during the DNA replication in vivo. The results revealed that the interaction of DNA with CNP resulted in DNA molecule binding and aggregation both in vivo and in vitro in a dose-dependent manner, and consequently inhabiting the E. coli growth. While this was a preliminary study, our results showed that this nanoparticle may have a significant impact on genomic activities.

  20. Image analysis of sludge aggregates obtained at preliminary treatment of sewage.

    Science.gov (United States)

    Smoczyński, L; Ratnaweera, H; Kosobucka, M; Kvaal, K; Smoczyński, M

    2014-01-01

    The results of wastewater treatment by Al and Fe salts and by electrocoagulation with aluminum electrodes are discussed and interpreted. Those processes used alone or combined with biological treatment, were analyzed for 50 and 90% removal of phosphates. Scanning electron microscopy (SEM) of the resulting sludge from three coagulation processes defined the perimeter P and area A of 129-142 differently sized objects in each contrast-enhanced image. Plots of lg A against lg P revealed that the analyzed sludge samples were made of self-similar aggregates-flocs with fractal characteristics. The slope of 'log plots' was used to determine surface fractal dimension Da, which was extrapolated to volumetric fractal dimension Dv. Dv was applied in a quantitative description of sludge aggregates-flocs. Aggregates-flocs of sludge obtained by Al ions (pre-polymerized Al and electrocoagulation) were characterized by higher values of Dv in comparison with sludge obtained by iron salts. The structure of {Al(OH)(3)} and {Fe(OH)(3)} aggregate-flocs was graphically simulated to determine the effect of size distribution and Dv on sweep flocculation and sludge separation and dehydration. Phosphate removal efficiency of 50% occurred at low ratios of Al:P and Fe:P. Adsorption-charge neutralization was suggested during coagulation with pre-polymerized coagulants, and sweep flow mechanism during electrocoagulation. PMID:25259494

  1. Mechanism of Suppression of Protein Aggregation by α-Crystallin

    Directory of Open Access Journals (Sweden)

    Boris I. Kurganov

    2009-03-01

    Full Text Available This review summarizes experimental data illuminating the mechanism of suppression of heat-induced protein aggregation by a-crystallin, one of the small heat shock proteins. The dynamic light scattering data show that the initial stage of thermal aggregation of proteins is the formation of the initial aggregates involving hundreds of molecules of the denatured protein. Further sticking of the starting aggregates proceeds in a regime of diffusion-limited cluster-cluster aggregation. The protective effect of a-crystallin is due to transition of the aggregation process to the regime of reaction-limited cluster-cluster aggregation, wherein the sticking probability for the colliding particles becomes lower than unity.

  2. Light scattering by aggregated red blood cells

    Science.gov (United States)

    Tsinopoulos, Stephanos V.; Sellountos, Euripides J.; Polyzos, Demosthenes

    2002-03-01

    In low flow rates, red blood cells (RBCs) fasten together along their axis of symmetry and form a so-called rouleaux. The scattering of He-Ne laser light by a rouleau consisting of n (2 less-than-or-equal n less-than-or-equal 8) average-sized RBCs is investigated. The interaction problem is treated numerically by means of an advanced axisymmetric boundary element--fast Fourier transform methodology. The scattering problem of one RBC was solved first, and the results showed that the influence of the RBC's membrane on the scattering patterns is negligible. Thus the rouleau is modeled as an axisymmetric, homogeneous, low-contrast dielectric cylinder, on the surface of which appears, owing to aggregated RBCs, a periodic roughness along the direction of symmetry. The direction of the incident laser light is considered to be perpendicular to the scatterer's axis of symmetry. The differential scattering cross sections in both perpendicular and parallel scattering planes and for all the scattering angles are calculated and presented in detail.

  3. Opportunities for Price Manipulation by Aggregators in Electricity Markets

    CERN Document Server

    Ruhi, Navid Azizan; Chen, Niangjun; Wierman, Adam

    2016-01-01

    Aggregators are playing an increasingly crucial role in the integration of renewable generation in power systems. However, the intermittent nature of renewable generation makes market interactions of aggregators difficult to monitor and regulate, raising concerns about potential market manipulation by aggregators. In this paper, we study this issue by quantifying the profit an aggregator can obtain through strategic curtailment of generation in an electricity market. We show that, while the problem of maximizing the benefit from curtailment is hard in general, efficient algorithms exist when the topology of the network is radial (acyclic). Further, we highlight that significant increases in profit are possible via strategic curtailment in practical settings.

  4. Fluorescent H-Aggregates Hosted by a Charged Cyclodextrin Cavity.

    Science.gov (United States)

    Mudliar, Niyati H; Singh, Prabhat K

    2016-05-23

    Most macrocyclic host molecules, including cyclodextrins, usually prevent self-aggregation of the guest organic molecules, by exploiting inclusion complexation of the guest with the host. In this work, it was found that a negatively charged β-cylcodextrin derivative induces aggregation of a well-known amyloid sensing dye, Thioflavin-T, and leads to an unprecedented formation of the rarely observed emissive H-type aggregates of the dye. PMID:27028039

  5. Mild hypothermia does not attenuate platelet aggregation and may even increase ADP-stimulated platelet aggregation after clopidogrel treatment

    OpenAIRE

    Erlinge David; Högberg Carl; Braun Oscar Ö

    2009-01-01

    Abstract Background Mild hypothermia is currently standard of care for cardiac arrest patients in many hospitals and a common belief is that hypothermia attenuates platelet aggregation. We wanted to examine the effects of clopidogrel on platelet aggregation during hypothermia. Methods Platelet reactivity at 37°C and 33°C was evaluated by light transmission aggregometry and vasodilator-stimulated phosphoprotein (VASP) in blood from healthy volunteers before, and 24 hours after, a 600 mg loadin...

  6. Colloidal Aggregate Structure under Shear by USANS

    Science.gov (United States)

    Chatterjee, Tirtha; van Dyk, Antony K.; Ginzburg, Valeriy V.; Nakatani, Alan I.

    2015-03-01

    Paints are complex formulations of polymeric binders, inorganic pigments, dispersants, surfactants, colorants, rheology modifiers, and other additives. A commercially successful paint exhibits a desired viscosity profile over a wide shear rate range from 10-5 s-1 for settling to >104 s-1 for rolling, and spray applications. Understanding paint formulation structure is critical as it governs the paint viscosity profile. However, probing paint formulation structure under shear is a challenging task due to the formulation complexity containing structures with different hierarchical length scales and their alterations under the influence of an external flow field. In this work mesoscale structures of paint formulations under shear are investigated using Ultra Small-Angle Neutron Scattering (rheo-USANS). Contrast match conditions were utilized to independently probe the structure of latex binder particle aggregates and the TiO2 pigment particle aggregates. Rheo-USANS data revealed that the aggregates are fractal in nature and their self-similarity dimensions and correlations lengths depend on the chemistry of the binder particles, the type of rheology modifier present and the shear stress imposed upon the formulation. These results can be explained in the framework of diffusion and reaction limited transient aggregates structure evolution under simple shear.

  7. Avoiding Deontic Explosion by Contextually Restricting Aggregation

    Science.gov (United States)

    Meheus, Joke; Beirlaen, Mathieu; van de Putte, Frederik

    In this paper, we present an adaptive logic for deontic conflicts, called P2.1 r , that is based on Goble's logic SDL a P e - a bimodal extension of Goble's logic P that invalidates aggregation for all prima facie obligations. The logic P2.1 r has several advantages with respect to SDL a P e. For consistent sets of obligations it yields the same results as Standard Deontic Logic and for inconsistent sets of obligations, it validates aggregation "as much as possible". It thus leads to a richer consequence set than SDL a P e. The logic P2.1 r avoids Goble's criticisms against other non-adjunctive systems of deontic logic. Moreover, it can handle all the 'toy examples' from the literature as well as more complex ones.

  8. Solving incomplete markets models by derivative aggregation

    OpenAIRE

    Tobias Grasl

    2013-01-01

    This article presents a novel computational approach to solving models with both uninsurable idiosyncratic and aggregate risk that uses projection methods, simulation and perturbation. The approach is shown to be both as efficient and as accurate as existing methods on a model based on Krusell and Smith (1998), for which prior solutions exist. The approach has the advantage of extending straightforwardly, and with reasonable computational cost, to models with a greater range of diversity betw...

  9. Nanotubular J-aggregates covered by transparent silica nanoshells

    CERN Document Server

    Qiao, Yan; Kirmse, Holm; Kirstein, Stefan; Rabe, Jürgen P

    2015-01-01

    Nanotubular J-aggregates of amphiphilic cyanine dyes exhibit highly attractive opto-electronic properties, reminiscent to natural light harvesting complexes. However, their photo-chemical and mechanical stabilities are limited. A robust transparent shell covering the J aggregates may alleviate these issues. Here, organic-inorganic hybrid nanotubes have been synthesized based on in-situ coating the nanotubular J-aggregates with silica through the sol-gel method. The growth of the shell is controlled by electrostatic adsorption of the silica precursors. The resulting silica nanoshells exhibit a regular superstructure that consists of ribbons that helically wind around the tubular aggregates. The molecular structure of the aggregates and hence their spectral properties remain unaffected by the silication process. The overall shell thickness can be controlled by the ratio and the absolute concentration of the precursors. The usage of a precursor containing diamine groups leads to the formation of bundles of the t...

  10. Study of Concrete by Replacing Fine Aggregate by ETP Sludge of TiO2

    Directory of Open Access Journals (Sweden)

    Sreehari Raj

    2015-08-01

    Full Text Available The rapid increase in construction activities leads to scarcity of conventional construction materials such as cement, fine aggregate and coarse aggregate. Researches are being conducted for finding cheaper materials. In India, there are many industries producing large amount of effluent treatment plant waste sludge which leads in problems of disposal. The final destination of effluent treatment plant sludge affects the environment. So alternative option is necessary for disposing effluent treatment sludge. In this study is subjected to the effective reuse of effluent treatment plant sludge of TiO2 pigment generated from Kerala Minerals and Metals Ltd (KMML. The aim of the thesis is to determine the strength parameters of concrete with the partial replacement of fine aggregate by waste sludge from KMML. Reuse of ETP sludge in concrete is an effective option for the problem of ultimate disposal up to greater extent. In this study the fine aggregate is replaced by the ETP sludge of TiO2 with different percentages such as 5%, 10%, 15%, 20%, and 25% in M35 concrete mix. The various tests such as compression, tensile and flexural strength are conducted.

  11. Suppression of Platelet Aggregation by Bordetella pertussis Adenylate Cyclase Toxin

    OpenAIRE

    Iwaki, Masaaki; Kamachi, Kazunari; Heveker, Nikolaus; Konda, Toshifumi

    1999-01-01

    The effect of Bordetella pertussis adenylate cyclase toxin (ACT) on platelet aggregation was investigated. This cell-invasive adenylate cyclase completely suppressed ADP (10 μM)-induced aggregation of rabbit platelets at 3 μg/ml and strongly suppressed thrombin (0.2 U/ml)-induced aggregation at 10 μg/ml. The suppression was accompanied by marked increase in platelet intracellular cyclic AMP (cAMP) content and was diminished by the anti-ACT monoclonal antibody B7E11. A catalytically inactive p...

  12. Developmental competence of porcine chimeric embryos produced by aggregation

    DEFF Research Database (Denmark)

    Li, Juan; Jakobsen, Jannik E.; Xiong, Qiang;

    2015-01-01

    either by parthenogenetic activation (PA) or handmade cloning (HMC). Results showed that the developmental competence of chimeric embryos, evaluated based on their blastocyst rate and total cell number per blastocyst, was increased when two whole 2-cell stage embryos (PA or HMC) were aggregated. In...... comparison, when two blastomeres were aggregated, the developmental competence of the chimeric embryos decreased if the blastomeres were either from PA or from HMC embryos, but not if they were from different sources, i.e. one PA and one HMC blastomere. To evaluate the cell contribution in embryo formation......The purpose of our study was to compare the developmental competence and blastomere allocation of porcine chimeric embryos formed by micro-well aggregation. Chimeras were created by aggregating either two blastomeres originating from 2-cell embryos or two whole embryos, where embryos were produced...

  13. Inhibition of platelet aggregation by transdermal glyceryl trinitrate.

    OpenAIRE

    R. Andrews; May, J. A.; Vickers, J.; Heptinstall, S

    1994-01-01

    OBJECTIVE--To determine the optimum conditions for the demonstration of an antiplatelet effect of nitric oxide and to use these conditions to elucidate the effects of a transdermal glyceryl trinitrate patch on platelet aggregation in normal volunteers. METHODS--An open prospective crossover study. The effects of nitric oxide on platelet aggregation in whole blood and platelet rich plasma as stimulated by adenosine diphosphate and U46619 was assessed in the presence and absence of iloprost and...

  14. Aggregation in charged nanoparticles solutions induced by different interactions

    Science.gov (United States)

    Abbas, S.; Kumar, Sugam; Aswal, V. K.; Kohlbrecher, J.

    2016-05-01

    Small-angle neutron scattering (SANS) has been used to study the aggregation of anionic silica nanoparticles as induced through different interactions. The nanoparticle aggregation is induced by addition of salt (NaCl), cationic protein (lysozyme) and non-ionic surfactant (C12E10) employing different kind of interactions. The results show that the interaction in presence of salt can be explained using DLVO theory whereas non-DLVO forces play important role for interaction of nanoparticles with protein and surfactant. The presence of salt screens the repulsion between charged nanoparticles giving rise to a net attraction in the DLVO potential. On the other hand, strong electrostatic attraction between nanoparticle and oppositely charged protein leads to protein-mediated nanoparticle aggregation. In case of non-ionic surfactant, the relatively long-range attractive depletion interaction is found to be responsible for the particle aggregation. Interestingly, the completely different interactions lead to similar kind of aggregate morphology. The nanoparticle aggregates formed are found to have mass fractal nature having a fractal dimension (~2.5) consistent with diffusion limited type of fractal morphology in all three cases.

  15. Aggregation and conformational change of mushroom (Agaricus bisporus) polyphenoloxidase subjected to thermal treatment.

    Science.gov (United States)

    Zhou, Lei; Liu, Wei; Zou, Liqiang; Xiong, Zhiqiang; Hu, Xiuting; Chen, Jun

    2017-01-01

    This study investigated changes in the activity, conformation and microstructure of mushroom polyphenoloxidase (PPO) subjected to thermal treatment. The inactivation of PPO can be achieved by high temperature-short time or mild temperature-long time treatment. Circular dichroism and fluorescence spectra suggested that heating process induced the rearrangement of secondary structure and the disruption of tertiary structure. Red shifts of fluorescence spectra showed positive correlations with the inactivation rate of PPO. There were significant differences in the conformation and molecular microstructure among PPO samples with the same relative activity, which were obtained by treating PPO at 45, 55 and 65°C for different times. In summary, PPO molecules were deformed at mild temperature, while higher temperature induced the formation of large aggregates. PPO with the same relative activity might exist in different forms. PMID:27507494

  16. Stability and heavy metal distribution of soil aggregates affected by application of apatite, lime, and charcoal.

    Science.gov (United States)

    Cui, Hongbiao; Ma, Kaiqiang; Fan, Yuchao; Peng, Xinhua; Mao, Jingdong; Zhou, Dongmei; Zhang, Zhongbin; Zhou, Jing

    2016-06-01

    Only a few studies have been reported on the stability and heavy metal distribution of soil aggregates after soil treatments to reduce the availability of heavy metals. In this study, apatite (22.3 t ha(-1)), lime (4.45 t ha(-1)), and charcoal (66.8 t ha(-1)) were applied to a heavy metal-contaminated soil for 4 years. The stability and heavy metal distribution of soil aggregates were investigated by dry and wet sieving. No significant change in the dry mean weight diameter was observed in any treatments. Compared with the control, three-amendment treatments significantly increased the wet mean weight diameter, but only charcoal treatment significantly increased the wet aggregate stability. The soil treatments increased the content of soil organic carbon, and the fraction 0.25-2 mm contained the highest content of soil organic carbon. Amendments' application slightly increased soil total Cu and Cd, but decreased the concentrations of CaCl2 -extractable Cu and Cd except for the fraction 2 and 0.25-2 mm contained the highest concentrations of CaCl2-extractable Cu and Cd, accounted for about 74.5-86.8 % of CaCl2-extractable Cu and Cd in soil. The results indicated that amendments' application increased the wet soil aggregate stability and decreased the available Cu and Cd. The distribution of available heavy metals in wet soil aggregates was not controlled by soil aggregate stability, but possibly by soil organic carbon. PMID:26893180

  17. Treatment of inflammatory root resorption using mineral trioxide aggregate: A case report

    Directory of Open Access Journals (Sweden)

    Roohollah Sharifi

    2014-01-01

    Full Text Available Introduction: This report presents a case to show inflammatory root resorption can be successfully treated by using mineral trioxide aggregate (MTA. Case Report: A central maxillary incisor of an eight-year-old boy was avulsed associated with crown fracture secondary to a fall. The tooth was stored in ice. Early attempts at pulpal revascularization of the replanted tooth proved unsuccessful. To stop inflammatory root resorption, long-term calcium hydroxide therapy was employed. Despite the use of calcium hydroxide, resorption continued. Subsequent to the failure of that treatment, MTA was used as a root canal filling material. At 20-month follow-up, the tooth was asymptomatic and had clinical signs of ankylosis but external inflammatory root resorption had stopped. Discussion: MTA may be considered as an alternative option for the treatment of continuous external inflammatory root resorption.

  18. Thermal Proprieties of Concrete Lightened by Wood Aggregates

    Directory of Open Access Journals (Sweden)

    D. Taoukil

    2011-02-01

    Full Text Available It is about an experimental study of the thermal proprieties of a concrete lightened by wood aggregates stemming from waste products of the carpentry work. We were especially interested in the comparison between the proprieties of concretes lightened by sawdust and those lightened by wood shavings. The determination of the thermal conductivity and diffusivity of various samples allowed us to demonstrate that the incorporation of wood aggregates in the concrete increases considerably its thermal insulation capacity. Also, we found that, at equal mass percentage of wood aggregates, the concretes elaborated from shavings present thermal insulation capacities better than those obtained from sawdust. On other hand, we have examined the influence of the water content on the thermophysical properties of the studied concretes. So, we have demonstrated and confirmed that the thermal conductivity and diffusivity of the studied materials are strongly dependent on the water content.

  19. Silibinin inhibits acetylcholinesterase activity and amyloid β peptide aggregation: a dual-target drug for the treatment of Alzheimer's disease.

    Science.gov (United States)

    Duan, Songwei; Guan, Xiaoyin; Lin, Runxuan; Liu, Xincheng; Yan, Ying; Lin, Ruibang; Zhang, Tianqi; Chen, Xueman; Huang, Jiaqi; Sun, Xicui; Li, Qingqing; Fang, Shaoliang; Xu, Jun; Yao, Zhibin; Gu, Huaiyu

    2015-05-01

    Alzheimer's disease (AD) is characterized by amyloid β (Aβ) peptide aggregation and cholinergic neurodegeneration. Therefore, in this paper, we examined silibinin, a flavonoid extracted from Silybum marianum, to determine its potential as a dual inhibitor of acetylcholinesterase (AChE) and Aβ peptide aggregation for AD treatment. To achieve this, we used molecular docking and molecular dynamics simulations to examine the affinity of silibinin with Aβ and AChE in silico. Next, we used circular dichroism and transmission electron microscopy to study the anti-Aβ aggregation capability of silibinin in vitro. Moreover, a Morris Water Maze test, enzyme-linked immunosorbent assay, immunohistochemistry, 5-bromo-2-deoxyuridine double labeling, and a gene gun experiment were performed on silibinin-treated APP/PS1 transgenic mice. In molecular dynamics simulations, silibinin interacted with Aβ and AChE to form different stable complexes. After the administration of silibinin, AChE activity and Aβ aggregations were down-regulated, and the quantity of AChE also decreased. In addition, silibinin-treated APP/PS1 transgenic mice had greater scores in the Morris Water Maze. Moreover, silibinin could increase the number of newly generated microglia, astrocytes, neurons, and neuronal precursor cells. Taken together, these data suggest that silibinin could act as a dual inhibitor of AChE and Aβ peptide aggregation, therefore suggesting a therapeutic strategy for AD treatment. PMID:25771396

  20. Dynamics of colloidal aggregation in microgravity by critical Casimir forces

    Science.gov (United States)

    Potenza, M. A. C.; Manca, A.; Veen, S. J.; Weber, B.; Mazzoni, S.; Schall, P.; Wegdam, G. H.

    2014-06-01

    By combining static and dynamic structure factor measurements under microgravity conditions, we obtain for the first time direct insight into the internal structure of colloidal aggregates formed over a wide range of particle attractions under ideal diffusion-limited conditions. By means of near-field scattering we measure the time-dependent density-density correlation function as the aggregation process evolves, and we determine the ratio of the hydrodynamic and gyration radius to elucidate the aggregate's internal structure as a function of its fractal dimension. Surprisingly, we find that despite the large variation of particle interactions, the mass is always evenly distributed in all objects with fractal dimension ranging from 2.55 for shallow potentials to 1.78 for deep ones.

  1. Colloidal aggregation in microgravity by critical Casimir forces

    Science.gov (United States)

    Veen, Sandra; Schall, Peter; Antoniuk, Oleg; Potenza, Marco; Alaimo, Matteo; Mazzoni, Stefano; Wegdam, Gerard

    2012-02-01

    We study aggregation and crystal growth of spherical Teflon colloids in binary liquid mixtures in microgravity by the critical Casimir effect. The critical Casimir effect induces interactions between colloids due to the confinement of bulk fluctuations (density or concentration) near the critical point of liquids. The strength and range of the interaction depends on the length scale of these fluctuations which increase as one approaches the critical point. The interaction potential can thus be tuned with temperature. We follow the growth of structures in real time with Near Field Scattering. Measurements are performed in microgravity in order to study pure diffusion limited aggregation, without disturbance by sedimentation or flow.

  2. Monitoring of Intracellular Tau Aggregation Regulated by OGA/OGT Inhibitors

    Directory of Open Access Journals (Sweden)

    Sungsu Lim

    2015-08-01

    Full Text Available Abnormal phosphorylation of tau has been considered as a key pathogenic mechanism inducing tau aggregation in multiple neurodegenerative disorders, collectively called tauopathies. Recent evidence showed that tau phosphorylation sites are protected with O-linked β-N-acetylglucosamine (O-GlcNAc in normal brain. In pathological condition, tau is de-glycosylated and becomes a substrate for kinases. Despite the importance of O-GlcNAcylation in tau pathology, O-GlcNAc transferase (OGT, and an enzyme catalyzing O-GlcNAc to tau, has not been carefully investigated in the context of tau aggregation. Here, we investigated intracellular tau aggregation regulated by BZX2, an inhibitor of OGT. Upon the inhibition of OGT, tau phosphorylation increased 2.0-fold at Ser199 and 1.5-fold at Ser396, resulting in increased tau aggregation. Moreover, the BZX2 induced tau aggregation was efficiently reduced by the treatment of Thiamet G, an inhibitor of O-GlcNAcase (OGA. Our results demonstrated the protective role of OGT in tau aggregation and also suggest the counter-regulatory mechanism of OGA and OGT in tau pathology.

  3. Uncertainty of USA GDP Forecasts Determined by The Variables Aggregation

    OpenAIRE

    Mihaela Bratu (Simionescu)

    2011-01-01

    The aggregation of the variables that compose an indicator, as GDP, which should be forecasted, is not mentioned explicitly in literature as a source of forecasts uncertainty. In this study based on data on U.S. GDP and its components in 1995-2010, we found that GDP one-step-ahead forecasts made by aggregating the components with variable weights, modeled using ARMA procedure, have a higher accuracy than those with constant weights or the direct forecasts. Excepting the GDP forecasts obtained...

  4. Can Aggregation Across Goods be Achieved by Neglecting The Problem? Property Inheritance and Aggregation Bias

    OpenAIRE

    Bertrand M. Koebel

    2002-01-01

    This article studies the problem of composite commodity in two different frameworks. In one case, aggregation across goods is analyzed for elementary goods that satisfy an optimality condition. The unrestricted case is also examined. The notion of an approximate aggregate representation is formalized and shown to be always possible. Can thereby aggregation issues simply be neglected in economic contributions? I show that the standard economic properties of initial functions are not necessaril...

  5. Colonization of diatom aggregates by the dinoflagellate Noctiluca scintillans

    DEFF Research Database (Denmark)

    Tiselius, P.; Kiørboe, Thomas

    1998-01-01

    coagulation of diatom cells and not by mucus feeding behavior of N. scintillans. N. scintillans can be positively buoyant, and estimates of encounter rates between N. scintillans and diatom aggregates during ascent demonstrates that this mechanism is sufficient to account for the observed colonization. The...

  6. Silver nanoparticle aggregation not triggered by an ionic strength mechanism

    Energy Technology Data Exchange (ETDEWEB)

    Botasini, Santiago; Mendez, Eduardo, E-mail: emendez@fcien.edu.uy [Instituto de Quimica Biologica, Universidad de la Republica, Laboratorio de Biomateriales (Uruguay)

    2013-04-15

    The synthesis of stable colloidal solutions of silver nanoparticles is a major goal in the industry to control their fate in aqueous solutions. The present work studies 10-20-nm silver nanoparticle aggregation triggered by the presence of chloride ions. The aggregation process was followed by UV-Vis-NIR spectroscopy and transmission electron microscopy. We found that the mechanism involved differs from the classic explanation of nanoparticle aggregation triggered by an increase in the ionic strength. Moreover, our results give evidence that even when nanoparticles are resistant to an increment of the total amount of ions, the formation of insoluble salts in the vicinity of the nanoparticle is enough to induce the aggregation. The presence of silver chloride around the silver nanoparticles was documented by an X-ray diffraction pattern and electrochemical methods because chloride anions are ubiquitous in real media; this alternative process jeopardized the development of many applications with silver nanoparticles that depend on the use of stable colloids.

  7. 40 CFR 279.32 - Used oil aggregation points owned by the generator.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 26 2010-07-01 2010-07-01 false Used oil aggregation points owned by... Collection Centers and Aggregation Points § 279.32 Used oil aggregation points owned by the generator. (a) Applicability. This section applies to owners or operators of all used oil aggregation points. A used...

  8. Anti-aggregation dispersion of ultrafine particles by electro-static technique

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The dispersion of ultrafine particles in the air can be achieved by mechanical method or surface modification. In this work, the electrostatic technique was first employed for anti-aggregation of ultrafine particles. When the relative humidity of the air is within the region of 70%-75%, effective storage time of ultrafine particles can reach 72 h after treatment by the electrostatic technique. The experi-mental results showed that this technique imparted ultrafine particles much more pronounced anti-aggregation property. In the dry air, the critical diameter of ultrafine particles anti-aggregated by the electrostatic technique is the function of particle property and charging field intensity. The critical diameter is inversely proportional to the square of the charging field intensity.

  9. The effect of shear rate on properties of aggregates formed in the water treatment process

    Czech Academy of Sciences Publication Activity Database

    Bubáková, Petra; Pivokonská, Lenka; Pivokonský, Martin

    Budapest: IWA, 2012, IWA-9867. [IWA International Conference for Young Water Professionals /6./ (IWA YWPC 2012). Budapest (HU), 10.07.2012-13.07.2012] R&D Projects: GA AV ČR IAA200600902 Institutional research plan: CEZ:AV0Z20600510 Keywords : aggregate size * fractal dimension * shear rate * water treatment Subject RIV: BK - Fluid Dynamics

  10. Inhibition of TDP-43 aggregation by nucleic acid binding.

    Directory of Open Access Journals (Sweden)

    Yi-Chen Huang

    Full Text Available The aggregation of TAR DNA-binding protein (TDP-43 has been shown as a hallmark of amyotrophic lateral sclerosis (ALS and frontotemporal lobar degeneration (FTLD since 2006. While evidence has suggested that mutation or truncation in TDP-43 influences its aggregation process, nevertheless, the correlation between the TDP-43 aggregation propensity and its binding substrates has not been fully established in TDP-43 proteinopathy. To address this question, we have established a platform based on the in vitro protein expression system to evaluate the solubility change of TDP-43 in response to factors such as nucleotide binding and temperature. Our results suggest that the solubility of TDP-43 is largely influenced by its cognate single-strand DNA (ssDNA or RNA (ssRNA rather than hnRNP, which is known to associate with TDP-43 C-terminus. The direct interaction between the refolded TDP-43, purified from E.coli, and ssDNA were further characterized by Circular Dichroism (CD as well as turbidity and filter binding assay. In addition, ssDNA or ssRNA failed to prevent the aggregation of the F147L/F149L double mutant or truncated TDP-43 (TDP208-414. Consistently, these two mutants form aggregates, in contrast with the wild-type TDP-43, when expressed in Neuro2a cells. Our results demonstrate an intimate relationship between the solubility of TDP-43 and its DNA or RNA binding affinity, which may shed light on the role of TDP-43 in ALS and FTLD.

  11. Aggregation by Provenance Types: A Technique for Summarising Provenance Graphs

    OpenAIRE

    Moreau, Luc

    2014-01-01

    As users become confronted with a deluge of provenance data, dedicated techniques are required to make sense of this kind of information. We present Aggregation by Provenance Types, a provenance graph analysis that is capable of generating provenance graph summaries. It proceeds by converting provenance paths up to some length k to attributes, referred to as provenance types, and by grouping nodes that have the same provenance types. The summary also includes numeric values representing the f...

  12. Composition and aggregation of extracellular polymeric substances (EPS) in hyperhaline and municipal wastewater treatment plants

    OpenAIRE

    Jie Zeng; Jun-Min Gao; You-Peng Chen; Peng Yan; Yang Dong; Yu Shen; Jin-Song Guo; Ni Zeng; Peng Zhang

    2016-01-01

    As important constituents of activated sludge flocs, extracellular polymeric substances (EPS) play significant roles in pollutants adsorption, the formation and maintenance of microbial aggregates, and the protection of microbes from external environmental stresses. In this work, EPS in activated sludge from a municipal wastewater treatment plant (M-WWTP) with anaerobic/anoxic/oxic (A2/O) process and a hyperhaline wastewater treatment plant (H-WWTP) with anaerobic/oxic (A/O) process were extr...

  13. Inhibition of Alzheimer amyloid β aggregation by polyvalent trehalose

    International Nuclear Information System (INIS)

    A glycopolymer carrying trehalose was found to suppress the formation of amyloid fibrils from the amyloid β peptide (1-42) (Aβ), as evaluated by thioflavin T assay and atomic force microscopy. Glycopolymers carrying sugar alcohols also changed the aggregation properties of Aβ, and the inhibitory effect depended on the type of sugar and alkyl side chain. Neutralization activity was confirmed by in vitro assay using HeLa cells. The glycopolymer carrying trehalose strongly inhibited amyloid formation and neutralized cytotoxicity.

  14. Reduction and degradation of amyloid aggregates by a pulsed radio-frequency cold atmospheric plasma jet

    International Nuclear Information System (INIS)

    Surface-borne amyloid aggregates with mature fibrils are used as a non-infectious prion model to evaluate cold atmospheric plasmas (CAPs) as a prion inactivation strategy. Using a helium-oxygen CAP jet with pulsed radio-frequency (RF) excitation, amyloid aggregates deposited on freshly cleaved mica discs are reduced substantially leaving only a few spherical fragments of sub-micrometer sizes in areas directly treated by the CAP jet. Outside the light-emitting part of the CAP jet, plasma treatment results in a 'skeleton' of much reduced amyloid stacks with clear evidence of fibril fragmentation. Analysis of possible plasma species and the physical configuration of the jet-sample interaction suggests that the skeleton structures observed are unlikely to have arisen as a result of physical forces of detachment, but instead by progressive diffusion of oxidizing plasma species into porous amyloid aggregates. Composition of chemical bonds of this reduced amyloid sample is very different from that of intact amyloid aggregates. These suggest the possibility of on-site degradation by CAP treatment with little possibility of spreading contamination elsewhere , thus offering a new reaction chemistry route to protein infectivity control with desirable implications for the practical implementation of CAP-based sterilization systems.

  15. Reduction and degradation of amyloid aggregates by a pulsed radio-frequency cold atmospheric plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Bayliss, D L; Walsh, J L; Iza, F; Kong, M G [Department of Electronic and Electrical Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom); Shama, G [Department of Chemical Engineering, Loughborough University, Leicestershire LE11 3TU (United Kingdom)], E-mail: m.g.kong@lboro.ac.uk

    2009-11-15

    Surface-borne amyloid aggregates with mature fibrils are used as a non-infectious prion model to evaluate cold atmospheric plasmas (CAPs) as a prion inactivation strategy. Using a helium-oxygen CAP jet with pulsed radio-frequency (RF) excitation, amyloid aggregates deposited on freshly cleaved mica discs are reduced substantially leaving only a few spherical fragments of sub-micrometer sizes in areas directly treated by the CAP jet. Outside the light-emitting part of the CAP jet, plasma treatment results in a 'skeleton' of much reduced amyloid stacks with clear evidence of fibril fragmentation. Analysis of possible plasma species and the physical configuration of the jet-sample interaction suggests that the skeleton structures observed are unlikely to have arisen as a result of physical forces of detachment, but instead by progressive diffusion of oxidizing plasma species into porous amyloid aggregates. Composition of chemical bonds of this reduced amyloid sample is very different from that of intact amyloid aggregates. These suggest the possibility of on-site degradation by CAP treatment with little possibility of spreading contamination elsewhere , thus offering a new reaction chemistry route to protein infectivity control with desirable implications for the practical implementation of CAP-based sterilization systems.

  16. Reduction and degradation of amyloid aggregates by a pulsed radio-frequency cold atmospheric plasma jet

    Science.gov (United States)

    Bayliss, D. L.; Walsh, J. L.; Shama, G.; Iza, F.; Kong, M. G.

    2009-11-01

    Surface-borne amyloid aggregates with mature fibrils are used as a non-infectious prion model to evaluate cold atmospheric plasmas (CAPs) as a prion inactivation strategy. Using a helium-oxygen CAP jet with pulsed radio-frequency (RF) excitation, amyloid aggregates deposited on freshly cleaved mica discs are reduced substantially leaving only a few spherical fragments of sub-micrometer sizes in areas directly treated by the CAP jet. Outside the light-emitting part of the CAP jet, plasma treatment results in a 'skeleton' of much reduced amyloid stacks with clear evidence of fibril fragmentation. Analysis of possible plasma species and the physical configuration of the jet-sample interaction suggests that the skeleton structures observed are unlikely to have arisen as a result of physical forces of detachment, but instead by progressive diffusion of oxidizing plasma species into porous amyloid aggregates. Composition of chemical bonds of this reduced amyloid sample is very different from that of intact amyloid aggregates. These suggest the possibility of on-site degradation by CAP treatment with little possibility of spreading contamination elsewhere , thus offering a new reaction chemistry route to protein infectivity control with desirable implications for the practical implementation of CAP-based sterilization systems.

  17. Evaluation of red blood cell aggregation in diabetes by computerized image analysis.

    Science.gov (United States)

    Foresto, P; D'Arrigo, M; Carreras, L; Cuezzo, R E; Valverde, J; Rasia, R

    2000-01-01

    Red blood cell (RBC) aggregation has been widely studied and its importance is well established in the rheology of microcirculation. RBC aggregation is a major factor responsible for the flow properties of blood. Increased RBC aggregation has been observed in several pathological states. Therefore, the measurement of erythrocyte aggregation is rheologically important for quantifying flow abnormality in pathological conditions. Normal RBC under low flow or at rest form rouleaux aggregates, while abnormal RBC aggregation may lead to the formation of irregular aggregate structures, which may be induced by cell-associated factors (reduced membrane sialic acid levels) but also by extracellular factors. The main objective of the present investigation was to study RBC aggregate morphology in diabetic patients, using direct microscopic observation and numerical processing of recorded digitized images. Blood samples were obtained from 20 diabetic patients and from 15 normal control subjects. The aggregate morphology was quantified by the so-called Aggregate Shape Parameter (ASP) defined as the ratio of the aggregate projected area to its square perimeter. ASP appeared significantly higher (p rouleaux aggregates provides a useful reference for measuring deviations of RBC aggregate morphology. Increased aggregation of RBC resulting from a decreased sialylation of glycophorins may be an important factor in the development of vascular diseases and in the microcirculation impairment. PMID:11188894

  18. Constructed wetlands with light expanded clay aggregates for agricultural wastewater treatment

    OpenAIRE

    Dordio, Ana V.; Carvalho, Alfredo Jorge Palace

    2013-01-01

    Constructed wetlands (CWs) are receiving a renewed attention as a viable phytotechnology for treating agricultural wastewaters and for the removal of more specific pollutants, in particular recalcitrant ones. In this work, the performance of CW mesocosms using light expanded clay aggregates (LECA) as the bed's substrate and planted with Phragmites australis was investigated for treatment of olive mill wastewater (OMW), swine wastewater (SW) contaminated with oxytetracycline and water contamin...

  19. Vitamin k3 inhibits protein aggregation: Implication in the treatment of amyloid diseases

    Science.gov (United States)

    Alam, Parvez; Chaturvedi, Sumit Kumar; Siddiqi, Mohammad Khursheed; Rajpoot, Ravi Kant; Ajmal, Mohd Rehan; Zaman, Masihuz; Khan, Rizwan Hasan

    2016-01-01

    Protein misfolding and aggregation have been associated with several human diseases such as Alzheimer’s, Parkinson’s and familial amyloid polyneuropathy etc. In this study, anti-fibrillation activity of vitamin k3 and its effect on the kinetics of amyloid formation of hen egg white lysozyme (HEWL) and Aβ-42 peptide were investigated. Here, in combination with Thioflavin T (ThT) fluorescence assay, circular dichroism (CD), transmission electron microscopy and cell cytotoxicity assay, we demonstrated that vitamin k3 significantly inhibits fibril formation as well as the inhibitory effect is dose dependent manner. Our experimental studies inferred that vitamin k3 exert its neuro protective effect against amyloid induced cytotoxicity through concerted pathway, modifying the aggregation formation towards formation of nontoxic aggregates. Molecular docking demonstrated that vitamin k3 mediated inhibition of HEWL and Aβ-42 fibrillogenesis may be initiated by interacting with proteolytic resistant and aggregation prone regions respectively. This work would provide an insight into the mechanism of protein aggregation inhibition by vitamin k3; pave the way for discovery of other small molecules that may exert similar effect against amyloid formation and its associated neurodegenerative diseases. PMID:27230476

  20. Aggregate stability by the "high energy moisture characteristic" method in an oxisol under differentiated management

    Directory of Open Access Journals (Sweden)

    Érika Andressa da Silva

    2014-10-01

    Full Text Available Studies testing the High Energy Moisture Characteristic (HEMC technique in tropical soils are still incipient. By this method, the effects of different management systems can be evaluated. This study investigated the aggregation state of an Oxisol under coffee with Brachiaria between crop rows and surface-applied gypsum rates using HEMC. Soil in an experimental area in the Upper São Francisco region, Minas Gerais, was studied at depths of 0.05 and 0.20 m in coffee rows. The treatments consisted of 0, 7, and 28 Mg ha-1 of agricultural gypsum rates distributed on the soil surface of the coffee rows, between which Brachiaria was grown and periodically cut, and compared with a treatment without Brachiaria between coffee rows and no gypsum application. To determine the aggregation state using the HEMC method, soil aggregates were placed in a Büchner funnel (500 mL and wetted using a peristaltic pump with a volumetric syringe. The wetting was applied increasingly at two pre-set speeds: slow (2 mm h-1 and fast (100 mm h-1. Once saturated, the aggregates were exposed to a gradually increasing tension by the displacement of a water column (varying from 0 to 30 cm to obtain the moisture retention curve [M = f (Ψ ], underlying the calculation of the stability parameters: modal suction, volume of drainable pores (VDP, stability index (slow and fast, VDP ratio, and stability ratio. The HEMC method conferred sensitivity in quantifying the aggregate stability parameters, and independent of whether gypsum was used, the soil managed with Brachiaria between the coffee rows, with regular cuts discharged in the crop row direction, exhibited a decreased susceptibility to disaggregation.

  1. Inactivation of enveloped virus by laser-driven protein aggregation

    Science.gov (United States)

    Tsen, Shaw-Wei D.; Chapa, Travis; Beatty, Wandy; Tsen, Kong-Thon; Yu, Dong; Achilefu, Samuel

    2012-12-01

    Ultrafast lasers in the visible and near-infrared range have emerged as a potential new method for pathogen reduction of blood products and pharmaceuticals. However, the mechanism of enveloped virus inactivation by this method is unknown. We report the inactivation as well as the molecular and structural effects caused by visible (425 nm) femtosecond laser irradiation on murine cytomegalovirus (MCMV), an enveloped, double-stranded DNA virus. Our results show that laser irradiation (1) caused a 5-log reduction in MCMV titer, (2) did not cause significant changes to the global structure of MCMV virions including membrane and capsid, as assessed by electron microscopy, (3) produced no evidence of double-strand breaks or crosslinking in MCMV genomic DNA, and (4) caused selective aggregation of viral capsid and tegument proteins. We propose a model in which ultrafast laser irradiation induces partial unfolding of viral proteins by disrupting hydrogen bonds and/or hydrophobic interactions, leading to aggregation of closely associated viral proteins and inactivation of the virus. These results provide new insight into the inactivation of enveloped viruses by visible femtosecond lasers at the molecular level, and help pave the way for the development of a new ultrafast laser technology for pathogen reduction.

  2. Selective inhibition of PAF-induced human platelet aggregation by garlic

    International Nuclear Information System (INIS)

    Garlic exudate (0.2-2.5 mg) prepared by squeezing fresh garlic cloves inhibited platelet aggregation induced by platelet activating factor (PAF) in a dose-dependent manner. No inhibition of aggregation was observed when adenosine-5-diphosphate (ADP) or arachidonic acid (AA) were used as aggregating agents. This selective effect of garlic against PAF-induced aggregation was also seen with aqueous or alcoholic garlic extracts. These results suggest that PAF antagonists are present in garlic. (author)

  3. Fractal dimensions of soy protein nanoparticle aggregates determined by dynamic mechanical method

    Science.gov (United States)

    The fractal dimension of the protein aggregates can be estimated by dynamic mechanical methods when the particle aggregates are imbedded in a polymer matrix. Nanocomposites were formed by mixing hydrolyzed soy protein isolate (HSPI) nanoparticle aggregates with styrene-butadiene (SB) latex, followe...

  4. Effect of water absorption by the aggregate on properties of high-strength lightweight concrete

    Energy Technology Data Exchange (ETDEWEB)

    Punkki, J.

    1995-12-31

    Recently, high-strength lightweight concrete has become an interesting building material for the offshore oil industry. This doctoral thesis presents an experimental investigation of the effect of water absorption by three different types of lightweight aggregates. One type did not show any water absorption ability at all and so represented no problem to the concrete production. For the two other high-strength aggregates, which were of more conventional types, the water absorption depended not only on the properties of the aggregates, but also on the concrete mixing procedure and the properties of the fresh cement paste. When water absorbing lightweight aggregate was used in a dry condition, the workability of the concrete was significantly reduced by the water absorption of the aggregate. This effect was not present when prewetted aggregate was used. The water absorption by the lightweight aggregate also affected the early compressive strength of concrete. After one day, dry aggregate gave on the average 10 MPa higher compressive strength than did prewetted aggregate. The strength-density ratio was affected by the moisture condition of the aggregate. Dry lightweight aggregate gave 9 MPa higher compressive strength at a density of 2000 kg/m{sup 3} compared to that of prewetted aggregate. The water absorption by the lightweight also affected the microstructure of the hardened concrete. Dry lightweight aggregate gave a slightly better microstructure than normal weight aggregate. The results indicate that the use of prewetted aggregate adversely affected the transition zone between the aggregate and the cement paste. 69 refs., 58 figs., 42 tabs.

  5. Use of mineral trioxide aggregate in the treatment of traumatized teeth in children: Two case reports

    Directory of Open Access Journals (Sweden)

    Ćetenović Bojana

    2013-01-01

    Full Text Available Introduction. Dental injuries in immature permanent teeth often result in endodontic complications. Apexification technique using calcium hydroxide is associated with certain flaws, such as long treatment time, the possibility of tooth fracture and incomplete calcification. The use of an apical plug employing mineral trioxide aggregate (MTA is an alternative treatment option. Case report. We reported the successful treatment of 4 maxillary incisors (in a 7-year-old boy and a 10-year-old girl with open apices and periapical lesions. Apical portions of the canals were filled with MTA plugs in both cases. Coronal parts of the root canals were filled with gutta-percha and sealer. Clinical findings were clear 6 months after the definite obturation with no pathological changes on the radiographs in both cases. Conclusion. The use of MTA for apical plugging appears to be a valid treatment option in traumatized immature teeth with endodontic complications.

  6. N-Acetylcysteine potentiates inhibition of platelet aggregation by nitroglycerin.

    OpenAIRE

    Loscalzo, J

    1985-01-01

    Platelet aggregation is currently felt to play an important role in the pathogenesis of ischemic vascular disorders. The smooth muscle relaxant, nitroglycerin, has been shown to inhibit platelet aggregation in vitro, but at concentrations that were felt to be unattainable in vivo. Because the in vivo action of nitroglycerin on smooth muscle cells has been shown to depend on the presence of reduced cytosolic sulfhydryl groups, the inhibitory effect of nitroglycerin on platelet aggregation was ...

  7. Muscle imaging in patients with tubular aggregate myopathy caused by mutations in STIM1

    OpenAIRE

    Tasca, Giorgio; D'Amico, Adele; Monforte, Mauro; Nadaj-Pakleza, Aleksandra; Vialle, Marc; Fattori, Fabiana; Vissing, John; Ricci, Enzo; Bertini, Enrico

    2015-01-01

    Tubular aggregate myopathy is a genetically heterogeneous disease characterized by tubular aggregates as the hallmark on muscle biopsy. Mutations in STIM1 have recently been identified as one genetic cause in a number of tubular aggregate myopathy cases. To characterize the pattern of muscle involvement in this disease, upper and lower girdles and lower limbs were imaged in five patients with mutations in STIM1, and the scans were compared with two patients with tubular aggregate myopathy not...

  8. Dynamics of protein aggregation and oligomer formation governed by secondary nucleation

    International Nuclear Information System (INIS)

    The formation of aggregates in many protein systems can be significantly accelerated by secondary nucleation, a process where existing assemblies catalyse the nucleation of new species. In particular, secondary nucleation has emerged as a central process controlling the proliferation of many filamentous protein structures, including molecular species related to diseases such as sickle cell anemia and a range of neurodegenerative conditions. Increasing evidence suggests that the physical size of protein filaments plays a key role in determining their potential for deleterious interactions with living cells, with smaller aggregates of misfolded proteins, oligomers, being particularly toxic. It is thus crucial to progress towards an understanding of the factors that control the sizes of protein aggregates. However, the influence of secondary nucleation on the time evolution of aggregate size distributions has been challenging to quantify. This difficulty originates in large part from the fact that secondary nucleation couples the dynamics of species distant in size space. Here, we approach this problem by presenting an analytical treatment of the master equation describing the growth kinetics of linear protein structures proliferating through secondary nucleation and provide closed-form expressions for the temporal evolution of the resulting aggregate size distribution. We show how the availability of analytical solutions for the full filament distribution allows us to identify the key physical parameters that control the sizes of growing protein filaments. Furthermore, we use these results to probe the dynamics of the populations of small oligomeric species as they are formed through secondary nucleation and discuss the implications of our work for understanding the factors that promote or curtail the production of these species with a potentially high deleterious biological activity

  9. Dynamics of protein aggregation and oligomer formation governed by secondary nucleation

    Energy Technology Data Exchange (ETDEWEB)

    Michaels, Thomas C. T., E-mail: tctm3@cam.ac.uk; Lazell, Hamish W.; Arosio, Paolo; Knowles, Tuomas P. J., E-mail: tpjk2@cam.ac.uk [Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom)

    2015-08-07

    The formation of aggregates in many protein systems can be significantly accelerated by secondary nucleation, a process where existing assemblies catalyse the nucleation of new species. In particular, secondary nucleation has emerged as a central process controlling the proliferation of many filamentous protein structures, including molecular species related to diseases such as sickle cell anemia and a range of neurodegenerative conditions. Increasing evidence suggests that the physical size of protein filaments plays a key role in determining their potential for deleterious interactions with living cells, with smaller aggregates of misfolded proteins, oligomers, being particularly toxic. It is thus crucial to progress towards an understanding of the factors that control the sizes of protein aggregates. However, the influence of secondary nucleation on the time evolution of aggregate size distributions has been challenging to quantify. This difficulty originates in large part from the fact that secondary nucleation couples the dynamics of species distant in size space. Here, we approach this problem by presenting an analytical treatment of the master equation describing the growth kinetics of linear protein structures proliferating through secondary nucleation and provide closed-form expressions for the temporal evolution of the resulting aggregate size distribution. We show how the availability of analytical solutions for the full filament distribution allows us to identify the key physical parameters that control the sizes of growing protein filaments. Furthermore, we use these results to probe the dynamics of the populations of small oligomeric species as they are formed through secondary nucleation and discuss the implications of our work for understanding the factors that promote or curtail the production of these species with a potentially high deleterious biological activity.

  10. Dynamics of protein aggregation and oligomer formation governed by secondary nucleation

    Science.gov (United States)

    Michaels, Thomas C. T.; Lazell, Hamish W.; Arosio, Paolo; Knowles, Tuomas P. J.

    2015-08-01

    The formation of aggregates in many protein systems can be significantly accelerated by secondary nucleation, a process where existing assemblies catalyse the nucleation of new species. In particular, secondary nucleation has emerged as a central process controlling the proliferation of many filamentous protein structures, including molecular species related to diseases such as sickle cell anemia and a range of neurodegenerative conditions. Increasing evidence suggests that the physical size of protein filaments plays a key role in determining their potential for deleterious interactions with living cells, with smaller aggregates of misfolded proteins, oligomers, being particularly toxic. It is thus crucial to progress towards an understanding of the factors that control the sizes of protein aggregates. However, the influence of secondary nucleation on the time evolution of aggregate size distributions has been challenging to quantify. This difficulty originates in large part from the fact that secondary nucleation couples the dynamics of species distant in size space. Here, we approach this problem by presenting an analytical treatment of the master equation describing the growth kinetics of linear protein structures proliferating through secondary nucleation and provide closed-form expressions for the temporal evolution of the resulting aggregate size distribution. We show how the availability of analytical solutions for the full filament distribution allows us to identify the key physical parameters that control the sizes of growing protein filaments. Furthermore, we use these results to probe the dynamics of the populations of small oligomeric species as they are formed through secondary nucleation and discuss the implications of our work for understanding the factors that promote or curtail the production of these species with a potentially high deleterious biological activity.

  11. Aggregation of encephalomyocarditis virus induced by radio-iodination

    International Nuclear Information System (INIS)

    Radio-iodination causes encephalomyocarditis virus to behave aberrantly when examined by affinity chromatography and to sediment rapidly during analysis on sucrose density gradients suggesting that aggregation had taken place. The change in physical properties of the virus occurred whether iodination was carried out with 125I or 131I, with radio-iodine from two different sources, or using two different iodination procedures. The changes were not observed in virus subjected to an iodination procedure in the absence of radio-iodine suggesting that modification of tyrosine residues was involved rather than a side reaction such as amino acid oxidation. It is recommended that caution be exercised when following the fate of radio-iodinated virus in any particular study because its behaviour may not reflect that of normal, non-iodinated virus present. (Auth.)

  12. Magnetic Microparticle Aggregation For Viscosity Determination By Magnetic Resonance

    OpenAIRE

    Hong, Rui; Cima, Michael J; Weissleder, Ralph; Josephson, Lee

    2008-01-01

    Micron-sized magnetic particles were induced to aggregate when placed in homogeneous magnetic fields, like those of magnetic resonance (MR) imagers and relaxometers, and then spontaneously returned to their dispersed state when removed from the field. Associated with the aggregation and dispersion of the magnetic particles were time dependent increases and decreases in the spin-spin relaxation time (T2) of the water. Magnetic nanoparticles, with far smaller magnetic moments per particle, did ...

  13. Impairment of autophagy by TTR V30M aggregates: in vivo reversal by TUDCA and curcumin.

    Science.gov (United States)

    Teixeira, Cristina A; Almeida, Maria do Rosário; Saraiva, Maria João

    2016-09-01

    Transthyretin (TTR)-related amyloidoses are diseases characterized by extracellular deposition of amyloid fibrils and aggregates in tissues composed of insoluble misfolded TTR that becomes toxic. Previous studies have demonstrated the ability of small compounds in preventing and reversing TTR V30M deposition in transgenic mice gastrointestinal (GI) tract as well as lowering biomarkers associated with cellular stress and apoptotic mechanisms. In the present study we aimed to study TTR V30M aggregates effect in autophagy, a cellular mechanism crucial for cell survival that has been implicated in the development of several neurodegenerative diseases. We were able to demonstrate in cell culture that TTR V30M aggregates cause a partial impairment of the autophagic machinery as shown by p62 accumulation, whereas early steps of the autophagic flux remain unaffected as shown by autophagosome number evaluation and LC3 turnover assay. Our studies performed in TTR V30M transgenic animals demonstrated that tauroursodeoxycholic acid (TUDCA) and curcumin effectively reverse p62 accumulation in the GI tract pointing to the ability of both compounds to modulate autophagy additionally to mitigate apoptosis. Overall, our in vitro and in vivo studies establish an association between TTR V30M aggregates and autophagy impairment and suggest the use of autophagy modulators as an additional and alternative therapeutic approach for the treatment of TTR V30M-related amyloidosis. PMID:27382986

  14. Blockade of the formation of insoluble ubiquitinated protein aggregates by EGCG3"Me in the alloxan-induced diabetic kidney.

    Directory of Open Access Journals (Sweden)

    Shuxian Cai

    Full Text Available BACKGROUND: Renal accumulation of reactive carbonyl compounds (RCCs has been linked to the progression of diabetic nephropathy. We previously demonstrated that carbonyl stress induces the formation of amino-carbonyl cross-links and sharply increases the content of β-sheet-rich structures, which is the seed of insoluble aggregates formation, and tea catechin (--epigallocatechin 3-gallate (EGCG can reverse this process in vitro and in vivo. In this study, methylated derivative (--epigallocatechin-3-O-(3-O-methyl-gallate (EGCG3"Me was hypothesized to neutralize carbonyl stress mediating the formation of insoluble ubiquitinated protein (IUP aggregates, and reduce the early development of diabetic nephropathy. METHODS AND RESULTS: Diabetes was induced in mice by intraperitoneally injecting alloxan monohydrate (200 mg/kg/d twice and administering EGCG3"Me by gavage for 15 d. Reagent case and western blot results showed that, in diabetic kidneys, the carbonyl proteins in the serum increased; and in insoluble protein fraction, 4-hydroxynonenal-modified proteins, IUP aggregates and p62 accumulated; FT-IR study demonstrated that the lipid content, anti-parallel β-sheet structure and aggregates increased. EGCG3"Me treatment could effectively reverse this process, even better than the negative control treatment. CONCLUSIONS: EGCG3"Me exhibiting anti-β-sheet-rich IUP aggregate properties, maybe represents a new strategy to impede the progression of diabetic nephropathy and other diabetic complications.

  15. Oligomerization and Aggregation of Bovine Pancreatic Ribonuclease A: Characteristic Events Observed by FTIR Spectroscopy

    OpenAIRE

    Yan, Yong-Bin; Zhang, Jun; He, Hua-Wei; Zhou, Hai-Meng

    2006-01-01

    Nonnative protein aggregation, which is a common feature in biotechnology, is also a clinical feature in more than 20 serious degenerative diseases. We studied the specific events of bovine pancreatic ribonuclease A thermal aggregation by a combination of second derivative infrared analysis and two-dimensional infrared correlation spectroscopy. By comparing the events that occur in reversible and irreversible thermal unfolding processes, certain events that were related to protein aggregation...

  16. Determination of the aggregation number for micelles by isothermal titration calorimetry

    DEFF Research Database (Denmark)

    Olesen, Niels Erik; Holm, Rene; Westh, Peter

    2014-01-01

    Isothermal titration calorimetry (ITC) has previously been applied to estimate the aggregation number (n), Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS) of micellization. However, some difficulties of micelle characterization by ITC still remain; most micelles have aggregation numbers...... insight into optimal design of titration protocols for micelle characterization. By applying the new method, the aggregation number of sodium dodecyl sulphate and glycochenodeoxycholate was determined at concentrations around their critical micelle concentration (CMC)...

  17. Mechanisms of sound seattering by biological targets and their aggregates

    Directory of Open Access Journals (Sweden)

    Natalia Gorska

    2006-03-01

    Full Text Available Natalia Gorska's thesis is based on a set of 9 papers published in scientific journals (Gorska & Klusek 1998, Gorska 2000, Gorska & Chu 2001a, b, Gorska & Ona 2003a, b and conference proceedings (Gorska & Klusek 1994, Gorska 1999, Gorska & Chu 2000, which broadly summarise her integrated research achievements in underwater acoustics from 1994 to 2003. She is the sole author of two of the articles (Gorska 1999, 2000, and is the first co-author, taking a leading part, in the others (Gorska & Klusek 1994, 1998, Gorska & Chu 2000, Gorska & Chu 200la, b, Gorska & Ona 2003a, b.     Her research objective was to work out the theoretical background to certain problems of sound scattering by biological targets - single individuals and aggregated layers of fish and zooplankton - in relation to environmental conditions in the sea. In the study she focused on acoustical extinction and backscattering, including the phenomenon of echo interference. In conjunction wit h the co-authors of papers Gorska & Ona 2003a, b, Gorska & Chu 2001a, b and Gorska & Chu 2000, she was able to apply and verify her theoretical results empirically.

  18. Group foraging by a stream minnow: shoals or aggregations?

    Science.gov (United States)

    Freeman, Mary C.; Grossman, G.D.

    1992-01-01

    The importance of social attraction in the formation of foraging groups was examined for a stream-dwelling cyprinid, the rosyside dace, Clinostomus funduloides. Dace arrivals and departures at natural foraging sites were monitored and tested for (1) tendency of dace to travel in groups, and (2) dependency of arrival and departure rates on group size. Dace usually entered and departed foraging sites independently of each other. Group size usually affected neither arrival rate nor departure probability. Thus, attraction among dace appeared weak; foraging groups most often resulted from dace aggregating in preferred foraging sites. The strongest evidence of social attraction was during autumn, when dace departure probability often decreased with increasing group size, possibly in response to increased threat of predation by a seasonally occurring predator. Dace also rarely avoided conspecifics, except when an aggressive individual defended a foraging site. Otherwise, there was little evidence of exploitative competition among dace for drifting prey or of foraging benefits in groups, because group size usually did not affect individual feeding rates. These results suggest that the benefits of group foraging demonstrated under laboratory conditions in other studies may not always apply to field conditions.

  19. The evaluation of the factors that cause aggregation during recombinant expression in E. coli is simplified by the employment of an aggregation-sensitive reporter

    OpenAIRE

    Martinez Lucia; Schultz Tina; de Marco Ario

    2006-01-01

    Abstract Background The yields of soluble recombinant proteins expressed in bacteria are often low due to the tendency of the heterologous proteins to form aggregates. Therefore, aggregation reporters have been envisaged to simplify the comparison among different expression conditions and to speed up the identification of suitable protocols that improve the solubility. The probe we used is composed by an IbpAB promoter specifically activated by protein aggregates fused to a sequence coding th...

  20. Increase on Strengths of Hot Weather Concrete by Self-Curing of Wet Porous Aggregate

    OpenAIRE

    Sampebulu’ V.

    2013-01-01

    The compressive and tensile strengths of concrete made in hot weather condition decreased due to loss of mixing water caused by high evaporation. One method to overcome the problem is the use of saturated fly ash aggregate. The water content in fly ash aggregate can flow out to the hardened cement paste to continue the hydration process. This ???self-curing??? mechanism could produce more hydration around the surface of fly ash aggregate which sub-sequently increases concrete strength. Experi...

  1. Regulation of synaptic Pumilio function by an aggregation-prone domain

    OpenAIRE

    Salazar, Anna M.; Silverman, Edward J.; Menon, Kaushiki P.; Zinn, Kai

    2010-01-01

    We identified Pumilio (Pum), a Drosophila translational repressor, in a computational search for metazoan proteins whose activities might be regulated by assembly into ordered aggregates. The search algorithm was based on evolutionary sequence conservation patterns observed for yeast prion proteins, which contain aggregation-prone glutamine/asparagine (Q/N)-rich domains attached to functional domains of normal amino acid composition. We examined aggregation of Pum and its nematode ortholog PU...

  2. Alkali silica reaction in concrete induced by mortar adhered to recycled aggregate

    OpenAIRE

    Etxeberria, M.; Vázquez, E.

    2010-01-01

    The durability of recycled concrete must be determined before this material can be used in construction. In this paper the alkali-silica reaction in recycled concrete is analyzed. The recycled concrete is made with recycled aggregates, composed by original limestone aggregates and adhered mortar with reactive silica sand, and high alkali content cement. Due to the manufacturing process used for concrete production and the high water absorption capacity of recycled aggregates, cement accumulat...

  3. Regulation of aggregate size and pattern by adenosine and caffeine in cellular slime molds

    OpenAIRE

    Jaiswal Pundrik; Soldati Thierry; Thewes Sascha; Baskar Ramamurthy

    2012-01-01

    Abstract Background Multicellularity in cellular slime molds is achieved by aggregation of several hundreds to thousands of cells. In the model slime mold Dictyostelium discoideum, adenosine is known to increase the aggregate size and its antagonist caffeine reduces the aggregate size. However, it is not clear if the actions of adenosine and caffeine are evolutionarily conserved among other slime molds known to use structurally unrelated chemoattractants. We have examined how the known factor...

  4. Platelet impedance aggregation in whole blood and its inhibition by antiplatelet drugs.

    OpenAIRE

    Mackie, I J; Jones, R.; Machin, S. J.

    1984-01-01

    Platelet aggregation was studied in citrated whole blood by an electrical impedance method. Blood samples from normal volunteers were studied with the aim of finding a suitable method for the routine study of samples from patients. An erratic tracing and low maximum aggregation were seen in samples with a high normal haematocrit. Optimal aggregation was seen when blood was diluted to a haematocrit of .300; isotonic saline was a better diluent than platelet poor plasma. No appreciable differen...

  5. In Vitro Spectrophotometry of Tooth Discoloration Induced by Tooth-Colored Mineral Trioxide Aggregate and Calcium-Enriched Mixture Cement

    OpenAIRE

    Arman, Marjan; Khalilak, Zohreh; Rajabi, Moones; Esnaashari, Ehsan; Saati, Keyvan

    2015-01-01

    Introduction: There are numerous factors that can lead to tooth discoloration after endodontic treatment, such as penetration of endodontic materials into the dentinal tubules during root canal treatment. The aim of this in vitro study was to compare discoloration induced by tooth colored mineral trioxide aggregate (MTA) and calcium-enriched mixture (CEM) cement in extracted human teeth. Methods and Materials: Thirty two dentin-enamel cuboid blocks (7×7×2 mm) were prepared from extracted maxi...

  6. Kinetic partitioning between aggregation and vesicle permeabilization by modified ADan

    DEFF Research Database (Denmark)

    Nesgaard, Lise W.; Vad, Brian; Christiansen, Gunna;

    2009-01-01

    changed to serines to emulate the reduced peptide. SerADan aggregates rapidly at pH 5.0 and 7.5 in a series of conformational transitions to form beta-sheet rich fibril-like structures, which nevertheless do not bind amyloid-specific dyes, probably due to the absence of organized beta-sheet contacts...

  7. Natural aggregate totally replacement by mechanically treated concrete waste

    Directory of Open Access Journals (Sweden)

    Junak Jozef

    2015-06-01

    Full Text Available This paper presents the results obtained from the research focused on the utilization of crushed concrete waste aggregates as a partial or full replacement of 4/8 and 8/16 mm natural aggregates fraction in concrete strength class C 16/20. Main concrete characteristics such as workability, density and compressive strength were studied. Compressive strength testing intervals for samples with recycled concrete aggregates were 2, 7, 14 and 28 days. The amount of water in the mixtures was indicative. For mixture resulting consistency required slump grade S3 was followed. Average density of all samples is in the range of 2250 kg/m3 to 2350 kg/m3. The highest compressive strength after 28 days of curing, 34.68 MPa, reached sample, which contained 100% of recycled material in 4/8 mm fraction and 60% of recycled aggregates in 8/16 mm fraction. This achieved value was only slightly different from the compressive strength 34.41 MPa of the reference sample.

  8. Strength regain in soil aggregate beds by swelling and shrinkage

    Directory of Open Access Journals (Sweden)

    R. Horn

    2006-06-01

    Full Text Available Strength regain in aggregate beds as a consequence of wetting and drying cycles was studied in two Andisols and one Mollisol from Chile, collected at two depths (0-10 and 40-60 cm. In the Mollisol, wetting and drying cycles promoted an increase of mechanical parameters (cohesion and precompression stress value, associated with increase of bulk density. The Andisols showed the same tendency, but in some coarse aggregate beds the measured values decreased or remained constant. After six cycles of wetting and drying, the restructuring of the aggregate beds from the Mollisol resembled more the measured properties of non-disturbed samples than the identically prepared samples from the Andisols. The change of pore water pressure during mechanical tests depends on the soil development: the Mollisol is sensitive to external load, during compression and shear tests the pore water pressure changed intensely, while in the younger Andisol, irrespective of the stress applied, the pore water pressure did not change significantly. It is possible to find a strength regain in natural aggregate beds, but further investigations are necessary to understand the processes of pore formation and functioning in Andisols and their role in the pore water pressure behaviour.

  9. Quantitative analysis of the effect of zidovudine, efavirenz, and ritonavir on insulin aggregation by multivariate curve resolution alternating least squares of infrared spectra

    International Nuclear Information System (INIS)

    Highlights: ► The structure of insulin can be changed via interaction with antiretroviral drugs. ► The chemical interaction promotes the formation of aggregates. ► This drug effect was evaluated by MCR-ALS coupled to IR spectroscopy. ► Formation of aggregates was favourable if drugs were able to form hydrogen bonds. ► Higher drug concentrations favoured formation of amorphous aggregates. - Abstract: Quantification of the effect of antiretroviral drugs on the insulin aggregation process is an important area of research due to the serious metabolic diseases observed in AIDS patients after prolonged treatment with these drugs. In this work, multivariate curve resolution alternating least squares (MCR-ALS) was applied to infrared monitoring of the insulin aggregation process in the presence of three antiretroviral drugs to quantify their effect. To evidence concentration dependence in this process, mixtures at two different insulin:drug molar ratios were used. The interaction between insulin and each drug was analysed by 1H NMR spectroscopy. In all cases, the aggregation process was monitored during 45 min by infrared spectroscopy. The aggregates were further characterised by scanning electron microscopy (SEM). MCR-ALS provided the spectral and concentration profiles of the different insulin–drug conformations that are involved in the process. Their feasible band boundaries were calculated using the MCR-BANDS methodology. The kinetic profiles describe the aggregation pathway and the spectral profiles characterise the conformations involved. The retrieved results show that each of the three drugs modifies insulin conformation in a different way, promoting the formation of aggregates. Ritonavir shows the strongest promotion of aggregation, followed by efavirenz and zidovudine. In the studied concentration range, concentration dependence was only observed for zidovudine, with shorter aggregation time obtained as the amount of zidovudine increased. This factor

  10. Quantitative analysis of the effect of zidovudine, efavirenz, and ritonavir on insulin aggregation by multivariate curve resolution alternating least squares of infrared spectra

    Energy Technology Data Exchange (ETDEWEB)

    Marti-Aluja, Idoia; Ruisanchez, Itziar [Analytical and Organic Chemistry Department, Universitat Rovira i Virgili, Marcelli Domingo s/n, Campus Sescelades, 43007 Tarragona (Spain); Larrechi, M. Soledad, E-mail: mariasoledad.larrechi@urv.cat [Analytical and Organic Chemistry Department, Universitat Rovira i Virgili, Marcelli Domingo s/n, Campus Sescelades, 43007 Tarragona (Spain)

    2013-01-14

    Highlights: Black-Right-Pointing-Pointer The structure of insulin can be changed via interaction with antiretroviral drugs. Black-Right-Pointing-Pointer The chemical interaction promotes the formation of aggregates. Black-Right-Pointing-Pointer This drug effect was evaluated by MCR-ALS coupled to IR spectroscopy. Black-Right-Pointing-Pointer Formation of aggregates was favourable if drugs were able to form hydrogen bonds. Black-Right-Pointing-Pointer Higher drug concentrations favoured formation of amorphous aggregates. - Abstract: Quantification of the effect of antiretroviral drugs on the insulin aggregation process is an important area of research due to the serious metabolic diseases observed in AIDS patients after prolonged treatment with these drugs. In this work, multivariate curve resolution alternating least squares (MCR-ALS) was applied to infrared monitoring of the insulin aggregation process in the presence of three antiretroviral drugs to quantify their effect. To evidence concentration dependence in this process, mixtures at two different insulin:drug molar ratios were used. The interaction between insulin and each drug was analysed by {sup 1}H NMR spectroscopy. In all cases, the aggregation process was monitored during 45 min by infrared spectroscopy. The aggregates were further characterised by scanning electron microscopy (SEM). MCR-ALS provided the spectral and concentration profiles of the different insulin-drug conformations that are involved in the process. Their feasible band boundaries were calculated using the MCR-BANDS methodology. The kinetic profiles describe the aggregation pathway and the spectral profiles characterise the conformations involved. The retrieved results show that each of the three drugs modifies insulin conformation in a different way, promoting the formation of aggregates. Ritonavir shows the strongest promotion of aggregation, followed by efavirenz and zidovudine. In the studied concentration range, concentration

  11. Regulation of aggregate size and pattern by adenosine and caffeine in cellular slime molds

    Directory of Open Access Journals (Sweden)

    Jaiswal Pundrik

    2012-01-01

    Full Text Available Abstract Background Multicellularity in cellular slime molds is achieved by aggregation of several hundreds to thousands of cells. In the model slime mold Dictyostelium discoideum, adenosine is known to increase the aggregate size and its antagonist caffeine reduces the aggregate size. However, it is not clear if the actions of adenosine and caffeine are evolutionarily conserved among other slime molds known to use structurally unrelated chemoattractants. We have examined how the known factors affecting aggregate size are modulated by adenosine and caffeine. Result Adenosine and caffeine induced the formation of large and small aggregates respectively, in evolutionarily distinct slime molds known to use diverse chemoattractants for their aggregation. Due to its genetic tractability, we chose D. discoideum to further investigate the factors affecting aggregate size. The changes in aggregate size are caused by the effect of the compounds on several parameters such as cell number and size, cell-cell adhesion, cAMP signal relay and cell counting mechanisms. While some of the effects of these two compounds are opposite to each other, interestingly, both compounds increase the intracellular glucose level and strengthen cell-cell adhesion. These compounds also inhibit the synthesis of cAMP phosphodiesterase (PdsA, weakening the relay of extracellular cAMP signal. Adenosine as well as caffeine rescue mutants impaired in stream formation (pde4- and pdiA- and colony size (smlA- and ctnA- and restore their parental aggregate size. Conclusion Adenosine increased the cell division timings thereby making large number of cells available for aggregation and also it marginally increased the cell size contributing to large aggregate size. Reduced cell division rates and decreased cell size in the presence of caffeine makes the aggregates smaller than controls. Both the compounds altered the speed of the chemotactic amoebae causing a variation in aggregate size

  12. Laboratory Investigation Of Partial Replacement Of Coarse Aggregate By Plastic Chips And Cement By Human Hair

    Directory of Open Access Journals (Sweden)

    A.S.Balaji

    2014-04-01

    Full Text Available The use of plastic is increasing day by day, although steps were taken to reduce its consumption. The suitability of recycled plastics as coarse aggregate in concrete and its advantage are discussed here. Experimental investigation was done using M20 mix and tests were carried out as per recommended procedures by relevant codes. As 100% replacement of natural coarse aggregate (NCA with plastic coarse aggregate (PCA is not feasible, partial replacement were examined. And also Hair is used as a fibred reinforcing material in concrete as partial replacement of cement. It has a high tensile strength which is equal to that of a copper wire with similar diameter. It is also available in abundance and at a very low cost. Tests were conducted to determine the properties of plastic aggregate and human hair such as density, specific gravity and crushing value. Experiments were conducted on concrete cubes with various percentages of human hair i.e. 0%, 0.5%, 1%, 1.5%, 2%, and 3% by weight of cement and with constant percentage of plastic aggregate as 20%.

  13. Induced growth of dendrite gold nanostructure by controlling self-assembly aggregation dynamics.

    Science.gov (United States)

    Abdellatif, M H; Abdelrasoul, G N; Scarpellini, A; Marras, S; Diaspro, A

    2015-11-15

    Self-assembly of gold nanoparticles (AuNPs) is an important growth mode for fabricating functional materials. In this work we report a dendrite structure formed by slowing down the aggregation dynamics of AuNPs self-assembly. The obtained results show that the aggregation dynamics is dominated by the Reaction Limited Aggregation Model (RLA) more than the Diffusion Limited Aggregation Model (DLA). In which the repulsion due to electrostatic forces is dominant by the Van Der Walls attraction forces, and low sticking probability of nanoparticles. The aggregation dynamics of AuNPs can be slowed down if the water evaporation of the drop casted colloidal AuNPs on a quartz substrate is slowed. Slowing down the evaporation allows electrostatic repulsion forces to decrease gradually. At certain point, the attraction forces become higher than the electrostatic repulsion and hence cluster aggregation take place slowly. The slow aggregation dynamics allows the nanoparticles to sample all possible orientation in the sticking site, searching for the lowest energy configuration. The size distribution of the nanoparticles in liquid is confirmed using dynamic light scattering based on Stokes-Einstein equation for diffusion coefficient in water. X-ray and photoluminescence (PL) spectra of the sample after aggregation showed a shift which is related to the aggregation compared with non-aggregated colloidal nanoparticles in the solution. The study shows that dendrite self similar structure can be formed by slowing down the aggregation dynamics of nanoparticles as a result of minimizing the Helmholtz free surface energy of the system. PMID:26233557

  14. Aggregation on finite ordinal scales by scale independent functions

    Czech Academy of Sciences Publication Activity Database

    Marichal, J. L.; Mesiar, Radko

    Vol. 2. Roma: University La Sapienza, 2004 - (Bouchon-Meunier, B.; Coletti, G.; Yager, R.), s. 1243-1250 ISBN 88-87242-54-2. [IPMU 2004 /10./. Perugia (IT), 04.07.2004-09.07.2004] R&D Projects: GA ČR GA402/04/1026 Institutional research plan: CEZ:AV0Z1075907 Keywords : aggregation functions * finite ordinal scales * order invariant functions Subject RIV: BA - General Mathematics

  15. The non-aggregated aggrecan in the human intervertebral disc can arise by a non-proteolytic mechanism

    Directory of Open Access Journals (Sweden)

    PJ Roughley

    2014-09-01

    Full Text Available Analysis of both the aggregated and non-aggregated fractions of aggrecan isolated from adult human intervertebral disc using immunoblotting with antibodies specific for the different domains constituting the aggrecan core protein or atomic force microscopy revealed that many components contained the G1 domain. However, little of the disc aggrecan was able to reform aggregates with hyaluronan, as determined by gel filtration chromatography, suggesting that the G1 domains had been rendered non-functional. Since previous studies have shown that disc aggrecan undergoes non-enzymatic glycation with age, the functional effect of such modification was investigated in vitro using bovine aggrecan isolated from young animals. Incubation of monomeric aggrecan with ribose to induce glycation rendered it unable to form complexes with hyaluronan stable to agarose gel electrophoresis or gel filtration chromatography. Similarly, extended treatment of intact proteoglycan aggregate with ribose resulted in destabilisation of the complex with separation of the aggrecan from the hyaluronan. Although it is clear that proteolysis occurs in the intervertebral disc and gives rise to some non-aggregating molecules, a different mechanism is required to explain the presence of many non-aggregating molecules bearing the G1 domain. The products of non-enzymatic glycation of the globular domains of aggrecan would account for this phenomenon and explain why some of the non-aggregating molecules are still large proteoglycans. While such molecules may be retained in the nucleus pulposus, they may be able to diffuse within it, reducing the ability of the tissue to resist compression under asymmetric loading such as bending and ultimately contributing to disc degeneration.

  16. Aggregation behaviour of amphiphilic cyclodextrins: the nucleation stage by atomistic molecular dynamics simulations

    Directory of Open Access Journals (Sweden)

    Giuseppina Raffaini

    2015-12-01

    Full Text Available Amphiphilically modified cyclodextrins may form various supramolecular aggregates. Here we report a theoretical study of the aggregation of a few amphiphilic cyclodextrins carrying hydrophobic thioalkyl groups and hydrophilic ethylene glycol moieties at opposite rims, focusing on the initial nucleation stage in an apolar solvent and in water. The study is based on atomistic molecular dynamics methods with a “bottom up” approach that can provide important information about the initial aggregates of few molecules. The focus is on the interaction pattern of amphiphilic cyclodextrin (aCD, which may interact by mutual inclusion of the substituent groups in the hydrophobic cavity of neighbouring molecules or by dispersion interactions at their lateral surface. We suggest that these aggregates can also form the nucleation stage of larger systems as well as the building blocks of micelles, vesicle, membranes, or generally nanoparticles thus opening new perspectives in the design of aggregates correlating their structures with the pharmaceutical properties.

  17. Aggregation behaviour of amphiphilic cyclodextrins: the nucleation stage by atomistic molecular dynamics simulations.

    Science.gov (United States)

    Raffaini, Giuseppina; Mazzaglia, Antonino; Ganazzoli, Fabio

    2015-01-01

    Amphiphilically modified cyclodextrins may form various supramolecular aggregates. Here we report a theoretical study of the aggregation of a few amphiphilic cyclodextrins carrying hydrophobic thioalkyl groups and hydrophilic ethylene glycol moieties at opposite rims, focusing on the initial nucleation stage in an apolar solvent and in water. The study is based on atomistic molecular dynamics methods with a "bottom up" approach that can provide important information about the initial aggregates of few molecules. The focus is on the interaction pattern of amphiphilic cyclodextrin (aCD), which may interact by mutual inclusion of the substituent groups in the hydrophobic cavity of neighbouring molecules or by dispersion interactions at their lateral surface. We suggest that these aggregates can also form the nucleation stage of larger systems as well as the building blocks of micelles, vesicle, membranes, or generally nanoparticles thus opening new perspectives in the design of aggregates correlating their structures with the pharmaceutical properties. PMID:26734094

  18. Aggregation behaviour of amphiphilic cyclodextrins: the nucleation stage by atomistic molecular dynamics simulations

    Science.gov (United States)

    Mazzaglia, Antonino; Ganazzoli, Fabio

    2015-01-01

    Summary Amphiphilically modified cyclodextrins may form various supramolecular aggregates. Here we report a theoretical study of the aggregation of a few amphiphilic cyclodextrins carrying hydrophobic thioalkyl groups and hydrophilic ethylene glycol moieties at opposite rims, focusing on the initial nucleation stage in an apolar solvent and in water. The study is based on atomistic molecular dynamics methods with a “bottom up” approach that can provide important information about the initial aggregates of few molecules. The focus is on the interaction pattern of amphiphilic cyclodextrin (aCD), which may interact by mutual inclusion of the substituent groups in the hydrophobic cavity of neighbouring molecules or by dispersion interactions at their lateral surface. We suggest that these aggregates can also form the nucleation stage of larger systems as well as the building blocks of micelles, vesicle, membranes, or generally nanoparticles thus opening new perspectives in the design of aggregates correlating their structures with the pharmaceutical properties. PMID:26734094

  19. Spontaneous motion of the oil-water interface induced by the generation of surfactant aggregates. In-situ measurement of aggregate formation with SAXS and SANS

    International Nuclear Information System (INIS)

    Motion of an oil-water interface induced by the formation of surfactant aggregates is reported. An oil-water system that generates surfactant aggregates at the oil-water interface is constructed with biomimetic motivation. We applied a system composed of ionic surfactant, co-surfactant and water, which is known to generate lamellar structure with low surfactant ratio (∼ a few wt.%). In our system, a cationic surfactant is dissolved in water, whereas co-surfactant is dissolved in hydrocarbon solvent. Setting the oil and the water in contact with each other, the aggregates were formed at the oil-water interface. Accompanied with the generation of surfactant aggregates, the oil-water interface showed extension and retraction of circular extrude within a quasi 2-dimensional cell. Furthermore, the aggregates formed pillar-like structure due to the interfacial motion. By in situ measurement with small angel X-ray scattering and small angle neutron scattering, we revealed the aggregates have the lamellar structure where their interlayer distance was 28 nm to 30 nm. The internal structure of the aggregate pillar is also revealed. SANS measurement further revealed that the aggregates do not contain large amount of the organic solvent. (author)

  20. Study of Optical Properties on Fractal Aggregation Using the GMM Method by Different Cluster Parameters

    Science.gov (United States)

    Chang, Kuo-En; Lin, Tang-Huang; Lien, Wei-Hung

    2015-04-01

    Anthropogenic pollutants or smoke from biomass burning contribute significantly to global particle aggregation emissions, yet their aggregate formation and resulting ensemble optical properties are poorly understood and parameterized in climate models. Particle aggregation refers to formation of clusters in a colloidal suspension. In clustering algorithms, many parameters, such as fractal dimension, number of monomers, radius of monomer, and refractive index real part and image part, will alter the geometries and characteristics of the fractal aggregation and change ensemble optical properties further. The cluster-cluster aggregation algorithm (CCA) is used to specify the geometries of soot and haze particles. In addition, the Generalized Multi-particle Mie (GMM) method is utilized to compute the Mie solution from a single particle to the multi particle case. This computer code for the calculation of the scattering by an aggregate of spheres in a fixed orientation and the experimental data have been made publicly available. This study for the model inputs of optical determination of the monomer radius, the number of monomers per cluster, and the fractal dimension is presented. The main aim in this study is to analyze and contrast several parameters of cluster aggregation aforementioned which demonstrate significant differences of optical properties using the GMM method finally. Keywords: optical properties, fractal aggregation, GMM, CCA

  1. Light Scattering by Fractal Dust Aggregates. I. Angular Dependence of Scattering

    Science.gov (United States)

    Tazaki, Ryo; Tanaka, Hidekazu; Okuzumi, Satoshi; Kataoka, Akimasa; Nomura, Hideko

    2016-06-01

    In protoplanetary disks, micron-sized dust grains coagulate to form highly porous dust aggregates. Because the optical properties of these aggregates are not completely understood, it is important to investigate how porous dust aggregates scatter light. In this study, the light scattering properties of porous dust aggregates were calculated using a rigorous method, the T-matrix method, and the results were then compared with those obtained using the Rayleigh–Gans–Debye (RGD) theory and Mie theory with the effective medium approximation (EMT). The RGD theory is applicable to moderately large aggregates made of nearly transparent monomers. This study considered two types of porous dust aggregates—ballistic cluster–cluster agglomerates (BCCAs) and ballistic particle–cluster agglomerates. First, the angular dependence of the scattered intensity was shown to reflect the hierarchical structure of dust aggregates; the large-scale structure of the aggregates is responsible for the intensity at small scattering angles, and their small-scale structure determines the intensity at large scattering angles. Second, it was determined that the EMT underestimates the backward scattering intensity by multiple orders of magnitude, especially in BCCAs, because the EMT averages the structure within the size of the aggregates. It was concluded that the RGD theory is a very useful method for calculating the optical properties of BCCAs.

  2. Internal deterioration of concrete by the oxidation of pyrrhotitic aggregates

    International Nuclear Information System (INIS)

    This paper presents research results on the causes of a severe concrete deterioration, which occurred in many building foundations approximately 2 years after construction. Concrete samples were investigated with X-ray diffraction (XRD) analysis, a scanning electron microscope (SEM) and a petrographic examination performed with a stereomicroscope. It was found that the early cracking of concrete stemmed from the oxidation of the pyrrhotite found in the anorthosite aggregates used to produce the concrete. The oxidation process led to the precipitation of iron hydroxides having a higher volume than the original pyrrhotite does. The presence of micas (biotite) close to the pyrrhotite seemed to promote and accelerate the oxidation process

  3. Aggregation of Scale Efficiency

    OpenAIRE

    Valentin Zelenyuk

    2012-01-01

    In this article we extend the aggregation theory in efficiency and productivity analysis by deriving solutions to the problem of aggregation of individual scale efficiency measures, primal and dual, into aggregate primal and dual scale efficiency measures of a group. The new aggregation result is coherent with aggregation framework and solutions for the other related efficiency measures that already exist in the literature.

  4. Quantification of alginate by aggregation induced by calcium ions and fluorescent polycations.

    Science.gov (United States)

    Zheng, Hewen; Korendovych, Ivan V; Luk, Yan-Yeung

    2016-01-01

    For quantification of polysaccharides, including heparins and alginates, the commonly used carbazole assay involves hydrolysis of the polysaccharide to form a mixture of UV-active dye conjugate products. Here, we describe two efficient detection and quantification methods that make use of the negative charges of the alginate polymer and do not involve degradation of the targeted polysaccharide. The first method utilizes calcium ions to induce formation of hydrogel-like aggregates with alginate polymer; the aggregates can be quantified readily by staining with a crystal violet dye. This method does not require purification of alginate from the culture medium and can measure the large amount of alginate that is produced by a mucoid Pseudomonas aeruginosa culture. The second method employs polycations tethering a fluorescent dye to form suspension aggregates with the alginate polyanion. Encasing the fluorescent dye in the aggregates provides an increased scattering intensity with a sensitivity comparable to that of the conventional carbazole assay. Both approaches provide efficient methods for monitoring alginate production by mucoid P. aeruginosa. PMID:26408812

  5. Changes of conformation and aggregation state induced by binding of lanthanide ions to insulin

    Institute of Scientific and Technical Information of China (English)

    程驿; 李荣昌; 王夔

    2002-01-01

    To clarify the mechanism of lanthanide ions (Ln3+) on the across-membrane transport of insulin and subsequent reducing blood glucose, the interactions of Ln3+with Zn-insulin and Zn-free insulin are investigated by spectroscopic methods. The results reveal that the binding of Ln3+ to insulin can induce its structure changes from secondary to quaternary structure, depending on the Ln3+ concentration. In the lower concentration, it triggers the conformational changes of insulin monomer in the binding region with insulin receptor (B(24-30)). It would affect insulin-insulin receptor interaction. Moreover, Ln3+ binding promotes the assembly of insulin monomer from dimer to polymer. The potency of Ln3+ in inducing insulin’s aggregation is stronger than that of Zn2+. Furthermore, the aggregation can be reversed partly by EDTA-treatment, indicating that it is not due to denaturation. Similar to Zn2+ effect, Ln3+ can stabilize insulin hexamer in a certain range of concentration, but is stronger than the former.

  6. Changes of conformation and aggregation state induced by binding of lanthanide ions to insulin

    Institute of Scientific and Technical Information of China (English)

    程驿; 李荣昌; 王夔

    2002-01-01

    To clarify the mechanism of lanthanide ions (Ln3+) on the across-membrane transport of insulin and subsequent reducing blood glucose, the interactions of Ln3+ with Zn-insulin and Zn-free insulin are investigated by spectroscopic methods. The results reveal that the binding of Ln3+ to insulin can induce its structure changes from secondary to quaternary structure, depending on the Ln3+ concentration. In the lower concentration, it triggers the conformational changes of insulin monomer in the binding region with insulin receptor (B(24-30)). It would affect insulin-insulin receptor interaction. Moreover, Ln3+ binding promotes the assembly of insulin monomer from dimer to polymer. The potency of Ln3+ in inducing insulin's aggregation is stronger than that of Zn2+. Furthermore, the aggregation can be reversed partly by EDTA-treatment, indicating that it is not due to denaturation. Similar to Zn2+ effect, Ln3+ can stabilize insulin hexamer in a certain range of concentration, but is stronger than the former.

  7. OUTWARD MOTION OF POROUS DUST AGGREGATES BY STELLAR RADIATION PRESSURE IN PROTOPLANETARY DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Tazaki, Ryo [Department of Astronomy, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake-cho, Sakyo-ku, Kyoto 606-8502 (Japan); Nomura, Hideko, E-mail: rtazaki@kusastro.kyoto-u.ac.jp [Department of Earth and Planetary Sciences, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551 (Japan)

    2015-02-01

    We study the dust motion at the surface layer of protoplanetary disks. Dust grains in the surface layer migrate outward owing to angular momentum transport via gas-drag force induced by the stellar radiation pressure. In this study we calculate the mass flux of the outward motion of compact grains and porous dust aggregates by the radiation pressure. The radiation pressure force for porous dust aggregates is calculated using the T-Matrix Method for the Clusters of Spheres. First, we confirm that porous dust aggregates are forced by strong radiation pressure even if they grow to be larger aggregates, in contrast to homogeneous and spherical compact grains, for which radiation pressure efficiency becomes lower when their sizes increase. In addition, we find that the outward mass flux of porous dust aggregates with monomer size of 0.1 μm is larger than that of compact grains by an order of magnitude at the disk radius of 1 AU, when their sizes are several microns. This implies that large compact grains like calcium-aluminum-rich inclusions are hardly transported to the outer region by stellar radiation pressure, whereas porous dust aggregates like chondritic-porous interplanetary dust particles are efficiently transported to the comet formation region. Crystalline silicates are possibly transported in porous dust aggregates by stellar radiation pressure from the inner hot region to the outer cold cometary region in the protosolar nebula.

  8. OUTWARD MOTION OF POROUS DUST AGGREGATES BY STELLAR RADIATION PRESSURE IN PROTOPLANETARY DISKS

    International Nuclear Information System (INIS)

    We study the dust motion at the surface layer of protoplanetary disks. Dust grains in the surface layer migrate outward owing to angular momentum transport via gas-drag force induced by the stellar radiation pressure. In this study we calculate the mass flux of the outward motion of compact grains and porous dust aggregates by the radiation pressure. The radiation pressure force for porous dust aggregates is calculated using the T-Matrix Method for the Clusters of Spheres. First, we confirm that porous dust aggregates are forced by strong radiation pressure even if they grow to be larger aggregates, in contrast to homogeneous and spherical compact grains, for which radiation pressure efficiency becomes lower when their sizes increase. In addition, we find that the outward mass flux of porous dust aggregates with monomer size of 0.1 μm is larger than that of compact grains by an order of magnitude at the disk radius of 1 AU, when their sizes are several microns. This implies that large compact grains like calcium-aluminum-rich inclusions are hardly transported to the outer region by stellar radiation pressure, whereas porous dust aggregates like chondritic-porous interplanetary dust particles are efficiently transported to the comet formation region. Crystalline silicates are possibly transported in porous dust aggregates by stellar radiation pressure from the inner hot region to the outer cold cometary region in the protosolar nebula

  9. Enhancement of red blood cell aggregation by plasma triglycerides.

    Science.gov (United States)

    Cicha, I; Suzuki, Y; Tateishi, N; Maeda, N

    2001-01-01

    The effects of plasma triglycerides level on human red blood cells (RBCs) indices, hematological parameters, RBCs aggregation velocity and whole blood viscosity were studied at 2 hours after high-fat or low-fat meal. Proteins, triglycerides and cholesterol levels of plasma were analysed. The RBCs rouleaux formation rate was measured in 70% autologous plasma (with 30% phosphate-buffered saline, PBS) or 1 g/dl dextran T70 solution (with 4 g/dl bovine serum albumin) in PBS, using a low-shear rheoscope. The results were grouped according to triglycerides content in plasma. No significant difference in whole blood viscosity, hematological parameters, RBC indices, protein and cholesterol content was observed between high-fat and low-fat blood samples. There was a significant increase in rouleaux formation rate of samples with high triglyceride levels, when measured in 70% autologous plasma, but it was not significant in dextran T70 containing medium. In conclusion, the results obtained suggest that alteration of plasma lipid levels as well as possible changes in the cell membrane lipid composition lead to enhanced RBC aggregation. PMID:11564913

  10. Radiation exposure and familial aggregation of cancers as risk factors for colorectal cancer after radioiodine treatment for thyroid carcinoma

    International Nuclear Information System (INIS)

    Purpose: In thyroid cancer patients, radioiodine treatment has been shown to be associated with an increased risk of colon carcinoma. The aim of this study in thyroid cancer patients was to evaluate the role of familial factors in the risk of colorectal cancer and their potential interaction with radioiodine exposure. Methods and Materials: We performed a case-control study on 15 colorectal cancer patients and 76 matched control subjects, nested in a cohort of 3708 thyroid cancer patients treated between 1933 and 1998. For each patient, the radiation dose delivered to the colon by radioiodine was estimated by use of standard tables. In those who received external radiation therapy, the average radiation doses delivered to the colon and rectum were estimated by use of DOSEg software. A complete familial history was obtained by face-to-face interviews, and a familial index was defined to evaluate the degree of familial aggregation. Results: The risk of colorectal cancer increased with familial aggregation of colorectal cancer (p = 0.02). After adjustment for the radiation dose delivered to the colon and rectum, the risk of colorectal cancer was 2.8-fold higher (95% CI, 1.0-8.0) for patients with at least one relative affected by colorectal cancer than for patients without such a family history (p = 0.05). The radiation dose delivered to the colon and rectum by 131I and external radiation therapy was associated with an increase of risk near the significance threshold (p = 0.1). No significant interaction was found between radiation dose and having an affected relative (p = 0.9). Conclusions: The role of familial background in the risk of colorectal cancer following a differentiated thyroid carcinoma appears to increase with the radiation dose delivered to the colon and rectum. However, the study population was small and no interaction was found between these two factors

  11. Involvement of Crawling and Attached Ciliates in the Aggregation of Particles in Wastewater Treatment Plants

    Directory of Open Access Journals (Sweden)

    Lucía Arregui

    2008-01-01

    Full Text Available The biological community in activated sludge wastewater plants is organized within this ecosystem as bioaggregates or flocs, in which the biotic component is embedded in a complex matrix comprised of extracellular polymeric substances mainly of microbial origin. The aim of this work is to study the role of different floc-associated ciliates commonly reported in wastewater treatment plants-crawling Euplotes and sessile Vorticella- in the formation of aggregates. Flocs, in experiments with ciliates and latex beads, showed more compactation and cohesion among particles than those in the absence of ciliates. Ciliates have been shown to contribute to floc formation through different mechanisms such as the active secretion of polymeric substances (extrusomes, their biological activities (movement and feeding strategies, or the cysts formation capacity of some species. Staining with lectins coupled to fluorescein showed that carbohydrate of the matrix contained glucose, manose, N-acetyl-glucosamine and galactose. Protein fraction revealed over the latex beads surfaces could probably be of bacterial origin, but nucleic acids represented an important fraction of the extracellular polymeric substances of ciliate origin.

  12. Core-shell biopolymer nanoparticles produced by electrostatic deposition of beet pectin onto heat-denatured beta-lactoglobulin aggregates.

    Science.gov (United States)

    Santipanichwong, R; Suphantharika, M; Weiss, J; McClements, D J

    2008-08-01

    The purpose of this study was to produce and characterize core-shell biopolymer particles based on electrostatic deposition of an anionic polysaccharide (beet pectin) onto amphoteric protein aggregates (heat-denatured beta-lactoglobulin [beta-lg]). Initially, the optimum conditions for forming stable protein particles were established by thermal treatment (80 degrees C for 15 min) of 0.5 wt% beta-lg solutions at different pH values (3 to 7). After heating, stable submicron-sized (d=100 to 300 nm) protein aggregates could be formed in the pH range from 5.6 to 6. Core-shell biopolymer particles were formed by mixing a suspension of protein aggregates (formed by heating at pH 5.8) with a beet pectin solution at pH 7 and then adjusting the pH to values where the beet pectin is adsorbed (< pH 6). The impact of pH (3 to 7) and salt concentration (0 to 250 mM NaCl) on the properties of the core-shell biopolymer particles formed was then established. The biopolymer particles were stable to aggregation from pH 4 to 6, but aggregated at lower pH values because they had a relatively small -potential. The biopolymer particles remained intact and stable to aggregation up to 250 mM NaCl at pH 4, indicating that they had good salt stability. The core-shell biopolymer particles prepared in this study may be useful for encapsulation and delivery of bioactive food components or as substitutes for lipid droplets. PMID:19241582

  13. Detection of Gold Nanoparticles Aggregation Growth Induced by Nucleic Acid through Laser Scanning Confocal Microscopy

    OpenAIRE

    Ramla Gary; Giovani Carbone; Gia Petriashvili; Maria Penelope De Santo; Riccardo Barberi

    2016-01-01

    The gold nanoparticle (GNP) aggregation growth induced by deoxyribonucleic acid (DNA) is studied by laser scanning confocal and environmental scanning electron microscopies. As in the investigated case the direct light scattering analysis is not suitable, we observe the behavior of the fluorescence produced by a dye and we detect the aggregation by the shift and the broadening of the fluorescence peak. Results of laser scanning confocal microscopy images and the fluorescence emission spectra ...

  14. A Text Classifier Model for Categorizing Feed Contents Consumed by a Web Aggregator

    OpenAIRE

    H.O.D. Longe; Fatai Salami

    2014-01-01

    This paper presents a method of using a Text Classifier to automatically categorize the content of web feeds consumed by a web aggregator. The pre-defined category of the feed to be consumed by the aggregator does not always match the content being consumed and categorizing the content using the pre-defined category of the feed curtails user experience as users would not see all the contents belonging to their category of interest. A web aggregator was developed and this was integrated with t...

  15. Fluid motion and solute distribution around sinking aggregates II : Implications for remote detection by colonizing zooplankters

    DEFF Research Database (Denmark)

    Kiørboe, Thomas; Thygesen, Uffe Høgsbro

    2001-01-01

    Marine snow aggregates are colonized by copepods, and encounter rates inferred from observed abundances of colonizers are high. We examined the potential for hydromechanical and chemical remote detection. The fluid disturbance generated by a sinking aggregate was described by solving the Navier...... account for the observed abundances of colonizers. We next solved the advection-diffusion equation to describe the chemical trail left by a leaking and sinking aggregate. The plume is long and slender and may be detected by a horizontally cruising copepod. From the model of the plume and literature- based...... estimates of size-dependent aggregate leakage rates of amino acids, we estimate that a threshold sensitivity to amino acids of 0.4 x 10(-7) M is required to account for observed abundances of colonizers. This is consistent with knowledge of the amino acid concentrations needed to elicit behavioral responses...

  16. Tomato yellow leaf curl virus confronts host degradation by sheltering in small/midsized protein aggregates.

    Science.gov (United States)

    Gorovits, Rena; Fridman, Lilia; Kolot, Mikhail; Rotem, Or; Ghanim, Murad; Shriki, Oz; Czosnek, Henryk

    2016-02-01

    Tomato yellow leaf curl virus (TYLCV) is a begomovirus transmitted by the whitefly Bemisia tabaci to tomato and other crops. TYLCV proteins are endangered by the host defenses. We have analyzed the capacity of the tomato plant and of the whitefly insect vector to degrade the six proteins encoded by the TYLCV genome. Tomato and whitefly demonstrated the highest proteolytic activity in the fractions containing soluble proteins, less-in large protein aggregates; a significant decrease of TYLCV proteolysis was detected in the intermediate-sized aggregates. All the six TYLCV proteins were differently targeted by the cytoplasmic and nuclear degradation machineries (proteases, ubiquitin 26S proteasome, autophagy). TYLCV could confront host degradation by sheltering in small/midsized aggregates, where viral proteins are less exposed to proteolysis. Indeed, TYLCV proteins were localized in aggregates of various sizes in both host organisms. This is the first study comparing degradation machinery in plant and insect hosts targeting all TYLCV proteins. PMID:26654789

  17. Temperature dependence of aggregated structure of β-carotene by absorption spectral experiment and simulation.

    Science.gov (United States)

    Lu, Liping; Wu, Jie; Wei, Liangshu; Wu, Fang

    2016-12-01

    β-carotene can self-assemble to form J- or H-type aggregate in hydrophilic environments, which is crucial for the proper functioning of biological system. Although several ways controlling the formation of the two types of aggregate in hydrated ethanol have been investigated in recent years, our study provided another way to control whether J- or H- β-carotene was formed and presented a method to investigate the aggregated structure. For this purpose, the aggregates of β-carotene formed at different temperatures were studied by UV-Vis spectra and a computational method based on Frenkel exciton was applied to simulate the absorption spectra to obtain the aggregated structure of the β-carotene. The analysis showed that β-carotene formed weakly coupled H-aggregate at 15°C in 1:1 ethanol-water solvent, and with the increase of temperature it tended to form J-type of aggregate. The absorption spectral simulation based on one-dimensional Frenkel exciton model revealed that good fit with the experiment was obtained with distance between neighbor molecules r=0.82nm, disorder of the system D=1500cm(-1) for H-type and r=1.04nm, D=1800cm(-1) for J-type. PMID:27348046

  18. Structure of Fullerene Aggregates in Pyridine/Water Solutions by Small-Angle Neutron Scattering

    CERN Document Server

    Aksenov, V L; Belushkin, A V; Mihailovic, D; Mrzel, A; Rosta, L; Serdyuk, I N; Timchenko, A A

    2001-01-01

    Results of small-angle neutron scattering experiments on fullerenes (Co_{60}) in pyridine/water solutions are reported. They confirm conclusions of the previous studies, in particular, dynamic light scattering experiments. Aggregates with characteristic radius of about 20 nm are formed in the solutions. The contrast variation using different combinations of protonated/deuterated components (water and pyridine) of the solutions points to the small pyridine content inside the aggregates. This fact testifies that the aggregates consist of a massive fullerene core covered by a thin pyridine shell.

  19. Shifts in the Aggregate Demand Curve: Treatment and Mistreatment in Intermediate Textbooks.

    Science.gov (United States)

    Rangazas, Peter; Shapiro, Edward

    1987-01-01

    Claims that many intermediate macroeconomic textbooks contain incorrect examples of aggregate demand curves. Diagrams correct and incorrect curves and discusses how incorrect diagrams can lead students to draw wrong conclusions. Argues that textbooks should not sacrifice correctness for simplicity. (RKM)

  20. Triggering by Paf-acether and adrenaline of cyclo-oxygenase-independent platelet aggregation.

    OpenAIRE

    Fouque, F.; Vargaftig, B B

    1984-01-01

    Platelet-activating factor (Paf-acether, 1-alkyl-2-acetyl-sn-glycero-3-phosphorylcholine) induced full aggregation and a limited release reaction of human platelets in plasma or in blood. Cyclo-oxygenase inhibition with aspirin only reduced aggregation when induced by threshold amounts of Paf-acether, whereas higher concentrations surmounted inhibition whether tested in citrated or in heparinized platelet-rich plasma or blood. Aspirin-induced inhibition of platelet secretion by Paf-acether wa...

  1. Outward Motion of Porous Dust Aggregates by Stellar Radiation Pressure in Protoplanetary Disks

    OpenAIRE

    Tazaki, Ryo; Nomura, Hideko

    2014-01-01

    We study the dust motion at the surface layer of protoplanetary disks. Dust grains in surface layer migrate outward due to angular momentum transport via gas-drag force induced by the stellar radiation pressure. In this study, we calculate mass flux of the outward motion of compact grains and porous dust aggregates by the radiation pressure. The radiation pressure force for porous dust aggregates is calculated using the T-Matrix Method for the Clusters of Spheres. First, we confirm that porou...

  2. Platelet-collagen adhesion enhances platelet aggregation induced by binding of VWF to platelets

    International Nuclear Information System (INIS)

    Ristocetin-induced platelet aggregation (RIPA) was evaluated in the presence of platelet-collagen adhesion. RIPA of normal donor platelet-rich plasma (PRP) demonstrated a primary wave of aggregation mediated by the binding of von Willebrand factor (VWF) to platelets and a secondary aggregation wave, due to a platelet-release reaction, initiated by VWF-platelet binding and inhibitable by acetylsalicylic acid (ASA). An enhanced RIPA was observed in PRP samples to which collagen had been previously added. These subthreshold concentrations of collagen, which by themselves were insufficient to induce aggregation, caused measurable platelet-collagen adhesion. Subthreshold collagen did not cause microplatelet aggregation, platelet release of [3H]serotonin, or alter the dose-responsive binding of 125I-labeled VWF to platelets, which occurred with increasing ristocetin concentrations. However, ASA inhibition of the platelet release reaction prevented collagen-enhanced RIPA. These results demonstrate that platelet-collagen adhesion altered the platelet-release reaction induced by the binding of VWF to platelets causing a platelet-release reaction at a level of VWF-platelet binding not normally initiating a secondary aggregation. These findings suggest that platelet-collagen adhesion enhances platelet function mediated by VWF

  3. Single particle optical sizing; aggregation of polystyrene latices by salt and polymer.

    OpenAIRE

    Pelssers, E.G.M.

    1988-01-01

    The subject of this thesis is the development of a Single Particle Optical Sizer (SPOS) which is capable of measuring in detail discrete particle size distributions in the colloidal size range. With this instrument we studied the aggregation of latices induced by polymer and salt, and found evidence for non-equilibrium flocculation.Chapter 2 is an inventory of the existing methods of measuring aggregation. A comparison is made with our SPOS instrument. The techniques are classified into three...

  4. Accelerated tau aggregation, apoptosis and neurological dysfunction caused by chronic oral administration of aluminum in a mouse model of tauopathies.

    Science.gov (United States)

    Oshima, Etsuko; Ishihara, Takeshi; Yokota, Osamu; Nakashima-Yasuda, Hanae; Nagao, Shigeto; Ikeda, Chikako; Naohara, Jun; Terada, Seishi; Uchitomi, Yosuke

    2013-11-01

    To clarify whether long-term oral ingestion of aluminum (Al) can increase tau aggregation in mammals, we examined the effects of oral Al administration on tau accumulation, apoptosis in the central nervous system (CNS) and motor function using tau transgenic (Tg) mice that show very slowly progressive tau accumulation. Al-treated tau Tg mice had almost twice as many tau-positive inclusions in the spinal cord as tau Tg mice without Al treatment at 12 months of age, a difference that reached statistical significance, and the development of pretangle-like tau aggregates in the brain was also significantly advanced from 9 months. Al exposure did not induce any tau pathology in wild-type (WT) mice. Apoptosis was observed in the hippocampus in Al-treated tau Tg mice, but was virtually absent in the other experimental groups. Motor function as assessed by the tail suspension test was most severely impaired in Al-treated tau Tg mice. Given our results, chronic oral ingestion of Al may more strongly promote tau aggregation, apoptosis and neurological dysfunction if individuals already had a pathological process causing tau aggregation. These findings may also implicate chronic Al neurotoxicity in humans, who frequently have had mild tau pathology from a young age. PMID:23574527

  5. Combined modeling of cell aggregation and adhesion mediated by receptor–ligand interactions under shear flow

    Directory of Open Access Journals (Sweden)

    Yu Du

    2015-11-01

    Full Text Available Blood cell aggregation and adhesion to endothelial cells under shear flow are crucial to many biological processes such as thrombi formation, inflammatory cascade, and tumor metastasis, in which these cellular interactions are mainly mediated by the underlying receptor–ligand bindings. While theoretical modeling of aggregation dynamics and adhesion kinetics of interacting cells have been well studied separately, how to couple these two processes remains unclear. Here we develop a combined model that couples cellular aggregation dynamics and adhesion kinetics under shear flow. The impacts of shear rate (or shear stress and molecular binding affinity were elucidated. This study provides a unified model where the action of a fluid flow drives cell aggregation and adhesion under the modulations of the mechanical shear flow and receptor–ligand interaction kinetics. It offers an insight into understanding the relevant biological processes and functions.

  6. Reference intervals for platelet aggregation assessed by multiple electrode platelet aggregometry

    DEFF Research Database (Denmark)

    Rubak, Peter; Villadsen, Kirsten; Hvas, Anne-Mette

    2012-01-01

    Abstract Introduction Analyses of platelet aggregation in hirudin whole blood using Multiplate® was validated. Reference intervals for the most commonly used agonists were established, and the association between platelet aggregation, age, gender and haematological values was analysed. Material and...... methods We included 121 healthy individuals to establish reference intervals and six healthy individuals for evaluation of the day-to-day variation. Platelet aggregation was evaluated on hirudin whole blood employing Multiplate® induced by arachidonic acid, ADP, collagen and ristocetin (RISTOlow and...... < 0.0003), except RISTOlow (p = 0.05). A reference interval is presented as 95% confidence interval suitable for any age and both sex. Day-to-day variation was < 11% for all agonists except for RISTOlow. No association was found between platelet aggregation and haematocrit or red blood cell count...

  7. Dynamics of a shear-induced aggregation process by a combined Monte Carlo-Stokesian Dynamics approach

    OpenAIRE

    Frungieri, Graziano; Vanni, Marco

    2016-01-01

    In the present work we investigated the collision efficiency of colloidal aggregates suspended in a shear flow. A Discrete Element Method (DEM), built in the framework of Stokesian Dynamics, was developed to model hydrodynamic and colloidal interactions acting on each primary particle composing the aggregates. Aggregates with complex geometries were generated by means of a combined DEM-Monte Carlo algorithm able to reproduce a shear-induced aggregation process occurring in a dilute colloidal ...

  8. The concentration-dependent aggregation of Ag NPs induced by cystine.

    Science.gov (United States)

    Afshinnia, K; Gibson, I; Merrifield, R; Baalousha, M

    2016-07-01

    Cystine is widely used in cell culture media. Cysteine, the reduced form of cystine, is widely used to scavenge dissolved Ag in eco-toxicological studies to differentiate dissolved vs. nanoparticle uptake and toxicity. However, little is known about the impact of cysteine and cystine on the aggregation behavior of Ag NPs, in particular as a function of Ag NP concentration. Herein, we investigate how cystine (0-300μM) affects the stability of citrate-, polyvinylpyrrolidone-, and polyethylene glycol-coated silver nanoparticles (cit-Ag NPs, PVP-Ag NPs and PEG-Ag NPs, respectively) with and without Suwannee River fulvic acid (SRFA) as a function of Ag NPs concentration using UV-vis spectroscopy at environmentally and ecotoxicologically relevant Ag NP concentrations (ca. 125-1000μgL(-1)). The results demonstrate, for the first time, the concentration-dependent aggregation of cit-Ag NPs in the presence of cystine with a shift in the critical coagulation concentration (CCC) to lower cystine concentrations at lower cit-Ag NP concentrations. At the highest cit-Ag NP concentration (1000μgL(-1)), reaction limited aggregation was only observed and no CCC was measured. SRFA slowed the aggregation of cit-Ag NPs by cystine and aggregation occurred in reaction limited aggregation (RLA) regime only. No CCC value was measured in the presence of SRFA. Cystine replaces citrate, PVP and PEG coatings, resulting in aggregation of both electrostatically and sterically stabilized Ag NPs. These findings are important in understanding the factors determining the behavior of Ag NPs in cell culture media. Also due to the similarity between cystine and cysteine, these results are important in understanding the uptake and toxicity of Ag NPs vs. Ag ions, and suggest that the reduction of the toxicity of Ag NPs in the presence of cysteine could be due to a combined effect of scavenging Ag(+) ions and Ag NP aggregation in the presence of cysteine. PMID:27016687

  9. Evaluation of water transfer from saturated lightweight aggregate to cement paste matrix by neutron radiography

    International Nuclear Information System (INIS)

    In high-strength concrete with low water-cement ratio, self-desiccation occurs due to cement hydration and causes shrinkage and an increased risk of cracking. While high-strength concrete has a denser matrix than normal-strength concrete, resulting in lower permeability, early-age cracks would cancel out this advantage. For the mitigation of this self-desiccation and resultant shrinkage, water-saturated porous aggregate, such as artificial lightweight aggregate, may be used in high-strength concrete. In this contribution, for the purpose of clarification of the volume change of high-strength concrete containing water-saturated lightweight aggregate, water transfer from the lightweight aggregate to cement paste matrix is visualized by neutron radiography. As a result, it is clear that water was supplied to the cement paste matrix in the range 3-8 mm from the surface of the aggregate, and the osmotic forces may yield water transfer around lightweight aggregate in a few hours after mixing.

  10. Inhibition of rat platelet aggregation by the diazeniumdiolate nitric oxide donor MAHMA NONOate

    Science.gov (United States)

    Homer, Kerry L; Wanstall, Janet C

    2002-01-01

    Inhibition of rat platelet aggregation by the nitric oxide (NO) donor MAHMA NONOate (Z-1-{N-methyl-N-[6-(N-methylammoniohexyl)amino]}diazen-1-ium-1,2-diolate) was investigated. The aims were to compare its anti-aggregatory effect with vasorelaxation, to determine the effects of the soluble guanylate cyclase inhibitor, ODQ (1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one), and to investigate the possible role of activation of sarco-endoplasmic reticulum calcium-ATPase (SERCA), independent of soluble guanylate cyclase, using thapsigargin. MAHMA NONOate concentration-dependently inhibited sub-maximal aggregation responses to collagen (2–10 μg ml−1) and adenosine diphosphate (ADP; 2 μM) in platelet rich plasma. It was (i) more effective at inhibiting aggregation induced by collagen than by ADP, and (ii) less potent at inhibiting platelet aggregation than relaxing rat pulmonary artery. ODQ (10 μM) caused only a small shift (approximately half a log unit) in the concentration-response curve to MAHMA NONOate irrespective of the aggregating agent. The NO-independent activator of soluble guanylate cyclase, YC-1 (3-(5′-hydroxymethyl-2′-furyl)-1-benzyl indazole; 1–100 μM), did not inhibit aggregation. The cGMP analogue, 8-pCPT-cGMP (8-(4-chlorophenylthio)guanosine 3′5′ cyclic monophosphate; 0.1–1 mM), caused minimal inhibition. On collagen-aggregated platelets responses to MAHMA NONOate (ODQ 10 μM present) were abolished by thapsigargin (200 nM). On ADP-aggregated platelets thapsigargin caused partial inhibition. Results with S-nitrosoglutathione (GSNO) resembled those with MAHMA NONOate. Glyceryl trinitrate and sodium nitroprusside were poor inhibitors of aggregation. Thus inhibition of rat platelet aggregation by MAHMA NONOate (like GSNO) is largely ODQ-resistant and, by implication, independent of soluble guanylate cyclase. A likely mechanism of inhibition is activation of SERCA. PMID:12429580

  11. A STDY ON EFFECT OF SIZE OF AGGREGATE ON COMPRESSIVE STRENGHT OF CONCRETE AND STRENGHT CHARACTERSTICS BY UTILIZATIION OF WASTE MATERIALS AS COURSE AGGREGATE IN CONCRETE

    Directory of Open Access Journals (Sweden)

    SETTIUBATHULA RAMYA

    2015-05-01

    Full Text Available Depletion of natural resources is a common phenomenon in developing countries like India due to rapid urbanization and Industrialization involving construction of Infrastructure and other amenities. In view of this, searching for suitable other viable alternative materials for concrete so that the existing natural resources could be preserved to the possible extent, for the future generation. To investigate the effect of size of aggregate on the compressive strength of concrete an experimental program was carried out. Four different sizes of coarse aggregates were used while developing the mix design. The sizes of coarse aggregate were 25mm, 20mm, 10mm and 4.75mm. Natural sand with fineness modules of 3.48 was used as fine aggregate. Ordinary Portland cement of 43 Grade was used as binding material. Different trials of mixing of coarse aggregate were made (25 mm and 20mm, 20mm and 10mm, 10mm and 4.75mm to investigate the influence of size of aggregate on compressive strength of concrete. Cubes of size 150mmx150mmx150mm were cast in laboratory and tested in Compression Testing Machine. It was concluded that 10mm and 4.75mm aggregates showed higher compressive strength than other types of aggregates. The tests revealed that on the replacement of 20% of ceramic tiles had increased the compressive strength of 13% more than that of conventional concrete. And it was observed that optimum ceramic tiles content was 20%. It is observed that by using 10% of plastic waste in concrete ,the fatigue characteristics of modified concrete has increased than that of plain cement concrete

  12. Biophysical signatures of noncovalent aggregates formed by a glucagonlike peptide-1 analog: a prototypical example of biopharmaceutical aggregation.

    Science.gov (United States)

    Doyle, Brandon L; Pollo, Mark J; Pekar, Allen H; Roy, Michael L; Thomas, Beth Ann; Brader, Mark L

    2005-12-01

    LY307161 is a 31 amino acid analog of glucagonlike peptide-1(7-37)OH susceptible to physical instability associated with pharmaceutical processing. Orthogonal biophysical studies were conducted to explore the origins of this physical instability and to distinguish pharmaceutically desirable states of this aggregating peptide from undesirable ones. Equilibrium sedimentation analysis established that LY307161 exists as a monomer at pH 3, and reversibly self-associates in the pH range 7.5-10.5. Causative factors for physical instability related to lyophilization conditions were investigated. Solution pH, acetonitrile content, and concentration of the peptide prior to lyophilization each impacted physicochemical properties of the resultant powders. A comparative study of two powder samples exhibiting physicochemically disparate properties established that LY307161 forms soluble noncovalent aggregates. FT-IR analyses in the solid and solution states identified a prominent band at 1657-1659 cm(-1) attributed to alpha-helix structure. Noncovalent soluble aggregate exhibited characteristic bands at 1615 and 1698 cm(-1) indicative of intermolecular beta-sheet structure. An agitation-induced, precipitated solid form of LY307161 exhibited a different FT-IR signature indicative of a conformationally distinct species. Circular dichroism and fluorescence spectroscopy, together with dynamic light scattering measurements and dye-aggregate complexation, provided additional insights into the distinctions between aggregated and native LY307161. PMID:16258989

  13. Regulation of synaptic Pumilio function by an aggregation-prone domain.

    Science.gov (United States)

    Salazar, Anna M; Silverman, Edward J; Menon, Kaushiki P; Zinn, Kai

    2010-01-13

    We identified Pumilio (Pum), a Drosophila translational repressor, in a computational search for metazoan proteins whose activities might be regulated by assembly into ordered aggregates. The search algorithm was based on evolutionary sequence conservation patterns observed for yeast prion proteins, which contain aggregation-prone glutamine/asparagine (Q/N)-rich domains attached to functional domains of normal amino acid composition. We examined aggregation of Pum and its nematode ortholog PUF-9 by expression in yeast. A domain of Pum containing the Q/N-rich sequence, denoted as NQ1, the entire Pum N terminus, and the complete PUF-9 protein localize to macroscopic aggregates (foci) in yeast. NQ1 and PUF-9 can generate the yeast Pin+ trait, which is transmitted by a heritable aggregate. NQ1 also assembles into amyloid fibrils in vitro. In Drosophila, Pum regulates postsynaptic translation at neuromuscular junctions (NMJs). To assess whether NQ1 affects synaptic Pum activity in vivo, we expressed it in muscles. We found that it negatively regulates endogenous Pum, producing gene dosage-dependent pum loss-of-function NMJ phenotypes. NQ1 coexpression also suppresses lethality and NMJ phenotypes caused by overexpression of Pum in muscles. The Q/N block of NQ1 is required for these phenotypic effects. Negative regulation of Pum by NQ1 might be explained by formation of inactive aggregates, but we have been unable to demonstrate that NQ1 aggregates in Drosophila. NQ1 could also regulate Pum by a "dominant-negative" effect, in which it would block Q/N-mediated interactions of Pum with itself or with cofactors required for translational repression. PMID:20071514

  14. Aggregate stability and associated C and N in a silty loam soil as affected by organic material inputs

    Institute of Scientific and Technical Information of China (English)

    LONG Pan; SUI Peng; GAO Wang-sheng; WANG Bin-bin; HUANG Jian-xiong; YAN Peng; ZOU Juan-xiu; YAN Ling-ling; CHEN Yuan-quan

    2015-01-01

    To make recycling utilization of organic materials produced in various agricultural systems, ifve kinds of organic materials were applied in a ifeld test, including crop straw (CS), biogas residue (BR), mushroom residue (MR), wine residue (WR), pig manure (PM), with a mineral fertilizer (CF) and a no-fertilizer (CK) treatment as a control. Our objectives were:i) to quantify the effects of organic materials on soil C and N accumulation;i ) to evaluate the effects of organic materials on soil aggregate stability, along with the total organic carbon (TOC), and N in different aggregate fractions;and i i) to assess the relationships among the organic material components, soil C and N, and C, N in aggregate fractions. The trial was conducted in Wuqiao County, Hebei Province, China. The organic materials were incorporated at an equal rate of C, and combined with a mineral fertilizer in amounts of 150 kg N ha-1, 26 kg P ha-1 and 124 kg K ha-1 respectively during each crop season of a wheat-maize rotation system. The inputted C quantity of each organic material treatment was equivalent to the total amount of C contained in the crop straw harvested in CS treatement in the previous season. TOC, N, water-stable aggregates, and aggregate-associated TOC and N were investigated. The results showed that organic material incorpora-tion increased soil aggregation and stabilization. On average, the soil macroaggregate proportion increased by 14%, the microaggregate proportion increased by 3%, and mean-weight diameter (MWD) increased by 20%. TOC content fol owed the order of PM>WR>MR>BR>CS>CK>CF;N content fol owed the order WR>PM>MR>BR>CS>CF>CK. No signiifcant correlation was found between TOC, N, and the quality of organic material. Soil silt and clay particles contained the largest part of TOC, whereas the smal macroaggregate fraction was the most sensitive to organic materials. Our results indicate that PM and WR exerted better effects on soil C and N accumulation, fol owed by MR

  15. Inhibition of Platelet Aggregation by the Leaf Extract of Carica papaya During Dengue Infection: An In Vitro Study.

    Science.gov (United States)

    Chinnappan, Shobia; Shettikothanuru Ramachandrappa, Vijayakumar; Tamilarasu, Kadhiravan; Krishnan, Uma Maheswari; Balakrishna Pillai, Agiesh Kumar; Rajendiran, Soundravally

    2016-04-01

    Dengue cases were reported to undergo platelet activation and thrombocytopenia by a poorly understood mechanism. Recent studies suggested that Carica papaya leaf extract could recover the platelet count in dengue cases. However, no studies have attempted to unravel the mechanism of the plant extract in platelet recovery. Since there are no available drugs to treat dengue and considering the significance of C. papaya in dengue treatment, the current study aimed to evaluate two research questions: First one is to study if the C. papaya leaf extract exerts its action directly on platelets and second one is to understand if the extract can specifically inhibit the platelet aggregation during dengue viral infection. Sixty subjects with dengue positive and 60 healthy subjects were recruited in the study. Platelet-rich plasma (PRP) and platelet-poor plasma were prepared from both the dengue-infected and healthy control blood samples. Effect of the leaf extract obtained from C. papaya leaves was assessed on plasma obtained as well as platelets collected from both healthy and dengue-infected individuals. Platelet aggregation was significantly reduced when leaf extract preincubated with dengue plasma was added into control PRP, whereas no change in aggregation when leaf extract incubated-control plasma was added into control PRP. Upon direct addition of C. papaya leaf extract, both dengue PRP and control PRP showed a significant reduction in platelet aggregation. Within the dengue group, PRP from severe and nonsevere cases showed a significant decrease in aggregation without any difference between them. From the study, it is evident that C. papaya leaf extract can directly act on platelet. The present study, the first of its kind, found that the leaf extract possesses a dengue-specific neutralizing effect on dengue viral-infected plasma that may exert a protective role on platelets. PMID:26910599

  16. Study of aggregation in a micellar solution within bentonite clay by SANS

    International Nuclear Information System (INIS)

    Aggregation studies of surfactant solutions exposed to different surfaces are relevant to their applications as detergents, oil recovery agents etc. The infusion of SDS micellar solutions into the pores of compacted normal bentonite clay and the clay saturated with sodium at different concentrations viz. 1, 2 and 5 molar percentages, has been studied here by small angle neutron scattering and X-ray diffraction. In the sodium saturated bentonite, the Na+ ion (having a positive scattering length) is held in the interlayer of the clay and on account of this, the scattering length density difference (i.e. contrast) between the bentonite matrix and the inter-layer pores is lower than the bentonite which has less sodium. The average pore size in normal bentonite clay is 13 Å while in the clay saturated with 1M Na+ ions it is 20 Å . For a 10% SDS solution, the micelles are prolate ellipsoids having average semi major and minor axes of 22.5 Å and 16.7 Å, respectively with an effective charge of 30 e.u. and an aggregation number of 75. Both aggregation number and effective charge increase with concentration of SDS solution. Sodium is present in normal bentonite but is enhanced in concentration in the case of sodium saturated bentonite. Aggregation number and micellar separation are reduced for SDS loaded into raw bentonite clay and then into Na saturated clay. Likewise, there is a reduction of fractional charge on the micelle in going from raw to sodium bentonite caused by the Na+ ions present on the surface of the clay pores which would be attracted to the negative surface of each micelle thereby reducing its net charge. The effective attraction between micelles and Na+ ion concentration control the growth of aggregates, their volumes and aggregation numbers. Hence the sodium ion in the bentonite plays a vital role in the change of these parameters by effectively reducing charge on the micellar aggregates.

  17. Aggregation of macrophages and fibroblasts is inhibited by a monoclonal antibody to the hyaluronate receptor

    Energy Technology Data Exchange (ETDEWEB)

    Green, S.J.; Underhill, C.B. (Georgetown Univ. Medical Center, Washington, DC (USA)); Tarone, G. (Univ. of Turin (Italy))

    1988-10-01

    To examine the role of the hyaluronate receptor in cell to cell adhesion, the authors have employed the K-3 monoclonal antibody (MAb) which specifically binds to the hyaluronate receptor and blocks its ability to interact with hyaluronate. In the first set of experiments, they investigated the spontaneous aggregation of SV-3T3 cells, which involves two distinct mechanisms, one of which is dependent upon the presence of divalent cation and the other is independent. The divalent cation-independent aggregation was found to be completely inhibited by both intact and Fab fragments of the K-3 MAb. In contrast, the K-3 MAb had no effect on the divalent cation-dependent aggregation of cells. In a second set of experiments, we examined alveolar macrophages. The presence of hyaluronate receptors on alveolar macrophages was demonstrated by the fact that detergent extracts of these cells could bind ({sup 3})hyaluronate, and this binding was blocked by the K-3 MAb. Immunoblot analysis of alveolar macrophages showed that the hyaluronate receptor had a M{sub r} of 99,500, which is considerably larger than the 85,000 M{sub r} for that on BHK cells. When hyaluronate was added to suspensions of alveolar macrophages, the cells were induced to aggregate. This effect was inhibited by the K-3 MAb, suggesting that the hyaluronate-induced aggregation was mediated by the receptor.

  18. Outward Motion of Porous Dust Aggregates by Stellar Radiation Pressure in Protoplanetary Disks

    CERN Document Server

    Tazaki, Ryo

    2014-01-01

    We study the dust motion at the surface layer of protoplanetary disks. Dust grains in surface layer migrate outward due to angular momentum transport via gas-drag force induced by the stellar radiation pressure. In this study, we calculate mass flux of the outward motion of compact grains and porous dust aggregates by the radiation pressure. The radiation pressure force for porous dust aggregates is calculated using the T-Matrix Method for the Clusters of Spheres. First, we confirm that porous dust aggregates are forced by strong radiation pressure even if they grow to be larger aggregates in contrast to homogeneous and spherical compact grains to which efficiency of radiation pressure becomes lower when their sizes increase. In addition, we find that the outward mass flux of porous dust aggregates with monomer size of 0.1 $\\mu$m is larger than that of compact grains by an order of magnitude at the disk radius of 1 AU, when their sizes are several microns. This implies that large compact grains like calcium-a...

  19. Tuning the thermal diffusivity of silver based nanofluids by controlling nanoparticle aggregation

    Science.gov (United States)

    Agresti, Filippo; Barison, Simona; Battiston, Simone; Pagura, Cesare; Colla, Laura; Fedele, Laura; Fabrizio, Monica

    2013-09-01

    With the aim of preparing stable nanofluids for heat exchange applications and to study the effect of surfactant on the aggregation of nanoparticles and thermal diffusivity, stable silver colloids were synthesized in water by a green method, reducing AgNO3 with fructose in the presence of poly-vinylpyrollidone (PVP) of various molecular weights. A silver nanopowder was precipitated from the colloids and re-dispersed at 4 vol% in deionized water. The Ag colloids were characterized by UV-visible spectroscopy, combined dynamic light scattering and ζ-potential measurements, and laser flash thermal diffusivity. The Ag nanopowders were characterized by scanning electron microscopy and thermal gravimetric analysis. It was found that the molecular weight of PVP strongly affects the ζ-potential and the aggregation of nanoparticles, thereby affecting the thermal diffusivity of the obtained colloids. In particular, it was observed that on increasing the molecular weight of PVP the absolute value of the ζ-potential is reduced, leading to increased aggregation of nanoparticles. A clear relation was identified between thermal diffusivity and aggregation, showing higher thermal diffusivity for nanofluids having higher aggregation. A maximum improvement of thermal diffusivity by about 12% was found for nanofluids prepared with PVP having higher molecular weight.

  20. Non surgical perforation repair by mineral trioxide aggregate under dental operating microscope

    OpenAIRE

    Mousumi Biswas; Dibyendu Mazumdar; Abhijit Neyogi

    2011-01-01

    Root perforation repair has historically been an unpredictable treatment modality, with an unacceptably high rate of clinical failure. Recent developments in the techniques and materials utilized in root perforation repair have dramatically enhanced the prognosis of both surgical and nonsurgical procedures. Mineral Trioxide Aggregate is a relatively new material that is being successfully used to repair perforations. Technological advancements such as the use of a Dental Operating Microscope ...

  1. The Heparin-Induced Thrombocytopenia and Thrombosis Syndrome: Treatment with Intraarterial Urokinase and Systemic Platelet Aggregation Inhibitors

    International Nuclear Information System (INIS)

    We report a case of the heparin-induced thrombocytopenia and thrombosis syndrome presenting with acute ischemia of a lower limb. The patient was successfully treated by withdrawal of heparin products, intraarterial urokinase, and platelet anti-aggregation therapy consisting of Dextran and aspirin

  2. Aggregation Of Volcanic Particles: Physical Constraints Provided By Field And Numerical Investigations

    Science.gov (United States)

    Rossi, E.; Bagheri, G.; Bonadonna, C.

    2014-12-01

    The characterization and parameterization of both sedimentation and aggregation of volcanic particles is necessary for an accurate description of the sink term in numerical models of tephra dispersal used for the evaluation of tephra hazards. Nonetheless, our understanding of particle fallout in various eruptive and atmospheric conditions is still limited mostly due to the lack of direct observations. A comparative investigation of sedimentation and aggregation of volcanic particles is here presented based on field experiments and numerical simulations. Field experiments are based on detailed observations of particle fallout during Vulcanian explosions and ash emissions at Sakurajima volcano (Japan) on August 3, 2013. Column height was up to about 3 km above sea level and the cloud spread with average velocity of about 7 ms-1 toward southeast direction. Aggregates that fell at a distance of about 4 km from the vent were filmed with a high-speed and high-resolution camera before depositing on collection glasses. In order to preserve and analyze particle aggregates with the Scanning Electron Microscope, collecting glasses were covered with a special adhesive tape. Dedicated trays were also used to collect the depositing tephra at five-minute intervals to investigate both accumulation rate and particle size. CILAS grain size analysis showed that mode of particles deposited on the ground decreased with time from 550 μm to 250 μm at the reference location. Aggregate size ranged between 400 and 900 μm (based on video analysis) and they mostly consist of a single or multiple particles acting as nuclei with diameter between 200 and 800 μm coated with ash particles (clusters. Aggregation significantly affected particle residence time in the spreading cloud by changing the associated settling velocity. Based on numerical constraints, aggregates were thought to be formed within the rising plume or at the corner with the horizontal cloud and within 200 seconds of the onset

  3. Investigation of aggregation in solvent extraction of lanthanides by acidic extractants (organophosphorus and naphthenic acid)

    Science.gov (United States)

    Zhou, N.; Wu, J.; Yu, Z.; Neuman, R.D.; Wang, D.; Xu, G.

    1997-01-01

    Three acidic extractants (I) di(2-ethylhexyl) phosphoric acid (HDEHP), (II) 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (HEHPEHE) and (III) naphthenic acid were employed in preparing the samples for the characterization of the coordination structure of lanthanide-extractant complexes and the physicochemical nature of aggregates formed in the organic diluent of the solvent extraction systems. Photo correlation spectroscopy (PCS) results on the aggregates formed by the partially saponified HDEHP in n-heptane showed that the hydrodynamic radius of the aggregates was comparable to the molecular dimensions of HDEHP. The addition of 2-octanol into the diluent, by which the mixed solvent was formed, increased the dimensions of the corresponding aggregates. Aggregates formed from the lanthanide ions and HDEHP in the organic phase of the extraction systems were found very unstable. In the case of naphthenic acid, PCS data showed the formation of w/o microemulsion from the saponified naphthenic acid in the mixed solvent. The extraction of lanthanides by the saponified naphthenic acid in the mixed solvent under the given experimental conditions was a process of destruction of the w/o microemulsion. A possible mechanism of the breakdown of the w/o microemulsion droplets is discussed.

  4. Effect of alginate on the aggregation kinetics of copper oxide nanoparticles (CuO NPs): bridging interaction and hetero-aggregation induced by Ca(2.).

    Science.gov (United States)

    Miao, Lingzhan; Wang, Chao; Hou, Jun; Wang, Peifang; Ao, Yanhui; Li, Yi; Lv, Bowen; Yang, Yangyang; You, Guoxiang; Xu, Yi

    2016-06-01

    The stability of CuO nanoparticles (NPs) is expected to play a key role in the environmental risk assessment of nanotoxicity in aquatic systems. In this study, the effect of alginate (model polysaccharides) on the stability of CuO NPs in various environmentally relevant ionic strength conditions was investigated by using time-resolved dynamic light scattering. Significant aggregation of CuO NPs was observed in the presence of both monovalent and divalent cations. The critical coagulation concentrations (CCC) were 54.5 and 2.9 mM for NaNO3 and Ca(NO3)2, respectively. The presence of alginate slowed nano-CuO aggregation rates over the entire NaNO3 concentration range due to the combined electrostatic and steric effect. High concentrations of Ca(2+) (>6 mM) resulted in stronger adsorption of alginate onto CuO NPs; however, enhanced aggregation of CuO NPs occurred simultaneously under the same conditions. Spectroscopic analysis revealed that the bridging interaction of alginate with Ca(2+) might be an important mechanism for the enhanced aggregation. Furthermore, significant coagulation of the alginate molecules was observed in solutions of high Ca(2+) concentrations, indicating a hetero-aggregation mechanism between the alginate-covered CuO NPs and the unabsorbed alginate. These results suggested a different aggregation mechanism of NPs might co-exist in aqueous systems enriched with natural organic matter, which should be taken into consideration in future studies. Graphical abstract Hetero-aggregation mechanism of CuO nanoparticles and alginate under high concentration of Ca(2.) PMID:26931664

  5. Muscle imaging in patients with tubular aggregate myopathy caused by mutations in STIM1.

    Science.gov (United States)

    Tasca, Giorgio; D'Amico, Adele; Monforte, Mauro; Nadaj-Pakleza, Aleksandra; Vialle, Marc; Fattori, Fabiana; Vissing, John; Ricci, Enzo; Bertini, Enrico

    2015-11-01

    Tubular aggregate myopathy is a genetically heterogeneous disease characterized by tubular aggregates as the hallmark on muscle biopsy. Mutations in STIM1 have recently been identified as one genetic cause in a number of tubular aggregate myopathy cases. To characterize the pattern of muscle involvement in this disease, upper and lower girdles and lower limbs were imaged in five patients with mutations in STIM1, and the scans were compared with two patients with tubular aggregate myopathy not caused by mutations in STIM1. A common pattern of involvement was found in STIM1-mutated patients, although with variable extent and severity of lesions. In the upper girdle, the subscapularis muscle was invariably affected. In the lower limbs, all the patients showed a consistent involvement of the flexor hallucis longus, which is very rarely affected in other muscle diseases, and a diffuse involvement of thigh and posterior leg with sparing of gracilis, tibialis anterior and, to a lesser extent, short head of biceps femoris. Mutations in STIM1 are associated with a homogeneous involvement on imaging despite variable clinical features. Muscle imaging can be useful in identifying STIM1-mutated patients especially among other forms of tubular aggregate myopathy. PMID:26255678

  6. Evaluation of Masonry Mortars Made with Mixed Recycled Aggregates by Different Processes

    OpenAIRE

    Iván Martínez Herrera; Miren Etxeberria Larrañaga; Elier Pavón de la Fé; Nelson Díaz Brito

    2012-01-01

    Havana produces over 1000 m3 of construction and demolition waste (CDW) per day. Most of these residues are of a mixed composition; they come either from collapsing buildings in disrepair or demolition that are not performed selectively. From the CDW, there are usually two ways to produce recycled aggregates; one is by sifting the debris through a 5mm sieve which is a practice widely used by residents in cities and the other from is by crushing the coarse fractions in recycled aggregate produ...

  7. Protein Folding and Aggregation into Amyloid: The Interference by Natural Phenolic Compounds

    Directory of Open Access Journals (Sweden)

    Massimo Stefani

    2013-06-01

    Full Text Available Amyloid aggregation is a hallmark of several degenerative diseases affecting the brain or peripheral tissues, whose intermediates (oligomers, protofibrils and final mature fibrils display different toxicity. Consequently, compounds counteracting amyloid aggregation have been investigated for their ability (i to stabilize toxic amyloid precursors; (ii to prevent the growth of toxic oligomers or speed that of fibrils; (iii to inhibit fibril growth and deposition; (iv to disassemble preformed fibrils; and (v to favor amyloid clearance. Natural phenols, a wide panel of plant molecules, are one of the most actively investigated categories of potential amyloid inhibitors. They are considered responsible for the beneficial effects of several traditional diets being present in green tea, extra virgin olive oil, red wine, spices, berries and aromatic herbs. Accordingly, it has been proposed that some natural phenols could be exploited to prevent and to treat amyloid diseases, and recent studies have provided significant information on their ability to inhibit peptide/protein aggregation in various ways and to stimulate cell defenses, leading to identify shared or specific mechanisms. In the first part of this review, we will overview the significance and mechanisms of amyloid aggregation and aggregate toxicity; then, we will summarize the recent achievements on protection against amyloid diseases by many natural phenols.

  8. Inhibition of IAPP Aggregation and Toxicity by Natural Products and Derivatives

    Directory of Open Access Journals (Sweden)

    Amit Pithadia

    2016-01-01

    Full Text Available Fibrillar aggregates of human islet amyloid polypeptide, hIAPP, a pathological feature seen in some diabetes patients, are a likely causative agent for pancreatic beta-cell toxicity, leading to a transition from a state of insulin resistance to type II diabetes through the loss of insulin producing beta-cells by hIAPP induced toxicity. Because of the probable link between hIAPP and the development of type II diabetes, there has been strong interest in developing reagents to study the aggregation of hIAPP and possible therapeutics to block its toxic effects. Natural products are a class of compounds with interesting pharmacological properties against amyloids which have made them interesting targets to study hIAPP. Specifically, the ability of polyphenolic natural products, EGCG, curcumin, and resveratrol, to modulate the aggregation of hIAPP is discussed. Furthermore, we have outlined possible mechanistic discoveries of the interaction of these small molecules with the peptide and how they may mitigate toxicity associated with peptide aggregation. These abundantly found agents have been long used to combat diseases for many years and may serve as useful templates toward developing therapeutics against hIAPP aggregation and toxicity.

  9. A Text Classifier Model for Categorizing Feed Contents Consumed by a Web Aggregator

    Directory of Open Access Journals (Sweden)

    H.O.D. Longe

    2014-09-01

    Full Text Available This paper presents a method of using a Text Classifier to automatically categorize the content of web feeds consumed by a web aggregator. The pre-defined category of the feed to be consumed by the aggregator does not always match the content being consumed and categorizing the content using the pre-defined category of the feed curtails user experience as users would not see all the contents belonging to their category of interest. A web aggregator was developed and this was integrated with the SVM classifier to automatically categorize feed content being consumed. The experimental results showed that the text classifier performs well in categorizing the content of feed being consumed and it also affirmed the disparity in the pre-defined category of the source feed and appropriate category of the consumed content.

  10. Proposing an Aggregate Production Planning Model by Goal Programming Approach, a Case Study

    Directory of Open Access Journals (Sweden)

    Mansoureh Farzam Rad

    2014-06-01

    Full Text Available Production planning is one of the most important functions in the process of production management. Production planning in the intermediate range of time is termed as aggregate production planning (APP. Aggregate production planning is an important upper level planning activity in a production management system. The present study tries to suggest an aggregate production planning model for products of Hafez tile factory during one year. Due to this fact that the director of the company seeks 3 main objectives to determine the optimal production rate, the linear goal planning method was employed. After solving the problem, in order to examine the efficiency and the distinctiveness of this method in compare to linear programming, the problem was modeled just by considering one objective then was solved by linear programming approach. The findings revealed the goal programming with multi objectives resulted more appropriate solution rather than linear programming with just one objective.

  11. Cylindrical aggregates of chlorophylls studied by small-angle neutron scatter

    International Nuclear Information System (INIS)

    Neutron small-angle scattering has demonstrated tubular chlorophyll aggregates formed by self-assembly of a variety of chlorophyll types in nonpolar solvents. The size and other properties of the tubular aggregates can be accounted for by stereochemical properties of the chlorophyll molecules. Features of some of the structures are remarkably similar to light harvesting chlorophyll complexes in vivo, particularly for photosynthetic bacteria. These nanotube chlorophyll structures may have applications as light harvesting biomaterials where efficient energy transfer occurs from an excited state which is highly delocalized

  12. Cylindrical aggregates of chlorophylls studied by small-angle neutron scatter

    Energy Technology Data Exchange (ETDEWEB)

    Worcester, D.L. [Univ. of Missouri, Columbus, MO (United States); Katz, J.J. [Argonne National Laboratory, IL (United States)

    1994-12-31

    Neutron small-angle scattering has demonstrated tubular chlorophyll aggregates formed by self-assembly of a variety of chlorophyll types in nonpolar solvents. The size and other properties of the tubular aggregates can be accounted for by stereochemical properties of the chlorophyll molecules. Features of some of the structures are remarkably similar to light harvesting chlorophyll complexes in vivo, particularly for photosynthetic bacteria. These nanotube chlorophyll structures may have applications as light harvesting biomaterials where efficient energy transfer occurs from an excited state which is highly delocalized.

  13. Synthesis of gold nanoparticles stabilised by metal-chelator and the controlled formation of close-packed aggregates by them

    Indian Academy of Sciences (India)

    Santanu Bhattacharya; Aasheesh Srivastava

    2003-10-01

    Nanoparticles have properties that can be fine-tuned by their size as well as shape. Hence, there is significant current interest in preparing nano-materials of small size dispersity and to arrange them in close-packed aggregates. This manuscript describes ways of synthesising gold nanoparticles using a metal-chelator derivative 1, as stabiliser. Controlled synthesis conditions lead to formation of nanoparticles thereby indicating the ability of 1 to act as efficient stabiliser. The nanoparticles formed were characterised by transmission electron microscopy and UV-Vis spectroscopy. TEM analysis showed the formation of dense aggregates of nanoparticles. This can be ascribed to the inter-particle hydrogen bonding possible by the carboxylic acid moiety of 1 that leads to aggregation. The aggregation can be controlled by the pH of the solution employed for dispersing the particles.

  14. Difference in aggregation between functional and toxic amyloids studied by atomistic simulations

    Science.gov (United States)

    Carballo Pacheco, Martin; Ismail, Ahmed E.; Strodel, Birgit

    Amyloids are highly structured protein aggregates, normally associated with neurodegenerative diseases such as Alzheimer's disease. In recent years, a number of nontoxic amyloids with physiologically normal functions, called functional amyloids, have been found. It is known that soluble small oligomers are more toxic than large fibrils. Thus, we study with atomistic explicit-solvent molecular dynamics simulations the oligomer formation of the amyloid- β peptide Aβ25 - 35, associated with Alzheimer's disease, and two functional amyloid-forming tachykinin peptides: kassinin and neuromedin K. Our simulations show that monomeric peptides in extended conformations aggregate faster than those in collapsed hairpin-like conformations. In addition, we observe faster aggregation by functional amyloids than toxic amyloids, which could explain their lack of toxicity.

  15. Rapid Formation of Cell Aggregates and Spheroids Induced by a "Smart" Boronic Acid Copolymer.

    Science.gov (United States)

    Amaral, Adérito J R; Pasparakis, George

    2016-09-01

    Cell surface engineering has emerged as a powerful approach to forming cell aggregates/spheroids and cell-biomaterial ensembles with significant uses in tissue engineering and cell therapeutics. Herein, we demonstrate that cell membrane remodeling with a thermoresponsive boronic acid copolymer induces the rapid formation of spheroids using either cancer or cardiac cell lines under conventional cell culture conditions at minute concentrations. It is shown that the formation of well-defined spheroids is accelerated by at least 24 h compared to non-polymer-treated controls, and, more importantly, the polymer allows for fine control of the aggregation kinetics owing to its stimulus response to temperature and glucose content. On the basis of its simplicity and effectiveness to promote cellular aggregation, this platform holds promise in three-dimensional tissue/tumor modeling and tissue engineering applications. PMID:27571512

  16. Assessing magnetic nanoparticle aggregation in polymer melts by dynamic magnetic susceptibility measurements

    Energy Technology Data Exchange (ETDEWEB)

    Sierra-Bermúdez, Sergio [Department of Chemical Engineering, University of Puerto Rico, P.O. Box 9000 Mayaguez, PR 00681 PR (United States); Maldonado-Camargo, Lorena P. [Department of Chemical Engineering, University of Florida, 1006 Center Drive, Gainesville, FL 32603 (United States); Orange, François [Department of Physics and Nanoscopy Facility, College of Natural Sciences, University of Puerto Rico, PO Box 70377, San Juan, PR 00936-8377 (United States); Guinel, Maxime J.-F. [Department of Physics and Nanoscopy Facility, College of Natural Sciences, University of Puerto Rico, PO Box 70377, San Juan, PR 00936-8377 (United States); Department of Chemistry, College of Natural Sciences, University of Puerto Rico, PO Box 70377, San Juan, PR 00936-8377 (United States); Rinaldi, Carlos, E-mail: carlos.rinaldi@bme.ufl.edu [J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, PO Box 116131, Gainesville, FL 32611-6131 (United States)

    2015-03-15

    Aggregation of magnetic nanoparticles in polymer melts was assessed using dynamic magnetic susceptibility measurements. Magnetic nanocomposites consisting of polybutadiene/CoFe{sub 2}O{sub 4} and polystyrene/CoFe{sub 2}O{sub 4} mixtures were prepared using different techniques and characterized using dynamic magnetic susceptibility measurements. The presence of nanoparticle aggregates determined using magnetic measurements was confirmed with transmission electron microscopy examinations. The results were in good agreement with predictions from the Flory–Huggins interaction parameters. - Highlights: • Oleic acid coated magnetic nanoparticles (MNPs) were dispersed in polymer melts. • MNPs dispersed well in polybutadiene but not in polystyrene. • Dynamic magnetic susceptibility (DMS) measurements assessed presence of aggregates. • DMS predictions were confirmed by transmission electron microscopy. • The Flory-Huggins interaction parameter correlated with MNP dispersion.

  17. Analysis of the End-by-Hop Protocol for Secure Aggregation in Sensor Networks

    DEFF Research Database (Denmark)

    Zenner, Erik

    In order to save bandwidth and thus battery power, sensor network measurements are sometimes aggregated en-route while being reported back to the querying server. Authentication of the measurements then becomes a challenge if message integrity is important for the application. At ESAS 2007, the End......-by-Hop protocol for securing in-network aggregation for sensor nodes was presented. The solution was claimed to be secure and efficient and to provide the possibility of trading off bandwidth against computation time on the server. In this paper, we disprove these claims. We describe several attacks against the...... proposed solution and point out shortcomings in the original complexity analysis. In particular, we show that the proposed solution is inferior to a naive solution without in-network aggregation both in security and in efficiency....

  18. Assessing magnetic nanoparticle aggregation in polymer melts by dynamic magnetic susceptibility measurements

    International Nuclear Information System (INIS)

    Aggregation of magnetic nanoparticles in polymer melts was assessed using dynamic magnetic susceptibility measurements. Magnetic nanocomposites consisting of polybutadiene/CoFe2O4 and polystyrene/CoFe2O4 mixtures were prepared using different techniques and characterized using dynamic magnetic susceptibility measurements. The presence of nanoparticle aggregates determined using magnetic measurements was confirmed with transmission electron microscopy examinations. The results were in good agreement with predictions from the Flory–Huggins interaction parameters. - Highlights: • Oleic acid coated magnetic nanoparticles (MNPs) were dispersed in polymer melts. • MNPs dispersed well in polybutadiene but not in polystyrene. • Dynamic magnetic susceptibility (DMS) measurements assessed presence of aggregates. • DMS predictions were confirmed by transmission electron microscopy. • The Flory-Huggins interaction parameter correlated with MNP dispersion

  19. Diffusion limited aggregation of particles with different sizes: Fractal dimension change by anisotropic growth

    Science.gov (United States)

    Braga, F. L.; Mattos, O. A.; Amorin, V. S.; Souza, A. B.

    2015-07-01

    Clusters formation models have been extensively studied in literature, and one of the main task of this research area is the analysis of the particle aggregation processes. Some work support that the main characteristics of this processes are strictly correlated to the cluster morphology, for example in DLA. It is expected that in the DLA clusters formation with particles containing different sizes the modification of the aggregation processes can be responsible for changes in the DLA morphology. The present article is going to analyze the formation of DLA clusters of particles with different sizes and show that the aggregates obtained by this approach generate an angle selection mechanism on dendritic growth that influences the shielding effect of the DLA edge and affect the fractal dimension of the clusters.

  20. A novel method for study of the aggregation of protein induced by metal ion aluminum(III) using resonance Rayleigh scattering technique

    Science.gov (United States)

    Long, Xiufen; Zhang, Caihua; Cheng, Jiongjia; Bi, Shuping

    2008-01-01

    We present a novel method for the study of the aggregation of protein induced by metal ion aluminum(III) using resonance Rayleigh scattering (RRS) technique. In neutral Tris-HCl medium, the effect of this aggregation of protein results in the enhancement of RRS intensity and the relationship between the enhancement of the RRS signal and the Al concentration is nonlinear. On this basis, we established a new method for the determination of the critical induced-aggregation concentrations ( CCIAC) of metal ion Al(III) inducing the protein aggregation. Our results show that many factors, such as, pH value, anions, salts, temperature and solvents have obvious effects. We also studied the extent of aggregation and structural changes using ultra-violet spectrometry, protein intrinsic fluorescence and circular dichroism to further understand the exact mechanisms of the aggregation characteristics of proteins induced by metal ion Al(III) at the molecular level, to help us to develop effective methods to investigate the toxicity of metal ion Al, and to provide theoretical and quantitative evidences for the development of appropriate treatments for neurodementia such as Parkinson's disease, Alzheimer's disease and dementia related to dialysis.

  1. How hydrophobically modified chitosans are stabilized by biocompatible lipid aggregates.

    Science.gov (United States)

    Ruocco, Nino; Frielinghaus, Heide; Vitiello, Giuseppe; D'Errico, Gerardino; Leal, Leslie G; Richter, Dieter; Ortona, Ornella; Paduano, Luigi

    2015-08-15

    Nanostructured hydrogels composed by biocompatible molecules are formulated and characterized. They are based on a polymer network formed by hydrophobically modified chitosans (HMCHIT or CnCHIT) in which vesicles of monoolein (MO) and oleic acid or sodium oleate (NaO), depending on pH, are embedded. The best conditions for gel formation, in terms of pH, length of the hydrophobic moieties of chitosan, and weight proportion among the three components were estimated by visual inspection of a large number of samples. Among all possible combinations, the system C12CHIT-MO-NaO in the weight proportion (1:1:1) is optimal for the formation of a well-structured gel-like system, which is also confirmed by rheological experiments. Electron paramagnetic resonance (EPR) measurements unambiguously show the presence of lipid bilayers in this mixture, indicating that MO-NaO vesicles are stabilized by C12CHIT even at acid pH. A wide small angle neutron scattering investigation performed on several ternary systems of general formula CnCHIT-MO-NaO shows that the length of the hydrophobic tail Cn is a crucial parameter in stabilizing the polymer network in which lipid vesicles are embedded. Structural parameters for the vesicles are determined by using a multilamellar model that admits the possibility of displacement of the center of each shell. The number of shells tends to be reduced by increasing the polymer content. The thickness and the distance between consecutive lamellae are not influenced by either the polymer or MO-NaO concentration. The hydrogel presented in this work, being fully biocompatible and nanostructured, is well-suited for possible application in drug delivery. PMID:25935287

  2. Aggregates formation by perylene-like dyes in Langmuir-Blodgett films

    International Nuclear Information System (INIS)

    Langmuir-Blodgett (LB) films formed of some organic dyes, namely 3,4,9,10-tetra-(n-alkoxy-carbonyl)-perylenes, and their mixtures with arachidic acid have been studied. The electronic absorption and fluorescence spectra were recorded. The results obtained have led to conclusions about formation of self-aggregates of dye molecules at the air-solid substrate interface. The absorption spectra have indicated that in the ground state some fraction of J-aggregates can be formed, whereas the fluorescence spectra have been dominated by the emission from excimer states

  3. Aggregates formation by perylene-like dyes in Langmuir-Blodgett films

    Energy Technology Data Exchange (ETDEWEB)

    Martynski, T. [Faculty of Technical Physics, Poznan University of Technology, Nieszawska 13A, 60-965 Poznan (Poland)], E-mail: martyns@phys.put.poznan.pl; Hertmanowski, R. [Faculty of Technical Physics, Poznan University of Technology, Nieszawska 13A, 60-965 Poznan (Poland); Stolarski, R. [Institute of Polymer Technology and Dyes, Lodz University of Technology, Stefanowskiego 12/16, 90-924 Lodz (Poland); Bauman, D. [Faculty of Technical Physics, Poznan University of Technology, Nieszawska 13A, 60-965 Poznan (Poland)

    2008-10-31

    Langmuir-Blodgett (LB) films formed of some organic dyes, namely 3,4,9,10-tetra-(n-alkoxy-carbonyl)-perylenes, and their mixtures with arachidic acid have been studied. The electronic absorption and fluorescence spectra were recorded. The results obtained have led to conclusions about formation of self-aggregates of dye molecules at the air-solid substrate interface. The absorption spectra have indicated that in the ground state some fraction of J-aggregates can be formed, whereas the fluorescence spectra have been dominated by the emission from excimer states.

  4. The Uncertainty of USA GDP Forecasts Determined by the Variables Aggregation

    OpenAIRE

    Bratu (Simionescu), Mihaela

    2011-01-01

    The aggregation of the variables that compose an indicator, as GDP, which should be forecasted, is not mentioned explicitly in literature as a source of forecasts uncertainty. In this study based on data on U.S. GDP and its components in 1995-2010, we found that GDP one-step-ahead forecasts made by aggregating the components with variable weights, modeled using ARMA procedure, have a higher accuracy than those with constant weights or the direct forecasts. Excepting the GDP forecasts obtained...

  5. Production of whey protein-based aggregates under ohmic heating

    OpenAIRE

    Pereira, Ricardo; Rodrigues, Rui M.; Ramos, Óscar L.; Malcata, F. X.; J. A. Teixeira; Vicente, A.A.

    2016-01-01

    Formation of whey protein isolate protein aggregates under the influence of moderate electric fields upon ohmic heating (OH) has been monitored through evaluation of molecular protein unfolding, loss of its solubility, and aggregation. To shed more light on the microstructure of the protein aggregates produced by OH, samples were assayed by transmission electron microscopy (TEM). Results show that during early steps of an OH thermal treatment, aggregation of whey proteins can be reduced with ...

  6. Sticky Pixels: Evolutionary Growth by Random Drop Ballistic Aggregation

    OpenAIRE

    Jonathan C. Roberts

    2001-01-01

    Over the years many techniques have been developed for simulating and modelling trees, ferns, crystals and natural structures. Indeed, many complex and realistic images have been formed. Often, these rely on rule based systems to create the structure, they start with a simple form and progressively refine it into a more complex form by applying rules. We use the notion of Sticky Pixels to form textures. The pixels (or objects) move around the space, when they touch another object they stick t...

  7. Elimination of Ferromagnetic Particles Aggregation for Investigation by Electron Microscopy

    Directory of Open Access Journals (Sweden)

    О.S. Kuzema

    2011-01-01

    Full Text Available It has been described the device for sample preparation of highly dispersed ferromagnetic powders including micropowders for permanent magnets, magnetic carriers, machine and mechanism components’ wear products contained in lubricants for investigation of these materials by light and electron microscopy. The device eliminates the coalescence of ferromagnetic particles and improves reliability of the results of such objects investigation. The technique of such device application has been described and exemplified for various materials investigation.

  8. Nitrification at Low pH by Aggregated Chemolithotrophic Bacteria

    OpenAIRE

    De Boer, W.; Klein Gunnewiek, P.J.A.; Veenhuis, M; Bock, E; Laanbroek, H. J.

    1991-01-01

    A study was performed to gain insight into the mechanism of acid-tolerant, chemolithotrophic nitrification. Microorganisms that nitrified at pH 4 were enriched from two Dutch acid soils. Nitrate production in the enrichment cultures was indicated to be of a chemolithoautotrophic nature as it was (i) completely inhibited by acetylene at a concentration as low as 1-mu-mol/liter and (ii) strongly retarded under conditions of carbon dioxide limitation. Electron microscopy of the enrichment cultur...

  9. Consensus Formation in Science Modeled by Aggregated Bibliographic Coupling

    DEFF Research Database (Denmark)

    Nicolaisen, Jeppe; Frandsen, Tove Faber

    2012-01-01

    Abstract: The level of consensus in science has traditionally been measured by a number of different methods. The variety is important as each method measures different aspects of science and consensus. Citation analytical studies have previously measured the level of consensus using the scientific...... (ABC) between documents. The advantages of the ABC-technique are demonstrated in a study of two selected disciplines in which the levels of consensus are measured using the proposed technique....

  10. Consensus formation in science modeled by aggregated bibliographic coupling

    DEFF Research Database (Denmark)

    Nicolaisen, Jeppe; Frandsen, Tove Faber

    2012-01-01

    The level of consensus in science has traditionally been measured by a number of different methods. The variety is important as each method measures different aspects of science and consensus. Citation analytical studies have previously measured the level of consensus using the scientific journal......) between documents. The advantages of the ABC-technique are demonstrated in a study of two selected disciplines in which the levels of consensus are measured using the propopsed technique....

  11. Adenosine-mediated inhibition of platelet aggregation by acadesine. A novel antithrombotic mechanism in vitro and in vivo.

    OpenAIRE

    Bullough, D A; Zhang, C.; Montag, A; Mullane, K. M.; Young, M A

    1994-01-01

    Inhibition of platelet aggregation by acadesine was evaluated both in vitro and ex vivo in human whole blood using impedance aggregometry, as well as in vivo in a canine model of platelet-dependent cyclic coronary flow reductions. In vitro, incubation of acadesine in whole blood inhibited ADP-induced platelet aggregation by 50% at 240 +/- 60 microM. Inhibition of platelet aggregation was time dependent and was prevented by the adenosine kinase inhibitor, 5'-deoxy 5-iodotubercidin, which block...

  12. Particle-bubble aggregate stability on static bubble generated by single nozzle on flotation process

    Science.gov (United States)

    Warjito, Harinaldi, Setyantono, Manus; Siregar, Sahala D.

    2016-06-01

    There are three sub-processes on flotation. These processes are intervening liquid film into critical thickness, rupture of liquid film forming three phase contact line, and expansion three phase contact line forming aggregate stability. Aggregate stability factor contribute to determine flotation efficiency. Aggregate stability has some important factors such as reagent and particle geometry. This research focussed on to understand effect of particle geometry to aggregate stability. Experimental setup consists of 9 x 9 x26 cm flotation column made of glass, bubble generator, particle feeding system, and high speed video camera. Bubble generator made from single nozzle with 0.3 mm diameter attached to programmable syringe pump. Particle feeding system made of pipette. Particle used in this research is taken from open pit Grasberg in Timika, Papua. Particle has sub-angular geometry and its size varies from 38 to 300 µm. Bubble-particle interaction are recorded using high speed video camera. Recordings from high speed video camera analyzed using image processing software. Experiment result shows that aggregate particle-bubble and induction time depends on particle size. Small particle (38-106 µm) has long induction time and able to rupture liquid film and also forming three phase contact line. Big particle (150-300 µm) has short induction time, so it unable to attach with bubble easily. This phenomenon is caused by apparent gravity work on particle-bubble interaction. Apparent gravity worked during particle sliding on bubble surface experience increase and reached its maximum magnitude at bubble equator. After particle passed bubble equator, apparent gravity force experience decrease. In conclusion particle size from 38-300 µm can form stable aggregate if particle attached with bubble in certain condition.

  13. A new amyloidosis caused by fibrillar aggregates of mutated corneodesmosin

    DEFF Research Database (Denmark)

    Caubet, Cécile; Bousset, Luc; Clemmensen, Ole;

    2010-01-01

    -terminal adhesive Gly/Ser-rich domain (GS domain) of the protein, abnormally accumulate as amorphous deposits at the periphery of hair follicles and in the papillary dermis of the patient skin. Here, we present evidence that the (mut)CDSN deposits display an affinity for amyloidophilic dyes, namely Congo red and......Heterozygous nonsense mutations in the CDSN gene encoding corneodesmosin (CDSN), an adhesive protein expressed in cornified epithelia and hair follicles, cause hypotrichosis simplex of the scalp (HSS), a nonsyndromic form of alopecia. Truncated mutants of CDSN ((mut)CDSN), which bear the N...... thioflavin T. We also detected the serum amyloid protein component in the dermis of HSS patients. We demonstrated that recombinant forms of (mut)CDSN and of the GS domain assemble in vitrointo ring-shaped oligomeric structures and fibrils. The amyloid-like nature of the fibrils was demonstrated by dye...

  14. Merging Knowledge Bases in Possibilistic Logic by Lexicographic Aggregation

    CERN Document Server

    Qi, Guilin; Liu, Weiru; Bell, David A

    2012-01-01

    Belief merging is an important but difficult problem in Artificial Intelligence, especially when sources of information are pervaded with uncertainty. Many merging operators have been proposed to deal with this problem in possibilistic logic, a weighted logic which is powerful for handling inconsistency and deal- ing with uncertainty. They often result in a possibilistic knowledge base which is a set of weighted formulas. Although possibilistic logic is inconsistency tolerant, it suers from the well-known "drowning effect". Therefore, we may still want to obtain a consistent possi- bilistic knowledge base as the result of merg- ing. In such a case, we argue that it is not always necessary to keep weighted informa- tion after merging. In this paper, we define a merging operator that maps a set of pos- sibilistic knowledge bases and a formula rep- resenting the integrity constraints to a clas- sical knowledge base by using lexicographic ordering. We show that it satisfies nine pos- tulates that generalize basic...

  15. Effect of surfactants on the removal and acute toxicity of aqueous nC60 aggregates in water treatment process.

    Science.gov (United States)

    Ge, Ling; Kirumba, George; Zhang, Bo; Pal, Amrita; He, Yiliang

    2015-07-01

    This work aimed to evaluate the effect of surfactants on the removal of aqueous nC60 aggregates by coagulation-filtration process and assess the acute toxicity of filtrates by Microtox test. Three surfactants including cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Triton X-100 (TX100) were selected representing cationic, anionic, and nonionic types, respectively. Results showed that the change of physicochemical properties of nC60 associating with different types of surfactants determined nC60's removal efficiency and acute toxicity. CTAB increased the number of large particles. It also changed the zeta potential of nC60 from negative to positive, leading to the low removal rates (17.3-50.2%) when CTAB concentration was designed in the range of 0.03-1 g/L, and the filtrates showed acute toxicity to bioluminescent bacteria (inhibition rate > 80%). On the contrary, TX100 obviously increased the proportion of small particles, and it is noteworthy that even less than 1 mg/L of nC60 (20% of the initial concentration) with TX100 remaining in filtrates could evoke phototoxicity due to reactive oxygen species (ROS) generation under UV irradiation. Compared to CTAB and TX100, SDS exerted an effect on the removal process and toxicity of nC60 only when concentration was beyond the critical micelle concentration (CMC; 2.5 g/L). These findings collectively suggest that characteristics of nC60 are flexible and strongly dependent on surfactant modification, as a result of which these particles could potentially find their way through water treatment route and exert a potential toxicity risk. PMID:25631739

  16. Island shapes and aggregation steered by the geometry of the substrate lattice

    OpenAIRE

    Casu, M.; Savu, S.; Schuster, B.; Biswas, I.; Raisch, C.; H. Marchetto; Schmidt, T.; Chassé, T.

    2012-01-01

    We find that island shapes and aggregation in diindenoperylene deposited on Au(100), Au(110), and Au(111) single crystals are steered by the anisotropy due to the lattice geometry of the substrate. This phenomenon may be exploited as a tool for molecular patterning of surfaces.

  17. Evaluating student's academic achievement by a non-additive aggregation operator

    Science.gov (United States)

    Abdullah, Siti Rohana Goh; Kasim, Maznah Mat; Ramli, Mohammad Fadzli; Sakib, Elyana

    2014-07-01

    In the context of multi-criteria decision making (MCDM), the average method used in Integrated Students Information System (ISIS) can be classified as an additive measure where the students' academic achievement are aggregated based on the assumption that there is no interaction among the evaluation criteria or the criteria are independent. This method is not suitable to be used if the schools look for equilibrium in their students' achievement. Thus, the non-additive aggregation operator is chosen to analyze students' academic achievements by further taking into accounts the interactions between the subjects. The measures of interaction were represented as λ-fuzzy measures. The effectiveness and success of this non-additive measures can be recognized by comparing the results of the new ranking which was obtained by nonadditive aggregation operator with the current approach of ranking that were based on the global scores using average score method. Throughout this study, it could be postulated that employing the non-additive aggregation operators to obtain an overall evaluation is more suitable because this method able to deal with interactions among subjects whereas the average method only assumes that there is no interaction between subjects or the subjects must be independent.

  18. Inhibition of platelet aggregation by polyaspartoyl L-arginine and its mechanism

    Institute of Scientific and Technical Information of China (English)

    Yin-ye WANG; Zhi-yu TANG; Min DONG; Xiao-yan LIU; Shi-qi PENG

    2004-01-01

    AIM: To observe the oral anti-platelet efficacy and the potential action mechanism of polyaspartoyl L-arginine (PDR), a new L-arginine rich compound. METHODS: Platelet aggregation was conducted by Born's method;bleeding time was determined using tail's bleeding time in mice; platelet adhesion was carried out with glass bottle method; nitric oxide (NO) was tested with Griess' method; and cAMP, thromboxane B2 (TXB2) and 6-keto-PGF1a were assessed with commercial kits. RESULTS: The inhibition by PDR (15-60 mg/kg ig or 10 mg/kg iv) of platelet aggregation induced by adenosine diphosphate (ADP), collagen or thrombin at 1 h after oral administration or at 20 min after iv injection for rats (P<0.01), and its (15 mg/kg, ig) inhibition of ADP-induced platelet aggregation for rabbits during 6 h after administration were observed. PDR (15-60 mg/kg) prolonged the bleeding time of mice (P<0.05) and (30 mg/kg) increased NO concentration in plasma. On the other hand PDR did not change the contents of cAMP in platelet and TXB2 or 6-keto-PGF1a in plasma. CONCLUSION: PDR is a novel, oral effective platelet aggregation inhibitor and its action mechanism possibly related to increasing NO generation.

  19. Inhibitory Effect of Waste Glass Powder on ASR Expansion Induced by Waste Glass Aggregate

    Directory of Open Access Journals (Sweden)

    Shuhua Liu

    2015-10-01

    Full Text Available Detailed research is carried out to ascertain the inhibitory effect of waste glass powder (WGP on alkali-silica reaction (ASR expansion induced by waste glass aggregate in this paper. The alkali reactivity of waste glass aggregate is examined by two methods in accordance with the China Test Code SL352-2006. The potential of WGP to control the ASR expansion is determined in terms of mean diameter, specific surface area, content of WGP and curing temperature. Two mathematical models are developed to estimate the inhibitory efficiency of WGP. These studies show that there is ASR risk with an ASR expansion rate over 0.2% when the sand contains more than 30% glass aggregate. However, WGP can effectively control the ASR expansion and inhibit the expansion rate induced by the glass aggregate to be under 0.1%. The two mathematical models have good simulation results, which can be used to evaluate the inhibitory effect of WGP on ASR risk.

  20. Differential Activation of Innate Immune Pathways by Distinct Islet Amyloid Polypeptide (IAPP) Aggregates.

    Science.gov (United States)

    Westwell-Roper, Clara; Denroche, Heather C; Ehses, Jan A; Verchere, C Bruce

    2016-04-22

    Aggregation of islet amyloid polypeptide (IAPP) contributes to beta cell dysfunction in type 2 diabetes and islet transplantation. Like other amyloidogenic peptides, human IAPP induces macrophage IL-1β secretion by stimulating both the synthesis and processing of proIL-1β, a pro-inflammatory cytokine that (when chronically elevated) impairs beta cell insulin secretion. We sought to determine the specific mechanism of IAPP-induced proIL-1β synthesis. Soluble IAPP species produced early during IAPP aggregation provided a Toll-like-receptor-2- (TLR2-) dependent stimulus for NF-κB activation in HEK 293 cells and bone marrow-derived macrophages (BMDMs). Non-amyloidogenic rodent IAPP and thioflavin-T-positive fibrillar amyloid produced by human IAPP aggregation failed to activate TLR2. Blockade of TLR6 but not TLR1 prevented hIAPP-induced TLR2 activation, consistent with stimulation of a TLR2/6 heterodimer. TLR2 and its downstream adaptor protein MyD88 were required for IAPP-induced cytokine production by BMDMs, a process that is partially dependent on autoinduction by IL-1. BMDMs treated with soluble but not fibrillar IAPP provided a TLR2-dependent priming stimulus for ATP-induced IL-1β secretion, whereas late IAPP aggregates induced NLRP3-dependent IL-1β secretion by LPS-primed macrophages. Moreover, inhibition of TLR2 and depletion of islet macrophages prevented up-regulation of Il1b and Tnf expression in human IAPP-expressing transgenic mouse islets. These data suggest participation by both soluble and fibrillar aggregates in IAPP-induced islet inflammation. IAPP-induced activation of TLR2 and secretion of IL-1 may be important therapeutic targets to prevent amyloid-associated beta cell dysfunction. PMID:26786104

  1. Synthesis and electrochemical properties of spherical and hollow-structured NiO aggregates created by combining the Kirkendall effect and Ostwald ripening

    Science.gov (United States)

    Cho, Jung Sang; Won, Jong Min; Lee, Jong-Heun; Kang, Yun Chan

    2015-11-01

    The Kirkendall effect and Ostwald ripening were successfully combined to prepare uniquely structured NiO aggregates. In particular, a NiO-C composite powder was first prepared using a one-pot spray pyrolysis, which was followed by a two-step post-treatment process. This resulted in the formation of micron-sized spherical and hollow-structured NiO aggregates through a synergetic effect that occurred between nanoscale Kirkendall diffusion and Ostwald ripening. The discharge capacity of the spherical and hollow-structured NiO aggregates at the 500th cycle was 1118 mA h g-1 and their capacity retention, which was measured from the second cycle, was nearly 100%. However, the discharge capacities of the solid NiO aggregates and hollow NiO shells were 631 and 150 mA h g-1, respectively, at the 500th cycle and their capacity retentions, which were measured from the second cycle, were 63 and 14%, respectively. As such, the spherical and hollow-structured NiO aggregates, which were formed through the synergetic effect of nanoscale Kirkendall diffusion and Ostwald ripening, have high structural stability during cycling and have excellent lithium storage properties.The Kirkendall effect and Ostwald ripening were successfully combined to prepare uniquely structured NiO aggregates. In particular, a NiO-C composite powder was first prepared using a one-pot spray pyrolysis, which was followed by a two-step post-treatment process. This resulted in the formation of micron-sized spherical and hollow-structured NiO aggregates through a synergetic effect that occurred between nanoscale Kirkendall diffusion and Ostwald ripening. The discharge capacity of the spherical and hollow-structured NiO aggregates at the 500th cycle was 1118 mA h g-1 and their capacity retention, which was measured from the second cycle, was nearly 100%. However, the discharge capacities of the solid NiO aggregates and hollow NiO shells were 631 and 150 mA h g-1, respectively, at the 500th cycle and their

  2. Protein adsorption, desorption, and aggregation mediated by solid-liquid interfaces.

    Science.gov (United States)

    Perevozchikova, Tatiana; Nanda, Hirsh; Nesta, Douglas P; Roberts, Christopher J

    2015-06-01

    Adsorption of proteins to solid-fluid interfaces is often empirically found to promote formation of soluble aggregates and larger, subvisible, and visible particles, but key stages in this process are often difficult to probe directly. Aggregation mediated by adsorption to water-silicon oxide (SiOx) interfaces, akin to hydrated glass surfaces, was characterized as a function of pH and ionic strength for alpha-chymotrypsinogen (aCgn) and for a monoclonal antibody (IgG1). A flow cell permitted neutron reflectivity for protein layers adsorbed to clean SiOx surfaces, as well as after successive "rinse" steps. Aggregates recovered in solution after gently "rinsing" the surface were characterized by neutron scattering, microscopy, and fluorescence spectroscopy. IgG1 molecules oriented primarily "flat" against the SiOx surface, with the primary protein layer desorbed to a minimal extent, whereas a diffuse overlayer was easily rinsed off. aCgn molecules were resistant to desorption when they appeared to be unfolded at the interface, but were otherwise easily removed. For cases where strong binding occurred, protein that did desorb was a mixture of monomer and small amounts of HMW aggregates (for aCgn) or subvisible particles (for IgG1). Changes in adsorption and/or unfolding with pH indicated that electrostatic interactions were important in all cases. PMID:25846460

  3. Modeling and analysis of ultrasound backscattering by spherical aggregates and rouleaux of red blood cells.

    Science.gov (United States)

    Teh, B G; Cloutier, G

    2000-01-01

    The present study concerns the modeling and analysis of ultrasound backscattering by red blood cell (RBC) aggregates, which under pathological conditions play a significant role in the rheology of blood within human vessels. A theoretical model based on the convolution between a tissue matrix and a point spread function, representing, respectively, the RBC aggregates and the characteristics of the ultrasound system, was used to examine the influence of the scatterer shape and size on the backscattered power. Both scatterers in the form of clumps of RBC aggregates and rouleaux were modeled. For all simulations, the hematocrit was kept constant at 10%, the ultrasound frequency was 10 MHz, the insonification angle was varied from 0 to 90 degrees , and the scatterer size (diameter for clumps and length for rouleaux) ranged from 4 mum to 120 mum. Under Rayleigh scattering by assuming a Poisson distribution of scatterers in space, the ultrasound backscattered power increased linearly with the particle volume. For non-Rayleigh scatterers, the intensity of the echoes diminished as the scatterer volume increased, with the exception of rouleaux at an angle of 90 degrees . As expected, the backscattered power was angularly dependent for anisotropic particles (rouleaux). The ultrasound backscattered power did not always increase with the size of the aggregates, especially when they were no longer Rayleigh scatterers. In the case of rouleaux, the anisotropy of the backscattered power is emphasized in the non-Rayleigh region. PMID:18238637

  4. Tramiprosate, a drug of potential interest for the treatment of Alzheimer's disease, promotes an abnormal aggregation of tau

    OpenAIRE

    Moreno Francisco J; Del Rio Joaquín; Hernández Félix; Santa-Maria Ismael; Avila Jesús

    2007-01-01

    Abstract Alzheimer's disease (AD) is characterized by the presence of two histopathological hallmarks; the senile plaques, or extracellular deposits mainly composed of amyloid-β peptide (Aβ), and the neurofibrillary tangles, or intraneuronal inclusions composed of hyperphosphorylated tau protein. Since Aβ aggregates are found in the pathological cases, several strategies are under way to develop drugs that interact with Aβ to reduce its assembly. One of them is 3-amino-1-propane sulfonic acid...

  5. Properties of Concrete with Tire Derived Aggregate Partially Replacing Coarse Aggregates

    OpenAIRE

    Gideon Siringi; Ali Abolmaali; Aswath, Pranesh B.

    2015-01-01

    Tire derived aggregate (TDA) has been proposed as a possible lightweight replacement for mineral aggregate in concrete. The role played by the amount of TDA replacing coarse aggregate as well as different treatment and additives in concrete on its properties is examined. Conventional concrete (without TDA) and concrete containing TDA are compared by examining their compressive strength based on ASTM C39, workability based on ASTM C143, splitting tensile strength based on ASTM C496, modulus of...

  6. Cell Surface Binding and Internalization of Aβ Modulated by Degree of Aggregation

    Directory of Open Access Journals (Sweden)

    David A. Bateman

    2011-01-01

    Full Text Available The amyloid peptides, Aβ40 and Aβ42, are generated through endoproteolytic cleavage of the amyloid precursor protein. Here we have developed a model to investigate the interaction of living cells with various forms of aggregated Aβ40/42. After incubation at endosomal pH 6, we observed a variety of Aβ conformations after 3 (Aβ3, 24 (Aβ24, and 90 hours (Aβ90. Both Aβ4224 and Aβ4024 were observed to rapidly bind and internalize into differentiated PC12 cells, leading to accumulation in the lysosome. In contrast, Aβ40/4290 were both found to only weakly associate with cells, but were observed as the most aggregated using dynamic light scattering and thioflavin-T. Internalization of Aβ40/4224 was inhibited with treatment of monodansylcadaverine, an endocytosis inhibitor. These studies indicate that the ability of Aβ40/42 to bind and internalize into living cells increases with degree of aggregation until it reaches a maximum beyond which its ability to interact with cells diminishes drastically.

  7. Aggregation tendencies in the p53 family are modulated by backbone hydrogen bonds.

    Science.gov (United States)

    Cino, Elio A; Soares, Iaci N; Pedrote, Murilo M; de Oliveira, Guilherme A P; Silva, Jerson L

    2016-01-01

    The p53 family of proteins is comprised of p53, p63 and p73. Because the p53 DNA binding domain (DBD) is naturally unstable and possesses an amyloidogenic sequence, it is prone to form amyloid fibrils, causing loss of functions. To develop p53 therapies, it is necessary to understand the molecular basis of p53 instability and aggregation. Light scattering, thioflavin T (ThT) and high hydrostatic pressure (HHP) assays showed that p53 DBD aggregates faster and to a greater extent than p63 and p73 DBDs, and was more susceptible to denaturation. The aggregation tendencies of p53, p63, and p73 DBDs were strongly correlated with their thermal stabilities. Molecular Dynamics (MD) simulations indicated specific regions of structural heterogeneity unique to p53, which may be promoted by elevated incidence of exposed backbone hydrogen bonds (BHBs). The results indicate regions of structural vulnerability in the p53 DBD, suggesting new targetable sites for modulating p53 stability and aggregation, a potential approach to cancer therapy. PMID:27600721

  8. Conformational Analysis of Misfolded Protein Aggregation by FRET and Live-Cell Imaging Techniques

    Directory of Open Access Journals (Sweden)

    Akira Kitamura

    2015-03-01

    Full Text Available Cellular homeostasis is maintained by several types of protein machinery, including molecular chaperones and proteolysis systems. Dysregulation of the proteome disrupts homeostasis in cells, tissues, and the organism as a whole, and has been hypothesized to cause neurodegenerative disorders, including amyotrophic lateral sclerosis (ALS and Huntington’s disease (HD. A hallmark of neurodegenerative disorders is formation of ubiquitin-positive inclusion bodies in neurons, suggesting that the aggregation process of misfolded proteins changes during disease progression. Hence, high-throughput determination of soluble oligomers during the aggregation process, as well as the conformation of sequestered proteins in inclusion bodies, is essential for elucidation of physiological regulation mechanism and drug discovery in this field. To elucidate the interaction, accumulation, and conformation of aggregation-prone proteins, in situ spectroscopic imaging techniques, such as Förster/fluorescence resonance energy transfer (FRET, fluorescence correlation spectroscopy (FCS, and bimolecular fluorescence complementation (BiFC have been employed. Here, we summarize recent reports in which these techniques were applied to the analysis of aggregation-prone proteins (in particular their dimerization, interactions, and conformational changes, and describe several fluorescent indicators used for real-time observation of physiological states related to proteostasis.

  9. Aggregation tendencies in the p53 family are modulated by backbone hydrogen bonds

    Science.gov (United States)

    Cino, Elio A.; Soares, Iaci N.; Pedrote, Murilo M.; de Oliveira, Guilherme A. P.; Silva, Jerson L.

    2016-01-01

    The p53 family of proteins is comprised of p53, p63 and p73. Because the p53 DNA binding domain (DBD) is naturally unstable and possesses an amyloidogenic sequence, it is prone to form amyloid fibrils, causing loss of functions. To develop p53 therapies, it is necessary to understand the molecular basis of p53 instability and aggregation. Light scattering, thioflavin T (ThT) and high hydrostatic pressure (HHP) assays showed that p53 DBD aggregates faster and to a greater extent than p63 and p73 DBDs, and was more susceptible to denaturation. The aggregation tendencies of p53, p63, and p73 DBDs were strongly correlated with their thermal stabilities. Molecular Dynamics (MD) simulations indicated specific regions of structural heterogeneity unique to p53, which may be promoted by elevated incidence of exposed backbone hydrogen bonds (BHBs). The results indicate regions of structural vulnerability in the p53 DBD, suggesting new targetable sites for modulating p53 stability and aggregation, a potential approach to cancer therapy. PMID:27600721

  10. Mineral trioxide aggregate apical plug method for the treatment of nonvital immature permanent maxillary incisors: Three case reports

    Directory of Open Access Journals (Sweden)

    Betül Günes

    2012-01-01

    Full Text Available Treatment of nonvital immature permanent teeth with calcium-hydroxide is associated with some difficulties such as weakened tooth fracture, root canal reinfection and long treatment time. Mineral trioxide aggregate (MTA apical plug method is an alternative treatment option for open apices, and has gained popularity in the recent times. In this case report, we have attempted to present successful treatment of three maxillary incisors with open apices and periapical lesions with MTA. After preparing the access cavity, the working length was determined. The root canals were irrigated with 2.5% Sodium hypochlorite (NaOCl and disinfected with calcium-hydroxide for two weeks. MTA was then placed in the apical 3 millimeters of the root canal. The remaining part of the root canal was filled with gutta-percha and the coronal restoration was finished with composite resin. After six months the radiographic examination showed a decrease of periapical lesions. At a 1-year and 18-months follow up, radiological and clinical successful healing of the incisor teeth was seen. MTA seems as an effective material for the apical plug method for the treatment of nonvital immature permanent teeth with open apices.

  11. Controlling the Ratio between Native-Like, Non-Native-Like, and Aggregated β-Lactoglobulin after Heat Treatment.

    Science.gov (United States)

    Delahaije, Roy J B M; Gruppen, Harry; van Eijk van Boxtel, Evelien L; Cornacchia, Leonardo; Wierenga, Peter A

    2016-06-01

    The amount of heat-denatured whey protein is typically determined by pH 4.6 precipitation. Using this method, a significant amount of nondenatured protein was reported even after long heating times. Apparently, a fraction of the unfolded protein refolds into the "native" state rather than form aggregates. This fact is known and has been explained using kinetic models. How the conditions affect the refolding and aggregation is, however, not fully understood. Therefore, this study investigates the unfolding, refolding, and aggregation process of β-lactoglobulin using circular dichroism and size-exclusion chromatography to characterize different folding variants and to quantify their content. The proteins remaining in solution at pH 4.6 were confirmed to be native-like. The nonaggregated fraction contains proteins with a native-like and two types of non-native-like conformations. The nonaggregated fraction increased with decreasing temperature (60-90 °C) and concentration (1-50 g/L) and increasing electrostatic repulsion (pH 7-8; 0-50 mM). The native-like fraction in the nonaggregated fraction was independent of pH, ionic strength, and concentration but increased with decreasing temperature. PMID:27186663

  12. Stimulation of r- vs. K- selected microorganisms by elevated atmospheric CO2 depends on soil aggregate size

    Science.gov (United States)

    Dorodnikov, M.; Blagodatskaya, E.; Blagodatsky, S.; Fangmeier, A.; Kuzyakov, Y.

    2009-04-01

    Increased root exudation under elevated atmospheric CO2 and the contrasting environments in soil macro- and microaggregates could affect microbial growth strategy. We investigated the effect of elevated CO2 on the contribution of fast- (r-strategists) and slow-growing microorganisms (K-strategists) in soil macro- and microaggregates. We fractionated the bulk soil from the ambient and elevated (for 5 years) CO2 treatments of FACE-Hohenheim (Stuttgart) into large macro- (>2 mm), small macro- (0.25-2.00 mm), and microaggregates (<0.25 mm) using an "optimal moist" sieving. Microbial biomass (Cmic), the maximal specific growth rate (μ), growing microbial biomass (GMB) and lag-period (tlag) were estimated by the kinetics of CO2 emission from bulk soil and aggregates amended with glucose and nutrients. Although Corg and Cmic were unaffected by elevated CO2, μ values were significantly higher under elevated than ambient CO2 for bulk soil, small macroaggregates, and microaggregates. The substrate induced respiratory response increased with the decreasing of aggregates size under both CO2 treatments. Based on changes in μ, GMB, and lag-period, we conclude that elevated atmospheric CO2 stimulated the r-selected microorganisms, especially in soil microaggregates. Such an increase in r-selected microorganisms could increase C turnover in terrestrial ecosystems in a future elevated atmospheric CO2 environment.

  13. Preparation of 166 Dy/166 Ho-Macro aggregates as an In vivo generator system for the treatment of arthrophaties

    International Nuclear Information System (INIS)

    The present work reports the obtention of macro aggregates of hydroxides of Dysprosium-166/Holmium-166 (166 Dy/166 Ho-MH), as a generator system in vivo to be used in the treatment of arthritis rheumatoid. The 166 Dy was obtained by neutron irradiation of 166 DyO3 (enriched to 98.45%) by 20 h in the TRIGA Mark III Reactor and 50 h of decay, to the oxide of 166 Dy/166 Ho formed, it was added HCl 0.12 N to obtain a final volume of 3.5 ml of solution of 166 Dy/166 Ho chloride. The solution of 166DyCl3 solution was obtained with an activity of 3.502 mCi (129 MBq), appropriate for the preparation of the radiopharmaceutical 166 Dy/166 Ho-MH. The separation of the 166 Dy from the 166 Ho, was carried out by chromatography in an cation exchange column, gaining an appropriate separation, obtaining a 166 Dy with a radionuclide purity greater than 90%. The 166 Dy/166 Ho-MH were prepared by addition to the solution of 166 DyCI3 NaOH 0.5 N low ultrasonic bath with later centrifugation, decanted and resuspension in saline solution, obtaining a radiopharmaceutical with a generator system 166 Dy/ 166 Ho with particles of size average of 3 μm, in form of 166 Dy / 166 Ho-MH. Under these conditions, it was obtained a radiochemical yield greater than 99%. The microscopic analysis and of filtration showed that the formulation doesn't present particles smaller than to 1 μm, neither greater to 50 μm, which will allow, the quick phagocytosis for the synoviocytes of the synovial membrane, and by consequence, an homogeneous distribution of the radiation dose could exist. The sedimentation velocity for the formulated suspension is of 0.04 cm/min that it will allow the administration of homogeneous activities of the radiopharmaceutical, to the no deposit in the injection devices. The studies of stability in vitro indicate us that inside the articulation, the particles won't probably reduce its size neither their radiochemical purity, for that the flight extra articular will be smaller that

  14. Ischemic Postconditioning Protects Neuronal Death Caused by Cerebral Ischemia and Reperfusion via Attenuating Protein Aggregation

    Directory of Open Access Journals (Sweden)

    Jianmin Liang, Jihang Yao, Guangming Wang, Ying Wang, Boyu Wang, Pengfei Ge

    2012-01-01

    Full Text Available Objective: To investigate the effect of ischemic postconditioning on protein aggregation caused by transient ischemia and reperfusion and to clarify its underlying mechanism.Methods: Two-vessel-occluded transient global ischemia rat model was used. The rats in ischemic postconditioning group were subjected to three cycles of 30-s/30-s reperfusion/clamping after 15min of ischemia. Neuronal death in the CA1 region was observed by hematoxylin-eosin staining, and number of live neurons was assessed by cell counting under a light microscope. Succinyl-LLVY-AMC was used as substrate to assay proteasome activity in vitro. Protein carbonyl content was spectrophotometrically measured to analyze protein oxidization. Immunochemistry and laser scanning confocal microscopy were used to observe the distribution of ubiquitin in the CA1 neurons. Western blotting was used to analyze the quantitative alterations of protein aggregates, proteasome, hsp70 and hsp40 in cellular fractions under different ischemic conditions.Results: Histological examination showed that the percentage of live neurons in the CA1 region was elevated from 5.21%±1.21% to 55.32%±5.34% after administration of ischemic postconditioning (P=0.0087. Western blotting analysis showed that the protein aggregates in the ischemia group was 32.12±4.87, 41.86±4.71 and 34.51±5.18 times higher than that in the sham group at reperfusion 12h, 24h and 48h, respectively. However, protein aggregates were alleviated significantly by ischemic postconditioning to 2.84±0.97, 13.72±2.13 and 14.37±2.42 times at each indicated time point (P=0.000032, 0.0000051 and 0.0000082. Laser scanning confocal images showed ubiquitin labeled protein aggregates could not be discerned in the ischemic postconditioning group. Further study showed that ischemic postconditioning suppressed the production of carbonyl derivatives, elevated proteasome activity that was damaged by ischemia and reperfusion, increased the expression

  15. Detection of Gold Nanoparticles Aggregation Growth Induced by Nucleic Acid through Laser Scanning Confocal Microscopy

    Science.gov (United States)

    Gary, Ramla; Carbone, Giovani; Petriashvili, Gia; De Santo, Maria Penelope; Barberi, Riccardo

    2016-01-01

    The gold nanoparticle (GNP) aggregation growth induced by deoxyribonucleic acid (DNA) is studied by laser scanning confocal and environmental scanning electron microscopies. As in the investigated case the direct light scattering analysis is not suitable, we observe the behavior of the fluorescence produced by a dye and we detect the aggregation by the shift and the broadening of the fluorescence peak. Results of laser scanning confocal microscopy images and the fluorescence emission spectra from lambda scan mode suggest, in fact, that the intruding of the hydrophobic moiety of the probe within the cationic surfactants bilayer film coating GNPs results in a Förster resonance energy transfer. The environmental scanning electron microscopy images show that DNA molecules act as template to assemble GNPs into three-dimensional structures which are reminiscent of the DNA helix. This study is useful to design better nanobiotechnological devices using GNPs and DNA. PMID:26907286

  16. Detection of Gold Nanoparticles Aggregation Growth Induced by Nucleic Acid through Laser Scanning Confocal Microscopy.

    Science.gov (United States)

    Gary, Ramla; Carbone, Giovani; Petriashvili, Gia; De Santo, Maria Penelope; Barberi, Riccardo

    2016-01-01

    The gold nanoparticle (GNP) aggregation growth induced by deoxyribonucleic acid (DNA) is studied by laser scanning confocal and environmental scanning electron microscopies. As in the investigated case the direct light scattering analysis is not suitable, we observe the behavior of the fluorescence produced by a dye and we detect the aggregation by the shift and the broadening of the fluorescence peak. Results of laser scanning confocal microscopy images and the fluorescence emission spectra from lambda scan mode suggest, in fact, that the intruding of the hydrophobic moiety of the probe within the cationic surfactants bilayer film coating GNPs results in a Förster resonance energy transfer. The environmental scanning electron microscopy images show that DNA molecules act as template to assemble GNPs into three-dimensional structures which are reminiscent of the DNA helix. This study is useful to design better nanobiotechnological devices using GNPs and DNA. PMID:26907286

  17. Diarrhea-associated biofilm formed by enteroaggregative Escherichia coli and aggregative Citrobacter freundii: a consortium mediated by putative F pili

    Directory of Open Access Journals (Sweden)

    Araújo Ana CG

    2010-02-01

    Full Text Available Abstract Background Enteroaggregative Escherichia coli (EAEC are enteropathogenic strains identified by the aggregative adhesion (AA pattern that share the capability to form biofilms. Citrobacter freundii is classically considered as an indigenous intestinal species that is sporadically associated with diarrhea. Results During an epidemiologic study focusing on infantile diarrhea, aggregative C. freundii (EACF and EAEC strains were concomitantly recovered from a severe case of mucous diarrhea. Thereby, the occurrence of synergic events involving these strains was investigated. Coinfection of HeLa cells with EACF and EAEC strains showed an 8-fold increase in the overall bacterial adhesion compared with single infections (P traA were capable of forming bacterial aggregates only in the presence of EACF. Scanning electronic microscopy analyses revealed that bacterial aggregates as well as enhanced biofilms formed by EACF and traA-positive EAEC were mediated by non-bundle forming, flexible pili. Moreover, mixed biofilms formed by EACF and traA-positive EAEC strains were significantly reduced using nonlethal concentration of zinc, a specific inhibitor of F pili. In addition, EAEC strains isolated from diarrheic children frequently produced single biofilms sensitive to zinc. Conclusions Putative F pili expressed by EAEC strains boosted mixed biofilm formation when in the presence of aggregative C. freundii.

  18. Binding and aggregation of pro-atrial natriuretic factor by calcium.

    Science.gov (United States)

    Thibault, G; Doubell, A F

    1992-04-01

    Analysis of atrial secretory granule content by sodium dodecyl sulfate-gel electrophoresis followed by a 45Ca2+ overlay assay indicates that a 17,000 protein binds 45Ca2+. This protein, which can be immunostained by atrial natriuretic factor (ANF) antiserum, corresponds to proANF. Ca2+ binding is proportional to the amount of proANF and pH dependent. Generation of ANF-(1-98) by thrombin digestion of proANF does not affect Ca2+ binding. Blocking the carboxyl groups of proANF and the use of NH2-terminal fragments bearing those carboxyl groups demonstrated that the Ca(2+)-interaction site is probably located within the highly acidic portion (11-30) of the propeptide. Ca2+ binding to proANF induces its aggregation that can be verified by sedimentation. ProANF aggregation is Ca2+ dependent, being optimal at 10 mM, partially pH dependent, and greatly increased by high concentrations of proANF. However, because of its relatively low-binding affinity, Ca2+ can be substituted by other divalent cations such as Sr2+, Ba2+, or Mg2+. The high level of Ca2+ in atrial secretory granules and the aggregation of proANF in the presence of Ca2+ suggest a possible involvement of these physicochemical properties in the condensed state of the matrix of secretory granules. Indeed, detergent solubilization of the membrane of the secretory granules in presence of Ca2+ resulted only in a partial dissolution of the dense core matrix. We therefore postulate that, in the Golgi complex, proANF and Ca2+ associate to form a condensed aggregate that helps package secretory material into secretory vesicles. PMID:1533094

  19. NOM removal from drinking water by chitosan coagulation and filtration through lightweight expanded clay aggregate filters

    Energy Technology Data Exchange (ETDEWEB)

    Eikebrokk, B.; Saltnes, T. [SINTEF, Trondheim (Norway). Dept. of Water & Wastewater, Applied Chemistry

    2002-09-01

    Recent innovations in Norway regarding coagulation-contact filtration for the removal of natural organic matter (NOM) include chitosan as a natural and biodegradable coagulant, and filter media based on lightweight expanded clay aggregates (Filtralite). The main advantages associated with chitosan are: reduced solids production compared with conventional coagulants; and treatment and disposal of natural, biodegradable sludge, which does not contain metal hydroxides from metal-based coagulants. Filtralite can be produced with an inverse relationship between grain size thus allowing an approximation to the ideal situation of decreasing grain size and density, in the direction of flow. Traditionally, this important property of a filter bed is utilised in up-flow filters, or in dual or multimedia down-flow filters with combinations of two or more filter media. This paper presents experimental results from pilot-scale treatment of NOM-containing raw waters using chitosan for coagulation and expanded clay aggregates as filter media. A dual media anthracite-sand filter and alum coagulant was used as a reference for comparison with conventional process configurations.

  20. Cytoplasmic translocation, aggregation, and cleavage of TDP-43 by enteroviral proteases modulate viral pathogenesis.

    Science.gov (United States)

    Fung, G; Shi, J; Deng, H; Hou, J; Wang, C; Hong, A; Zhang, J; Jia, W; Luo, H

    2015-12-01

    We have previously demonstrated that infection by coxsackievirus B3 (CVB3), a positive-stranded RNA enterovirus, results in the accumulation of insoluble ubiquitin-protein aggregates, which resembles the common feature of neurodegenerative diseases. The importance of protein aggregation in viral pathogenesis has been recognized; however, the underlying regulatory mechanisms remain ill-defined. Transactive response DNA-binding protein-43 (TDP-43) is an RNA-binding protein that has an essential role in regulating RNA metabolism at multiple levels. Cleavage and cytoplasmic aggregation of TDP-43 serves as a major molecular marker for amyotrophic lateral sclerosis and frontotemporal lobar degeneration and contributes significantly to disease progression. In this study, we reported that TDP-43 is translocated from the nucleus to the cytoplasm during CVB3 infection through the activity of viral protease 2A, followed by the cleavage mediated by viral protease 3C. Cytoplasmic translocation of TDP-43 is accompanied by reduced solubility and increased formation of protein aggregates. The cleavage takes place at amino-acid 327 between glutamine and alanine, resulting in the generation of an N- and C-terminal cleavage fragment of ~35 and ~8 kDa, respectively. The C-terminal product of TDP-43 is unstable and quickly degraded through the proteasome degradation pathway, whereas the N-terminal truncation of TDP-43 acts as a dominant-negative mutant that inhibits the function of native TDP-43 in alternative RNA splicing. Lastly, we demonstrated that knockdown of TDP-43 results in an increase in viral titers, suggesting a protective role for TDP-43 in CVB3 infection. Taken together, our findings suggest a novel model by which cytoplasmic redistribution and cleavage of TDP-43 as a consequence of CVB3 infection disrupts the solubility and transcriptional activity of TDP-43. Our results also reveal a mechanism evolved by enteroviruses to support efficient viral infection. PMID

  1. Excitation transfer pathways in excitonic aggregates revealed by the stochastic Schrödinger equation

    Energy Technology Data Exchange (ETDEWEB)

    Abramavicius, Vytautas, E-mail: vytautas.ab@gmail.com; Abramavicius, Darius, E-mail: darius.abramavicius@ff.vu.lt [Faculty of Physics, Department of Theoretical Physics, Vilnius University, Saulėtekio 9, LT-10222 Vilnius (Lithuania)

    2014-02-14

    We derive the stochastic Schrödinger equation for the system wave vector and use it to describe the excitation energy transfer dynamics in molecular aggregates. We suggest a quantum-measurement based method of estimating the excitation transfer time. Adequacy of the proposed approach is demonstrated by performing calculations on a model system. The theory is then applied to study the excitation transfer dynamics in a photosynthetic pigment-protein Fenna-Matthews-Olson (FMO) aggregate using both the Debye spectral density and the spectral density obtained from earlier molecular dynamics simulations containing strong vibrational high-frequency modes. The obtained results show that the excitation transfer times in the FMO system are affected by the presence of the vibrational modes; however, the transfer pathways remain the same.

  2. Excitation transfer pathways in excitonic aggregates revealed by the stochastic Schr\\"odinger equation

    CERN Document Server

    Abramavicius, Vytautas

    2014-01-01

    We derive the stochastic Schr\\"odinger equation for the system wave vector and use it to describe the excitation energy transfer dynamics in molecular aggregates. We suggest a quantum-measurement based method of estimating the excitation transfer time. Adequacy of the proposed approach is demonstrated by performing calculations on a model system. The theory is then applied to study the excitation transfer dynamics in a photosynthetic pigment-protein Fenna-Matthews-Olson (FMO) aggregate using both the Debye spectral density and the spectral density obtained from earlier molecular dynamics simulations containing strong vibrational high-frequency modes. The obtained results show that the excitation transfer times in the FMO system are affected by the presence of the vibrational modes, however the transfer pathways remain the same.

  3. Discrepancies over the onset of surfactant monomer aggregation interpreted by fluorescence, conductivity and surface tension methods

    Directory of Open Access Journals (Sweden)

    Maria de Fátima Carvalho Costa

    1998-06-01

    Full Text Available Molecular probe techniques have made important contributions to the determination of microstructure of surfactant assemblies such as size, stability, micropolarity and conformation. Conductivity and surface tension were used to determine the critical aggregation concentration (cac of polymer-surfactant complexes and the critical micellar concentration (cmc of aqueous micellar aggregates. The results are compared with those of fluorescent techniques. Several surfactant systems were examined, 1-butanol-sodium dodecylsulfate (SDS mixtures, solutions containing poly(ethylene oxide-SDS, poly(vinylpyrrolidone-SDS and poly(acrylic acid-alkyltrimethylammonium bromide complexes. We found differences between the cac and cmc values obtained by conductivity or surface tension and those obtained by techniques which use hydrophobic probe.

  4. Single-shot measurement of soot aggregate sizes by wide-angle light scattering (WALS)

    Science.gov (United States)

    Oltmann, H.; Reimann, J.; Will, S.

    2012-01-01

    The wide-angle light scattering (WALS) approach has been utilized for the measurement of soot aggregate sizes (radii of gyration) in flames on a single-shot basis. Key elements are a pulsed laser and an ellipsoidal mirror, which images the light scattered within a plane onto an intensified CCD camera, thus allowing for an instantaneous acquisition of a full scattering diagram with high resolution. Results for a laminar premixed flame exhibit good agreement with averaged data and demonstrate the feasibility of the method. The applicability of the technique to unsteady combustion processes is demonstrated by measuring aggregate sizes in a weakly turbulent jet-diffusion flame. In both cases light scattering results are verified by data obtained from electron microscopy analysis of sampled soot.

  5. Properties of Cement Mortar by Use of Hot-Melt Polyamides as Substitute for Fine Aggregate

    Directory of Open Access Journals (Sweden)

    Xiongzhou Yuan

    2015-06-01

    Full Text Available This paper presents an experimental study on use of hot-melt polyamide (HMP to prepare mortar specimens with improved crack healing and engineering properties. The role of HMP in the crack repairing of cement mortar subjected to several rounds of heat treatment was investigated. Compatibility between HMP and hydraulic cement was investigated through X-ray diffraction (XRD and Fourier transform infrared spectra (FTIR technology. Mortar specimens were prepared using standard cement mortar mixes with HMP at 1%, 3% and 5% (by volume for fine aggregate substitute. After curing for 28 days, HMP specimens were subjected to heating at temperature of 160 °C for one, two, and three days and then natural cooling down to ambient temperature. Mechanical and durability properties of the heated HMP mortars were evaluated and compared with those of the corresponding mortars without heating. The microscopic observation of the interfacial transition zone (ITZ of HMP mortar was conducted through environmental scanning electron microscopy (ESEM. Results reveal that incorporation of HMP improves the workability of the HMP/cement binder while leading to decrease in compressive strength and durability. The heated HMP mortars after exposure to heating for one, two, and three days exhibit no obvious change in compressive strength while presenting notable increase in flexural strength and durability compared with the corresponding mortars without heating. The XRD, FTIR and ESEM analyses indicate that no obvious chemical reaction occurs between HMP and hydraulic cement, and thus the self-repairing for interfacial micro-crack in HMP/cement composite system is ascribed to the physical adhesion of HMP to cement matrix rather than the chemical bonding between them.

  6. Characteristics of airborne gold aggregates generated by spark discharge and high temperature evaporation furnace: Mass-mobility relationship and surface area

    OpenAIRE

    Svensson, Christian; Ludvigsson, Linus; Meuller, Bengt; Eggersdorfer, M.L.; Deppert, Knut; Bohgard, Mats; Pagels, Joakim; Messing, Maria; Rissler, Jenny

    2015-01-01

    The properties of gas-borne aggregates are important in nano-technology and for potential health effects. Gold aggregates from three generators (one commercial and one custom built spark discharge generator and one high-temperature furnace) have been characterized. The aggregate surface areas were determined using five approaches - based on aggregation theory and/or measured aggregate properties. The characterization included mass-mobility relationships, effective densities (assessed by an Ae...

  7. Aggregation in manpower planning

    OpenAIRE

    Wijngaard, J

    1983-01-01

    In manpower planning, as in all other kinds of planning, an important choice is the level of aggregation. The proper level of aggregation depends on the flexibility (mobility) of the personnel. This dependency is investigated in this paper. The manpower system considered is characterized by two dimensions, level and function group. Conditions are derived for aggregate long-term planning (aggregation over function group) combined with one-period disaggregation being optimal.

  8. Protein aggregation and bioprocessing

    OpenAIRE

    Cromwell, Mary E. M.; Hilario, Eric; Jacobson, Fred

    2006-01-01

    Protein aggregation is a common issue encountered during manufacture of biotherapeutics. It is possible to influence the amount of aggregate produced during the cell culture and purification process by carefully controlling the environment (eg, media components) and implementing appro-priate strategies to minimize the extent of aggregation. Steps to remove aggregates have been successfully used at a manufacturing scale. Care should be taken when developing a process to monitor the compatibili...

  9. Measurement of interaction forces between red blood cells in aggregates by optical tweezers

    Energy Technology Data Exchange (ETDEWEB)

    Maklygin, A Yu; Priezzhev, A V; Karmenian, A; Nikitin, Sergei Yu; Obolenskii, I S; Lugovtsov, Andrei E; Kisun Li

    2012-06-30

    We have fabricated double-beam optical tweezers and demonstrated the possibility of their use for measuring the interaction forces between red blood cells (erythrocytes). It has been established experimentally that prolonged trapping of red blood cells in a tightly focused laser beam does not cause any visible changes in their shape or size. We have measured the interaction between red blood cells in the aggregate, deformed by optical tweezers.

  10. Wastewater treatment by flotation

    Directory of Open Access Journals (Sweden)

    F.P. Puget

    2000-12-01

    Full Text Available This work deals with the performance analysis of a separation set-up characterized by the ejector-hydrocyclone association, applied in the treatment of a synthetic dairy wastewater effluent. The results obtained were compared with the results from a flotation column (cylindrical body of a hydrocyclone operated both batch and continuously. As far as the experimental set-up studied in this work and the operating conditions imposed to the process, it is possible to reach a 25% decrease in the total effluent chemical oxygen demand (COD. This corresponds approximately to 60% of the COD of the material in suspension. The best results are obtained for ratios air flow rate-feed flow rate (Qair/Q L greater then 0.15 and for ratios underflow rate-overflow rate (Qu/Qo lower than 1.0.

  11. Synthesis and electrochemical properties of spherical and hollow-structured NiO aggregates created by combining the Kirkendall effect and Ostwald ripening.

    Science.gov (United States)

    Cho, Jung Sang; Won, Jong Min; Lee, Jong-Heun; Kang, Yun Chan

    2015-12-14

    The Kirkendall effect and Ostwald ripening were successfully combined to prepare uniquely structured NiO aggregates. In particular, a NiO-C composite powder was first prepared using a one-pot spray pyrolysis, which was followed by a two-step post-treatment process. This resulted in the formation of micron-sized spherical and hollow-structured NiO aggregates through a synergetic effect that occurred between nanoscale Kirkendall diffusion and Ostwald ripening. The discharge capacity of the spherical and hollow-structured NiO aggregates at the 500(th) cycle was 1118 mA h g(-1) and their capacity retention, which was measured from the second cycle, was nearly 100%. However, the discharge capacities of the solid NiO aggregates and hollow NiO shells were 631 and 150 mA h g(-1), respectively, at the 500(th) cycle and their capacity retentions, which were measured from the second cycle, were 63 and 14%, respectively. As such, the spherical and hollow-structured NiO aggregates, which were formed through the synergetic effect of nanoscale Kirkendall diffusion and Ostwald ripening, have high structural stability during cycling and have excellent lithium storage properties. PMID:26549333

  12. Clay induced aggregation of a tetra-cationic metalloporphyrin in Layer by Layer self assembled film

    Science.gov (United States)

    Banik, Soma; Bhattacharjee, J.; Hussain, S. A.; Bhattacharjee, D.

    2015-12-01

    Porphyrins have a general tendency to form aggregates in ultrathin films. Also electrostatic adsorption of cationic porphyrins onto anionic nano clay platelets results in the flattening of porphyrin moieties. The flattening is evidenced by the red-shifting of Soret band with respect to the aqueous solution. In the present communication, we have studied the clay induced aggregation behaviour of a tetra-cationic metalloporphyrin Manganese (III) 5, 10, 15, 20-tetra (4 pyridyl)-21 H, 23 H-porphine chloride tetrakis (methochloride) (MnTMPyP) in Layer-by-Layer (LbL) self assembled film. The adsorption of dye molecules onto nano clay platelets resulted in the flattening of the meso substituent groups of the dye chromophore. In Layer-by-Layer ultrathin film, the flattened porphyrin molecules tagged nano clay platelets were further associated to form porphyrin aggregates. This has been clearly demonstrated from the UV-vis absorption spectroscopic studies. Atomic Force Microscopic (AFM) studies gave visual evidence of the association of organo-clay hybrid molecules in the LbL film.

  13. A look into amyloid formation by transthyretin: aggregation pathway and a novel kinetic model.

    Science.gov (United States)

    Faria, Tiago Q; Almeida, Zaida L; Cruz, Pedro F; Jesus, Catarina S H; Castanheira, Pedro; Brito, Rui M M

    2015-03-21

    The aggregation of proteins into insoluble amyloid fibrils is the hallmark of many, highly debilitating, human pathologies such as Alzheimer's or Parkinson's disease. Transthyretin (TTR) is a homotetrameric protein implicated in several amyloidoses like Senile Systemic Amyloidosis (SSA), Familial Amyloid Polyneuropathy (FAP), Familial Amyloid Cardiomyopathy (FAC), and the rare Central Nervous System selective Amyloidosis (CNSA). In this work, we have investigated the kinetics of TTR aggregation into amyloid fibrils produced by the addition of NaCl to acid-unfolded TTR monomers and we propose a mathematically simple kinetic mechanism to analyse the aggregation kinetics of TTR. We have conducted circular dichroism, intrinsic tryptophan fluorescence and thioflavin-T emission experiments to follow the conformational changes accompanying amyloid formation at different TTR concentrations. Kinetic traces were adjusted to a two-step model with the first step being second-order and the second being unimolecular. The molecular species present in the pathway of TTR oligomerization were characterized by size exclusion chromatography coupled to multi-angle light scattering and by transmission electron microscopy. The results show the transient accumulation of oligomers composed of 6 to 10 monomers in agreement with reports suggesting that these oligomers may be the causative agent of cell toxicity. The results obtained may prove to be useful in understanding the mode of action of different compounds in preventing fibril formation and, therefore, in designing new drugs against TTR amyloidosis. PMID:25694367

  14. JUDGMENT AGGREGATION AND PREFERENCE AGGREGATION

    OpenAIRE

    Joanna Ochremiak

    2011-01-01

    In the paper we present an introduction to the theory of judgment aggregation and discuss its relation to the theory of preference aggregation. We compare the formal model of judgment aggregation, based on logic, with the formal model of preference aggregation. Finally, we present a theorem in judgmentaggregation which is an exact analogue of Arrow's theorem for strict preferences.

  15. CONGESTIVE HEART FAILURE IN DOGS IS ASSOCIATED WITH INCREASED PLATELET LEUKOCYTE AGGREGATION MEASURED BY FLOW CYTOMETRY

    DEFF Research Database (Denmark)

    Tarnow, Inge; Andreasen, Susanne SH; Olsen, Lisbeth Høier; Moesgaard, Sophia Gry; Rasmussen, Caroline Elisabeth; Kristensen, Annemarie Thuri; Falk, Bo Torkel

    2010-01-01

    binding),monocyte-platelet (MPAs) and neutrophil-platelet aggregates (NPAs) defined as leukocytes positive for CD61 were measured by whole blood flow cytometry asmarkers of platelet activation. For every dog platelet activation was assessed in unstimulated samples, and in response to exogenously added......CONGESTIVE HEART FAILURE IN DOGS IS ASSOCIATED WITH ENHANCED PLATELET-LEUKOCYTE AGGREGATES - A MARKER FOR PLATELET ACTIVATION. I Tarnow1, LH Olsen2, SHS Andreasen2, SG Moesgaard2, CE Rasmussen2, AT Kristensen1, T Falk2. 1Departments of Small Animal Clinical Sciences and 2Animal and Veterinary Basic...... adenosine diphosphate (ADP), thrombin and a synthetic thromboxane A2 analogue 1 epinephrine. Complete blood count and biochemical screening were performed in all dogs. Dogs with CHF had higher MPAs (p 5 0.014) and NPAs ( p 5 0.021) compared to controls (2-way analysis of variance for repeated measurements)....

  16. Modeling compressive strength of recycled aggregate concrete by Artificial Neural Network, Model Tree and Non-linear Regression

    Directory of Open Access Journals (Sweden)

    Neela Deshpande

    2014-12-01

    Full Text Available In the recent past Artificial Neural Networks (ANN have emerged out as a promising technique for predicting compressive strength of concrete. In the present study back propagation was used to predict the 28 day compressive strength of recycled aggregate concrete (RAC along with two other data driven techniques namely Model Tree (MT and Non-linear Regression (NLR. Recycled aggregate is the current need of the hour owing to its environmental friendly aspect of re-use of the construction waste. The study observed that, prediction of 28 day compressive strength of RAC was done better by ANN than NLR and MT. The input parameters were cubic meter proportions of Cement, Natural fine aggregate, Natural coarse Aggregates, recycled aggregates, Admixture and Water (also called as raw data. The study also concluded that ANN performs better when non-dimensional parameters like Sand–Aggregate ratio, Water–total materials ratio, Aggregate–Cement ratio, Water–Cement ratio and Replacement ratio of natural aggregates by recycled aggregates, were used as additional input parameters. Study of each network developed using raw data and each non dimensional parameter facilitated in studying the impact of each parameter on the performance of the models developed using ANN, MT and NLR as well as performance of the ANN models developed with limited number of inputs. The results indicate that ANN learn from the examples and grasp the fundamental domain rules governing strength of concrete.

  17. Analysis of familial aggregation of atopic eczema and other atopic diseases by ODDS RATIO regression models.

    Science.gov (United States)

    Diepgen, T L; Blettner, M

    1996-05-01

    In order to determine the relative importance of genetics and the environment on the occurrence of atopic diseases, we investigated the familial aggregation of atopic eczema, allergic rhinitis, and allergic asthma in the relatives of 426 patients with atopic eczema and 628 subjects with no history of eczema (5,136 family members in total). Analyses were performed by regression models for odds ratios (OR) allowing us to estimate OR for the familial aggregation and simultaneously to adjust for other covariates. Three models were analyzed assuming that the OR i) is the same among any two members of a family, ii) depends on different familial constellations, i.e., whether the pairs are siblings, parents, or parent/sibling pairs, and iii) is not the same between the father and the children and between the mother and the children. The OR of familial aggregation for atopic eczema was 2.16 (95% confidence interval (95%-CI) 1.58-2.96) if no distinction was made between the degree of relationship. Further analyses within the members of the family showed a high OR among siblings (OR = 3.86; 95%-CI 2.10-7.09), while the OR between parents and siblings was only 1.90 (95%-CI 1.31-2.97). Only for atopic eczema was the familial aggregation between fathers and siblings (ms: OR = 2.66; fs: OR = 1.29). This can be explained by stronger maternal heritability, shared physical environment of mother and child, or environmental events that affect the fetus in utero. Since for all atopic diseases a stronger correlation was found between siblings than between siblings and parents, our study indicates that environmental factors, especially during childhood, seem to explain the recently observed increased frequencies of atopic diseases. PMID:8618061

  18. Aggregation of sea urchin phagocytes is augmented in vitro by lipopolysaccharide.

    Science.gov (United States)

    Majeske, Audrey J; Bayne, Christopher J; Smith, L Courtney

    2013-01-01

    Development of protocols and media for culturing immune cells from marine invertebrates has not kept pace with advancements in mammalian immune cell culture, the latter having been driven by the need to understand the causes of and develop therapies for human and animal diseases. However, expansion of the aquaculture industry and the diseases that threaten these systems creates the need to develop cell and tissue culture methods for marine invertebrates. Such methods will enable us to better understand the causes of disease outbreaks and to develop means to avoid and remedy epidemics. We report a method for the short-term culture of phagocytes from the purple sea urchin, Strongylocentrotus purpuratus, by modifying an approach previously used to culture cells from another sea urchin species. The viability of cultured phagocytes from the purple sea urchin decreases from 91.6% to 57% over six days and phagocyte morphology changes from single cells to aggregates leading to the formation of syncytia-like structures. This process is accelerated in the presence of lipopolysaccharide suggesting that phagocytes are capable of detecting this molecular pattern in culture conditions. Sea urchin immune response proteins, called Sp185/333, are expressed on the surface of a subset of phagocytes and have been associated with syncytia-like structures. We evaluated their expression in cultured phagocytes to determine their possible role in cell aggregation and in the formation of syncytia-like structures. Between 0 and 3 hr, syncytia-like structures were observed in cultures when only ~10% of the cells were positive for Sp185/333 proteins. At 24 hr, ~90% of the nuclei were Sp185/333-positive when all of the phagocytes had aggregated into syncytia-like structures. Consequently, we conclude that the Sp185/333 proteins do not have a major role in initiating the aggregation of cultured phagocytes, however the Sp185/333 proteins are associated with the clustered nuclei within the

  19. Quantifying the Aggregation Factor in Carbon Nano tube Dispersions by Absorption Spectroscopy

    International Nuclear Information System (INIS)

    Absorption spectroscopy in the ultraviolet-visible-near infrared (UV-Vis-NIR) wavelength region has been used to quantify the aggregation factor of single-walled carbon nano tubes (SWCNTs) in liquid media through a series of controlled experiments. SWCNT bundles are dispersed in selected solvents using a calibrated ultrasonicator, which helps in determining the true amount of energy used in the exfoliation process. We also establish the selectivity of the centrifugation process, under the conditions used, in removing the nano tube aggregates as a function of the sonication time and the dispersion solvent. This study, along with the calibration of the sonication process, is shown to be very important for measuring the true aggregation factor of SWCNTs through a modified approach. We also show that the systematic characterization of SWCNT dispersions by optical spectroscopy significantly contributes to the success of di electrophoresis (DEP) of nano tubes at predefined on-chip positions. The presence of individually dispersed SWCNTs in the dispersions is substantiated by di electrophoretic assembly and post-DEP electromechanical measurements.

  20. Enhanced charge transport properties by strengthened necks between TiO2 aggregates for dye sensitized solar cells

    International Nuclear Information System (INIS)

    The electron diffusion in the TiO2 aggregate network was enhanced through the addition of TiO2 nanoparticles with preferential filling at the necks between adjacent TiO2 aggregates, which resulted in strengthening the connections, while retaining the porous structure of the TiO2 network. The fortified necks was found to reduce the transport resistance (Rt) by allowing facile transfer of electrons from one aggregate to another, while the scattering effect of the TiO2 aggregate network got weakened with adding the TiO2 nanoparticles as a result of reduction of the light scattering centers such as the necks and gaps between the aggregates. However, due to the increase in surface area as the TiO2 nanoparticles were added, the diminished light scattering effect of the aggregate network was compensated and even the highest performance was achieved when the 10% TiO2 nanoparticle was added into the TiO2 aggregate film, suggesting that widening necks between sub-micrometer sized light scatters such as an aggregate would be a good strategy in achieving further improvement of power conversion efficiency of dye sensitized solar cells through the improved charge transport property. - Highlights: • The added nanoparticles fill the necks preferentially. • The fortified necks made electron transport in the TiO2 network facilitated. • Balancing between light scattering and dye uptake should be considered

  1. Light absorption and scattering by aggregates: Application to black carbon and snow grains

    International Nuclear Information System (INIS)

    A geometric-optics surface-wave approach has been developed for the computation of light absorption and scattering by nonspherical particles for application to aggregates and snow grains with external and internal mixing structures. Aggregates with closed- (internal mixing) and open-cell configurations are constructed by means of stochastic procedures using homogeneous and core-shell spheres with smooth or rough surfaces as building blocks. The complex aggregate shape and composition can be accounted for by using the hit-and-miss Monte Carlo geometric photon tracing method. We develop an integral expression for diffraction by randomly oriented aggregates based on Babinet's principle and a photon-number weighted geometric cross section. With reference to surface-wave contributions originally developed for spheres, we introduce a nonspherical correction factor using a non-dimensional volume parameter such that it is 1 for spheres and 0 for elongated particles. The extinction efficiency, single-scattering albedo, and asymmetry factor results for randomly oriented columns and plates compare reasonably well with those determined from the finite-difference time domain (FDTD) and the discrete dipole approximation (DDA) computer codes for size parameters up to about 20. The present theoretical approach covers all size ranges and is particularly attractive from the perspective of efficient light absorption and scattering calculations for complex particle shape and inhomogeneous composition. We show that under the condition of equal volume and mass, the closed-cell configuration has larger absorption than its open-cell counterpart for both ballistic and diffusion-limited aggregates. Because of stronger absorption in the closed-cell case, most of the scattered energy is confined to forward directions, leading to a larger asymmetry factor than the open-cell case. Additionally, light absorption for randomly oriented snowflakes is similar to that of their spherical counterparts

  2. Active protein aggregates induced by terminally attached self-assembling peptide ELK16 in Escherichia coli

    Directory of Open Access Journals (Sweden)

    Zhou Bihong

    2011-02-01

    Full Text Available Abstract Background In recent years, it has been gradually realized that bacterial inclusion bodies (IBs could be biologically active. In particular, several proteins including green fluorescent protein, β-galactosidase, β-lactamase, alkaline phosphatase, D-amino acid oxidase, polyphosphate kinase 3, maltodextrin phosphorylase, and sialic acid aldolase have been successfully produced as active IBs when fused to an appropriate partner such as the foot-and-mouth disease virus capsid protein VP1, or the human β-amyloid peptide Aβ42(F19D. As active IBs may have many attractive advantages in enzyme production and industrial applications, it is of considerable interest to explore them further. Results In this paper, we report that an ionic self-assembling peptide ELK16 (LELELKLK2 was able to effectively induce the formation of cytoplasmic inclusion bodies in Escherichia coli (E. coli when attached to the carboxyl termini of four model proteins including lipase A, amadoriase II, β-xylosidase, and green fluorescent protein. These aggregates had a general appearance similar to the usually reported cytoplasmic inclusion bodies (IBs under transmission electron microscopy or fluorescence confocal microscopy. Except for lipase A-ELK16 fusion, the three other fusion protein aggregates retained comparable specific activities with the native counterparts. Conformational analyses by Fourier transform infrared spectroscopy revealed the existence of newly formed antiparallel beta-sheet structures in these ELK16 peptide-induced inclusion bodies, which is consistent with the reported assembly of the ELK16 peptide. Conclusions This has been the first report where a terminally attached self-assembling β peptide ELK16 can promote the formation of active inclusion bodies or active protein aggregates in E. coli. It has the potential to render E. coli and other recombinant hosts more efficient as microbial cell factories for protein production. Our observation might

  3. The prediction of the freeze/thaw durability of coarse aggregate in concrete by mercury intrusion porosimetry

    Science.gov (United States)

    Lindgren, M. N.

    1980-10-01

    Aggregates from fifty-two Indiana highway cores were tested as were five rock samples supplied by the Portland Cement Association. The Expected Durability Factor values were determined from the pore size distributions, and an average value was assigned to each pavement associated with the cores. These values were then compared with the field performance of the pavement to ascertain the borderline between EDF values for durable and for nondurable aggregates. A good correlation between the field performance and the average EDF values was found. A pavement will be durable if its coarse aggregate has an EDF value greater than 50 for 90% or more of the aggregate. This criterion applies to stone and gravel aggregates with a maximum size of 1-1/2 to 2-1/2 inches. The pavement will be durable for at lest thirty years.

  4. Calculating excited states of molecular aggregates by the renormalized excitonic method

    CERN Document Server

    Ma, Yingjin

    2013-01-01

    In this paper, we apply the recently developed \\emph{ab initio} renormalized excitonic method (REM) to the excitation energy calculations of various molecular aggregates, through the extension of REM to the time-dependent density functional theory (TDDFT). Tested molecular aggregate systems include one-dimensional hydrogen-bonded water chains, ring crystals with $\\pi$-$\\pi$ stacking or van-der Waals interactions and the general aqueous systems with polar and non-polar solutes. The basis set factor as well as the effect of the exchange-correlation functionals are also investigated. The results indicate that the REM-TDDFT method with suitable basis set and exchange-correlation functionals can give good descriptions of excitation energies and excitation area for lowest electronic excitations in the molecular aggregate systems with economic computational costs. It's shown that the deviations of REM-TDDFT excitation energies from those by standard TDDFT are much less than 0.1 eV and the computational time can be r...

  5. Inhibition of IAPP aggregation by insulin depends on the insulin oligomeric state regulated by zinc ion concentration

    OpenAIRE

    Praveen Nedumpully-Govindan; Feng Ding

    2015-01-01

    While islet amyloid polypeptide (IAPP) aggregation is associated with β-cell death in type-II diabetes (T2D), environmental elements of β-cell granules — e.g. high concentrations of insulin and Zn2+ — inhibit IAPP aggregation in healthy individuals. The inhibition by insulin is experimentally known, but the role of Zn2+ is controversial as both correlations and anti-correlations at the population level are observed between T2D risk and the activity of a β-cell specific zinc ion transporter, Z...

  6. Effect of the pre-treatment and the aggregate content on the adhesion strength of repair mortars on Miocene porous limestone

    Science.gov (United States)

    Szemerey-Kiss, Balázs; Török, Ákos

    2016-04-01

    The adhesion between porous limestone and newly prepared repair mortars are crucial in the preservation of historic stone structures. Besides mechanical compatibility other matches such as chemical composition and porosity are also essential, but the current research focuses on the adhesion strength of repair mortars that are used in the restoration of Hungarian porous limestone. 8 mortars (4 commercial and 4 specially prepared) were selected for the tests. Mortars with different amount of aggregate were prepared and caste to stone surface. The stone substrate was highly porous Miocene limestone. The strength was tested by standardized pull-out tests which method is commonly used for concrete testing. The limestone surfaces were either used in their natural conditions or were pre-treated (pre-wetting). The strength of the stone/mortar bond was tested. The failure mechanism was documented and various failure modes were identified. Strength test results suggest that especially pre-treatment influences strongly the pull-out strength at mortar/stone interface. Increasing aggregate content also reduces pull out strength of tested repair mortars, but at various rates depending on the mortar type. The financial support of OTKA post-doctoral grant to BSZK (reference number is: PD 112-955) and National Research, Development and Innovation (NKFI) Fund to ÁT (ref. no. K 116532) are appreciated.

  7. Colonization of marine snow aggregates by invertebrate zooplankton : Abundance, scaling, and possible role

    DEFF Research Database (Denmark)

    Kiørboe, Thomas

    2000-01-01

    I compiled literature observations of abundances of invertebrate zooplankters associated with marine snow aggregates in the euphotic zone. Abundances, normalized with ambient concentrations of colonizers, scale with equivalent aggregate radius raised to power 2.27. Different taxonomic groups show...

  8. Light scattering by fractal dust aggregates: I. Angular dependence of scattering

    CERN Document Server

    Tazaki, Ryo; Okuzumi, Satoshi; Kataoka, Akimasa; Nomura, Hideko

    2016-01-01

    In protoplanetary disks, micron-sized dust grains coagulate to form highly porous dust aggregates. Because the optical properties of these aggregates are not completely understood, it is important to investigate how porous dust aggregates scatter light. In this study, the light scattering properties of porous dust aggregates were calculated using a rigorous method, the T-matrix method, and the results were then compared with those obtained using the Rayleigh-Gans-Debye (RGD) theory and Mie theory with the effective medium approximation (EMT). The RGD theory is applicable to moderately large aggregates made of nearly transparent monomers. This study considered two types of porous dust aggregates, ballistic cluster-cluster agglomerates (BCCAs) and ballistic particle-cluster agglomerates (BPCAs). First, the angular dependence of the scattered intensity was shown to reflect the hierarchical structure of dust aggregates; the large-scale structure of the aggregates is responsible for the intensity at small scatteri...

  9. Effect of the surfactant tween 80 on the detachment and dispersal of Salmonella enterica serovar Thompson single cells and aggregates from cilantro leaves as revealed by image analysis.

    Science.gov (United States)

    Brandl, Maria T; Huynh, Steven

    2014-08-01

    Salmonella enterica has the ability to form biofilms and large aggregates on produce surfaces, including on cilantro leaves. Aggregates of S. enterica serovar Thompson that remained attached to cilantro leaves after rigorous washing and that were present free or bound to dislodged leaf tissue in the wash suspension were observed by confocal microscopy. Measurement of S. Thompson population sizes in the leaf washes by plate counts failed to show an effect of 0.05% Tween 80 on the removal of the pathogen from cilantro leaves 2 and 6 days after inoculation. On the contrary, digital image analysis of micrographs of single cells and aggregates of green fluorescent protein (GFP)-S. Thompson present in cilantro leaf washes revealed that single cells represented 13.7% of the cell assemblages in leaf washes containing Tween 80, versus 9.3% in those without the surfactant. Moreover, Tween 80 decreased the percentage of the total S. Thompson cell population located in aggregates equal to or larger than 64 cells from 9.8% to 4.4% (P < 0.05). Regression analysis of the frequency distribution of aggregate size in leaf washes with and without Tween 80 showed that the surfactant promoted the dispersal of cells from large aggregates into smaller ones and into single cells (P < 0.05). Our study underlines the importance of investigating bacterial behavior at the scale of single cells in order to uncover trends undetectable at the population level by bacterial plate counts. Such an approach may provide valuable information to devise strategies aimed at enhancing the efficacy of produce sanitization treatments. PMID:24907336

  10. Nattokinase improves blood flow by inhibiting platelet aggregation and thrombus formation

    OpenAIRE

    Jang, Ja-Young; Kim, Tae-Su; Cai, Jingmei; Kim, Jihyun; Kim, Youngeun; Shin, Kyungha; Kim, Kwang Sei; Park, Sung Kyeong; Lee, Sung-Pyo; Choi, Ehn-Kyoung; Rhee, Man Hee; Kim, Yun-Bae

    2013-01-01

    The effects of nattokinase on the in vitro platelet aggregation and in vivo thrombosis were investigated in comparison with aspirin. Rabbit platelet-rich plasma was incubated with nattokinase and aggregation inducers collagen and thrombin, and the platelet aggregation rate was analyzed. Nattokinase significantly inhibited both the collagen- and thrombin-induced platelet aggregations. Nattokinase also reduced thromboxane B2 formation from collagen-activated platelets in a concentration-depende...

  11. A Soluble Aggregated Thermophile Metalloaminopeptidase Produced by an Alcalophile Strain of Bacillus halodurans

    Directory of Open Access Journals (Sweden)

    S. Dabonné

    2011-01-01

    Full Text Available H4 strain isolated from Lake Bogoria was found to be Bacillus halodurans. The Bacteria produced an extracellular peptidase activity toward substrates Ile-pNA, Met-pNA and Val-pNA. It also hydrolyzed small peptides. A purification procedure including ion-exchange chromatography ion exchange DEAE and sizeexclusion chromatography followed by Sodium dodecyl sulphate-polyacrymalide gel electrophoresis (SDSPAGE revealed the aggregated form of the enzyme. The three substrates are hydrolyzed by a single catalytic site. The enzyme inactivated by bestatin, and 1,10-phenanthroline is a metalloaminopeptidase whose activity is maximal at pH 9.0 and 65ºC.

  12. Soil aggregate stability as affected by clay mineralogy and polyacrylamide addition

    Science.gov (United States)

    The addition of polyacrylamide (PAM) to soil leads to stabilization of existing aggregates and improved bonding between, and aggregation of adjacent soil particles However, the dependence of PAM efficacy as an aggregate stabilizing agent on soil-clay mineralogy has not been studied. Sixteen soil sam...

  13. Hydrogen metabolism by decomposing cyanobacterial aggregates in Big Soda Lake, Nevada

    Energy Technology Data Exchange (ETDEWEB)

    Oremland, R.S.

    1983-05-01

    Hydrogen production by incubated cyanobacterial epiphytes occurred only in the dark, was stimulated by C/sub 2/H/sub 2/, and was inhibited by O/sub 2/. Addition of NO/sub 3//sup -/ inhibited dark, anaerobic H/sub 2/ production, whereas the addition of NH/sub 4//sup +/ inhibited N/sub 2/ fixation (C/sub 2/H/sub 2/ reduction) but not dark H/sub 2/ production. Aerobically incubated cyanobacterial aggregates consumed H/sub 2/, but light-incubated rates (3.6 mu mol of H/sub 2/ g-1 h-1) were statistically equivalent to dark uptake rates (4.8 mu mol of H/sub 2/ g-1 h-1), which were statistically equivalent to dark, anaerobic production rates (2.5 to 10 mu mol of H/sub 2/ g-1 h-1). Production rates of H/sub 2/ were fourfold higher for aggregates in a more advanced stage of decomposition. Enrichment cultures of H/sub 2/-producing fermentative bacteria were recovered from freshly harvested, H/sub 2/-producing cyanobacterial aggregates. Hydrogen production in these cyanobacterial communities appears to be caused by the resident bacterial flora and not by the cyanobacteria. In situ areal estimates of dark H/sub 2/ production by submerged epiphytes (6.8 mu mol of H/sub 2/ m-2 h-1) were much lower than rates of light-driven N/sub 2/ fixation by the epiphytic cyanobacteria (310 mu mol of C/sub 2/H/sub 4/ meters -2 h-1). (26 Refs.)

  14. The influence of conditions of agitation on the properties of aggregates formed during treatment of water with content of humic substances

    Czech Academy of Sciences Publication Activity Database

    Pivokonská, Lenka; Pivokonský, Martin

    London : IWA Publishing, 2005, s. 643-648. ISBN 9781843395652. [IWA international conference on particle separation 2005. Seoul (KP), 01.06.2005-03.06.2005] R&D Projects: GA ČR GA103/04/0929 Institutional research plan: CEZ:AV0Z20600510 Keywords : water treatment * degree of aggregation * particle size distribution Subject RIV: DA - Hydrology ; Limnology

  15. Degradable polymeric nanoparticles by aggregation of thermoresponsive polymers and ``click'' chemistry

    Science.gov (United States)

    Dworak, Andrzej; Lipowska, Daria; Szweda, Dawid; Suwinski, Jerzy; Trzebicka, Barbara; Szweda, Roza

    2015-10-01

    This study describes a novel approach to the preparation of crosslinked polymeric nanoparticles of controlled sizes that can be degraded under basic conditions. For this purpose thermoresponsive copolymers containing azide and alkyne functions were obtained by ATRP of di(ethylene glycol) monomethyl ether methacrylate (D) and 2-aminoethyl methacrylate (A) followed by post polymerization modification. The amino groups of A were reacted with propargyl chloroformate or 2-azido-1,3-dimethylimidazolinium hexafluorophosphate, which led to two types of copolymers. Increasing the temperature of aqueous solutions of the mixed copolymers caused their aggregation into spherical nanoparticles composed of both types of chains. Their dimensions could be controlled by changing the concentration and heating rate of the solutions. Covalent stabilization of aggregated chains was performed by a ``click'' reaction between the azide and alkyne groups. Due to the presence of a carbamate bond the nanoparticles undergo pH dependent degradation under mild basic conditions. The proposed procedure opens a route to new carriers for the controlled release of active species.This study describes a novel approach to the preparation of crosslinked polymeric nanoparticles of controlled sizes that can be degraded under basic conditions. For this purpose thermoresponsive copolymers containing azide and alkyne functions were obtained by ATRP of di(ethylene glycol) monomethyl ether methacrylate (D) and 2-aminoethyl methacrylate (A) followed by post polymerization modification. The amino groups of A were reacted with propargyl chloroformate or 2-azido-1,3-dimethylimidazolinium hexafluorophosphate, which led to two types of copolymers. Increasing the temperature of aqueous solutions of the mixed copolymers caused their aggregation into spherical nanoparticles composed of both types of chains. Their dimensions could be controlled by changing the concentration and heating rate of the solutions. Covalent

  16. Topological Self-Similar Networks Introduced by Diffusion-Limited Aggregation Mechanism

    Institute of Scientific and Technical Information of China (English)

    YANG Lei; PEI Wen-Jiang; LI Tao; CHEUNG Yiu-Ming; HE Zhen-Ya

    2008-01-01

    @@ We propose a model for growing fractal networks based on the mechanisms learned from the diffusion-limited aggregation (DLA) model in fractal geometries in the viewpoint of network.By studying the DLA network,our model introduces multiplicative growth,aging and geographical preferential attachment mechanisms,whereby featuring topological self-similar property and hierarchical modularity.According to the results of theoretical analysis and simulation,the degree distribution of the proposed model shows a mixed degree distribution (i.e.,exponential and algebraic degree distribution) and the fractal dimension and clustering coefficient can be tuned by changing the values of parameters.

  17. Scalable evaluation of platelet aggregation by the degree of blood migration

    Science.gov (United States)

    Song, Suk-Heung; Lim, Chae-Seung; Shin, Sehyun

    2013-12-01

    Platelet aggregation plays a key role in vascular thrombosis. Antiplatelet drug therapy is commonly used for the prevention of abnormal platelet aggregation. So, measuring platelet aggregation function is critically important in clinical field. Here, we introduce a scalable evaluation method of platelet aggregation measured with the degree of blood migration through microchannel in a microfluidic chip. Unlike conventional methods that require expertise with system physics to operate devices, our approach is using microfluidics system, which requires only a syringe vacuum. The scalable migration factors, migration distance and touchdown time, are capable of distinguishing various antiplatelet drug effects under microfluidics and would be effective for the quick and easy evaluation of quantitative platelet aggregation.

  18. ARK: Aggregation of Reads by K-Means for Estimation of Bacterial Community Composition.

    Directory of Open Access Journals (Sweden)

    David Koslicki

    Full Text Available Estimation of bacterial community composition from high-throughput sequenced 16S rRNA gene amplicons is a key task in microbial ecology. Since the sequence data from each sample typically consist of a large number of reads and are adversely impacted by different levels of biological and technical noise, accurate analysis of such large datasets is challenging.There has been a recent surge of interest in using compressed sensing inspired and convex-optimization based methods to solve the estimation problem for bacterial community composition. These methods typically rely on summarizing the sequence data by frequencies of low-order k-mers and matching this information statistically with a taxonomically structured database. Here we show that the accuracy of the resulting community composition estimates can be substantially improved by aggregating the reads from a sample with an unsupervised machine learning approach prior to the estimation phase. The aggregation of reads is a pre-processing approach where we use a standard K-means clustering algorithm that partitions a large set of reads into subsets with reasonable computational cost to provide several vectors of first order statistics instead of only single statistical summarization in terms of k-mer frequencies. The output of the clustering is then processed further to obtain the final estimate for each sample. The resulting method is called Aggregation of Reads by K-means (ARK, and it is based on a statistical argument via mixture density formulation. ARK is found to improve the fidelity and robustness of several recently introduced methods, with only a modest increase in computational complexity.An open source, platform-independent implementation of the method in the Julia programming language is freely available at https://github.com/dkoslicki/ARK. A Matlab implementation is available at http://www.ee.kth.se/ctsoftware.

  19. Tillage practices in the conterminous United States, 1989-2004-Datasets Aggregated by Watershed

    Science.gov (United States)

    Baker, Nancy T.

    2011-01-01

    This report documents the methods used to aggregate county-level tillage practices to the 8-digit hydrologic unit (HU) watershed. The original county-level data were collected by the Conservation Technology Information Center (CTIC). The CTIC collects tillage data by conducting surveys about tillage systems for all counties in the United States. Tillage systems include three types of conservation tillage (no-till, ridge-till, and mulch-till), reduced tillage, and intensive tillage. Total planted acreage for each tillage practice for each crop grown is reported to the CTIC. The dataset includes total planted acreage by tillage type for selected crops (corn, cotton, grain sorghum, soybeans, fallow, forage, newly established permanent pasture, spring and fall seeded small grains, and 'other' crops) for 1989-2004. Two tabular datasets, based on the 1992 enhanced and 2001 National Land Cover Data (NLCD), are provided as part of this report and include the land-cover area-weighted interpolation and aggregation of acreage for each tillage practice in each 8-digit HU watershed in the conterminous United States for each crop. Watershed aggregations were done by overlying the 8-digit HU polygons with a raster of county boundaries and a raster of either the enhanced 1992 or the 2001 NLCD for cultivated land to derive a county/land-cover area weighting factor. The weighting factor then was applied to the county-level tillage data for the counties within each 8-digit HU and summed to yield the total acreage of each tillage type within each 8-digit HU watershed.

  20. Aggregation of polyQ proteins is increased upon yeast aging and affected by Sir2 and Hsf1: novel quantitative biochemical and microscopic assays.

    Directory of Open Access Journals (Sweden)

    Aviv Cohen

    Full Text Available Aging-related neurodegenerative disorders, such as Parkinson's, Alzheimer's and Huntington's diseases, are characterized by accumulation of protein aggregates in distinct neuronal cells that eventually die. In Huntington's disease, the protein huntingtin forms aggregates, and the age of disease onset is inversely correlated to the length of the protein's poly-glutamine tract. Using quantitative assays to estimate microscopically and capture biochemically protein aggregates, here we study in Saccharomyces cerevisiae aging-related aggregation of GFP-tagged, huntingtin-derived proteins with different polyQ lengths. We find that the short 25Q protein never aggregates whereas the long 103Q version always aggregates. However, the mid-size 47Q protein is soluble in young logarithmically growing yeast but aggregates as the yeast cells enter the stationary phase and age, allowing us to plot an "aggregation timeline". This aging-dependent aggregation was associated with increased cytotoxicity. We also show that two aging-related genes, SIR2 and HSF1, affect aggregation of the polyQ proteins. In Δsir2 strain the aging-dependent aggregation of the 47Q protein is aggravated, while overexpression of the transcription factor Hsf1 attenuates aggregation. Thus, the mid-size 47Q protein and our quantitative aggregation assays provide valuable tools to unravel the roles of genes and environmental conditions that affect aging-related aggregation.

  1. Exchange bias and magnetic behaviour of iron nanoclusters prepared by the gas aggregation technique

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez-Marcos, J., E-mail: sanchej@icmm.csic.es [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain); Laguna-Marco, M.A.; Martinez-Morillas, R. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain); Jimenez-Villacorta, F. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain); SpLine Spanish CRG Beamline at the European Synchrotron Radiation Facilities, ESRF-BP 220-38043 Grenoble Cedex (France); Cespedes, E. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain); Menendez, N. [Dep. Quimica-Fisica Aplicada, Universidad Autonoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Prieto, C. [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Cientificas, Cantoblanco, 28049 Madrid (Spain)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Gas aggregation phase technique allows obtaining {alpha}-Fe{sub 2}O{sub 3} nanoparticles. Black-Right-Pointing-Pointer We have reported exchange bias up to 3250 Oe at 2 K. Black-Right-Pointing-Pointer Exchange bias may be tuned by different stoichiometry of {alpha}-Fe{sub 2}O{sub 3} nanoparticles. - Abstract: Iron nanoclusters have been deposited by the gas-phase aggregation technique to form multilayered structures with outstanding exchange-bias (H{sub E}) values up to H{sub E} = 3300 Oe at low temperatures. In order to explain the observed magnetic properties, composition and crystallographic phase have been determined by X-ray absorption spectroscopy. A metal-oxide core-shell arrangement has to be discarded to explain the large obtained values of H{sub E} since structural results show nanoclusters formed by the antiferromagnetic {alpha}-Fe{sub 2}O{sub 3} oxide. Moreover, nanoparticles of few nanometers formed by substoichiometric {alpha}-Fe{sub 2}O{sub 3} explain the observed weak ferromagnetism and let to understand the origin of large exchange bias by the interaction between different spin sublattice configurations provided by the low iron coordination at surface.

  2. Influence of an inhomogeneous magnetic field on erythrocyte aggregation mechanism--an analysis by He-Ne laser aggregometer

    International Nuclear Information System (INIS)

    The influence of the inhomogeneous magnetic field (IMF) on the erythrocytes and their aggregates, while sedimenting in a glass chamber under gravity, is analyzed. The aggregation data are acquired by using online He-Ne laser aggregometer and are represented in terms of various dynamic parameters. The analysis shows that the sedimentation of the erythrocytes and their aggregates is accelerated in the presence of the IMF. Thus, this technique could be applied in the study of blood samples in diseases with altered hemoglobin properties

  3. Inhibition of aggregation of amyloid peptides by beta-sheet breaker peptides and their binding affinity.

    Science.gov (United States)

    Viet, Man Hoang; Ngo, Son Tung; Lam, Nguyen Sy; Li, Mai Suan

    2011-06-01

    The effects of beta-sheet breaker peptides KLVFF and LPFFD on the oligomerization of amyloid peptides were studied by all-atom simulations. It was found that LPFFD interferes the aggregation of Aβ(16-22) peptides to a greater extent than does KLVFF. Using the molecular mechanics-Poisson-Boltzmann surface area (MM-PBSA) method, we found that the former binds more strongly to Aβ(16-22). Therefore, by simulations, we have clarified the relationship between aggregation rates and binding affinity: the stronger the ligand binding, the slower the oligomerization process. The binding affinity of pentapeptides to full-length peptide Aβ(1-40) and its mature fibrils has been considered using the Autodock and MM-PBSA methods. The hydrophobic interaction between ligands and receptors plays a more important role for association than does hydrogen bonding. The influence of beta-sheet breaker peptides on the secondary structures of monomer Aβ(1-40) was studied in detail, and it turns out that, in their presence, the total beta-sheet content can be enhanced. However, the aggregation can be slowed because the beta-content is reduced in fibril-prone regions. Both pentapeptides strongly bind to monomer Aβ(1-40), as well as to mature fibrils, but KLVFF displays a lower binding affinity than LPFFD. Our findings are in accord with earlier experiments that both of these peptides can serve as prominent inhibitors. In addition, we predict that LPFFD inhibits/degrades the fibrillogenesis of full-length amyloid peptides better than KLVFF. This is probably related to a difference in their total hydrophobicities in that the higher the hydrophobicity, the lower the inhibitory capacity. The GROMOS96 43a1 force field with explicit water and the force field proposed by Morris et al. (Morris et al. J. Comput. Chem. 1998, 19, 1639 ) were employed for all-atom molecular dynamics simulations and Autodock experiments, respectively. PMID:21563780

  4. Aggregation-Enhanced Raman Scattering by a Water-Soluble Porphyrin

    Science.gov (United States)

    Akins, Daniel L.

    1995-01-01

    Much interest in our laboratory has focused on aggregation of organic compounds, particularly cyanine dyes and porphyrins. For this discussion we have applied absorption and Raman scattering spectroscopies to characterize aggregated TSPP (tetrakis-(p-sulfonatophynyl) porphyrin) in aqueous solution. Based on concentration, pH and ionic strength dependence of TSPP absorption, we deduce that aggregation evolves through the formation of TSPP diacid and that the diacid is the repeating unit in the aggregate. The Raman bands of TSPP in strongly acidic solution lead us further to conclude that vibrations of adjacent molecules are perturbed in a fashion that is consistent with the pyrrolic ring in the porphinato macrocycle being ruffled, and that two aggregate arrangements occur: specifically J- and H-type aggregates. Furthermore, aggregation enhancement is advanced as a viable mechanism to explain enhanced Raman Scattering for homogeneous aqueous phase TSPP, where the surface-enhancement mechanism is not applicable.

  5. Tillage Practices in the Conterminous United States, 1989-2004--Datasets Aggregated by Watershed; tillage_lu92e

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset is an aggregation of county-level tillage practices to the 8-digit hydrologic unit watershed. The original county-level data were collected by the...

  6. Tillage Practices in the Conterminous United States, 1989-2004--Datasets by Aggregated Watershed; ds573_tillage_lu01

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This dataset is an aggregation of county-level tillage practices to the 8-digit hydrologic unit watershed. The original county-level data were collected by the...

  7. Field-induced aggregates in a bilayer ferrofluid characterized by ultrasound spectroscopy

    International Nuclear Information System (INIS)

    This paper presents dynamic changes in ferrofluid properties during a magnetic field sweep. The study reported was performed on a ferrofluid with a double layer of surfactant used to prevent aggregation of particles. The ferrofluid parameters (the radius and volume of the cluster, the elastic force constant) were studied by the ultrasound wave absorption method as a function of the dynamically changing magnetic field. During the application of the magnetic field from 0 to 100 kA m-1 the structure in the ferrofluid evolves and become anisotropic. The magnetic field was found to stimulate formation of micrometre clusters and exponential increase in the elastic force constant

  8. The aggregation kinetics of Alzheimer’s β-amyloid peptide is controlled by stochastic nucleation

    OpenAIRE

    Hortschansky, Peter; Schroeckh, Volker; Christopeit, Tony; Zandomeneghi, Giorgia; Fändrich, Marcus

    2005-01-01

    We report here a recombinant expression system that allows production of large quantities of Alzheimer’s Aβ(1–40) peptide. The material is competent to dissolve in water solutions with “random-coil properties,” although its conformation and factual oligomerization state are determined by the physico-chemical solution conditions. When dissolved in 50 mM sodium phosphate buffer (pH 7.4) at 37°C, the peptide is able to undergo a nucleated polymerization reaction. The aggregation profile is chara...

  9. Abrupt growth of large aggregates by correlated coalescences in turbulent flow

    CERN Document Server

    Bec, Jeremie; Saw, Ewe Wei; Homann, Holger

    2015-01-01

    Smoluchowski's coagulation kinetics is here shown to fail when the coalescing species are dilute and transported by a turbulent flow. The intermittent Lagrangian motion involves correlated violent events that lead to an unexpected rapid occurrence of the largest particles. This new phenomena is here quantified in terms of the anomalous scaling of turbulent three-point motion, leading to significant corrections in macroscopic processes that are critically sensitive to the early-stage emergence of large embryonic aggregates, as in planet formation or rain precipitation.

  10. Abrupt growth of large aggregates by correlated coalescences in turbulent flow

    Science.gov (United States)

    Bec, Jérémie; Ray, Samriddhi Sankar; Saw, Ewe Wei; Homann, Holger

    2016-03-01

    Smoluchowski's coagulation kinetics is here shown to fail when the coalescing species are dilute and transported by a turbulent flow. The intermittent Lagrangian motion involves correlated violent events that lead to an unexpected rapid occurrence of the largest particles. This new phenomena is here quantified in terms of the anomalous scaling of turbulent three-point motion, leading to significant corrections in macroscopic processes that are critically sensitive to the early-stage emergence of large embryonic aggregates, as in planet formation or rain precipitation.

  11. Modulation of platelet aggregation by areca nut and betel leaf ingredients: roles of reactive oxygen species and cyclooxygenase.

    Science.gov (United States)

    Jeng, Jiiang-Huei; Chen, Shiao-Yun; Liao, Chang-Hui; Tung, Yuan-Yii; Lin, Bor-Ru; Hahn, Liang-Jiunn; Chang, Mei-Chi

    2002-05-01

    There are 2 to 6 billion betel quid (BQ) chewers in the world. Areca nut (AN), a BQ component, modulates arachidonic acid (AA) metabolism, which is crucial for platelet function. AN extract (1 and 2 mg/ml) stimulated rabbit platelet aggregation, with induction of thromboxane B2 (TXB2) production. Contrastingly, Piper betle leaf (PBL) extract inhibited AA-, collagen-, and U46619-induced platelet aggregation, and TXB2 and prostaglandin-D2 (PGD2) production. PBL extract also inhibited platelet TXB2 and PGD2 production triggered by thrombin, platelet activating factor (PAF), and adenosine diphosphate (ADP), whereas little effect on platelet aggregation was noted. Moreover, PBL is a scavenger of O2(*-) and *OH, and inhibits xanthine oxidase activity and the (*)OH-induced PUC18 DNA breaks. Deferoxamine, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (BAPTA) and neomycin prevented AN-induced platelet aggregation and TXB2 production. Indomethacin, genistein, and PBL extract inhibited only TXB2 production, but not platelet aggregation. Catalase, superoxide dismutase, and dimethylthiourea (DMT) showed little effect on AN-induced platelet aggregation, whereas catalase and DMT inhibited the AN-induced TXB2 production. These results suggest that AN-induced platelet aggregation is associated with iron-mediated reactive oxygen species production, calcium mobilization, phospholipase C activation, and TXB2 production. PBL inhibited platelet aggregation via both its antioxidative effects and effects on TXB2 and PGD2 production. Effects of AN and PBL on platelet aggregation and AA metabolism is crucial for platelet activation in the oral mucosa and cardiovascular system in BQ chewers. PMID:11978487

  12. Impaired platelet aggregation and sustained bleeding in mice lacking the fibrinogen motif bound by integrin alpha IIb beta 3.

    OpenAIRE

    Holmbäck, K; Danton, M J; Suh, T T; Daugherty, C. C.; Degen, J L

    1996-01-01

    Blood loss at sites of vascular rupture is controlled by the adhesion and aggregation of platelets and the formation of an insoluble fibrin matrix. Fibrinogen is considered to be critical in these processes by both providing an abundant dimeric ligand for alpha IIb beta 3-mediated platelet aggregation, and serving as the fundamental building block of the fibrin polymer. To establish an in vivo model system to examine in detail the importance of alpha IIb beta 3-fibrinogen interactions in plat...

  13. Differences in the Pathways of Proteins Unfolding Induced by Urea and Guanidine Hydrochloride: Molten Globule State and Aggregates

    OpenAIRE

    Povarova, Olga I.; Kuznetsova, Irina M.; Turoverov, Konstantin K.

    2010-01-01

    It was shown that at low concentrations guanidine hydrochloride (GdnHCl) can cause aggregation of proteins in partially folded state and that fluorescent dye 1-anilinonaphthalene-8-sulfonic acid (ANS) binds with these aggregates rather than with hydrophobic clusters on the surface of protein in molten globule state. That is why the increase in ANS fluorescence intensity is often recorded in the pathway of protein denaturation by GdnHCl, but not by urea. So what was previously believed to be t...

  14. Aggregation of sea urchin phagocytes is augmented in vitro by lipopolysaccharide.

    Directory of Open Access Journals (Sweden)

    Audrey J Majeske

    Full Text Available Development of protocols and media for culturing immune cells from marine invertebrates has not kept pace with advancements in mammalian immune cell culture, the latter having been driven by the need to understand the causes of and develop therapies for human and animal diseases. However, expansion of the aquaculture industry and the diseases that threaten these systems creates the need to develop cell and tissue culture methods for marine invertebrates. Such methods will enable us to better understand the causes of disease outbreaks and to develop means to avoid and remedy epidemics. We report a method for the short-term culture of phagocytes from the purple sea urchin, Strongylocentrotus purpuratus, by modifying an approach previously used to culture cells from another sea urchin species. The viability of cultured phagocytes from the purple sea urchin decreases from 91.6% to 57% over six days and phagocyte morphology changes from single cells to aggregates leading to the formation of syncytia-like structures. This process is accelerated in the presence of lipopolysaccharide suggesting that phagocytes are capable of detecting this molecular pattern in culture conditions. Sea urchin immune response proteins, called Sp185/333, are expressed on the surface of a subset of phagocytes and have been associated with syncytia-like structures. We evaluated their expression in cultured phagocytes to determine their possible role in cell aggregation and in the formation of syncytia-like structures. Between 0 and 3 hr, syncytia-like structures were observed in cultures when only ~10% of the cells were positive for Sp185/333 proteins. At 24 hr, ~90% of the nuclei were Sp185/333-positive when all of the phagocytes had aggregated into syncytia-like structures. Consequently, we conclude that the Sp185/333 proteins do not have a major role in initiating the aggregation of cultured phagocytes, however the Sp185/333 proteins are associated with the clustered

  15. Equivalent models of wind farms by using aggregated wind turbines and equivalent winds

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, L.M.; Garcia, C.A.; Saenz, J.R. [Department of Electrical Engineering, EPS Algeciras, University of Cadiz, Avda. Ramon Puyol, s/n. 11202 Algeciras, Cadiz (Spain); Jurado, F. [Department of Electrical Engineering, EPS Linares, University of Jaen, C/ Alfonso X, n 28. 23700 Linares, Jaen (Spain)

    2009-03-15

    As a result of the increasing wind farms penetration on power systems, the wind farms begin to influence power system, and therefore the modeling of wind farms has become an interesting research topic. In this paper, new equivalent models of wind farms equipped with wind turbines based on squirrel-cage induction generators and doubly-fed induction generators are proposed to represent the collective behavior on large power systems simulations, instead of using a complete model of wind farms where all the wind turbines are modeled. The models proposed here are based on aggregating wind turbines into an equivalent wind turbine which receives an equivalent wind of the ones incident on the aggregated wind turbines. The equivalent wind turbine presents re-scaled power capacity and the same complete model as the individual wind turbines, which supposes the main feature of the present equivalent models. Two equivalent winds are evaluated in this work: (1) the average wind from the ones incident on the aggregated wind turbines with similar winds, and (2) an equivalent incoming wind derived from the power curve and the wind incident on each wind turbine. The effectiveness of the equivalent models to represent the collective response of the wind farm at the point of common coupling to grid is demonstrated by comparison with the wind farm response obtained from the detailed model during power system dynamic simulations, such as wind fluctuations and a grid disturbance. The present models can be used for grid integration studies of large power system with an important reduction of the model order and the computation time. (author)

  16. Equivalent models of wind farms by using aggregated wind turbines and equivalent winds

    International Nuclear Information System (INIS)

    As a result of the increasing wind farms penetration on power systems, the wind farms begin to influence power system, and therefore the modeling of wind farms has become an interesting research topic. In this paper, new equivalent models of wind farms equipped with wind turbines based on squirrel-cage induction generators and doubly-fed induction generators are proposed to represent the collective behavior on large power systems simulations, instead of using a complete model of wind farms where all the wind turbines are modeled. The models proposed here are based on aggregating wind turbines into an equivalent wind turbine which receives an equivalent wind of the ones incident on the aggregated wind turbines. The equivalent wind turbine presents re-scaled power capacity and the same complete model as the individual wind turbines, which supposes the main feature of the present equivalent models. Two equivalent winds are evaluated in this work: (1) the average wind from the ones incident on the aggregated wind turbines with similar winds, and (2) an equivalent incoming wind derived from the power curve and the wind incident on each wind turbine. The effectiveness of the equivalent models to represent the collective response of the wind farm at the point of common coupling to grid is demonstrated by comparison with the wind farm response obtained from the detailed model during power system dynamic simulations, such as wind fluctuations and a grid disturbance. The present models can be used for grid integration studies of large power system with an important reduction of the model order and the computation time

  17. Experimental Study of Active Path Block in a Multi-Bifurcated Flow by Microbubble Aggregation

    Science.gov (United States)

    Shigehara, Nobuhiko; Demachi, Fumi; Koda, Ren; Mochizuki, Takashi; Masuda, Kohji; Ikeda, Seiichi; Arai, Fumihito; Miyamoto, Yoshitaka; Chiba, Toshio

    2013-07-01

    We previously reported our attempts at the active control of microbubble aggregations using acoustic radiation force, which propels microbubbles and adjusts the size of aggregations. However, because we used simple-shape artificial blood vessels, the behavior of aggregations in a small channel, e.g., the probability to obstruct the bloodstream, and the possibility of embolization, has not been predicted. Thus, we designed and fabricated a multi-bifurcated artificial blood vessel to apply to the production and active control of microbubble aggregations. Then, we introduced two kinds of ultrasound transducers for producing and propelling aggregations. First, we produced aggregations in a flow to measure their size and investigate their variation according to the emission duration of ultrasound. Then, we control the aggregations in an artificial blood vessel to verify their controllability. When ultrasound was stopped, the aggregations flaked off the vessel wall and flowed downstream, were propelled to the desired path, and finally were caught at a narrow path. We verified the same experiment under similar parameters to calculate the probability of realizing a path block. When the flow velocity was 20 mm/s, almost 50% of the aggregations were induced to flow through the desired path and a maximum probability of realizing a path block of 86% was achieved with the formation of aggregations.

  18. Water stable aggregates of Japanese Andisol as affected by hydrophobicity and drying temperature

    Directory of Open Access Journals (Sweden)

    Leelamanie D.A.L.

    2014-06-01

    Full Text Available Hydrophobicity is a property of soils that reduces their affinity for water, which may help impeding the pressure build-up within aggregates, and reducing aggregate disruption. The purpose of this study was to examine the relation of soil hydrophobicity and drying temperature to water stability of aggregates while preventing the floating of dry aggregates using unhydrophobized and hydrophobized surface Andisol. Soil was hydrophobized using stearic acid into different hydrophobicities. Hydrophobicity was determined using sessile drop contact angle and water drop penetration time (WDPT. Water stability of aggregates (%WSA was determined using artificially prepared model aggregates. The %WSA increased as the contact angle and WDPT increased. Contact angle and WDPT, which provided maximum %WSA showing less than 1 s of floating, was around 100° and 5 s, respectively. Although the %WSA gradually increased with increasing contact angle and WDPT above this level, high levels of hydrophobicity initiated aggregate floating, which would cause undesirable effects of water repellency. Heating at 50°C for 5 h d-1 significantly affected %WSA and hydrophobicity in hydrophobized samples, but did not in unhydrophobized samples. The results indicate that the contact angle and wetting rate (WDPT are closely related with the water stability of aggregates. The results further confirm that high levels of hydrophobicities induce aggregate floating, and the drying temperature has differential effects on hydrophobicity and aggregate stability depending on the hydrophobic materials present in the soil.

  19. Hsp70 chaperones accelerate protein translocation and the unfolding of stable protein aggregates by entropic pulling.

    Science.gov (United States)

    De Los Rios, Paolo; Ben-Zvi, Anat; Slutsky, Olga; Azem, Abdussalam; Goloubinoff, Pierre

    2006-04-18

    Hsp70s are highly conserved ATPase molecular chaperones mediating the correct folding of de novo synthesized proteins, the translocation of proteins across membranes, the disassembly of some native protein oligomers, and the active unfolding and disassembly of stress-induced protein aggregates. Here, we bring thermodynamic arguments and biochemical evidences for a unifying mechanism named entropic pulling, based on entropy loss due to excluded-volume effects, by which Hsp70 molecules can convert the energy of ATP hydrolysis into a force capable of accelerating the local unfolding of various protein substrates and, thus, perform disparate cellular functions. By means of entropic pulling, individual Hsp70 molecules can accelerate unfolding and pulling of translocating polypeptides into mitochondria in the absence of a molecular fulcrum, thus settling former contradictions between the power-stroke and the Brownian ratchet models for Hsp70-mediated protein translocation across membranes. Moreover, in a very different context devoid of membrane and components of the import pore, the same physical principles apply to the forceful unfolding, solubilization, and assisted native refolding of stable protein aggregates by individual Hsp70 molecules, thus providing a mechanism for Hsp70-mediated protein disaggregation. PMID:16606842

  20. The aggregation behavior of zinc-free insulin studied by small-angle neutron scattering

    DEFF Research Database (Denmark)

    Pedersen, J.S.; Hansen, S.; Bauer, R.

    1994-01-01

    The aggregation behavior of zinc-free insulin has been studied by small-angle neutron scattering as a function of pH and ionic strength of the solution. The pair distance distribution functions for the 12 samples have been obtained by indirect Fourier transformation. The results show that the...... diameter of the aggregates is 40 Angstrom at pH 11 and 10 mM NaCl, independent of the protein concentration. The largest diameter of about 120 Angstrom is found for pH 8, 100 mM NaCl, and a protein concentration of 10 mg/ml. Estimates of the pair distance distribution functions, free of inter...... monomer mass and 14 Angstrom to 6.8 times the monomer mass and 31 Angstrom, respectively. The mass distribution between the oligomers was determined by a model based on the crystal structure of zinc-free insulin. The results from this model and the Fourier transformations have been compared to an...

  1. Characterization of Two Second-Site Mutations Preventing Wild Type Protein Aggregation Caused by a Dominant Negative PMA1 Mutant

    OpenAIRE

    Pilar Eraso; Francisco Portillo; Mazón, María J.

    2013-01-01

    The correct biogenesis and localization of Pma1 at the plasma membrane is essential for yeast growth. A subset of PMA1 mutations behave as dominant negative because they produce aberrantly folded proteins that form protein aggregates, which in turn provoke the aggregation of the wild type protein. One approach to understand this dominant negative effect is to identify second-site mutations able to suppress the dominant lethal phenotype caused by those mutant alleles. We isolated and character...

  2. Inhibition of adenosine diphosphate-induced platelet aggregation by alpha-lipoic acid and dihydroquercetin in vitro

    OpenAIRE

    Ivan S Ivanov; Sidehmenova, Anastasia V.; Vera I Smol′yakova; Chernysheva, Galina A.; Plotnikov, Mark B.

    2014-01-01

    Objectives: To investigate the antiplatelet activity of alpha-lipoic acid (α-LA) and dihydroquercetin (DHQ). Materials and Methods: Antiplatelet activity of the α-LA and DHQ was evaluated in rich platelet plasma of rat. The platelet aggregation was induced by adenosine diphosphate (ADP) in concentration of 4 Χ 10 -5 Μ. Results: α-LA and DHQ inhibited platelet aggregation in concentration-dependent manner. The antiplatelet activity of α-LA was more pronounced than DHQ. DHQ also increas...

  3. Highly sensitive determination of poly(hexamethylene guanidine) by Rayleigh scattering using aggregation of silver nanoparticles

    International Nuclear Information System (INIS)

    We have found that low concentrations of the polycationic disinfectant poly(hexamethylene guanidine) hydrochloride (PHMG) induce the aggregation of citrate-stabilized silver nanoparticles (AgNPs) in aqueous solution. Based on this finding, we have worked out a method to the determination of PHMG. The protocol includes the steps of (a) centrifuging the water sample, (b) addition of an aliquot of the colloidal solution of the AgNPs, and (c) measurement of the intensity of scattered light. The method is surprisingly selective in that comparable concentrations of surfactants, humic acids and protein do not interfere. Besides, an up to 50 mM concentration NaCl, and up to 5 mM of Mg(II) or Ca(II) are tolerated. Other cationic polyelectrolytes, polyethyleneimine and poly(dimethyldiallyammonium chloride), also cause aggregation of AgNPs but to a lesser extent. The determination of PHMG was performed in spiked samples (run-off, tap and swimming pool waters) with detection limits of 2·10−8, 4·10−7, and 6·10−6 M (by monomer unit), respectively. The linear ranges are wider and the detection limits are lower than those of known spectrophotometric methods. It is necessary, however, to correct the calibration plot for background scattering by the sample and to establish a calibration plot for each kind of water sample. Notwithstanding this, the approach is attractive because it is sensitive, rapid, and simple. (author)

  4. Light scattering by large clusters of dipoles as an analog for cometary dust aggregates

    International Nuclear Information System (INIS)

    This paper addresses the question as to whether the characteristics of solar radiation scattered by cometary dust can be intrinsically attributed to light scattering by a number of interacting electric dipoles. We calculate light scattering by an ensemble of dipoles having the polarizability of an isolated sphere using the discrete dipole approximation. Our results are consistent with the recent successful model that describes cometary dust as large aggregate particles consisting of optically dark submicrometer-size monomers. We show that by calculating electric dipole-dipole interactions the overall trend of the optical properties can be studied. Calculating higher scattering orders is currently limited by computer capabilities, but is required for a better quantitative description of light scattering by cometary dust. We finally discuss the different model parameters considered for investigating the optical properties of cometary dust

  5. Proposing an Aggregate Production Planning Model by Goal Programming Approach, a Case Study

    OpenAIRE

    Mansoureh Farzam Rad; Hadi Shirouyehzad

    2014-01-01

    Production planning is one of the most important functions in the process of production management. Production planning in the intermediate range of time is termed as aggregate production planning (APP). Aggregate production planning is an important upper level planning activity in a production management system. The present study tries to suggest an aggregate production planning model for products of Hafez tile factory during one year. Due to this fact that the director of the company seeks ...

  6. The effects of vincristine on platelet aggregation studied by a filter loop technique in the rat.

    OpenAIRE

    Bee, D; Leach, E.; Martin, J. F.; Suggett, A. J.

    1980-01-01

    1 A method for measuring aggregation of platelets of adenosine diphosphate (ADP) is described using a filter inserted into the flowing aortic blood in the rat. 2 Repeated infusions of ADP resulted in a fall in the calculated aggregation index without significant changes in the platelet count. 3 Vincristine (0.05 mg/kg) intravenously caused significant inhibition of ADP-induced platelet aggregation. 4 Infusion of ADP caused some peripheral vasodilatation though it is unlikely that this contrib...

  7. Breakup of Finite-Size Colloidal Aggregates in Turbulent Flow Investigated by Three-Dimensional (3D) Particle Tracking Velocimetry.

    Science.gov (United States)

    Saha, Debashish; Babler, Matthaus U; Holzner, Markus; Soos, Miroslav; Lüthi, Beat; Liberzon, Alex; Kinzelbach, Wolfgang

    2016-01-12

    Aggregates grown in mild shear flow are released, one at a time, into homogeneous isotropic turbulence, where their motion and intermittent breakup is recorded by three-dimensional particle tracking velocimetry (3D-PTV). The aggregates have an open structure with a fractal dimension of ∼2.2, and their size is 1.4 ± 0.4 mm, which is large, compared to the Kolmogorov length scale (η = 0.15 mm). 3D-PTV of flow tracers allows for the simultaneous measurement of aggregate trajectories and the full velocity gradient tensor along their pathlines, which enables us to access the Lagrangian stress history of individual breakup events. From this data, we found no consistent pattern that relates breakup to the local flow properties at the point of breakup. Also, the correlation between the aggregate size and both shear stress and normal stress at the location of breakage is found to be weaker, when compared with the correlation between size and drag stress. The analysis suggests that the aggregates are mostly broken due to the accumulation of the drag stress over a time lag on the order of the Kolmogorov time scale. This finding is explained by the fact that the aggregates are large, which gives their motion inertia and increases the time for stress propagation inside the aggregate. Furthermore, it is found that the scaling of the largest fragment and the accumulated stress at breakup follows an earlier established power law, i.e., dfrag ∼ σ(-0.6) obtained from laminar nozzle experiments. This indicates that, despite the large size and the different type of hydrodynamic stress, the microscopic mechanism causing breakup is consistent over a wide range of aggregate size and stress magnitude. PMID:26646289

  8. The aggregation and diffusion of asphaltenes studied by GPU-accelerated dissipative particle dynamics

    Science.gov (United States)

    Wang, Sibo; Xu, Junbo; Wen, Hao

    2014-12-01

    The heavy crude oil consists of thousands of compounds and much of them have large molecular weights and complex structures. Studying the aggregation and diffusion behavior of asphaltenes can facilitate the understanding of the heavy crude oil. In previous studies, the fused aromatic rings were treated as rigid bodies so that dissipative particle dynamics (DPD) integrated with the quaternion method can be used to study asphaltene systems. In this work, DPD integrated with the quaternion method is implemented on graphics processing units (GPUs). Compared with the serial program, tens of times speedup can be achieved when simulations performed on a single GPU. Using multiple GPUs can provide faster computation speed and more storage space for simulations of significant large systems. By using large systems, simulations of the asphaltene-toluene system at extremely dilute concentrations can be performed. The determined diffusion coefficients of asphaltenes are similar to that in experimental studies. At last, the aggregation behavior of asphaltenes in heptane was investigated, and the simulation results agreed with the modified Yen model. Monomers, nanoaggregates and clusters were observed from the simulations at different concentrations.

  9. Enhancing stabilities of lipase by enzyme aggregate coating immobilized onto ionic liquid modified mesoporous materials

    Science.gov (United States)

    Zou, Bin; Song, Chunyan; Xu, Xiaping; Xia, Jiaojiao; Huo, Shuhao; Cui, Fengjie

    2014-08-01

    Mesoporous material SBA-15 as the matrix and hydrophilic methyl imidazolium ionic liquids [MSiIM]+BF4- as modifier were involved in preparing ionic liquid modified materials as enzyme carriers through after-grafting silane coupling reaction. The method of enzyme aggregates coating was firstly used to immobilize porcine pancreatic lipase (PPL) onto ionic liquid modified SBA-15. Characterization before and after modification and immobilization were conducted using infrared spectroscopy (FT-IR), differential thermal-thermal analysis (DTA-TG) and N2 adsorption-desorption method (BET). The results indicated that the ordering degree of SBA-15 declined after ionic liquid modification, but mesoporous structure remained. After enzyme immobilization, pore size and specific surface area of carrier became smaller. The cross-linking agent amount, reaction temperature and pH were optimized in this paper. The result demonstrated that the initial activity of enzyme was raised from 35% to 53% after five times recycle by enzyme aggregate coating. 74% of the original activity remained after 25 days storage.

  10. Suppression of Aggrus/podoplanin-induced platelet aggregation and pulmonary metastasis by a single-chain antibody variable region fragment

    International Nuclear Information System (INIS)

    Almost all highly metastatic tumor cells possess high platelet aggregating abilities, thereby form large tumor cell-platelet aggregates in the microvasculature. Embolization of tumor cells in the microvasculature is considered to be the first step in metastasis to distant organs. We previously identified the platelet aggregation-inducing factor expressed on the surfaces of highly metastatic tumor cells and named as Aggrus. Aggrus was observed to be identical to the marker protein podoplanin (alternative names, T1α, OTS-8, and others). Aggrus is frequently overexpressed in several types of tumors and enhances platelet aggregation by interacting with the platelet receptor C-type lectin-like receptor 2 (CLEC-2). Here, we generated a novel single-chain antibody variable region fragment (scFv) by linking the variable regions of heavy and light chains of the neutralizing anti-human Aggrus monoclonal antibody MS-1 with a flexible peptide linker. Unfortunately, the generated KM10 scFv failed to suppress Aggrus-induced platelet aggregation in vitro. Therefore, we performed phage display screening and finally obtained a high-affinity scFv, K-11. K-11 scFv was able to suppress Aggrus-induced platelet aggregation in vitro. Moreover, K-11 scFv prevented the formation of pulmonary metastasis in vivo. These results suggest that K-11 scFv may be useful as metastasis inhibitory scFv and is expected to aid in the development of preclinical and clinical examinations of Aggrus-targeted cancer therapies

  11. Rational Aggregation

    OpenAIRE

    Bruce Chapman

    2002-01-01

    In two recent papers, Christian List and Philip Pettit have argued that there is a problem in the aggregation of reasoned judgements that is akin to the aggregation of the preference problem in social choice theory.1 Indeed, List and Pettit prove a new general impossibility theorem for the aggregation of judgements, and provide a propositional interpretation of the social choice problem that suggests it is a special case of their impossibility result.2 Specifically, they show that no judgemen...

  12. beta-Sheet Aggregation of Kisspeptin-10 is Stimulated by Heparin but Inhibited by Amphiphiles

    DEFF Research Database (Denmark)

    Nielsen, Søren Bang; Franzmann, Magnus; Basaiawmoit, Rajiv Vaid; Wimmer, Reinhard; Mikkelsen, Jens D; Otzen, Daniel Erik

    2010-01-01

    The murine 10-residue neurohormone kisspeptin (YNWNSFGLRY) is an important regulator of reproductive behavior and gonadotrophin secretion. It is known to form a random coil in solution, but undergoes a structural change in the presence of membranes although the nature of this change is not fully...... submicellar concentrations of zwitterionic and anionic surfactants. Unlike previous reports, our NMR data do not indicate persistent structure in the presence of zwitterionic surfactant micelles. Thus kisspeptin can aggregate under physiologically relevant conditions provided heparin is present, but the...

  13. Platelet–leukocyte aggregation induced by PAR agonists: regulation by nitric oxide and matrix metalloproteinases

    OpenAIRE

    Chung, Ada W Y; Radomski, Anna; Alonso-Escolano, David; Jurasz, Paul; Stewart, Michael W; Malinski, Tadeusz; Radomski, Marek W

    2004-01-01

    Platelet–leukocyte aggregation (PLA) links haemostasis to inflammation. The role of nitric oxide (NO) and matrix metalloproteinases (MMP-1, -2, -3, -9) in PLA regulation was studied.Homologous human platelet–leukocyte suspensions were stimulated with thrombin (0.1–3 nM) and other proteinase activated receptor-activating peptides (PAR-AP), including PAR1AP (0.5–10 μM), PAR4AP (10–70 μM), and thrombin receptor-activating peptide (1–35 μM).PLA was studied using light aggregometry with simultaneo...

  14. Absorption Spectra of Astaxanthin Aggregates

    OpenAIRE

    Olsina, Jan; Durchan, Milan; Minofar, Babak; Polivka, Tomas; Mancal, Tomas

    2012-01-01

    Carotenoids in hydrated polar solvents form aggregates characterized by dramatic changes in their absorption spectra with respect to monomers. Here we analyze absorption spectra of aggregates of the carotenoid astaxanthin in hydrated dimethylsulfoxide. Depending on water content, two types of aggregates were produced: H-aggregates with absorption maximum around 390 nm, and J-aggregates with red-shifted absorption band peaking at wavelengths >550 nm. The large shifts with respect to absorption...

  15. Provenance for Aggregate Queries

    OpenAIRE

    Yael Amsterdamer; Daniel Deutch; Val Tannen

    2011-01-01

    We study in this paper provenance information for queries with aggregation. Provenance information was studied in the context of various query languages that do not allow for aggregation, and recent work has suggested to capture provenance by annotating the different database tuples with elements of a commutative semiring and propagating the annotations through query evaluation. We show that aggregate queries pose novel challenges rendering this approach inapplicable. Consequently, we propose...

  16. Diffusion in aggregated soil.

    OpenAIRE

    Rappoldt, C.

    1992-01-01

    The structure of an aggregated soil is characterized by the distribution of the distance from an arbitrary point in the soil to the nearest macropore or crack. From this distribution an equivalent model system is derived to which a diffusion model can be more easily applied. The model system consists of spherical, or cylindrical or plane aggregates, which do not represent the individual aggregates of the soil, however. The radii of the spheres, cylinders or plane sheets represent different le...

  17. Lumenal peroxisomal protein aggregates are removed by concerted fission and autophagy events

    NARCIS (Netherlands)

    Manivannan, Selvambigai; de Boer, Rinse; Veenhuis, Marten; van der Klei, Ida J.

    2013-01-01

    We demonstrated that in the yeast Hansenula polymorpha peroxisome fission and degradation are coupled processes that are important to remove intra-organellar protein aggregates. Protein aggregates were formed in peroxisomes upon synthesis of a mutant catalase variant. We showed that the introduction

  18. Discrepancies over the onset of surfactant monomer aggregation interpreted by fluorescence, conductivity and surface tension methods

    OpenAIRE

    1998-01-01

    Molecular probe techniques have made important contributions to the determination of microstructure of surfactant assemblies such as size, stability, micropolarity and conformation. Conductivity and surface tension were used to determine the critical aggregation concentration (cac) of polymer-surfactant complexes and the critical micellar concentration (cmc) of aqueous micellar aggregates. The results are compared with those of fluorescent techniques. Several surfactant systems were examined,...

  19. Solving frictional contact problems by two aggregate-function-based algorithms

    Institute of Scientific and Technical Information of China (English)

    Suyan He; Hongwu Zhang; Xingsi Li; Ron Marshall

    2005-01-01

    Three dimensional frictional contact problems are formulated as linear complementarity problems based on the parametric variational principle. Two aggregate-functionbased algorithms for solving complementarity problems are proposed. One is called the self-adjusting interior point algorithm, the other is called the aggregate function smoothing algorithm. Numerical experiment shows the efficiency of the proposed two algorithms.

  20. Clogging of landfill tyre and aggregate drainage layers by methanogenic leachate and implications for practice.

    Science.gov (United States)

    Beaven, R P; Hudson, A P; Knox, K; Powrie, W; Robinson, J P

    2013-02-01

    This paper reports the results of pilot scale tests carried out to investigate the clogging of shredded and baled tyres in comparison with aggregates when percolated by leachates representative of those generated by methanogenic stage landfills. Realistic lifetime loading rates of methanogenic leachate were applied, and clogging was not generally apparent in any of the drainage media studied. This is in apparent contrast to many other studies that have demonstrated the susceptibility of all forms of drainage media to biological and chemical clogging when percolated with high strength organic and calcium rich leachates. The reasons for this difference are identified, the implications for landfill drainage system design are discussed and some suggestions for operational practice are presented for discussion. PMID:23206518

  1. Stabilization of Organic Matter by Interactions with Iron Oxides: Relative Importance of Sorption vs. Aggregation

    Science.gov (United States)

    Jin, L.; Berhe, A. A.

    2015-12-01

    Persistence of organic matter in soil is largely determined by the environmental conditions that organic compounds encounter in the environment. The most important stabilization mechanisms for carbon in soil include chemical and physical association of organic compounds with soil minerals. However, to date, we don't have a complete understanding of the relative contribution of each process to carbon stabilization, especially under different soil conditions. To develop better process-level understanding of these stabilization mechanisms, the relative importance of chemical vs. physical mechanisms of carbon stabilization facilitated by iron oxides at different soil solution conditions using a variety of advanced approaches including electron microscopy and infrared spectroscopy is determined. Our preliminary results suggest that aggregation may be the dominant process in mineral-organic associations. These results improve our understanding of factors that regulate persistence of organic matter in soil system.

  2. The G46S-hPAH mutant protein: a model to study the rescue of aggregation-prone PKU mutations by chaperones.

    Science.gov (United States)

    Leandro, João; Saraste, Jaakko; Leandro, Paula; Flatmark, Torgeir

    2011-01-01

    Phenylketonuria (PKU), the most common inborn error of metabolism, is caused by dysfunction of the liver enzyme phenylalanine hydroxylase (PAH), with more than 550 PAH gene mutations identified to date. A large number of these mutations result in mutant forms of the enzyme displaying reduced stability, increased propensity to aggregate, and accelerated in cellulo degradation. Loss or reduction of human PAH activity results in hyperphenylalaninemia (HPA) which, if untreated, results in severe mental retardation and impaired cognitive development. Until now, strict low phenylalanine diet has been the most effective therapy, but as a protein misfolding disease PKU is a good candidate for treatment by natural/chemical/pharmacological chaperones. The natural cofactor of human PAH, (6R)-L-erythro-5,6,7,8-tetrahydrobiopterin (BH(4)), has already been approved for oral treatment of HPA, giving a positive response in mild forms of the disease showing considerable residual enzymatic activity. In the case of the most severe forms of PKU, ongoing studies with chemical and pharmacological chaperones to rescue misfolded mutant proteins from aggregation and degradation are providing promising results. The PKU mutation G46S is associated with a severe form of the disease, resulting in an aggregation-prone protein. The human PAH mutant G46S is rapidly degraded in the cellular environment and, in vitro (upon removal of its stabilizing fusion partner maltose binding protein (MBP)) self-associates to form higher-order oligomers/fibrils. Here, we present an in vitro experimental model system to study the modulation of G46S aggregation by chemical/pharmacological chaperones, which may represent a useful approach to study the rescue of other severe PKU mutations by chemical/pharmacological chaperones. PMID:21871828

  3. Stochastic structural model of rock and soil aggregates by continuum-based discrete element method

    Institute of Scientific and Technical Information of China (English)

    WANG; Yuannian; ZHAO; Manhong; LI; Shihai; J.G.; Wang

    2005-01-01

    This paper first presents a stochastic structural model to describe the random geometrical features of rock and soil aggregates. The stochastic structural model uses mixture ratio, rock size and rock shape to construct the microstructures of aggregates,and introduces two types of structural elements (block element and jointed element) and three types of material elements (rock element, soil element, and weaker jointed element)for this microstructure. Then, continuum-based discrete element method is used to study the deformation and failure mechanism of rock and soil aggregate through a series of loading tests. It is found that the stress-strain curve of rock and soil aggregates is nonlinear, and the failure is usually initialized from weaker jointed elements. Finally, some factors such as mixture ratio, rock size and rock shape are studied in detail. The numerical results are in good agreement with in situ test. Therefore, current model is effective for simulating the mechanical behaviors of rock and soil aggregates.

  4. Aggregate breakdown and surface seal development influenced by rain intensity, slope gradient and soil particle size

    Directory of Open Access Journals (Sweden)

    S. Arjmand Sajjadi

    2014-12-01

    Dmax 4.75 mm were in the finest size classes of 0.02 and 0.043 mm, respectively for all slope gradients and rain intensities. The soil containing finer aggregates exhibited higher transportability of pre-detached material than the soil containing larger aggregates. Also, IR increased with increasing slope gradient, rain intensity and aggregate size under unsteady state conditions because of less development of surface seal. But under steady state conditions, no significant relationship was found between slope and IR. The finding of this study revealed the importance of rain intensity, slope steepness and soil aggregate size on aggregate breakdown and seal formation, which can control infiltration rate and the consequent runoff and erosion rates.

  5. Deposition and characterization of Pt nanocluster films by means of gas aggregation cluster source

    International Nuclear Information System (INIS)

    In this study we report on the deposition of Pt nanocluster films prepared by gas aggregation source that was operated with argon as working gas. The aim of this study was optimization of deposition process as well as determination of properties of deposited nanocluster films and their temporal stability. It was found that the production of Pt nanoclusters reached maximum value for pressure of 100 Pa and increases monotonously with magnetron current. The deposition rate at optimized deposition conditions was 0.7 nm of the Pt nanocluster film per second. Deposited films were porous and composed of 4 nm Pt nanoclusters. The nanoclusters were metallic and no sights of their oxidation were observed after 1 year on open air as witnessed by X-ray photoelectron spectroscopy. Regarding the electrical properties, a dramatic decrease of the resistivity was observed with increasing amount of deposited nanoclusters. This decrease saturated for the films approximately 50 nm thick. Such behavior indicates transition between different mechanisms of electrical conductivity: charge hopping for thin discontinuous films and current conduction through conducting path formed when higher amount of nanoclusters is deposited. Different mechanisms of electrical conduction for thin and thick layers of Pt were confirmed by subsequent investigation of temperature dependence of resistivity. In addition, no changes in resistivity were observed after one year on open air that confirms stability of produced Pt nanocluster films. - Highlights: • Pt nanocluster films were deposited by gas aggregation nanocluster source. • Conditions leading to effective deposition of Pt nanocluster films were found. • Deposited nanocluster films have good temporal stability. • Electrical properties of Pt films were found to depend on their thickness

  6. An aggregated indicator of air-pollution impacts involved by transports

    International Nuclear Information System (INIS)

    We intend to build a global environmental impact indicator of air pollution to assess transport infrastructures, technologies or flows. This indicator tries to be simple and transparent to facilitate its use in decision-making. The intention is for the indicator to be like the Global Warming Potential (GWP), which establishes a relationship between the emission of six greenhouse gases and the average temperature increase of the Earth. The indicator therefore allows estimating the global environmental impact of transport-generated air pollution, while simultaneously conserving the value of the environmental impact of each type of air pollution and the emission assessment. This work is based on an environmental impact typology, a set of indicators, and aggregation architecture of atmospheric pollution. The typology is established as a function of the specific and homogenous characteristics of each type of pollution in terms of pollutants, impact mechanisms, targets and environmental impacts. To ensure exhaustiveness and non-redundancy, 10 types of air pollution impact are proposed: greenhouse effect, ozone depletion, direct eco-toxicity (this type of pollution excludes greenhouse effects on nature, ozone depletion, eutrophication, acidification and photochemical pollution), eutrophication, acidification, photochemical pollution, restricted direct health effects (not taking into account welfare, and excluding the effects on health of the greenhouse effect, ozone depletion, acidification and photochemical pollution), sensitive pollution (annoyance caused by odours and fumes), and degradation of common and historical man-made heritage. Indicators similar to GWP can be identified in the literature for each type of atmospheric pollution, except for the degradation of common and historical man-made heritage, for which none indicator have been suggested. However, these indicators do not seem to have achieved wide scientific consensus, except for GWP, which may make it

  7. Weighted aggregation

    Science.gov (United States)

    Feiveson, A. H. (Principal Investigator)

    1979-01-01

    The use of a weighted aggregation technique to improve the precision of the overall LACIE estimate is considered. The manner in which a weighted aggregation technique is implemented given a set of weights is described. The problem of variance estimation is discussed and the question of how to obtain the weights in an operational environment is addressed.

  8. Aggregation states of polymers at non-solvent interfaces by neutron reflectivity

    International Nuclear Information System (INIS)

    The aggregation states of polystyrene (PS) thin films at interfaces with non-solvents such as water, methanol and hexane were examined by specular neutron reflectivity and sum-frequency generation vibrational spectroscopy. The density profiles of the PS thin films along the direction normal to the interface with water and methanol were comparable to that in air. However, this was not the case of the film in hexane exhibiting a diffused interfacial layer due to swelling. Also, the local conformation of PS at the outermost region of the films was quite sensitive to the surrounding environment and responded consequently to a change in its environment. This was the case for typical non-solvents such as water and methanol. The extent of the conformational change might be explained in terms of the interfacial energy. Similar experiments are also performed for poly(methyl methacrylate) (PMMA). Results so obtained are compared with each other.

  9. Deterioration of limestone aggregate mortars by liquid sodium in fast breeder reactor environment

    International Nuclear Information System (INIS)

    Highlights: • Limestone mortars were exposed to liquid sodium exposure at 550 °C. • Micro-analytical techniques were used to characterize the exposed specimens. • The performance of limestone mortar was greatly influenced by w/c. • The fundamental degradation mechanisms of limestone mortars were identified. - Abstract: Hot liquid sodium at 550 °C can interact with concrete in the scenario of an accidental spillage of sodium in liquid metal cooled fast breeder reactors. To protect the structural concrete from thermo-chemical degradation, a sacrificial layer of limestone aggregate concrete is provided over it. This study investigates the fundamental mechanisms of thermo-chemical interaction between the hot liquid sodium and limestone mortars at 550 °C for a duration of 30 min in open air. The investigation involves four different types of cement with variation of water-to-cement ratios (w/c) from 0.4 to 0.6. Comprehensive analysis of experimental results reveals that the degree of damage experienced by limestone mortars displayed an upward trend with increase in w/c ratios for a given type of cement. Performance of fly ash based Portland pozzolana cement was superior to other types of cements for a w/c of 0.55. The fundamental degradation mechanisms of limestone mortars during hot liquid sodium interactions include alterations in cement paste phase, formation of sodium compounds from the interaction between solid phases of cement paste and aggregate, modifications of interfacial transition zone (ITZ), decomposition of CaCO3, widening and etching of rhombohedral cleavages, and subsequent breaking through the weakest rhombohedral cleavage planes of calcite, staining, ferric oxidation in grain boundaries and disintegration of impurity minerals in limestone

  10. Protein carbonylation and aggregation precede neuronal apoptosis induced by partial glutathione depletion

    Directory of Open Access Journals (Sweden)

    Jianzheng Zheng

    2012-04-01

    Full Text Available While the build-up of oxidized proteins within cells is believed to be toxic, there is currently no evidence linking protein carbonylation and cell death. In the present study, we show that incubation of nPC12 (neuron-like PC12 cells with 50 μM DEM (diethyl maleate leads to a partial and transient depletion of glutathione (GSH. Concomitant with GSH disappearance there is increased accumulation of PCOs (protein carbonyls and cell death (both by necrosis and apoptosis. Immunocytochemical studies also revealed a temporal/spatial relationship between carbonylation and cellular apoptosis. In addition, the extent of all three, PCO accumulation, protein aggregation and cell death, augments if oxidized proteins are not removed by proteasomal degradation. Furthermore, the effectiveness of the carbonyl scavengers hydralazine, histidine hydrazide and methoxylamine at preventing cell death identifies PCOs as the toxic species. Experiments using well-characterized apoptosis inhibitors place protein carbonylation downstream of the mitochondrial transition pore opening and upstream of caspase activation. While the study focused mostly on nPC12 cells, experiments in primary neuronal cultures yielded the same results. The findings are also not restricted to DEM-induced cell death, since a similar relationship between carbonylation and apoptosis was found in staurosporine- and buthionine sulfoximine-treated nPC12 cells. In sum, the above results show for the first time a causal relationship between carbonylation, protein aggregation and apoptosis of neurons undergoing oxidative damage. To the best of our knowledge, this is the first study to place direct (oxidative protein carbonylation within the apoptotic pathway.

  11. Measuring ecosystem functioning of soil mega-aggregates produced by soil/litter mix-feeding animals

    Science.gov (United States)

    Kaneko, N.

    2009-04-01

    Some soil animals are soil/litter mix-feeders. They are known to produce long-lasting soil structures (e.g. casts and molting chamber), and these structures will modify resource availability and environmental conditions for plants and soil organisms. Good examples are epigeic Megascolecid earthworms (Uchida et al., 2004) and Xystodesmid millipeds (Toyota et al., 2006), both found in Japan. In this study we examined chemical, physical and biological properties of soil focusing on multi-functioning of aggregates made by these animals. Since 2003, we manipulated densities of epigeic earthworms in a field encloser (35 m2) (three replications) at a cool temperate forest in Japan. At a no-worm (NW) treatment, all the worms have been collected every year by hand. At the same place, we prepared a control treatment in an encloser (Closed control; CC) and outside the encloser (Open control; OC). We examined surface soil and plant growth after 5-years field manipulation of oak dominated forest. Growth of two Liliaceae forest floor herbs; Smilacina japonica and Polygonatum odoratum, and oak (Quercus crispula) seedlings and canopy oak trees were recorded. Reduction of aggregates after elimination of earthworms was observed in a field condition. The manipulation site showed decreased soil pH, Ca, Mg, and P concentration and total carbon storage was also reduced. There was a negative significant correlation between casts abundance and soil NH4-N, and a positive significance was observed between casts abundance and growth of S. japonica, and oak seedlings. Radial growth of canopy oak trees was decreased at NW treatment compared to CC and OC. Leaf N contents of oak seedling at NW were significantly lower in NW, but canopy oak trees did not show any difference in leaf-N. Although S. japonica and P. odoratum were both found in a same forest floor, S. japonica is known as nutrient limited plants in spring, whereas P. odoratum is light limited. Oak seedlings are depending early growth

  12. Exploring new biological functions of amyloids: bacteria cell agglutination mediated by host protein aggregation.

    Directory of Open Access Journals (Sweden)

    Marc Torrent

    Full Text Available Antimicrobial proteins and peptides (AMPs are important effectors of the innate immune system that play a vital role in the prevention of infections. Recent advances have highlighted the similarity between AMPs and amyloid proteins. Using the Eosinophil Cationic Protein as a model, we have rationalized the structure-activity relationships between amyloid aggregation and antimicrobial activity. Our results show how protein aggregation can induce bacteria agglutination and cell death. Using confocal and total internal reflection fluorescence microscopy we have tracked the formation in situ of protein amyloid-like aggregates at the bacteria surface and on membrane models. In both cases, fibrillar aggregates able to bind to amyloid diagnostic dyes were detected. Additionally, a single point mutation (Ile13 to Ala can suppress the protein amyloid behavior, abolishing the agglutinating activity and impairing the antimicrobial action. The mutant is also defective in triggering both leakage and lipid vesicle aggregation. We conclude that ECP aggregation at the bacterial surface is essential for its cytotoxicity. Hence, we propose here a new prospective biological function for amyloid-like aggregates with potential biological relevance.

  13. Reactivation of protein aggregates by mortalin and Tid1--the human mitochondrial Hsp70 chaperone system.

    Science.gov (United States)

    Iosefson, Ohad; Sharon, Shelly; Goloubinoff, Pierre; Azem, Abdussalam

    2012-01-01

    The mitochondrial 70-kDa heat shock protein (mtHsp70), also known in humans as mortalin, is a central component of the mitochondrial protein import motor and plays a key role in the folding of matrix-localized mitochondrial proteins. MtHsp70 is assisted by a member of the 40-kDa heat shock protein co-chaperone family named Tid1 and a nucleotide exchange factor. Whereas, yeast mtHsp70 has been extensively studied in the context of protein import in the mitochondria, and the bacterial 70-kDa heat shock protein was recently shown to act as an ATP-fuelled unfolding enzyme capable of detoxifying stably misfolded polypeptides into harmless natively refolded proteins, little is known about the molecular functions of the human mortalin in protein homeostasis. Here, we developed novel and efficient purification protocols for mortalin and the two spliced versions of Tid1, Tid1-S, and Tid1-L and showed that mortalin can mediate the in vitro ATP-dependent reactivation of stable-preformed heat-denatured model aggregates, with the assistance of Mge1 and either Tid1-L or Tid1-S co-chaperones or yeast Mdj1. Thus, in addition of being a central component of the protein import machinery, human mortalin together with Tid1, may serve as a protein disaggregating machine which, for lack of Hsp100/ClpB disaggregating co-chaperones, may carry alone the scavenging of toxic protein aggregates in stressed, diseased, or aging human mitochondria. PMID:21811887

  14. Rapid and ultrasensitive colorimetric detection of mercury(II) by chemically initiated aggregation of gold nanoparticles

    International Nuclear Information System (INIS)

    The article describes a method for rapid and visual determination of Hg(II) ion using unmodified gold nanoparticles (Au-NPs). It involves the addition of Au-NPs to a solution containing Hg(II) ions which, however, does not induce a color change. Next, a solution of lysine is added which induces the aggregation of the Au-NPs and causes the color of the solution to change from wine-red to purple. The whole on-site detection process can be executed in less than 15 min. Other amines (ethylenediamine, arginine, and melamine) were also investigated with respect to their capability to induce aggregation. Notably, only amines containing more than one amino group were found to be effective, but a 0.4 μM and pH 8 solution of lysine was found to give the best results. The detection limits for Hg (II) are 8.4 pM (for instrumental read-out) and 10 pM (for visual read-out). To the best of our knowledge, this LOD is better than those reported for any other existing rapid screening methods. The assay is not interfered by the presence of other common metal ions even if present in 1000-fold excess over Hg(II) concentration. It was successfully applied to the determination of Hg(II) in spiked tap water samples. We perceive that this method provides an excellent tool for rapid and ultrasensitive on-site determination of Hg(II) ions at low cost, with relative ease and minimal operation. (author)

  15. Vanillin restrains non-enzymatic glycation and aggregation of albumin by chemical chaperone like function.

    Science.gov (United States)

    Awasthi, Saurabh; Saraswathi, N T

    2016-06-01

    Vanillin a major component of vanilla bean extract is commonly used a natural flavoring agent. Glycation is known to induce aggregation and fibrillation of globular proteins such as albumin, hemoglobin. Here we report the inhibitory potential of vanillin toward early and advanced glycation modification and amyloid like aggregation of albumin based on the determination of both early and advanced glycation and conformational changes in albumin using circular dichroism. Inhibition of aggregation and fibrillation of albumin was determined based on amyloid specific dyes i.e., Congo red and Thioflavin T and microscopic imaging. It was evident that vanillin restrains glycation of albumin and exhibits protective effect toward its native conformation. PMID:26893056

  16. Inhibition of Pathogenic Mutant SOD1 Aggregation in Cultured Motor Neuronal Cells by Prevention of Its SUMOylation on Lysine 75.

    Science.gov (United States)

    Dangoumau, Audrey; Marouillat, Sylviane; Burlaud Gaillard, Julien; Uzbekov, Rustem; Veyrat-Durebex, Charlotte; Blasco, Hélène; Arnoult, Christophe; Corcia, Philippe; Andres, Christian R; Vourc'h, Patrick

    2016-01-01

    Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the selective death of motor neurons. Mutations in the SOD1 gene encoding the superoxide dismutase 1 are present in 15% of familial ALS cases and in 2% of sporadic cases. These mutations are associated with the formation of SOD1-positive aggregates. The mechanisms of aggregation remain unknown, but posttranslational modifications of SOD1 may be involved. Here, we report that NSC-34 motor neuronal cells expressing mutant SOD1 contained aggregates positive for small ubiquitin modifier-1 (SUMO-1), and in parallel a reduced level of free SUMO-1. CLEM (correlative light and electron microscopy) analysis showed nonorganized cytosolic aggregates for all mutations tested (SOD1A4V, SOD1V31A, and SOD1G93C). We next show that preventing the SUMOylation of mutant SOD1 by the substitution of lysine 75, the SUMOylation site of SOD1, significantly reduces the number of motor neuronal cells with aggregates. These results support the need for further research on the SUMOylation pathways, which may be a potential therapeutic target in ALS. PMID:26605782

  17. Structural phase transition of merocyanine J-aggregate induced by ion-recombination in the aqueous sub-phase

    Science.gov (United States)

    Kato, Noritaka; Saito, Kentaro; Uesu, Yoshiaki

    2000-08-01

    By using the sub-phase, which contains two different kinds of counter-ions, we found a reversible thermochromic transition between different J-aggregate states of amphiphilic merocyanine dye (MD) molecules in the monolayer at the air-water interface. This chromatic change is attributed to the structural phase transition of MD J-aggregate crystallites induced by the mutual recombination of different counter-ions to MD molecules. The drastic morphological change of the MD monolayer during the transition is revealed by the in-situ observation using a multipurpose non-linear optical microscope.

  18. Bacterial entombment by intratubular mineralization following orthograde mineral trioxide aggregate obturation:a scanning electron microscopy study

    Institute of Scientific and Technical Information of China (English)

    Jun Sang Yoo; Qiang Zhu; Kee-Yeon Kum; Seok-Woo Chang; So Ram Oh; Hiran Perinpanayagam; Sang-Min Lim; Yeon-Jee Yoo; Yeo-Rok Oh; Sang-Bin Woo; Seung-Hyun Han

    2014-01-01

    The time domain entombment of bacteria by intratubular mineralization following orthograde canal obturation with mineral trioxide aggregate (MTA) was studied by scanning electron microscopy (SEM). Single-rooted human premolars (n560) were instrumented to an apical size #50/0.06 using ProFile and treated as follows:Group 1 (n510) was filled with phosphate buffered saline (PBS);Group 2 (n510) was incubated with Enterococcus faecalis for 3 weeks, and then filled with PBS;Group 3 (n520) was obturated orthograde with a paste of OrthoMTA (BioMTA, Seoul, Korea) and PBS;and Group 4 (n520) was incubated with E. faecalis for 3 weeks and then obturated with OrthoMTA–PBS paste. Following their treatments, the coronal openings were sealed with PBS-soaked cotton and intermediate restorative material (IRM), and the roots were then stored in PBS for 1, 2, 4, 8 or 16 weeks. After each incubation period, the roots were split and their dentin/MTA interfaces examined in both longitudinal and horizontal directions by SEM. There appeared to be an increase in intratubular mineralization over time in the OrthoMTA-filled roots (Groups 3 and 4). Furthermore, there was a gradual entombment of bacteria within the dentinal tubules in the E. faecalis inoculated MTA-filled roots (Group 4). Therefore, the orthograde obturation of root canals with OrthoMTA mixed with PBS may create a favorable environment for bacterial entombment by intratubular mineralization.

  19. Lanosterol reverses protein aggregation in cataracts.

    Science.gov (United States)

    Zhao, Ling; Chen, Xiang-Jun; Zhu, Jie; Xi, Yi-Bo; Yang, Xu; Hu, Li-Dan; Ouyang, Hong; Patel, Sherrina H; Jin, Xin; Lin, Danni; Wu, Frances; Flagg, Ken; Cai, Huimin; Li, Gen; Cao, Guiqun; Lin, Ying; Chen, Daniel; Wen, Cindy; Chung, Christopher; Wang, Yandong; Qiu, Austin; Yeh, Emily; Wang, Wenqiu; Hu, Xun; Grob, Seanna; Abagyan, Ruben; Su, Zhiguang; Tjondro, Harry Christianto; Zhao, Xi-Juan; Luo, Hongrong; Hou, Rui; Perry, J Jefferson P; Gao, Weiwei; Kozak, Igor; Granet, David; Li, Yingrui; Sun, Xiaodong; Wang, Jun; Zhang, Liangfang; Liu, Yizhi; Yan, Yong-Bin; Zhang, Kang

    2015-07-30

    The human lens is comprised largely of crystallin proteins assembled into a highly ordered, interactive macro-structure essential for lens transparency and refractive index. Any disruption of intra- or inter-protein interactions will alter this delicate structure, exposing hydrophobic surfaces, with consequent protein aggregation and cataract formation. Cataracts are the most common cause of blindness worldwide, affecting tens of millions of people, and currently the only treatment is surgical removal of cataractous lenses. The precise mechanisms by which lens proteins both prevent aggregation and maintain lens transparency are largely unknown. Lanosterol is an amphipathic molecule enriched in the lens. It is synthesized by lanosterol synthase (LSS) in a key cyclization reaction of a cholesterol synthesis pathway. Here we identify two distinct homozygous LSS missense mutations (W581R and G588S) in two families with extensive congenital cataracts. Both of these mutations affect highly conserved amino acid residues and impair key catalytic functions of LSS. Engineered expression of wild-type, but not mutant, LSS prevents intracellular protein aggregation of various cataract-causing mutant crystallins. Treatment by lanosterol, but not cholesterol, significantly decreased preformed protein aggregates both in vitro and in cell-transfection experiments. We further show that lanosterol treatment could reduce cataract severity and increase transparency in dissected rabbit cataractous lenses in vitro and cataract severity in vivo in dogs. Our study identifies lanosterol as a key molecule in the prevention of lens protein aggregation and points to a novel strategy for cataract prevention and treatment. PMID:26200341

  20. Benthic life in the pelagic: Aggregate encounter and degradation rates by pelagic harpacticoid copepods

    DEFF Research Database (Denmark)

    Koski, Marja; Kiørboe, Thomas; Takahashi, K.

    2005-01-01

    We measured field abundances, feeding rates, swimming behavior, and particle colonization of two harpacticoids, the pelagic Microsetella norvegica and the semibenthic Amonardia normanni, to examine (1) if aggregates have a significant role in harpacticoid nutrition and (2) if harpacticoids contri...

  1. Milk protein suspensions enriched with three essential minerals: Physicochemical characterization and aggregation induced by a novel enzymatic pool.

    Science.gov (United States)

    Lombardi, Julia; Spelzini, Darío; Corrêa, Ana Paula Folmer; Brandelli, Adriano; Risso, Patricia; Boeris, Valeria

    2016-04-01

    Structural changes of casein micelles and their aggregation induced by a novel enzymatic pool isolated from Bacillus spp. in the presence of calcium, magnesium or zinc were investigated. The effect of cations on milk protein structure was studied using fluorescence and dynamic light scattering. In the presence of cations, milk protein structure rearrangements and larger casein micelle size were observed. The interaction of milk proteins with zinc appears to be of a different nature than that with calcium or magnesium. Under the experimental conditions assayed, the affinity of each cation for some groups present in milk proteins seems to play an important role, besides electrostatic interaction. On the other hand, the lowest aggregation times were achieved at the highest calcium and zinc concentrations (15 mM and 0.25 mM, respectively). The study found that the faster the aggregation of casein micelles, the less compact the gel matrix obtained. Cation concentrations affected milk protein aggregation kinetics and the structure of the aggregates formed. PMID:26803666

  2. Aggregation of gold nanoparticles followed by methotrexate release enables Raman imaging of drug delivery into cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Durgadas, C. V.; Sharma, C. P.; Paul, W.; Rekha, M. R. [Sree Chitra Tirunal Institute for Medical Sciences and Technology, Biosurface Technology Division (India); Sreenivasan, K., E-mail: sreeni@sctimst.ac.in [Sree Chitra Tirunal Institute for Medical Sciences and Technology, Laboratory for Polymer Analysis, Biomedical Technology Wing (India)

    2012-09-15

    This study refers an aqueous synthesis of methotrexate (MTX)-conjugated gold nanoparticles (GNPs), their interaction with HepG2 cells, and the use of Raman imaging to observe cellular internalization and drug delivery. GNPs of average size 3.5-5 nm were stabilized using the amine terminated bifunctional biocompatible copolymer and amended by conjugating MTX, an anticancer drug. The nanoparticles were released MTX at a faster rate in acidic pH and subsequently found to form aggregates. The Raman signals of cellular components were found to be enhanced by the aggregated particles enabling the mapping to visualize site-specific drug delivery. The methodology seems to have potential in optimizing the characteristics of nanodrug carriers for emptying the cargo precisely at specified sites.Graphical AbstractDrug release induced particle aggregation enhances Raman signals to aid in imaging.

  3. Aggregation of gold nanoparticles followed by methotrexate release enables Raman imaging of drug delivery into cancer cells

    International Nuclear Information System (INIS)

    This study refers an aqueous synthesis of methotrexate (MTX)-conjugated gold nanoparticles (GNPs), their interaction with HepG2 cells, and the use of Raman imaging to observe cellular internalization and drug delivery. GNPs of average size 3.5–5 nm were stabilized using the amine terminated bifunctional biocompatible copolymer and amended by conjugating MTX, an anticancer drug. The nanoparticles were released MTX at a faster rate in acidic pH and subsequently found to form aggregates. The Raman signals of cellular components were found to be enhanced by the aggregated particles enabling the mapping to visualize site-specific drug delivery. The methodology seems to have potential in optimizing the characteristics of nanodrug carriers for emptying the cargo precisely at specified sites.Graphical AbstractDrug release induced particle aggregation enhances Raman signals to aid in imaging.

  4. Inhibition of bacterial aggregation by serum- and blood-derived proteins.

    OpenAIRE

    Malamud, D; Brown, C; Goldman, R

    1984-01-01

    Human and animal sera contain potent inhibitors of saliva-mediated aggregation of oral streptococci. The inhibitors consist of a high-molecular-weight heat-labile factor and a lower-molecular-weight heat-activated factor. The latter appears to be serum albumin. Analyses of purified blood-derived proteins indicated that several high-molecular-weight proteins (fibrinogen, fibronectin, and ferritin) were able to inhibit aggregation at low concentrations. These data suggest that high-molecular-we...

  5. Levels of Supramolecular Chirality of Polyglutamine Aggregates Revealed by Vibrational Circular Dichroism

    OpenAIRE

    Kurouski, Dmitry; Kar, Karunakar; Wetzel, Ronald; Dukor, Rina K; Lednev, Igor K.; Nafie, Laurence A.

    2013-01-01

    Polyglutamine (PolyQ) aggregates are a hallmark of several severe neurodegenerative diseases, expanded CAG-repeat diseases in which inheritance of an expanded polyQ sequence above a pathological threshold is associated with a high risk of disease. Application of vibrational circular dichroism (VCD) reveals that these PolyQ fibril aggregates exhibit a chiral supramolecular organization that is distinct from the supramolecular organization of previously observed amyloid fibrils. PolyQ fibrils g...

  6. Homotypic aggregation of human cell lines by HLA class II-, class Ia- and HLA-G-specific monoclonal antibodies

    DEFF Research Database (Denmark)

    Odum, Niels; Ledbetter, J A; Martin, P;

    1991-01-01

    two anti-beta 2-microglobulin mAb had variable, weak effects. The aggregation response was an active, temperature-sensitive process which was almost totally abrogated by azide and by cytochalasins B and E, but unaffected by colchicine, EDTA, aphidicolin, actinomycin D and protein tyrosine kinase...

  7. Aggregation of human platelets by endotoxic glycolipid-bearing Salmonella minnesota Re595 is prevented by synthetic peptide analogs of cell adhesion sites of fibrinogen and fibronectin

    International Nuclear Information System (INIS)

    Thrombocytopenia often accompanies sepsis due to endotoxin producing gram-negative bacteria. The authors have observed that mutant Re595 of S. minnesota induced aggregation of human platelets separated from plasma fibrinogen (Theta) and other proteins. This aggregation is dependent on ADP secreted from storage granules in response to mutant Re595. Platelet aggregation induced by mutant Re595 was prevented by simultaneously added EDTA and EGTA (5mM), whereas secretion of 14C-serotonin was maintained. Preincubation of platelets with chelators (1 hr, 370C), known to dissociate irreversibly the platelet membrane glycoprotein IIb x IIIa complex, abolished aggregation while serotonin secretion was decreased by only one fourth. Since the GPIIb x IIIa complex constitutes the receptor for Theta, its role was examined using synthetic peptide analogs of sites on gamma and alpha chains of Theta. Gamma 400-411 (225 μM) inhibited platelet aggregation induced by mutant Re595 while serotonin secretion was unaffected. Alpha 572-575 (RGDS; 100 μM), analogous to cell adhesion site of fibronectin, also prevented aggregation induced by mutant Re595. Thus, mutant Re595 causes platelet aggregation which is divalent cation-dependent and proceeds via receptor pathway for secreted adhesive macromolecules

  8. Changes in bacterial communities accompanied by aggregation in a fed-batch composting reactor.

    Science.gov (United States)

    Watanabe, Keiko; Nagao, Norio; Toda, Tatsuki; Kurosawa, Norio

    2008-05-01

    The contents of fed-batch composting (FBC) reactors often aggregate after prolonged operation. This process leads to irreversible breakdown of the decomposition reaction and possible alteration of the bacterial communities. We compared the structures of bacterial communities in reactors under aggregate and optimal conditions. The results of 16S rRNA gene clone analysis showed that populations of the family Bacillaceae (such as Bacillus spp., Cerasibacillus spp., Gracilibacillus spp.), which dominate (98%) under optimal condition, were significantly decreased under aggregate condition. In contrast, populations of the family Staphylococcaceae considerably increased after aggregation and accounted for 53% of the total. Phylogenetic analysis also showed that anaerobes or facultative anaerobes related to Tetragenococcus halophilus, Atopostipes suicloacalis, Jeotgalicoccus pinnipedialis, and Staphylococcus spp. were dominant in the aggregates. These results suggested that aerobic Gram-positive bacteria mainly contributed to organic degradation and that aggregation created some anaerobic environment, which promoted the growth of bacterial communities usually not found in well-functioning FBC reactors. PMID:18231830

  9. Formation of oriented nickel aggregates in rutile single crystals by Ni implantation

    International Nuclear Information System (INIS)

    The magnetic and electrical properties of Ni implanted single crystalline TiO2 rutile were studied for nominal implanted fluences between 0.5×1017 cm−2 and 2.0×1017 cm−2 with 150 keV energy, corresponding to maximum atomic concentrations between 9 at% and 27 at% at 65 nm depth, in order to study the formation of metallic oriented aggregates. The results indicate that the as implanted crystals exhibit superparamagnetic behavior for the two higher fluences, which is attributed to the formation of nanosized nickel clusters with an average size related with the implanted concentration, while only paramagnetic behavior is observed for the lowest fluence. Annealing at 1073 K induces the aggregation of the implanted nickel and enhances the magnetization in all samples. The associated anisotropic behavior indicates preferred orientations of the nickel aggregates in the rutile lattice consistent with Rutherford backscattering spectrometry—channelling results. Electrical conductivity displays anisotropic behavior but no magnetoresistive effects were detected. - Author-Highlights: • Ni nano-aggregates were grown on TiO2 using Ni implantation with different fluences. • In the as implanted state, the aggregates size is a function of the implanted fluence. • Ni aggregates are oriented within the rutile structure-2 orientations are proposed

  10. The influence of agitation on aggregates formed during treatment of water with a content of humic substances

    Czech Academy of Sciences Publication Activity Database

    Pivokonská, Lenka; Pivokonský, Martin

    2006-01-01

    Roč. 6, č. 1 (2006), s. 211-218. ISSN 1606-9749 R&D Projects: GA AV ČR KJB200600501 Institutional research plan: CEZ:AV0Z20600510 Keywords : Aggregation * humic substances * particle size distribution Subject RIV: BK - Fluid Dynamics

  11. Characterisation of crude oil components, asphaltene aggregation and emulsion stability by means of near infrared spectroscopy and multivariate analysis

    Energy Technology Data Exchange (ETDEWEB)

    Aske, Narve

    2002-06-01

    Effective separation of water-in-crude oil emulsions is a central challenge for the oil industry on the Norwegian Continental Shelf, especially with the future increase in subsea and even down-hole processing of well fluids. The mechanisms and properties governing emulsion stability are far from fully understood but the indigenous surface active crude oil components are believed to play a major role. In this work a thorough physico-chemical characterisation of a set of crude oils originating from a variety of production fields has been performed. Crude oil properties responsible for emulsion stability were identified by use of multivariate analysis techniques like partial least squares regression (PLS) and principal component analysis (PCA). Interfacial elasticity along with both asphaltene content and asphaltene aggregation state were found to be main contributors to emulsion stability. Information on a crude oils ability to form elastic crude oil-water interfaces was found to be especially crucial when discussing emulsion stability. However, measured values of interfacial elasticity were highly dependent on asphaltene aggregation state. Several experimental techniques was utilised and partly developed for the crude oil characterisation. A high-pressure liquid chromatography (HPLC) scheme was developed for SARA-fractionation of crude oils and an oscillating pendant drop tensiometer was used for characterisation of interfacial rheological properties. For emulsion stability a cell for determining the stability as a function of applied electric fields was used. In addition, near infrared spectroscopy (NIR) was used throughout the work both for chemical and physical characterisation of crude oils and model systems. High pressure NIR was used to study the aggregation of asphaltenes by pressure depletion. A new technique for detection of asphaltene aggregation onset pressures based on NIR combined with PCA was developed. It was also found that asphaltene aggregation is

  12. Vibrational energy flow between modes by dynamic mode coupling in THIATS J-aggregates.

    Science.gov (United States)

    Hasegawa, Daisuke; Nakata, Kazuaki; Tokunaga, Eiji; Okamura, Kotaro; Du, Juan; Kobayashi, Takayoshi

    2013-11-14

    We performed ultrafast pump-probe spectroscopy of J-aggregates of 3,3'-disulfopropyl-5,5'-dichloro-9-ethyl thiacarbocyanine triethylammonium (THIATS), one of the most typical cyanine dyes, and detected excited molecular vibrations, using a sub-10 fs pulse laser. The time-resolved two-dimensional difference absorption (ΔA) spectra are observed between -314 and 1267 fs. By performing the Fourier transform and spectrogram analysis, vibrational modes in THIATS are observed at 285, 485, 555, 824, and 1633 cm(-1) and there was a modulation of the vibrational frequencies around 1633 cm(-1) which depend on the delay time, respectively. By the analysis of the modulation, energy flow is found to take place from other modes to the 1633 cm(-1) mode through the low frequency mode with ∼50 cm(-1). Also, by fitting the real-time traces of ΔA with the sum of two exponential functions and a constant term, the average lifetimes of three electronically excited states were found to be τ1 = 52 ± 5 fs and τ2 = 540 ± 78 fs. By performing single-exponential fitting around the stationary absorption peak at 1.990 eV, in the negative time range, the electronic dephasing time, T2(ele), is determined to be 18.30 fs. PMID:24111914

  13. Dynamics of aggregate stability and soil organic C distribution as affected by climatic aggressiveness: a mesocosm approach

    Science.gov (United States)

    Pellegrini, Sergio; Elio Agnelli, Alessandro; Costanza Andrenelli, Maria; Barbetti, Roberto; Castelli, Fabio; Costantini, Edoardo A. C.; Lagomarsino, Alessandra; Pasqui, Massimiliano; Tomozeiu, Rodica; Razzaghi, Somayyeh; Vignozzi, Nadia

    2014-05-01

    In the framework of a research project aimed at evaluating the adaptation scenarios of the Italian agriculture to the current climate change, a mesocosm experiment under controlled conditions was set up for studying the dynamics of soil aggregate stability and organic C in different size fractions. Three alluvial loamy soils (BOV - Typic Haplustalfs coarse-loamy; CAS - Typic Haplustalfs fine-loamy; MED - Typic Hapludalfs fine-loamy) along a climatic gradient (from dryer to moister pedoclimatic conditions) in the river Po valley (northern Italy), under crop rotation for animal husbandry from more than 40 years, were selected. The Ap horizons (0-30cm) were taken and placed in 9 climatic chambers under controlled temperature and rainfall. Each soil was subjected to three different climate scenarios in terms of erosivity index obtained by combining Modified Fournier and Bagnouls-Gaussen indexes: i) typical (TYP), the median year of each site related to the 1961-1990 reference period; ii) maximum aggressive year (MAX) observed in the same period, and iii) the simulated climate (SIM), obtained by projections of climate change precipitation and temperature for the period 2021-2050 as provided by the IPCC-A1B emission scenario. In the climatic chambers the year climate was reduced to six months. The soils were analyzed for particle size distribution, aggregate stability by wet and dry sieving, and organic C content at the beginning and at the end of the trial. The soils showed different behaviour in terms of aggregate stability and dynamics of organic C in the diverse size fractions. The soils significantly differed in terms of initial mean weight diameter (MWD) (CAS>MED>BOV). A general reduction of MWD in all sites was observed at the end of the experiment, with the increase of the smallest aggregate fractions (0.250-0.05 mm). In particular, BOV showed the maximum decrease of the aggregate stability and MED the lowest. C distribution in aggregate fractions significantly

  14. Inhibition of Human Transthyretin Aggregation by Non-Steroidal Anti-Inflammatory Compounds: A Structural and Thermodynamic Analysis

    Directory of Open Access Journals (Sweden)

    Luis Mauricio T. R. Lima

    2013-03-01

    Full Text Available Transthyretin (TTR is a homotetrameric protein that circulates in plasma and cerebral spinal fluid (CSF whose aggregation into amyloid fibrils has been associated with at least two different amyloid diseases: senile systemic amyloidosis (SSA and familial amyloid polyneuropathy (FAP. In SSA aggregates are composed of WT-TTR, while in FAP more than 100 already-described variants have been found in deposits. Until now, TTR-related diseases have been untreatable, although a new drug called Tafamidis has been approved only in Europe to specifically treat V30M patients. Thus, new strategies are still necessary to treat FAP caused by other variants of TTR. TTR has two channels in the dimer interface that bind to the hormone thyroxin and that have been used to accommodate anti-amyloidogenic compounds. These compounds stabilize the tetramers, rendering TTR less amyloidogenic. Here, we investigated the effects of three non-steroidal anti-inflammatory compounds—sulindac (SUL, indomethacin (IND and lumiracoxib (LUM—as tetramer stabilizers and aggregation inhibitors. WT-TTR and the very aggressive TTR variant L55P were used as models. These compounds were able to stabilize TTR against high hydrostatic pressure (HHP, increasing the ΔGf by several kcal. They were also effective in inhibiting WT-TTR and L55P acid- or HHP-induced aggregation; in particular, LUM and IND were very effective, inhibiting almost 100% of the aggregation of both proteins under certain conditions. The species formed when aggregation was performed in the presence of these compounds were much less toxic to cells in culture. The crystal structures of WT-TTR bound to the three compounds were solved at high resolution, allowing the identification of the relevant protein:drug interactions. We discuss here the ligand-binding features of LUM, IND and SUL to TTR, emphasizing the critical interactions that render the protein more stable and less amyloidogenic.

  15. Determination of acetamiprid by a colorimetric method based on the aggregation of gold nanoparticles

    International Nuclear Information System (INIS)

    A method was developed for the detection of the insecticide acetamiprid based on the strong interaction of the cyano group of acetamiprid with gold nanoparticles (AuNPs). The interaction results in the aggregation of gold nanoparticles and is accompanied by a color change from red to purple. The concentration of acetamiprid can be determined qualitatively and quantitatively by visually monitoring the color change or by using a spectrometer. Transmittance electron microscopy and UV-vis spectroscopy have been used to characterize the process. The experimental parameters were optimized with regard to the size of the AuNPs, pH, and incubation time. Under optimal experimental conditions, linear relationships between the logarithm of the concentration of acetamiprid and the absorbance were found over the range of 0.66 to 6.6 μM for AuNPs with diameters of 22.0 ± 1.0 nm and of 6.6-66 μM for AuNPs with diameters of 15.0 ± 1.0 nm. This method was successfully applied to detect acetamiprid in vegetables. (author)

  16. EXOPOLYSACCHARIDE PRODUCTION BY DROUGHT TOLERANT BACILLUS SPP. AND EFFECT ON SOIL AGGREGATION UNDER DROUGHT STRESS

    Directory of Open Access Journals (Sweden)

    Sandhya Vardharajula

    2014-08-01

    Full Text Available Exopolysaccharides (EPS of microbial origin with novel functionality, reproducible physico-chemical properties, are important class of polymeric materials. EPS are believed to protect bacterial cells from dessication, produce biofilms, thus enhancing the cells chances of bacterial colonizing special ecological niches. In rhizosphere, EPS are known to be useful to improve the moisture-holding capacity. Three Bacillus spp. strains identified by 16s rDNA sequence analysis as B. amyloliquefaciens strain HYD-B17; B. licheniformis strain HYTAPB18; B. subtilis strain RMPB44 were studied for the ability to tolerate matric stress and produce EPS under different water potentials. EPS production in all the three Bacillus spp strains increased with increasing water stress indicating correlation between drought stress tolerance and EPS production. Among the isolates, strain HYD-17 showed highest production of EPS. The exopolysaccharide composition of the three strains was further analyzed by HPLC. Drought stress influenced the ratio of sugars in EPS and glucose was found as major sugar in strains HYTAPB18 and RMPB44 whereas raffinose was major sugar found in strain HYD-B17. Inoculation of EPS producing Bacillus spp. strains in soil resulted in good soil aggregation under drought stress conditions at different incubation periods. This study shows that exposure to water stress conditions affects the composition and ratios of sugars in EPS produced by Bacillus spp. strains HYD-B17, HYTAPB18 and RMPB44 influencing abiotic stress tolerance of the microorganisms.

  17. Estimation of anti-platelet drugs on human platelet aggregation with a novel whole blood aggregometer by a screen filtration pressure method

    OpenAIRE

    Sudo, Toshiki; Ito, Hideki; Ozeki, Yasushi; Kimura, Yukio

    2001-01-01

    The effects of anti-platelet drugs on human whole blood aggregation were evaluated using a novel whole blood aggregometer by a screen filtration pressure (SFP) method.The SFP whole blood aggregometer was found to successfully detect whole blood aggregation induced by ADP, collagen and TRAP by measuring the SFP of blood samples. The platelet aggregation threshold index (PATI), the concentration of agonist required with an inducing pressure rate of 50%, varied time-dependently after collection ...

  18. On the aggregate grid load imposed by battery health-conscious charging of plug-in hybrid electric vehicles

    Science.gov (United States)

    Bashash, Saeid; Moura, Scott J.; Fathy, Hosam K.

    2011-10-01

    This article examines the problem of estimating the aggregate load imposed on the power grid by the battery health-conscious charging of plug-in hybrid electric vehicles (PHEVs). The article begins by generating a set of representative daily trips using (i) the National Household Travel Survey (NHTS) and (ii) a Markov chain model of both federal and naturalistic drive cycles. A multi-objective optimizer then uses each of these trips, together with PHEV powertrain and battery degradation models, to optimize both PHEV daily energy cost and battery degradation. The optimizer achieves this by varying (i) the amounts of charge obtained from the grid by each PHEV, and (ii) the timing of this charging. The article finally computes aggregate PHEV power demand by accumulating the charge patterns optimized for individual PHEV trips. The results of this aggregation process show a peak PHEV load in the early morning (between 5.00 and 6.00 a.m.), with approximately half of all PHEVs charging simultaneously. The ability to charge at work introduces smaller additional peaks in the aggregate load pattern. The article concludes by exploring the sensitivity of these results to the relative weighting of the two optimization objectives (energy cost and battery health), battery size, and electricity price.

  19. Research on Marketing Cooperation System Based on Multi-Agent Services Aggregation Driven by Requirement

    Directory of Open Access Journals (Sweden)

    Hong ZHOU

    2010-11-01

    Full Text Available The web service has great significance and value since it represents a large industrial sector and huge trade interests, but the function of a single web service is too small to satisfy the need of service requestor, so it is necessary to combine a mount of simple services to satisfy the complex and dynamic requirement in practice, then the problem of web services composition is one of the research hotspot. This paper generalized the primary interaction processes between enterprise and customer in marketing, encapsulated the special function for marketing works as the agent, and considered the marketing as the cooperation process of agents focusing on requirements, and based on that a multi-agent based marketing cooperation system (MAMCS is established and the agent ontology is designed according to JADE, finally the negotiation mechanism is built. The method of multi-agent services aggregation driven by requirement supposed in this paper can improve the utilizing effect of service, reduce the difficulty of services composition, and realize the automatic purpose of services composition. Moreover, by combining the merits of agent technique the initiation and intelligence of the services are improved, that safeguard the best interests of the service providers due to they have an option on requirements.

  20. Aggregate productivity and aggregate technology

    OpenAIRE

    Susanto Basu; John G. Fernald

    1997-01-01

    Aggregate productivity and aggregate technology are meaningful but distinct concepts. We show that a slightly-modified Solow productivity residual measures changes in economic welfare, even when productivity and technology differ because of distortions such as imperfect competition. We then present a general accounting framework that identifies several new non-technological gaps between productivity and technology, gaps reflecting imperfections and frictions in output and factor markets. Empi...

  1. Triggering of inflammasome by aggregated α-synuclein, an inflammatory response in synucleinopathies.

    Directory of Open Access Journals (Sweden)

    Gaia Codolo

    Full Text Available Parkinson's disease (PD is one of the most common neurodegenerative diseases. It is characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta of the brain. Another feature is represented by the formation in these cells of inclusions called Lewy bodies (LB, principally constituted by fibrillar α-synuclein (αSyn. This protein is considered a key element in the aetiology of a group of neurodegenerative disorders termed synucleinopathies, which include PD, but the cellular and molecular mechanisms involved are not completely clear. It is established that the inflammatory process plays a crucial role in the pathogenesis and/or progression of PD; moreover, it is known that aggregated αSyn, released by neurons, activates microglia cells to produce pro-inflammatory mediators, such as IL-1β. IL-1β is one of the strongest pro-inflammatory cytokines; it is produced as an inactive mediator, and its maturation and activation requires inflammasome activation. In particular, the NLRP3 inflammasome is activated by a wide variety of stimuli, among which are crystallized and particulate material. In this work, we investigated the possibility that IL-1β production, induced by fibrillar αSyn, is involved the inflammasome activation. We demonstrated the competence of monomeric and fibrillar αSyn to induce synthesis of IL-1β, through TLR2 interaction; we found that the secretion of the mature cytokine was a peculiarity of the fibrillated protein. Moreover, we observed that the secretion of IL-1β involves NLRP3 inflammasome activation. The latter relies on the phagocytosis of fibrillar αSyn, followed by increased ROS production and cathepsin B release into the cytosol. Taken together, our data support the notion that fibrillar αSyn, likely released by neuronal degeneration, acts as an endogenous trigger inducing a strong inflammatory response in PD.

  2. Feasibility of a Pulsed Sequencing Batch reactor with anaerobic aggregated biomass for the treatment of low strength wastewaters

    OpenAIRE

    Brito, A. G.; Rodrigues, A.C.; Melo, L. F.

    1997-01-01

    This study concerns an assessment of a SBR operation that associates anaerobic aggregated biomass with a pulsed action during the reaction phase, a system named Pulsed Sequencing Batch Reactor (P-SBR). The system uses a diaphragm pump as a pulsator unit to increase the liquid-solid contact, in order to avoid dead zones and possible external mass transfer resistance. A preliminary study of the operation of the reactor was performed with a low strength synthetic wastewater with a COD near 1000 ...

  3. Experimental Investigation of CFRP Confined Columns Damaged by Alkali Aggregate Reaction

    Directory of Open Access Journals (Sweden)

    Siti Radziah Abdullah

    2012-10-01

    Full Text Available Fiber reinforced polymer is the most effective repair material in use to enhance the strength and ductility of deteriorated reinforced concrete columns. Often, fiber reinforced polymer (FRP provides passive confinement to columns until the dilation and cracking of concrete occurs. In the case of concrete suspected of Alkali Aggregate Reaction (AAR where concrete undergoes expansion, FRP wrap provides active confinement to the expanded concrete. In this study, the performance of carbon fiber reinforced polymer (CFRP wrapped columns damaged by AAR is evaluated based on the number of FRP layers and the time of the polymer application which provides two types of confinement: active or passive. The columns were tested under axial compression to evaluate the residual strength of the columns in comparison with unwrapped columns. The results reveal that the strength of the wrapped columns is enhanced with an increase in the number of CFRP layers. The strength of the columns under passive confinement is higher than the columns under active confinement. Under active confinement, early CFRP wrapping leads to improvement in the strength of the columns.

  4. Tooth discoloration induced by a novel mineral trioxide aggregate-based root canal sealer

    Science.gov (United States)

    Lee, Dae-Sung; Lim, Myung-Jin; Choi, Yoorina; Rosa, Vinicius; Hong, Chan-Ui; Min, Kyung-San

    2016-01-01

    Objectives: The aim of this study was to evaluate tooth discoloration caused by contact with a novel injectable mineral trioxide aggregate (MTA)-based root canal sealer (Endoseal; Maruchi, Wonju, Korea) compared with a widely used resin-based root canal sealer (AHplus; Dentsply De Trey, Konstanz, Germany) and conventional MTA (ProRoot; Dentsply, Tulsa, OK, USA). Materials and Methods: Forty standardized bovine tooth samples were instrumented and divided into three experimental groups and one control group (n = 10/group). Each material was inserted into the cavity, and all specimens were sealed with a self-adhesive resin. Based on CIE Lab system, brightness change (ΔL) and total color change (ΔE) of each specimen between baseline and 1, 2, 4, and 8 weeks were obtained. Results: At all time points, Endoseal showed no significant difference in ΔL and ΔE compared to AHplus and control group (P > 0.05), whereas the ProRoot group showed significantly higher ΔL and ΔE values than the Endoseal group at 2, 4, and 8 weeks (P MTA and a similar color change to AHplus. Conclusions: Within the limitations of this study, our data indicate that the MTA-based sealer produces a similar amount of tooth discoloration as AHplus which is considered to be acceptable. PMID:27403062

  5. Understanding Packing Patterns in Crystals by Analysis of Small Aggregates: A Case Study of CS2.

    Science.gov (United States)

    Singh, Gurmeet; Verma, Rahul; Gadre, Shridhar R

    2015-12-31

    The molecular electrostatic potential (MESP) of the CS2 molecule, in conjunction with the cluster building algorithm, is utilized for generating trial geometries of medium-sized (CS2)n (n = 5-8) aggregates. MESP features suggest crossed, parallel stacked, T-shaped and L-shaped geometries for CS2 clusters. These initial geometries are subjected to geometry optimization employing second-order Møller-Plesset (MP2) theory, with correlation consistent aug-cc-pvDZ (aDZ) basis set. Single-point energies at MP2/aTZ levels are calculated for the estimation of binding energies at complete basis set (CBS) limit. The minimal nature of the reported structures is confirmed by doing vibrational frequency run at MP2/aDZ level of theory using the molecular tailoring approach (MTA). The two- and three-body interaction energies are computed for clusters with n = 5, 6, and 7 and these are suggestive of change in contact patterns with increasing n. Such an analysis is found to offer a qualitative explanation of the packing pattern found in the crystal structure. PMID:26650761

  6. Effect of Dentin Bonding Agent on the Prevention of Tooth Discoloration Produced by Mineral Trioxide Aggregate

    Directory of Open Access Journals (Sweden)

    Majid Akbari

    2012-01-01

    Full Text Available Objective. Determination of the effect of dentin bonding agent (DBA on the prevention of tooth discoloration produced by mineral trioxide aggregate (MTA. Methods. 50 teeth were endodontically treated and after removal of 3 mm of obturating materials were divided into five groups. In white MTA (WMTA and grey MTA (GMTA groups, these materials were placed in root canal below the orifice. In DBA + WMTA and DBA + GMTA groups, DBAs were applied in the access cavity. Then, 3 mm of WMTA and GMTA was placed. The last 10 teeth served as control. All of teeth were restored and color measurement was recorded for each specimen at this time and 6 months later. Results. The mean tooth discoloration in WMTA and GMTA groups was significantly more than DBA + WMTA and DBA + GMTA groups, respectively. There was no significant difference between DBA + WMTA and DBA + GMTA groups and control group. Conclusion. Application of DBA before MTA may prevent tooth discoloration.

  7. Generating nanoscale aggregates from colloidal nanoparticles by various aerosol spray techniques

    Energy Technology Data Exchange (ETDEWEB)

    Mahurin, Shannon Mark [ORNL; Cheng, Mengdawn [ORNL

    2007-01-01

    Growing interest in the environmental and health effects of engineered nanostructured materials requires accurate control of cluster morphology and size in order to make valid interpretations of nanomaterial toxicity. We report the comparison of three methods for the generation of aggregated uniform polystyrene latex (PSL) nanospheres from a colloidal suspension. Atomization, ultrasonic generation and electrospray, which utilize distinct mechanisms for the formation of liquid droplets from a PSL colloidal suspension, are explored as potential methods for nanostructured material synthesis. Electrospray produced isolated PSL particles most suited for use in experiments involving exposure to non-aggregated nanoparticles. Though producing the largest cluster size, ultrasonic generation proved to be a relatively straightforward process for reproducibly generating nanoparticle aggregates. Further advantages and disadvantages of each method are presented in relation to future toxicology experiments.

  8. An ethanol extract of Ramulus mori improves blood circulation by inhibiting platelet aggregation.

    Science.gov (United States)

    Lee, Jiyun; Kwon, Gayeung; Park, Jieun; Kim, Jeong-Keun; Choe, Soo Young; Seo, Yoonhee; Lim, Young-Hee

    2016-07-01

    Inappropriate platelet aggregation can cause blood coagulation and thrombosis. In this study, the effect of an ethanol extract of Ramulus mori (ERM) on blood circulation was investigated. The antithrombotic activity of ERM on rat carotid arterial thrombosis was evaluated in vivo, and the effect of ERM on platelet aggregation and blood coagulation time was evaluated ex vivo. To evaluate the safety of ERM, its cytotoxicity to platelets and its effect on tail bleeding time were assessed; ERM was not toxic to rat platelets and did not prolong bleeding time. Moreover, administering ERM to rats had a significant preventive effect on carotid arterial thrombosis in vivo, and significantly inhibited adenosine diphosphate- and collagen-induced platelet aggregation ex vivo, whereas it did not prolong coagulation periods, such as prothrombin time and activated partial thromboplastin time. The results suggest that ERM is effective in improving blood circulation via antiplatelet activity rather than anticoagulation activity. PMID:26967156

  9. Spiking neurons can discover predictive features by aggregate-label learning.

    Science.gov (United States)

    Gütig, Robert

    2016-03-01

    The brain routinely discovers sensory clues that predict opportunities or dangers. However, it is unclear how neural learning processes can bridge the typically long delays between sensory clues and behavioral outcomes. Here, I introduce a learning concept, aggregate-label learning, that enables biologically plausible model neurons to solve this temporal credit assignment problem. Aggregate-label learning matches a neuron's number of output spikes to a feedback signal that is proportional to the number of clues but carries no information about their timing. Aggregate-label learning outperforms stochastic reinforcement learning at identifying predictive clues and is able to solve unsegmented speech-recognition tasks. Furthermore, it allows unsupervised neural networks to discover reoccurring constellations of sensory features even when they are widely dispersed across space and time. PMID:26941324

  10. Three-dimensional printed polymeric system to encapsulate human mesenchymal stem cells differentiated into islet-like insulin-producing aggregates for diabetes treatment

    Science.gov (United States)

    Sabek, Omaima M; Farina, Marco; Fraga, Daniel W; Afshar, Solmaz; Ballerini, Andrea; Filgueira, Carly S; Thekkedath, Usha R; Grattoni, Alessandro; Gaber, A Osama

    2016-01-01

    Diabetes is one of the most prevalent, costly, and debilitating diseases in the world. Pancreas and islet transplants have shown success in re-establishing glucose control and reversing diabetic complications. However, both are limited by donor availability, need for continuous immunosuppression, loss of transplanted tissue due to dispersion, and lack of vascularization. To overcome the limitations of poor islet availability, here, we investigate the potential of bone marrow–derived mesenchymal stem cells differentiated into islet-like insulin-producing aggregates. Islet-like insulin-producing aggregates, characterized by gene expression, are shown to be similar to pancreatic islets and display positive immunostaining for insulin and glucagon. To address the limits of current encapsulation systems, we developed a novel three-dimensional printed, scalable, and potentially refillable polymeric construct (nanogland) to support islet-like insulin-producing aggregates’ survival and function in the host body. In vitro studies showed that encapsulated islet-like insulin-producing aggregates maintained viability and function, producing steady levels of insulin for at least 4 weeks. Nanogland—islet-like insulin-producing aggregate technology here investigated as a proof of concept holds potential as an effective and innovative approach for diabetes cell therapy. PMID:27152147

  11. Vascular pentraxin 3 controls arterial thrombosis by targeting collagen and fibrinogen induced platelets aggregation

    Science.gov (United States)

    Bonacina, F.; Barbieri, S.S.; Cutuli, L.; Amadio, P.; Doni, A.; Sironi, M.; Tartari, S.; Mantovani, A.; Bottazzi, B.; Garlanda, C.; Tremoli, E.; Catapano, A.L.; Norata, G.D.

    2016-01-01

    Aim The long pentraxin PTX3 plays a non-redundant role during acute myocardial infarction, atherosclerosis and in the orchestration of tissue repair and remodeling during vascular injury, clotting and fibrin deposition. The aim of this work is to investigate the molecular mechanisms underlying the protective role of PTX3 during arterial thrombosis. Methods and results PTX3 KO mice transplanted with bone marrow from WT or PTX3 KO mice presented a significant reduction in carotid artery blood flow following FeCl3 induced arterial thrombosis (− 80.36 ± 11.5% and − 95.53 ± 4.46%), while in WT mice transplanted with bone marrow from either WT or PTX3 KO mice, the reduction was less dramatic (− 45.55 ± 1.37% and − 53.39 ± 9.8%), thus pointing to a protective effect independent of a hematopoietic cell's derived PTX3. By using P-selectin/PTX3 double KO mice, we further excluded a role for P-selectin, a target of PTX3 released by neutrophils, in vascular protection played by PTX3. In agreement with a minor role for hematopoietic cell-derived PTX3, platelet activation (assessed by flow cytometric expression of markers of platelet activation) was similar in PTX3 KO and WT mice as were haemostatic properties. Histological analysis indicated that PTX3 localizes within the thrombus and the vessel wall, and specific experiments with the N-terminal and the C-terminal PTX3 domain showed the ability of PTX3 to selectively dampen either fibrinogen or collagen induced platelet adhesion and aggregation. Conclusion PTX3 interacts with fibrinogen and collagen and, by dampening their pro-thrombotic effects, plays a protective role during arterial thrombosis. PMID:26976330

  12. ASSESSMENT OF RECYCLED AGGREGATE CONCRETE

    OpenAIRE

    Ahmad Mujahid Ahmad Zaidi

    2009-01-01

    Used of recycled aggregate (RA) in concrete can be described in environmental protection and economical terms. The application of recycled aggregate to use in construction activities have been practice by developed European countries and also of some Asian countries. This paper reports the results of an experimental study on the mechanical properties of recycled aggregate concrete (RAC) as compared to natural aggregate concrete (NAC). The effects of size of RA on compressive strength were dis...

  13. Fundamental Study on the Development of Structural Lightweight Concrete by Using Normal Coarse Aggregate and Foaming Agent

    Directory of Open Access Journals (Sweden)

    Han-Seung Lee

    2014-06-01

    Full Text Available Structural lightweight concrete (SLWC has superior properties that allow the optimization of super tall structure systems for the process of design. Because of the limited supply of lightweight aggregates in Korea, the development of structural lightweight concrete without lightweight aggregates is needed. The physical and mechanical properties of specimens that were cast using normal coarse aggregates and different mixing ratios of foaming agent to evaluate the possibility of creating structural lightweight concrete were investigated. The results show that the density of SLWC decreases as the dosage of foaming agent increases up to a dosage of 0.6%, as observed by SEM. It was also observed that the foaming agent induced well separated pores, and that the size of the pores ranged from 50 to 100 μm. Based on the porosity of concrete specimens with foaming agent, compressive strength values of structural lightweight foam concrete (SLWFC were obtained. It was also found that the estimated values from proposed equations for compressive strength and modulus of elasticity of SLWFC, and values obtained by actual measurements were in good agreement. Thus, this study confirms that new structural lightweight concrete using normal coarse aggregates and foaming agent can be developed successfully.

  14. The effect of liquid environment on size and aggregation of gold nanoparticles prepared by pulsed laser ablation

    International Nuclear Information System (INIS)

    The effects of liquid environment on nucleation, growth and aggregation of gold nanoparticles were studied. Gold nanoparticles were prepared by pulsed laser ablation in deionised water with various concentrations of ethanol and also in pure ethanol. UV/visible extinction and TEM observations were employed for characterization of optical properties and particle sizes respectively. Preparation in water results in smaller size, shorter wavelength of maximum extinction and stable solution with an average size of 6 nm. Nanoparticles in solution with low concentration ethanol up to 20 vol% are very similar to those prepared in water. In the mixture of deionised water and 40 up to 80 vol% ethanol, wavelength of maximum extinction shows a red shift and mean size of nanoparticles was increased to 8.2 nm. Meanwhile, in this case, nanoparticles cross-linked each other and formed string type structures. In ethanol, TEM experiments show a mean size of 18 nm and strong aggregation of nanoparticles. The data were discussed qualitatively by considering effects of polarity of surrounding molecules on growth mechanism and aggregation. This study provided a technique to control size, cross-linking and aggregation of gold nanoparticles via changing the nature of liquid carrier medium

  15. Growth hormone aggregates in the rat adenohypophysis

    Science.gov (United States)

    Farrington, M.; Hymer, W. C.

    1990-01-01

    Although it has been known for some time that GH aggregates are contained within the rat anterior pituitary gland, the role that they might play in pituitary function is unknown. The present study examines this issue using the technique of Western blotting, which permitted visualization of 11 GH variants with apparent mol wt ranging from 14-88K. Electroelution of the higher mol wt variants from gels followed by their chemical reduction with beta-mercaptoethanol increased GH immunoassayability by about 5-fold. With the blot procedure we found 1) that GH aggregates greater than 44K were associated with a 40,000 x g sedimentable fraction; 2) that GH aggregates were not present in glands from thyroidectomized rats, but were in glands from the thyroidectomized rats injected with T4; 3) that GH aggregates were uniquely associated with a heavily granulated somatotroph subpopulation isolated by density gradient centrifugation; and 4) that high mol wt GH forms were released from the dense somatotrophs in culture, since treatment of the culture medium with beta-mercaptoethanol increased GH immunoassayability by about 5-fold. Taken together, the results show that high mol wt GH aggregates are contained in secretory granules of certain somatotrophs and are also released in aggregate form from these cells in vitro.

  16. Investigating the effect of ballasting by CaCO 3 in Emiliania huxleyi: I. Formation, settling velocities and physical properties of aggregates

    Science.gov (United States)

    Engel, Anja; Szlosek, Jennifer; Abramson, Lynn; Liu, Zhanfei; Lee, Cindy

    2009-08-01

    To investigate the role of ballasting by biogenic minerals in the export of organic matter in the ocean, a laboratory experiment was conducted comparing aggregate formation and settling velocity of non-calcifying and calcifying strains of the coccolithophore Emiliania huxleyi. Experiments were conducted by making aggregates using a roller table and following aggregate properties during incubation for a period of 40 days. Size, shape, and settling velocities of aggregates were described by image analysis of video pictures recorded during the roller tank incubation. Our results show that biogenic calcite has a strong effect on the formation rate and abundance of aggregates and on aggregate properties such as size, excess density, porosity, and settling velocity. Aggregates of calcifying cells (AGG CAL) formed faster, were smaller and had higher settling velocities, excess densities, and mass than those of non-calcifying cells (AGG NCAL). AGG CAL showed no loss during the duration of the experiment, whereas AGG NCAL decreased in size after 1 month of incubation. Potential mechanisms that can explain the different patterns in aggregate formation are discussed. Comparison of settling velocities of AGG CAL and AGG NCAL with aggregates formed by diatoms furthermore indicated that the ballast effect of calcite is greater than that of opal. Together these results help to better understand why calcite is of major importance for organic matter fluxes to the deep ocean.

  17. Rapid in vitro biocompatibility assay of endovascular stents by flow cytometry using platelet activation and platelet-leukocyte aggregation.

    Science.gov (United States)

    Tárnok, A; Mahnke, A; Müller, M; Zotz, R J

    1999-02-15

    Clinical studies suggest that stent design and surface texture are responsible for differences in biocompatibility of metallic endovascular stents. A simple in vitro experimental setup was established to test stent-induced degree of platelet and leukocyte activation and platelet-leukocyte aggregation by flow cytometry. Heparin-coated tantalum stents and gold-coated and uncoated stainless steel stents were tested. Stents were implanted into silicone tubes and exposed to blood from healthy volunteers. Platelet and leukocyte activation and percentage of leukocyte-platelet aggregates were determined in a whole-blood assay by subsequent staining for activation-associated antigens (CD41a, CD42b, CD62p, and fibrinogen binding) and leukocyte antigens (CD14 and CD45) and flow cytometric analysis. Blood taken directly after venous puncture or exposed to the silicone tube alone was used as negative controls. Positive control was in vitro stimulation with thrombin receptor activating peptide (TRAP-6). Low degree of platelet activation and significant increase in monocyte- and neutrophil-platelet aggregation were observed in blood exposed to stents (P coated stents continuously induced less platelet activation and leukocyte-platelet aggregation than uncoated stainless steel stents of the same length and shorter stents of the same structure. Stent surface coating and texture plays a role in platelet and leukocyte activation and leukocyte-platelet aggregation. Using this simple in vitro assay and whole blood and flow cytometry, it seems possible to differentiate stents by their potency to activate platelets and/or leukocytes. This assay could be applied for improving the biocompatibility of coronary stents. PMID:10088974

  18. Sedimentation and aggregation of magnetite nanoparticles in water by a gradient magnetic field

    International Nuclear Information System (INIS)

    Magnetite (γ-Fe3O4) nanoparticles are promising effective sorbents for water cleaning of heavy metal, radionuclides, organic and biological materials. A good sorption capacity can be achieved due to their high specific surface area. Application of gradient magnetic fields helps to separate the magnetic nanoparticles from the water suspension, which is rather hard to do using the conventional mechanical filtration and sedimentation methods without coagulants. The sedimentation dynamics of magnetite nanoparticles with sizes of 10–20 nm in aqueous media in the presence of a gradient magnetic field was studied by optical and NMR relaxometry methods. The gradient magnetic field was produced by a series of strip permanent magnets with B ≤ 0.5 T, dB/dz ≤ 0.13 T/cm and in some cases enhanced by a steel grid with sharp edges (dB/dz ≤ 5 T/cm). Dynamic Light Scattering in the water suspension with different nanoparticle concentrations (c0 = 0.1–1 g/l) revealed the characteristic features in the aggregate formation, which is reflected in the sedimentation behavior. The sedimentation rate of the nanoparticles in water and in magnetic fields is higher for less concentrated suspensions (c0 = 0.1 g/l) than for more concentrated ones (c0 = 1 g/l), which might be connected with the formation of a gel structures due to a strong magnetic attraction between ferromagnetic nanoparticles. In 180 min this resulted in the reduction of the iron concentration in water down to 0.4 mg/l, which is close to hygienic and environmental norms for drinking water and fishery

  19. Sedimentation and aggregation of magnetite nanoparticles in water by a gradient magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Medvedeva, I., E-mail: ivmed@imp.uran.ru; Bakhteeva, Yu.; Zhakov, S. [Ural Branch of the Russian Academy of Sciences, Institute of Metal Physics (Russian Federation); Revvo, A. [Ural State Mining University (Russian Federation); Byzov, I.; Uimin, M.; Yermakov, A.; Mysik, A. [Ural Branch of the Russian Academy of Sciences, Institute of Metal Physics (Russian Federation)

    2013-11-15

    Magnetite (γ-Fe{sub 3}O{sub 4}) nanoparticles are promising effective sorbents for water cleaning of heavy metal, radionuclides, organic and biological materials. A good sorption capacity can be achieved due to their high specific surface area. Application of gradient magnetic fields helps to separate the magnetic nanoparticles from the water suspension, which is rather hard to do using the conventional mechanical filtration and sedimentation methods without coagulants. The sedimentation dynamics of magnetite nanoparticles with sizes of 10–20 nm in aqueous media in the presence of a gradient magnetic field was studied by optical and NMR relaxometry methods. The gradient magnetic field was produced by a series of strip permanent magnets with B ≤ 0.5 T, dB/dz ≤ 0.13 T/cm and in some cases enhanced by a steel grid with sharp edges (dB/dz ≤ 5 T/cm). Dynamic Light Scattering in the water suspension with different nanoparticle concentrations (c{sub 0} = 0.1–1 g/l) revealed the characteristic features in the aggregate formation, which is reflected in the sedimentation behavior. The sedimentation rate of the nanoparticles in water and in magnetic fields is higher for less concentrated suspensions (c{sub 0} = 0.1 g/l) than for more concentrated ones (c{sub 0} = 1 g/l), which might be connected with the formation of a gel structures due to a strong magnetic attraction between ferromagnetic nanoparticles. In 180 min this resulted in the reduction of the iron concentration in water down to 0.4 mg/l, which is close to hygienic and environmental norms for drinking water and fishery.

  20. Rowing faster by surface treatment

    NARCIS (Netherlands)

    Greidanus, A.J.; Delfos, R.; Westerweel, J.

    2012-01-01

    The largest part of hydrodynamic drag during rowing, sailing or canoeing is the turbulent skin friction (80-90%). Higher velocities can be achieved by reducing the friction drag as a result of surface treatment. This research focuses on the development, characterization, and testing of drag-reducing

  1. Towards a 2D Model Biopolymer Polycrystalline Aggregation Based on Smoluchowski-type Dynamics Supplemented by Computer Experiment

    International Nuclear Information System (INIS)

    Based on a 2D version of the Smoluchowski-type model, formulated in a phase space of the linear objects' sizes R-s in terms of the mesoscopic nonequilibrium thermodynamics (MNET) as a guiding formalism/mechanism, we are looking in a comparative way for its basic trends and characteristics in a suitably designed Monte Carlo (MC) computer experiment on model biopolymer aggregation. The preliminary small-scale simulation results indicate that the examined hydrophobic-polar HP (dis)ordered aggregations bear two-type signatures of the underlying (complex) Smoluchowski dynamics. The first one is associated with a phase-separative tendency, showing up, in suitable conditions, lamellar ordering within the cluster, intermingled randomly with an amorphous phase. This is the case called by us the cylindrolite formation. The second-type signature, in turn, seems to point out some more disordered-from-within overall HP aggregations, presumably resulting in establishing a large HP mega-cluster, tending to span all over the available 2D simulation space. The quantitative characteristics derived so far show up at best an approximative tendency towards interpolating between this two types of aggregation/phase-separation signatures. A certain hope for better adjusting theory to computer simulation may come from realizing a non-Markovian character of the process which, for example, enables one to manipulate with the time scale in a case-sensitive, presumably excluded-area involving manner. (author)

  2. Fluorescence lifetime heterogeneity in aggregates of LHCII revealed by time-resolved microscopy.

    Science.gov (United States)

    Barzda, V; de Grauw, C J; Vroom, J; Kleima, F J; van Grondelle, R; van Amerongen, H; Gerritsen, H C

    2001-01-01

    Two-photon excitation, time-resolved fluorescence microscopy was used to investigate the fluorescence quenching mechanisms in aggregates of light-harvesting chlorophyll a/b pigment protein complexes of photosystem II from green plants (LHCII). Time-gated microscopy images show the presence of large heterogeneity in fluorescence lifetimes not only for different LHCII aggregates, but also within a single aggregate. Thus, the fluorescence decay traces obtained from macroscopic measurements reflect an average over a large distribution of local fluorescence kinetics. This opens the possibility to resolve spatially different structural/functional units in chloroplasts and other heterogeneous photosynthetic systems in vivo, and gives the opportunity to investigate individually the excited states dynamics of each unit. We show that the lifetime distribution is sensitive to the concentration of quenchers contained in the system. Triplets, which are generated at high pulse repetition rates of excitation (>1 MHz), preferentially quench domains with initially shorter fluorescence lifetimes. This proves our previous prediction from singlet-singlet annihilation investigations (Barzda, V., V. Gulbinas, R. Kananavicius, V. Cervinskas, H. van Amerongen, R. van Grondelle, and L. Valkunas. 2001. Biophys. J. 80:2409-2421) that shorter fluorescence lifetimes originate from larger domains in LHCII aggregates. We found that singlet-singlet annihilation has a strong effect in time-resolved fluorescence microscopy of connective systems and has to be taken into consideration. Despite that, clear differences in fluorescence decays can be detected that can also qualitatively be understood. PMID:11423435

  3. VAPOR PHASE MERCURY SORPTION BY ORGANIC SULFIDE MODIFIED BIMETALLIC IRON-COPPER NANOPARTICLE AGGREGATES

    Science.gov (United States)

    Novel organic sulfide modified bimetallic iron-copper nanoparticle aggregate sorbent materials have been synthesized for removing elemental mercury from vapor streams at elevated temperatures (120-140 °C). Silane based (disulfide silane and tetrasulfide silane) and alkyl sulfide ...

  4. Aggregate formation in a freshwater bacterial strain induced by growth state and conspecific chemical cues

    Czech Academy of Sciences Publication Activity Database

    Blom, J. F.; Horňák, Karel; Šimek, Karel; Pernthaler, J.

    2010-01-01

    Roč. 12, č. 9 (2010), s. 2486-2495. ISSN 1462-2912 R&D Projects: GA ČR(CZ) GA206/08/0015 Institutional research plan: CEZ:AV0Z60170517 Keywords : aggregate formation * Sphingobium sp. * chemical cues * growth state Subject RIV: EE - Microbiology, Virology Impact factor: 5.537, year: 2010

  5. Aggregation and structural changes of α(S1)-, β- and κ-caseins induced by homocysteinylation.

    Science.gov (United States)

    Stroylova, Yulia Y; Zimny, Jaroslaw; Yousefi, Reza; Chobert, Jean-Marc; Jakubowski, Hieronim; Muronetz, Vladimir I; Haertlé, Thomas

    2011-10-01

    Elevated homocysteine levels are resulting in N-homocysteinylation of lysyl residues in proteins and they correlate with a number of human pathologies. However, the role of homocysteinylation of lysyl residues is still poorly known. In order to study the features of homocysteinylation of intrinsically unstructured proteins (IUP) bovine caseins were used as a model. α(S1)-, β- and κ-caseins, showing different aggregations and micelle formation, were modified with homocysteine-thiolactone and their physico-chemical properties were studied. Efficiency of homocysteine incorporation was estimated to be about 1.5, 2.1 and 1.3 homocysteyl residues per one β-, α(S1)-, and κ-casein molecule, respectively. Use of intrinsic and extrinsic fluorescent markers such as Trp, thioflavin T and ANS, reveal structural changes of casein structures after homocysteinylation reflected by an increase in beta-sheet content, which in some cases may be characteristic of amyloid-like transformations. CD spectra also show an increase in beta-sheet content of homocysteinylated caseins. Casein homocysteinylation leads in all cases to aggregation. The sizes of aggregates and aggregation rates were dependent on homocysteine thiolactone concentration and temperature. DLS and microscopic studies have revealed the formation of large aggregates of about 1-3μm. Homocysteinylation of α(S1)- and β-caseins results in formation of regular spheres. Homocysteinylated κ-casein forms thin unbranched fibrils about 400-800nm long. In case of κ-casein amyloidogenic effect of homocysteinylation was confirmed by Congo red spectra. Taken together, data indicate that N-homocysteinylation provokes significant changes in properties of native caseins. A comparison of amyloidogenic transformation of 3 different casein types, belonging to the IUP protein family, shows that the efficiency of amyloidogenic transformation upon homocysteinylation depends on micellization capacity, additional disulphide bonds and

  6. Charged Dust Aggregate Interactions

    Science.gov (United States)

    Matthews, Lorin; Hyde, Truell

    2015-11-01

    A proper understanding of the behavior of dust particle aggregates immersed in a complex plasma first requires a knowledge of the basic properties of the system. Among the most important of these are the net electrostatic charge and higher multipole moments on the dust aggregate as well as the manner in which the aggregate interacts with the local electrostatic fields. The formation of elongated, fractal-like aggregates levitating in the sheath electric field of a weakly ionized RF generated plasma discharge has recently been observed experimentally. The resulting data has shown that as aggregates approach one another, they can both accelerate and rotate. At equilibrium, aggregates are observed to levitate with regular spacing, rotating about their long axis aligned parallel to the sheath electric field. Since gas drag tends to slow any such rotation, energy must be constantly fed into the system in order to sustain it. A numerical model designed to analyze this motion provides both the electrostatic charge and higher multipole moments of the aggregate while including the forces due to thermophoresis, neutral gas drag, and the ion wakefield. This model will be used to investigate the ambient conditions leading to the observed interactions. This research is funded by NSF Grant 1414523.

  7. Platelet activation and aggregation

    DEFF Research Database (Denmark)

    Jensen, Maria Sander; Larsen, O H; Christiansen, Kirsten; Fenger-Eriksen, C; Ingerslev, J; Sørensen, Benny

    2013-01-01

    This study introduces a new laboratory model of whole blood platelet aggregation stimulated by endogenously generated thrombin, and explores this aspect in haemophilia A in which impaired thrombin generation is a major hallmark. The method was established to measure platelet aggregation initiated...... by tissue factor evaluated by means of impedance aggregometry. Citrated whole blood from healthy volunteers and haemophilia A patients with the addition of inhibitors of the contact pathway and fibrin polymerization was evaluated. In healthy persons, a second wave of platelet aggregation was found to...... coincide with the thrombin burst and to be abolished by thrombin inhibitors. In this system, platelet aggregation in severe haemophilia A (n = 10) was found to be significantly decreased as compared with healthy individuals (912 ± 294 vs. 1917 ± 793 AU × min, P = 0.003), most probably due to the weak level...

  8. Kinetic behaviours of aggregate growth driven by time-dependent migration, birth and death

    International Nuclear Information System (INIS)

    We propose a dynamic growth model to mimic some social phenomena, such as the evolution of cities' population, in which monomer migrations occur between any two aggregates and monomer birth/death can simultaneously occur in each aggregate. Considering the fact that the rate kernels of migration, birth and death processes may change with time, we assume that the migration rate kernel is ijf(t), and the self-birth and death rate kernels are ig1(t) and ig2(t), respectively. Based on the mean-field rate equation, we obtain the exact solution of this model and then discuss semi-quantitatively the scaling behaviour of the aggregate size distribution at large times. The results show that in the long-time limit, (i) if ∫t0g1(t') dt'/∫t0g2(t') dt' ≥ 1 or exp{∫t0[g2(t') - g1(t')] dt'}/∫t0f(t') dt' → 0, the aggregate size distribution ak(t) can obey a generalized scaling form; (ii) if ∫t0g1(t') dt'/∫t0g2(t') dt' → 0 and exp ∫t0[g2(t') - g1(t') dt'/∫t0f(t') dt' → ∞, ak(t) can take a scale-free form and decay exponentially in size k; (iii) ak(t) will satisfy a modified scaling law in the remaining cases. Moreover, the total mass of aggregates depends strongly on the net birth rate g1(t) - g2(t) and evolves exponentially as exp{∫t0[g1(t') - g2(t')] dt'}, which is in qualitative agreement with the evolution of the total population of a country in real world

  9. Basic Oxygen Furnace steel slag aggregates for phosphorus treatment. Evaluation of its potential use as a substrate in constructed wetlands.

    Science.gov (United States)

    Blanco, Ivan; Molle, Pascal; Sáenz de Miera, Luis E; Ansola, Gemma

    2016-02-01

    Basic Oxygen Furnace (BOF) steel slag aggregates from NW Spain were tested in batch and column experiments to evaluate its potential use as a substrate in constructed wetlands (CWs). The objectives of this study were to identify the main P removal mechanisms of BOF steel slag and determine its P removal capacity. Also, the results were used to discuss the suitability of this material as a substrate to be used in CWs. Batch experiments with BOF slag aggregates and increasing initial phosphate concentrations showed phosphate removal efficiencies between 84 and 99% and phosphate removal capacities from 0.12 to 8.78 mg P/g slag. A continuous flow column experiment filled with BOF slag aggregates receiving an influent synthetic solution of 15 mg P/L during 213 days showed a removal efficiency greater than 99% and a phosphate removal capacity of 3.1 mg P/g slag. In both experiments the main P removal mechanism was found to be calcium phosphate precipitation which depends on Ca(2+) and OH(-) release from the BOF steel slag after dissolution of Ca(OH)2 in water. P saturation of slag was reached within the upper sections of the column which showed phosphate removal capacities between 1.7 and 2.5 mg P/g slag. Once Ca(OH)2 was completely dissolved in these column sections, removal efficiencies declined gradually from 99% until reaching stable outlet concentrations with P removal efficiencies around 7% which depended on influent Ca(2+) for limited continuous calcium phosphate precipitation. PMID:26722756

  10. Feasibility of a pulsed sequencing batch reactor with anaerobic aggregated biomass for the treatment of low strenght wastewaters

    OpenAIRE

    Brito, A. G.; Rodrigues, A.C.; Melo, L. F.

    1997-01-01

    This study concerns an assessment of a SBR operation that associates anaerobic aggregated biomass with a pulsed action during the reaction phase, a system named Pulsed Sequencing Batch Reactor (P-SBR). The system uses a diaphragm pump as a pulsator unit to increase the liquid-solid contact, in order to avoid dead zones and possible external mass transfer resistance. A preliminary study of the operation of the reactor was performed with a low strenght synthetic wastewater with a COD near 1000m...

  11. Energy transfer dynamics in trimers and aggregates of light-harvesting complex II probed by 2D electronic spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Enriquez, Miriam M.; Zhang, Cheng; Tan, Howe-Siang, E-mail: howesiang@ntu.edu.sg [Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore); Akhtar, Parveen; Garab, Győző; Lambrev, Petar H., E-mail: lambrev@brc.hu [Institute of Plant Biology, Biological Research Centre, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged (Hungary)

    2015-06-07

    The pathways and dynamics of excitation energy transfer between the chlorophyll (Chl) domains in solubilized trimeric and aggregated light-harvesting complex II (LHCII) are examined using two-dimensional electronic spectroscopy (2DES). The LHCII trimers and aggregates exhibit the unquenched and quenched excitonic states of Chl a, respectively. 2DES allows direct correlation of excitation and emission energies of coupled states over population time delays, hence enabling mapping of the energy flow between Chls. By the excitation of the entire Chl b Q{sub y} band, energy transfer from Chl b to Chl a states is monitored in the LHCII trimers and aggregates. Global analysis of the two-dimensional (2D) spectra reveals that energy transfer from Chl b to Chl a occurs on fast and slow time scales of 240–270 fs and 2.8 ps for both forms of LHCII. 2D decay-associated spectra resulting from the global analysis identify the correlation between Chl states involved in the energy transfer and decay at a given lifetime. The contribution of singlet–singlet annihilation on the kinetics of Chl energy transfer and decay is also modelled and discussed. The results show a marked change in the energy transfer kinetics in the time range of a few picoseconds. Owing to slow energy equilibration processes, long-lived intermediate Chl a states are present in solubilized trimers, while in aggregates, the population decay of these excited states is significantly accelerated, suggesting that, overall, the energy transfer within the LHCII complexes is faster in the aggregated state.

  12. Energy transfer dynamics in trimers and aggregates of light-harvesting complex II probed by 2D electronic spectroscopy

    International Nuclear Information System (INIS)

    The pathways and dynamics of excitation energy transfer between the chlorophyll (Chl) domains in solubilized trimeric and aggregated light-harvesting complex II (LHCII) are examined using two-dimensional electronic spectroscopy (2DES). The LHCII trimers and aggregates exhibit the unquenched and quenched excitonic states of Chl a, respectively. 2DES allows direct correlation of excitation and emission energies of coupled states over population time delays, hence enabling mapping of the energy flow between Chls. By the excitation of the entire Chl b Qy band, energy transfer from Chl b to Chl a states is monitored in the LHCII trimers and aggregates. Global analysis of the two-dimensional (2D) spectra reveals that energy transfer from Chl b to Chl a occurs on fast and slow time scales of 240–270 fs and 2.8 ps for both forms of LHCII. 2D decay-associated spectra resulting from the global analysis identify the correlation between Chl states involved in the energy transfer and decay at a given lifetime. The contribution of singlet–singlet annihilation on the kinetics of Chl energy transfer and decay is also modelled and discussed. The results show a marked change in the energy transfer kinetics in the time range of a few picoseconds. Owing to slow energy equilibration processes, long-lived intermediate Chl a states are present in solubilized trimers, while in aggregates, the population decay of these excited states is significantly accelerated, suggesting that, overall, the energy transfer within the LHCII complexes is faster in the aggregated state

  13. Soil aggregation and aggregate associated organic carbon and total nitrogen under long-term contrasting soil management regimes in loess soil

    Institute of Scientific and Technical Information of China (English)

    XIE Jun-yu; XU Ming-gang; Qiangjiu Ciren; YANG Yang; ZHANG Shu-lan; SUN Ben-hua; YANG Xue-yun

    2015-01-01

    This study investigated the effects of three contrasting soil management regimes and different nutrient treatments on the distribution of water-stable aggregates (>2, 1–2, 0.5–1, 0.25–0.5, and 0.25 mm) and mean weight diameter (MWD) at 0–10 and 10–20 cm soil horizons compared with Cropping, whereas Falow yielded lower values of above two parameters. Abandonment increased SOC and TN contents in al aggregate sizes by 17–62%and 6–60%, respectively, at 0–10 cm soil layer compared with Cropping. Conversely, Falow decreased SOC and TN contents in al aggregates by 7–27% and 7–25%, respectively. Nevertheless, the three soil management regimes presented similar SOC contents in al aggregates at 10–20 cm soil horizon. Only Cropping showed higher TN content in >0.5 mm aggregates than the two other regimes. Consequently, Abandonment enhanced the partitioning proportions of SOC and TN in >1 mm macro-aggregates, and Falow promoted these proportions in micro-aggregates compared with Cropping. Under Cropping, long-term fertilization did not affect the distribution of aggregates and MWD values compared with those under CK, except for NPK treatment. Fertilizer treatments enhanced SOC and TN contents in aggregates at al tested soil depths. However, fertilization did not affect the partitioning proportions of SOC and TN contents in al aggregates compared with CK. Comprehensive results showed that different soil management regimes generated varied patterns of SOC and TN sequestration in loess soil. Abandonment enhanced soil aggregation and sequestered high amounts of SOC and TN in macro-aggregates. Long-term amendment of organic manure integrated with NPK maintained soil aggregate stability and improved SOC and TN sequestration in al aggregates in loess soil subjected to dryland farming.

  14. CYP-independent inhibition of platelet aggregation in rabbits by a mixed disulfide conjugate of clopidogrel.

    Science.gov (United States)

    Zhang, H; Lauver, D A; Hollenberg, P F

    2014-12-01

    Dual antiplatelet therapy with clopidogrel and aspirin has been the standard of care in the United States for patients with acute coronary syndromes (ACS) and/or undergoing percutaneous coronary interventions (PCI). However, the effectiveness of clopidogrel varies significantly among different sub-populations due to inter-individual variability. In this study we examined the antiplatelet potential of a novel mixed disulfide conjugate of clopidogrel with the aim to overcome the inter-individual variability. In the metabolic studies using human liver microsomes and cDNA-expressed P450s, we confirmed that multiple P450s are involved in the bioactivation of 2-oxoclopidogrel to H4, one of the diastereomers of the pharmacologically active metabolite (AM) possessing antiplatelet activity. Results from kinetic studies demonstrated that 2C19 is the most active in converting 2-oxoclopidogrel to H4 with a catalytic efficiency of 0.027 µM⁻¹min⁻¹ in the reconstituted system. On the basis of this finding, we were able to biosynthesise the conjugate of clopidogrel with 3-nitropyridine-2-thiol, referred to as clopNPT, and examined its antiplatelet activity in male New Zealand white rabbits. After administration as intravenous bolus at 2 mg/kg, the clopNPT conjugate was rapidly converted to the AM leading to the inhibition of platelet aggregation (IPA). Analyses of the blood samples drawn at various time points showed that intravenous administration of clopNPT led to ~70% IPA within 1 hour and the IPA persisted for more than 3 hours. Since the antiplatelet activity of clopNPT does not require bioactivation by P450s, the mixed disulfide conjugate of clopidogrel has the potential to overcome the inter-individual variability in clopidogrel therapy. PMID:25230737

  15. Proteins aggregation and human diseases

    Science.gov (United States)

    Hu, Chin-Kun

    2015-04-01

    Many human diseases and the death of most supercentenarians are related to protein aggregation. Neurodegenerative diseases include Alzheimer's disease (AD), Huntington's disease (HD), Parkinson's disease (PD), frontotemporallobar degeneration, etc. Such diseases are due to progressive loss of structure or function of neurons caused by protein aggregation. For example, AD is considered to be related to aggregation of Aβ40 (peptide with 40 amino acids) and Aβ42 (peptide with 42 amino acids) and HD is considered to be related to aggregation of polyQ (polyglutamine) peptides. In this paper, we briefly review our recent discovery of key factors for protein aggregation. We used a lattice model to study the aggregation rates of proteins and found that the probability for a protein sequence to appear in the conformation of the aggregated state can be used to determine the temperature at which proteins can aggregate most quickly. We used molecular dynamics and simple models of polymer chains to study relaxation and aggregation of proteins under various conditions and found that when the bending-angle dependent and torsion-angle dependent interactions are zero or very small, then protein chains tend to aggregate at lower temperatures. All atom models were used to identify a key peptide chain for the aggregation of insulin chains and to find that two polyQ chains prefer anti-parallel conformation. It is pointed out that in many cases, protein aggregation does not result from protein mis-folding. A potential drug from Chinese medicine was found for Alzheimer's disease.

  16. Properties of Concrete with Tire Derived Aggregate Partially Replacing Coarse Aggregates

    Directory of Open Access Journals (Sweden)

    Gideon Siringi

    2015-01-01

    Full Text Available Tire derived aggregate (TDA has been proposed as a possible lightweight replacement for mineral aggregate in concrete. The role played by the amount of TDA replacing coarse aggregate as well as different treatment and additives in concrete on its properties is examined. Conventional concrete (without TDA and concrete containing TDA are compared by examining their compressive strength based on ASTM C39, workability based on ASTM C143, splitting tensile strength based on ASTM C496, modulus of rupture (flexural strength based on ASTM C78, and bond stress based on ASTM C234. Results indicate that while replacement of coarse aggregates with TDA results in reduction in strength, it may be mitigated with addition of silica fume to obtain the desired strength. The greatest benefit of using TDA is in the development of a higher ductile product while utilizing recycled TDA.

  17. Pressure effects on the structure, kinetic, and thermodynamic properties of heat-induced aggregation of protein studied by FT-IR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Taniguchi, Y [Applied Chemistry Department, Ritsumeikan University, Kusatsu, Shiga 525-8577 (Japan); Okuno, A [Research Department 3, Central Research, Bridgestone Co. Kodaira, Tokyo 187-8531 (Japan); Kato, M, E-mail: taniguti@sk.ritsumei.ac.j [Pharmaceutical Sciences Department, Ritsumeikan University, Kusatsu, Shiga 525-8577 (Japan)

    2010-03-01

    Pressure can retrain the heat-induced aggregation and dissociate the heat-induced aggregates. We observed the aggregation-preventing pressure effect and the aggregates-dissociating pressure effect to characterize the heat-induced aggregation of equine serum albumin (ESA) by FT-IR spectroscopy. The results suggest the {alpha}-helical structure collapses at the beginning of heat-induced aggregation through the swollen structure, and then the rearrangement of structure to the intermolecular {beta}-sheet takes place through partially unfolded structure. We determined the activation volume for the heat-induced aggregation ({Delta}V'' = +93 ml/mol) and the partial molar volume difference between native state and heat-induced aggregates ({Delta}V=+32 ml/mol). This positive partial molar volume difference suggests that the heat-induced aggregates have larger internal voids than the native structure. Moreover, the positive volume change implies that the formation of the intermolecular {beta}-sheet is unfavorable under high pressure.

  18. Organic carbon, water repellency and soil stability to slaking at aggregate and intra-aggregate scales

    Science.gov (United States)

    Jordán López, Antonio; García-Moreno, Jorge; Gordillo-Rivero, Ángel J.; Zavala, Lorena M.; Cerdà, Artemi; Alanís, Nancy; Jiménez-Compán, Elizabeth

    2015-04-01

    intensity of WR in aggregates of different sizes. [ii] the intra-aggregate distribution of OC and the intensity of WR and [iii] the structural stability of soil aggregates relative to the OC content and the intensity of WR in soils under different crops (apricot, citrus and wheat) and different treatments (conventional tilling and mulching). Soil samples were collected from an experimental area (Luvic Calcisols and Calcic Luvisols) in the province of Sevilla (Southern Spain) under different crops (apricot, citrus and wheat) and different management types (conventional tillage with moldboard plow) and mulching (no-tilling and addition of wheat residues at rates varying between 5 and 8 Mg/ha/year). At each sampling site, soil blocks (50 cm long × 50 cm wide × 10 cm deep) were carefully collected to avoid disturbance of aggregates as much as possible and transported to the laboratory. At field moist condition, undisturbed soil aggregates were separated by hand. In order to avoid possible interferences due to disturbance by handling, aggregates broken during this process were discarded. Individual aggregates were arranged in paper trays and air-dried during 7 days under laboratory standard conditions. After air-drying, part of each sample was carefully divided for different analyses: [i] part of the original samples was sieved (2 mm) to eliminate coarse soil particles and homogenized for characterization of OC and N contents, C/N ratio and texture; [ii] part of the aggregates were dry-sieved (0.25-0.5, 0.5-1 and 1-2 mm) or measured with a caliper (2-5, 5-10 and 10-15 mm) and separated in different sieve-size classes for determination of WR and OC content; [iii] aggregates 10-15 mm in size were selected for obtaining aggregate layers using a soil aggregate erosion (SAE) apparatus and WR and OC content were determined at each layer; finally, [iv] in order to study the relation between stability to slaking, WR and OC, these properties were determined in 90 air-dried aggregates

  19. [Analysis of proteins synthesized in aggregates of dissociated blastula and gastrula cells of Pleurodeles waltlii (Amphibia, urodela) by electrophoresis in polyacrylamide gradients].

    Science.gov (United States)

    Boucaut, J C; Desvaux, F X

    1976-09-20

    The protein synthesis manifested by aggregates of blastula and gastrula dissociated cells were studied by means of polyacylamide gradient gel electrophoresis. This method permits a comparative analysis of protein electrophoretic mobilities in aggregates and controls. In all cases, the data obtained establish the identity of protein banding and confirm an egg laying polymorphism. PMID:825304

  20. Tillage system effects on stability and sorptivity of soil aggregates

    Directory of Open Access Journals (Sweden)

    M. Turski

    2006-09-01

    Full Text Available Stability and sorptivity of soil aggregates play an important role in numerous soil processes and functions. They are largely influenced by tillage methods. We have compared the effects of long-term application of various tillage systems on aggregate bulk density, rate of wetting, sorptivity, water stability, tensile strength and bulk density of silt loam Eutric Fluvisol. Tillage treatments were: 1 ploughing to the depth of 20 cm (CT, 2 ploughing to 20 cm every 6 years and harrowing to 5 cm in the remaining years (S/CT, 3 harrowing to 5 cm each year (S, 4 sowing to uncultivated soil (NT, all in a micro-plot experiment. Bulk density of soil aggregates was determined by wax method, sorptivity – by a steady state flow, water stability – by drop impact method, and tensile strength – by crushing test. Tillage had a significant effect on the aggregate characteristics. Soil aggregate bulk density and water stability were greater and rate of wetting and sorptivity were smaller in reduced and no-tillage treatments compared with CT. Greater soil organic matter and bulk density accompanied greater water stability. Smaller rate of wetting and sorptivity can be associated with lower aggregate porosity. The differences in the rate of wetting, sorptivity, and water stability of the initially air-dry soil aggregates and bulk density between the tillage treatments were relatively greater than those in the tensile strength.

  1. Aggregation resistant zwitterated superparamagnetic nanoparticles

    International Nuclear Information System (INIS)

    Superparamagnetic nanoparticles (NPs) are promising for biomedical applications since they can be directed toward the organ of interest using an external magnetic field. They are also good contrast agents for magnetic resonance imaging and have potential for the treatment of malignant tumors (i.e., hyperthermia). Therefore, there is a need to produce stable, non-aggregating superparamagnetic nanomaterials that can withstand the in vivo environment. In this work, the colloidal stability of a dispersion of iron oxide NPs was enhanced by functionalizing them with a short zwitterionic siloxane shell in aqueous media. The stabilization procedure yields superparamagnetic nanomaterials, ca. 10 nm in diameter, with saturation magnetization of about 54 emu/g that resist aggregation at physiological salt concentration, temperature, and pH. The loading of the zwitterionic shell was established with diffuse reflectance infrared spectroscopy and thermal gravimetric analysis. X-ray and electron diffraction verified the starting magnetite phase, and that no change in phase occurred on surface functionalization.

  2. Discovery of novel PDE9 inhibitors capable of inhibiting Aβ aggregation as potential candidates for the treatment of Alzheimer’s disease

    Science.gov (United States)

    Su, Tao; Zhang, Tianhua; Xie, Shishun; Yan, Jun; Wu, Yinuo; Li, Xingshu; Huang, Ling; Luo, Hai-Bin

    2016-02-01

    Recently, phosphodiesterase-9 (PDE9) inhibitors and biometal-chelators have received much attention as potential therapeutics for the treatment of Alzheimer’s disease (AD). Here, we designed, synthesized, and evaluated a novel series of PDE9 inhibitors with the ability to chelate metal ions. The bioassay results showed that most of these molecules strongly inhibited PDE9 activity. Compound 16 showed an IC50 of 34 nM against PDE9 and more than 55-fold selectivity against other PDEs. In addition, this compound displayed remarkable metal-chelating capacity and a considerable ability to halt copper redox cycling. Notably, in comparison to the reference compound clioquinol, it inhibited metal-induced Aβ1-42 aggregation more effectively and promoted greater disassembly of the highly structured Aβ fibrils generated through Cu2+-induced Aβ aggregation. These activities of 16, together with its favorable blood-brain barrier permeability, suggest that 16 may be a promising compound for treatment of AD.

  3. Study on aggregation behavior of low density lipoprotein in hen egg yolk plasma by asymmetrical flow field-flow fractionation coupled with multiple detectors.

    Science.gov (United States)

    Dou, Haiyang; Magnusson, Emma; Choi, Jaeyeong; Duan, Fei; Nilsson, Lars; Lee, Seungho

    2016-02-01

    In this study, asymmetrical flow field-flow fractionation (AF4) coupled online with UV, multiangle light scattering (MALS), and fluorescence (FS) detectors (AF4-UV-MALS-FS) was employed for separation and characterization of egg yolk plasma. AF4 provided separation of three major components of the egg yolk plasma i.e. soluble proteins, low density lipoproteins (LDL) and their aggregates, based on their respective hydrodynamic sizes. Identification of LDL was confirmed by staining the sample with a fluorescent dye, Nile Red. The effect of carrier liquids on aggregation of LDL was investigated. Collected fractions of soluble proteins were characterized using sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE). Moreover, the effect of heat and enzymatic treatment on egg yolk plasma was investigated. The results suggest that enzymatic treatment with phospholipase A2 (PLA2) significantly enhances the heat stability of LDL. The results show that AF4-UV-MALS-FS is a powerful tool for the fractionation and characterization of egg yolk plasma components. PMID:26304341

  4. Inhibition of the Crystal Growth and Aggregation of Calcium Oxalate by Algae Sulfated Polysaccharide In-vitro

    Institute of Scientific and Technical Information of China (English)

    Xiu Mei WU; Jian Ming OUYANG; Sui Ping DENG; Ying Zhou CEN

    2006-01-01

    The influence of sulfated polysaccharide (SPS) isolated from marine algae Sargassum fusiforme on the morphology and phase compositions of urinary crystal calcium oxalate was investigated in vitro by means of scanning electron microscopy and X-ray diffraction. SPS maybe is a potential inhibitor to CaOxa urinary stones by inhibiting the growth of calcium oxalate monohydrate (COM), preventing the aggregation of COM, and inducing the formation of calcium oxalate dihydrate (COD) crystals.

  5. Absorption Spectra of Astaxanthin Aggregates

    CERN Document Server

    Olsina, Jan; Minofar, Babak; Polivka, Tomas; Mancal, Tomas

    2012-01-01

    Carotenoids in hydrated polar solvents form aggregates characterized by dramatic changes in their absorption spectra with respect to monomers. Here we analyze absorption spectra of aggregates of the carotenoid astaxanthin in hydrated dimethylsulfoxide. Depending on water content, two types of aggregates were produced: H-aggregates with absorption maximum around 390 nm, and J-aggregates with red-shifted absorption band peaking at wavelengths >550 nm. The large shifts with respect to absorption maximum of monomeric astaxanthin (470-495 nm depending on solvent) are caused by excitonic interaction between aggregated molecules. We applied molecular dynamics simulations to elucidate structure of astaxanthin dimer in water, and the resulting structure was used as a basis for calculations of absorption spectra. Absorption spectra of astaxanthin aggregates in hydrated dimethylsulfoxide were calculated using molecular exciton model with the resonance interaction energy between astaxanthin monomers constrained by semi-e...

  6. HOMOSEXUALITY : TREATMENT BY BEHAVIOUR MODIFICATION

    OpenAIRE

    Pradhan, P. V.; Ayyar, K.S.; Bagadia, V.N.

    1982-01-01

    SUMMARY We present here the treatment of thirteen homosexuals by behaviour modification techniques. With classical electrical aversion and positive conditioning 8(61%) out of thirteen patients showed a change in orientation lasting on a six-month 1 year follow up. A marriageable age and indirect social pressures were positively correlated with improvement whereas the presence of a steady homosexual partner and habitual passive anal intercourse indicated a poor response. The techniques, the as...

  7. Treatment Options by Stage (Melanoma)

    Science.gov (United States)

    ... of Skin Cancer Skin Cancer Screening Research Melanoma Treatment (PDQ®)–Patient Version General Information About Melanoma Key ... Certain factors affect prognosis (chance of recovery) and treatment options. The prognosis (chance of recovery ) and treatment ...

  8. Coagulation with limited aggregations

    CERN Document Server

    Bertoin, Jean

    2012-01-01

    Smoluchowski's coagulation equations can be used as elementary mathematical models for the formation of polymers. We review here some recent contributions on a variation of this model in which the number of aggregations for each atom is a priori limited. Macroscopic results in the deterministic setting can be explained at the microscopic level by considering a version of stochastic coalescence with limited aggregations, which can be related to the so-called random configuration model of random graph theory.

  9. Analysis of patterns formed by two-component diffusion limited aggregation.

    Science.gov (United States)

    Postnikov, E B; Ryabov, A B; Loskutov, A

    2010-11-01

    We consider diffusion limited aggregation of particles of two different kinds. It is assumed that a particle of one kind may adhere only to another particle of the same kind. The particles aggregate on a linear substrate which consists of periodically or randomly placed particles of different kinds. We analyze the influence of initial patterns on the structure of growing clusters. It is shown that at small distances from the substrate, the cluster structures repeat initial patterns. However, starting from a critical distance the initial periodicity is abruptly lost, and the particle distribution tends to a random one. An approach describing the evolution of the number of branches is proposed. Our calculations show that the initial pattern can be detected only at the distance which is not larger than approximately one and a half of the characteristic pattern size. PMID:21230475

  10. Aggregation-resistant VHs selected by in vitro evolution tend to have disulfide-bonded loops and acidic isoelectric points.

    Science.gov (United States)

    Arbabi-Ghahroudi, M; To, R; Gaudette, N; Hirama, T; Ding, W; MacKenzie, R; Tanha, J

    2009-02-01

    When panned with a transient heat denaturation approach against target enzymes, a human V(H) (antibody heavy chain variable domain) phage display library yielded V(H)s with composite characteristics of binding, non-aggregation and reversible thermal unfolding. Moreover, selection was characterized by enrichment for V(H)s with (i) an even number of disulfide forming Cys residues in complementarity-determining region (CDR) 1 and CDR3 and (ii) acidic isoelectric points. This parallels naturally occurring camelid and shark single-domain antibodies (sdAbs) which are also characterized by (i) solubility and reversible unfolding, (ii) a high occurrence of disulfide forming Cys in their CDRs, particularly, in CDR1 and CDR3 and (iii) acidic V(H)s as inferred here by a pI distribution analysis, reported here, of pools of human and camelid V(H) and V(H)H (camelid heavy chain antibody V(H)) sequences. Our results, reinforced by previous observations by others, suggest that protein acidification may yet be another mechanism nature has devised to create functional sdAbs and that this concept along with the inclusion of inter-CDR disulfide linkages may be applied to human V(H) domains/libraries for non-aggregation optimization. In addition, calculation of theoretical pIs of V(H)s selected by panning may be used for rapid and precise identification of non-aggregating V(H)s. PMID:19033278

  11. Fingerprints of four crop models as affected by soil input data aggregation

    Czech Academy of Sciences Publication Activity Database

    Angulo, C.; Gaiser, T.; Rötter, R. P.; Børgesen, C. D.; Hlavinka, Petr; Trnka, Miroslav; Ewert, F.

    2014-01-01

    Roč. 61, NOV 2014 (2014), s. 35-48. ISSN 1161-0301 R&D Projects: GA MŠk(CZ) EE2.3.20.0248; GA MŠk(CZ) EE2.4.31.0056; GA MZe QJ1310123 Institutional support: RVO:67179843 Keywords : crop model * soil data * spatial resolution * yield distribution * aggregation Subject RIV: EH - Ecology, Behaviour Impact factor: 2.704, year: 2014

  12. Colonization of wheat roots by an exopolysaccharide-producing pantoea agglomerans strain and its effect on rhizosphere soil aggregation

    Science.gov (United States)

    Amellal; Burtin; Bartoli; Heulin

    1998-10-01

    The effect of bacterial secretion of an exopolysaccharide (EPS) on rhizosphere soil physical properties was investigated by inoculating strain NAS206, which was isolated from the rhizosphere of wheat (Triticum durum L.) growing in a Moroccan vertisol and was identified as Pantoea aglomerans. Phenotypic identification of this strain with the Biotype-100 system was confirmed by amplified ribosomal DNA restriction analysis. After inoculation of wheat seedlings with strain NAS206, colonization increased at the rhizoplane and in root-adhering soil (RAS) but not in bulk soil. Colonization further increased under relatively dry conditions (20% soil water content; matric potential, -0.55 MPa). By means of genetic fingerprinting using enterobacterial repetitive intergenic consensus PCR, we were able to verify that colonies counted as strain NAS206 on agar plates descended from inoculated strain NAS206. The intense colonization of the wheat rhizosphere by these EPS-producing bacteria was associated with significant soil aggregation, as shown by increased ratios of RAS dry mass to root tissue (RT) dry mass (RAS/RT) and the improved water stability of adhering soil aggregates. The maximum effect of strain NAS206 on both the RAS/RT ratio and aggregate stability was measured at 24% average soil water content (matric potential, -0.20 MPa). Inoculated strain NAS206 improved RAS macroporosity (pore diameter, 10 to 30 &mgr;m) compared to the noninoculated control, particularly when the soil was nearly water saturated (matric potential, -0.05 MPa). Our results suggest that P. agglomerans NAS206 can play an important role in the regulation of the water content (excess or deficit) of the rhizosphere of wheat by improving soil aggregation. PMID:9758793

  13. Microbial properties of soil aggregates created by earthworms and other factors: spherical and prismatic soil aggregates from unreclaimed post-mining sites

    Czech Academy of Sciences Publication Activity Database

    Frouz, J.; Krištůfek, Václav; Livečková, M.; van Loo, D.; Jacobs, P.; van Hoorebeke, L.

    2011-01-01

    Roč. 56, č. 1 (2011), s. 36-43. ISSN 0015-5632 R&D Projects: GA MŠk LC06066; GA MŠk 2B08023; GA AV ČR 1QS600660505 Institutional research plan: CEZ:AV0Z60660521 Keywords : microbial properties * earthworms * spherical and prismatic soil aggregates Subject RIV: EH - Ecology, Behaviour Impact factor: 0.677, year: 2011

  14. Effect of the surfactant Tween 80 on the detachment and dispersal of Salmonella enterica Thompson single cells and aggregates from cilantro leaves as revealed by image analysis

    Science.gov (United States)

    Biofilms formed by human enteric pathogens on plants are a great concern to the produce industry. Salmonella enterica has the ability to form biofilms and large aggregates on leaf surfaces, including on cilantro leaves. Aggregates that remained attached after rigorous washing of cilantro leaves and ...

  15. Inhibition of adenosine diphosphate-induced platelet aggregation by alpha-lipoic acid and dihydroquercetin in vitro

    Directory of Open Access Journals (Sweden)

    Ivan S Ivanov

    2014-01-01

    Full Text Available Objectives: To investigate the antiplatelet activity of alpha-lipoic acid (α-LA and dihydroquercetin (DHQ. Materials and Methods: Antiplatelet activity of the α-LA and DHQ was evaluated in rich platelet plasma of rat. The platelet aggregation was induced by adenosine diphosphate (ADP in concentration of 4 Χ 10 -5 Μ. Results: α-LA and DHQ inhibited platelet aggregation in concentration-dependent manner. The antiplatelet activity of α-LA was more pronounced than DHQ. DHQ also increased the antiplatelet activity of α-LA by 1.4 times. Conclusion: Combined simultaneous use of α-LA and DHQ possessed the high antiplatelet activity, and DHQ potentiated the activity of α-LA.

  16. Preparation of Cross-Linked Glucoamylase Aggregates Immobilization by Using Dextrin and Xanthan Gum as Protecting Agents

    Directory of Open Access Journals (Sweden)

    Xiao-Dong Li

    2016-05-01

    Full Text Available In this paper glucoamylase from Aspergillus niger was immobilized by using a modified version of cross-linked enzyme aggregates (CLEA. The co-aggregates were cross-linked with glutaraldehyde; meanwhile dextrin and xanthan gum as protecting agents were added, which provides high affinity with the enzyme molecules. The immobilized glucoamylase was stable over a broad range of pH (3.0–8.0 and temperature (55–75 °C; dependence shows more catalytic activity than a free enzyme. The thermostability, kinetic behavior, and first-order inactivation rate constant (ki were investigated. The two types of protector made the immobilized glucoamylase more robust than the free form. Both of the immobilized enzymes have excellent recyclability, retaining over 45% of the relative activity after 24 runs. In addition, immobilized enzymes reduced only 40% of the initial activity after three months by the storability measure, indicating high activity.

  17. Comparison of aggregation and feeding responses by normal and irradiated fruit flies, Ceratitis capitata and Anastrepha suspensa (Diptera: Tephritidae)

    International Nuclear Information System (INIS)

    Olfactory, aggregatory, and feeding responses of normal (untreated) laboratory stocks of Mediterranean fruit fly (medfly), Ceratitis capitata (Wiedemann), and of Caribbean fruit fly (caribfly), Anastrepha suspensa (Loew), were compared to those of flies irradiated (10 krad in air) 2 days before eclosion. Females of both species consumed greater quantities of protein hydrolysate solutions, entered protein hydrolysate-baited olfactory traps, and aggregated on agar plates containing protein hydrolysate in greater numbers than males of the same age and condition. However, male medflies consumed more sucrose than did females of the same age and condition. In the medfly, irradiation resulted in reduced olfactory response, reduced total food intake by flies of both sexes, and a significant reduction in aggregation on and intake of protein hydrolysate by females and of sugar consumption by males. In the irradiated caribfly, there was a significant reduction in olfactory response of females to yeast hydrolysate. In both sexes, aggregation on and consumption of yeast hydrolysate were reduced. Effects of irradiation on feeding behavior are discussed in relation to the biology of the flies and their control by the sterile insect release method

  18. Generation of Soluble Advanced Glycation End Products Receptor (sRAGE)-Binding Ligands during Extensive Heat Treatment of Whey Protein/Lactose Mixtures Is Dependent on Glycation and Aggregation.

    Science.gov (United States)

    Liu, Fahui; Teodorowicz, Małgorzata; Wichers, Harry J; van Boekel, Martinus A J S; Hettinga, Kasper A

    2016-08-24

    Heating of protein- and sugar-containing materials is considered the primary factor affecting the formation of advanced glycation end products (AGEs). This study aimed to investigate the influence of heating conditions, digestion, and aggregation on the binding capacity of AGEs to the soluble AGE receptor (sRAGE). Samples consisting of mixtures of whey protein and lactose were heated at 130 °C. An in vitro infant digestion model was used to study the influence of heat treatment on the digestibility of whey proteins. The amount of sRAGE-binding ligands before and after digestion was measured by an ELISA-based sRAGE-binding assay. Water activity did not significantly affect the extent of digestibility of whey proteins dry heated at pH 5 (ranging from 3.3 ± 0.2 to 3.6 ± 0.1% for gastric digestion and from 53.5 ± 1.5 to 64.7 ± 1.1% for duodenal digestion), but there were differences in cleavage patterns of peptides among the samples heated at different pH values. Formation of sRAGE-binding ligands depended on the formation of aggregates and was limited in the samples heated at pH 5. Moreover, the sRAGE-binding activity of digested sample was changed by protease degradation and correlated with the digestibility of samples. In conclusion, generation of sRAGE-binding ligands during extensive heat treatment of whey protein/lactose mixtures is limited in acidic heating condition and dependent on glycation and aggregation. PMID:27460534

  19. Analysis of the aggregation structure from amphiphilic block copolymers in solutions by small-angle x-ray scattering

    CERN Document Server

    Rong Li Xia; Wang Jun; Wei Liu He; Li Fu Mian; Li Zi Chen

    2002-01-01

    The aggregation structure of polystyrene-p vinyl benzoic amphiphilic block copolymers which were prepared in different conditions was investigated by synchrotron radiation small-angle x-ray scattering (SAXS). The micelle was self-assembled in selective solvents of the block copolymers. Authors' results demonstrate that the structure of the micelle depends on the factors, such as the composition of the copolymers, the nature of the solvent and the concentration of the solution

  20. Morphological and mechanical response characterization of nanofiber aggregates of pva produced by electrospinning sol-gel process

    OpenAIRE

    Amigó Borrás, Vicente; Franco Medina, Edgar; DELVASTO ARJONA, SILVIO; ZULUAGA CORRALES, FABIO

    2013-01-01

    [EN] This work deals with the preparation of poly (vinyl alcohol) solutions composed of a surface active agent, an acid and water. With this solution firstly electrospun nanofiber mats and then nanofiber aggregates were obtained by electrospinning/sol-gel process. The samples were morphologically characterized using scanning electron microscopy (SEM) and Atomic Force Microscopy (AFM), obtaining superficial roughness values, distribution and average diameter before and after the electrospinnin...

  1. COX-2 Inhibition by Use of Rofecoxib or High Dose Aspirin Enhances ADP-Induced Platelet Aggregation in Fresh Blood

    OpenAIRE

    Borgdorff, P.; Handoko, M.L.; Wong, Y.Y.; Tangelder, G.J.

    2010-01-01

    Aim: Increased cardiovascular risk after use of selective or nonselective cyclooxygenase-2 (COX-2)-inhibitors might partly be caused by enhanced platelet aggregability. However, an effect of COX-2 inhibition on platelets has so far not been observed in humans. Methods: We tested in healthy volunteers the effect of COX-2-inhibition nearly in-vivo, i.e. immediately after and even during blood sampling. Results: Measurement within 2 minutes after venipuncture, but not 60 minutes later, showed th...

  2. Cyanide wastes treatment by bioremediation

    International Nuclear Information System (INIS)

    The results of the development of an autochthonous consortium of degrader microorganisms of the cyanide for the application in the biological treatment of the dangerous wastes of cyanide, were presented. The autochthonous microorganisms obtained were lyophilized in different protective environments, such as gelatin and lactose broth at different temperatures (-35, -45, -55 and -65). A pretreatment method in slurry was applied for the preliminary treatment of the cyanide wastes: for the preliminary leaching of the waste, with periods between 3 and 5 days and a posterior treatment, by aerated lagoons, applying the consortium of lyophilized microorganisms. Eight different lyophilized were obtained in different temperature conditions and with two lyophilization protective media that have presented excellent recovery at six months of lyophilization. The consortium of lyophilized microorganisms has presented 70 to 80 percent of viability, with cyanide removal percentages higher than 95% and it can be conserved active for a prolonged time (for years). The lyophilized microorganisms can be applied in the biodegradation of the cyanide wastes from the gold mines or any other cyanide waste such as metal electroplanting baths, as well as from jewelry manufacturing. (author)

  3. The influence of protein aggregation on adsorption kinetics

    Science.gov (United States)

    Rovner, Joel; Roberts, Christopher; Furst, Eric; Hudson, Steven

    2015-03-01

    When proteins adsorb to an air-water interface they lower the surface tension and may form an age-dependent viscoelastic film. Protein adsorption to surfaces is relevant to both commercial uses and biological function. The rate at which the surface tension decreases depends strongly on temperature, solution pH, and protein structure. These kinetics also depend on the degree to which the protein is aggregated in solution. Here we explore these differences using Chymotrypsinogen as a model protein whose degree of aggregation is adjusted through controlled heat treatment and measured by chromatography. To study these effects we have used a micropipette tensiometer to produce a spherical-cap bubble whose interfacial pressure was controlled - either steady or oscillating. Short heat treatment produced small soluble aggregates, and these adsorbed faster than the original protein monomer. Longer heat treatment produced somewhat larger soluble aggregates which adsorbed more slowly. These results point to complex interactions during protein adsorption.

  4. Complex polyion-surfactant ion salts in equilibrium with water: changing aggregate shape and size by adding oil.

    Science.gov (United States)

    Bernardes, Juliana S; Norrman, Jens; Piculell, Lennart; Loh, Watson

    2006-11-23

    The phase behavior of ternary mixtures containing an alkyltrimethylammonium polyacrylate complex salt, water, and a nonpolar "oil" (n-decanol, p-xylene or cyclohexane) is investigated. The complex salts were prepared with short or long polyacrylates (30 or 6000 repeating units) and with hexadecyltrimethylammonium or dodecyltrimethylammonium surfactant ions. Phase diagrams and structures were determined by visual inspection and small-angle X-ray scattering analyses. Systems containing decanol display a predominance of lamellar phases, while hexagonal phases prevail in systems containing p-xylene or cyclohexane. The difference is interpreted as a result of the different locations of the oils within the surfactant aggregates. Decanol is incorporated at the aggregate interface, leading to a decrease in its curvature, which favors the appearance of lamellar structures. p-Xylene and cyclohexane, on the other hand, are mostly incorporated in the interior of the cylindrical aggregate, as reflected by its swelling as the oil content increases. The comparison of these results with those reported for similar systems with monovalent (bromide) counterions indicates a much more limited swelling of the lamellar phases with polymeric counterions by water. This limited swelling behavior is predominantly ascribed to bridging due to the polyions. PMID:17107195

  5. Study of the influence of ultraviolet radiation on aggregative properties of blood red cell by light backscattering

    International Nuclear Information System (INIS)

    The method based on the fact of measurable intensity of backscattered laser beam resulting from the angular distribution of scattered light is investigated. The method permits study of the mechanisms of aggregation and disaggregation processes by ultraviolet radiation and action of some inductors. The ultraviolet light acting directly on erythrocyte rouleaus of 10 x 100 μ causes the scattering of laser beam of wavelength 632,8 nm. According the above mentioned fact at an agle of approximately 1800 the light intensity is measured. Stabilized blood sample is exposed to laser beam by means of fiber optics. Backscattering light transmitted through the photomultiplier and direct current supply is recorded. Quantitative concept of erythrocyte aggregation process is calculated from the plot. Blood sample is mixed by magnetic mixer and the measuring temperature is kept constantly at 370C. Accordingly, the present model can adequately reproduce complex blood red cells kinetics. The influence of ultraviolet radiation and different kinds of inductors on erythrocytes' aggregation is experimentally studied depending on time. 2 figs. (B.Sh.)

  6. Selenite Reduction by Anaerobic Microbial Aggregates: Microbial Community Structure, and Proteins Associated to the Produced Selenium Spheres

    KAUST Repository

    Gonzalez-Gil, Graciela

    2016-04-26

    Certain types of anaerobic granular sludge, which consists of microbial aggregates, can reduce selenium oxyanions. To envisage strategies for removing those oxyanions from wastewater and recovering the produced elemental selenium (Se0), insights into the microbial community structure and synthesis of Se0 within these microbial aggregates are required. High-throughput sequencing showed that Veillonellaceae (c.a. 20%) and Pseudomonadaceae (c.a.10%) were the most abundant microbial phylotypes in selenite reducing microbial aggregates. The majority of the Pseudomonadaceae sequences were affiliated to the genus Pseudomonas. A distinct outer layer (∼200 μm) of selenium deposits indicated that bioreduction occurred in the outer zone of the microbial aggregates. In that outer layer, SEM analysis showed abundant intracellular and extracellular Se0 (nano)spheres, with some cells having high numbers of intracellular Se0 spheres. Electron tomography showed that microbial cells can harbor a single large intracellular sphere that stretches the cell body. The Se0 spheres produced by the microorganisms were capped with organic material. X-ray photoelectron spectroscopy (XPS) analysis of extracted Se0 spheres, combined with a mathematical approach to analyzing XPS spectra from biological origin, indicated that proteins and lipids were components of the capping material associated to the Se0 spheres. The most abundant proteins associated to the spheres were identified by proteomic analysis. Most of the proteins or peptide sequences capping the Se0 spheres were identified as periplasmic outer membrane porins and as the cytoplasmic elongation factor Tu protein, suggesting an intracellular formation of the Se0 spheres. In view of these and previous findings, a schematic model for the synthesis of Se0 spheres by the microorganisms inhabiting the granular sludge is proposed.

  7. Selenite Reduction by Anaerobic Microbial Aggregates: Microbial Community Structure, and Proteins Associated to the Produced Selenium Spheres

    Science.gov (United States)

    Gonzalez-Gil, Graciela; Lens, Piet N. L.; Saikaly, Pascal E.

    2016-01-01

    Certain types of anaerobic granular sludge, which consists of microbial aggregates, can reduce selenium oxyanions. To envisage strategies for removing those oxyanions from wastewater and recovering the produced elemental selenium (Se0), insights into the microbial community structure and synthesis of Se0 within these microbial aggregates are required. High-throughput sequencing showed that Veillonellaceae (c.a. 20%) and Pseudomonadaceae (c.a.10%) were the most abundant microbial phylotypes in selenite reducing microbial aggregates. The majority of the Pseudomonadaceae sequences were affiliated to the genus Pseudomonas. A distinct outer layer (∼200 μm) of selenium deposits indicated that bioreduction occurred in the outer zone of the microbial aggregates. In that outer layer, SEM analysis showed abundant intracellular and extracellular Se0 (nano)spheres, with some cells having high numbers of intracellular Se0 spheres. Electron tomography showed that microbial cells can harbor a single large intracellular sphere that stretches the cell body. The Se0 spheres produced by the microorganisms were capped with organic material. X-ray photoelectron spectroscopy (XPS) analysis of extracted Se0 spheres, combined with a mathematical approach to analyzing XPS spectra from biological origin, indicated that proteins and lipids were components of the capping material associated to the Se0 spheres. The most abundant proteins associated to the spheres were identified by proteomic analysis. Most of the proteins or peptide sequences capping the Se0 spheres were identified as periplasmic outer membrane porins and as the cytoplasmic elongation factor Tu protein, suggesting an intracellular formation of the Se0 spheres. In view of these and previous findings, a schematic model for the synthesis of Se0 spheres by the microorganisms inhabiting the granular sludge is proposed. PMID:27199909

  8. Investigation of helium interstitials aggregation in silicon: Why bubbles formation by a self-trapping mechanism does not work

    Energy Technology Data Exchange (ETDEWEB)

    Pizzagalli, L., E-mail: Laurent.Pizzagalli@univ-poitiers.fr [Institut Pprime, CNRS UPR 3346, Université de Poitiers, SP2MI, BP 30179, Boulevard Marie et Pierre Curie, 86962 Futuroscope Chasseneuil Cedex (France); David, M.-L. [Institut Pprime, CNRS UPR 3346, Université de Poitiers, SP2MI, BP 30179, Boulevard Marie et Pierre Curie, 86962 Futuroscope Chasseneuil Cedex (France); Charaf-Eddin, A. [CINaM, Campus de Luminy, Case 913, 13288 Marseille Cedex 9 (France)

    2015-06-01

    First-principles calculations of the aggregation of helium interstitials in silicon have been performed to determine whether the first steps of helium-filled bubbles formation could occur by a self-trapping mechanism. These simulations show that the interaction between helium interstitials is repulsive, of low magnitude, and that this effect will saturate for a large number of interstitials. Considering the relaxation of the computational cell only leads to a small reduction of the binding energy. These results imply that the aggregation of interstitial helium atoms is highly unlikely in silicon, which allowed us to conclude that a self-trapping mechanism can not occur, and that an initial amount of vacancies is required for helium-filled bubbles formation.

  9. Second harmonic generation response by gold nanoparticles at the polarized water/2-octanone interface: from dispersed to aggregated particles

    Energy Technology Data Exchange (ETDEWEB)

    Galletto, P [Laboratoire d' Electrochimie Physique et Analytique, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); Girault, H H [Laboratoire d' Electrochimie Physique et Analytique, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); Gomis-Bas, C [Centre for Nanoscale Science, Department of Chemistry, University of Liverpool, Liverpool L69 3BX (United Kingdom); Schiffrin, D J [Centre for Nanoscale Science, Department of Chemistry, University of Liverpool, Liverpool L69 3BX (United Kingdom); Antoine, R [Universite Lyon 1, Laboratoire de Spectrometrie Ionique et Moleculaire, UMR CNRS 5579, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France); Broyer, M [Universite Lyon 1, Laboratoire de Spectrometrie Ionique et Moleculaire, UMR CNRS 5579, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France); Brevet, P F [Universite Lyon 1, Laboratoire de Spectrometrie Ionique et Moleculaire, UMR CNRS 5579, 43 boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex (France)

    2007-09-19

    Gold nanoparticles with a diameter of approximately 20 nm have been observed at the polarized water/2-octanone interface by the nonlinear optical technique of second harmonic generation. Electric field induced adsorption of the gold particles at this liquid/liquid interface is clearly observed and confirms that these are negatively charged. The process is quasi-reversible at high potential sweep rates, but aggregation at the interface is observed at slower sweep rates through the loss of the nonlinear optical signal. The time evolution of the second harmonic signal is also reported during potential step experiments. After a rapid increase due to adsorption, a continuous decrease in the nonlinear optical signal intensity is observed due to aggregation of the particles into large islands at the interface. Diffusion of these large islands at the interface was observed for a longer timescale through large signal fluctuations.

  10. Investigation of helium interstitials aggregation in silicon: Why bubbles formation by a self-trapping mechanism does not work

    International Nuclear Information System (INIS)

    First-principles calculations of the aggregation of helium interstitials in silicon have been performed to determine whether the first steps of helium-filled bubbles formation could occur by a self-trapping mechanism. These simulations show that the interaction between helium interstitials is repulsive, of low magnitude, and that this effect will saturate for a large number of interstitials. Considering the relaxation of the computational cell only leads to a small reduction of the binding energy. These results imply that the aggregation of interstitial helium atoms is highly unlikely in silicon, which allowed us to conclude that a self-trapping mechanism can not occur, and that an initial amount of vacancies is required for helium-filled bubbles formation

  11. Grb2 is regulated by foxd3 and has roles in preventing accumulation and aggregation of mutant huntingtin.

    Directory of Open Access Journals (Sweden)

    Shounak Baksi

    Full Text Available Growth factor receptor protein binding protein 2 (Grb2 is known to be associated with intracellular growth and proliferation related signaling cascades. Huntingtin (Htt, a ubiquitously expressed protein, when mutated, forms toxic intracellular aggregates - the hallmark of Huntington's disease (HD. We observed an elevated expression of Grb2 in neuronal cells in animal and cell models of HD. Grb2 overexpression was predominantly regulated by the transcription factor Forkhead Box D3 (Foxd3. Exogenous expression of Grb2 also reduced aggregation of mutant Htt in Neuro2A cells. Grb2 is also known to interact with Htt, depending on epidermal growth factor receptor (EGFR activation. Grb2- mutant Htt interaction in the contrary, took place in vesicular structures, independent of EGFR activation that eventually merged with autophagosomes and activated the autophagy machinery helping in autophagosome and lysosome fusion. Grb2, with its emerging dual role, holds promise for a survival mechanism for HD.

  12. Mechanical Degradation of Aggregate by the Los Angeles-, the Micro-Deval- and the Nordic Test Methods

    Science.gov (United States)

    Erichsen, E.; Ulvik, A.; Sævik, K.

    2011-05-01

    The quality of aggregate used as buildings materials is defined by European Standard test methods. According to the agreement within the European Economic Area, each individual country decides test methods of current interest. Among the Nordic countries, the Los Angeles-, micro-Deval- and the Nordic test are the most common methods used to decide the mechanical properties of the aggregate. The three test methods are all drum test where the degradation of the material occur by rotation between the test material and steel balls together with, or without water. The mechanical test methods are empirical and are believed to express either resistance to fragmentation or wearing. The results of this study show that analysing the particle size distribution of a material after the drum testing give indication of which type and degree of degradation the test material is exposed to. Knowledge of the type of degradation for the test methods is important compared to the understanding of the real breakdown of the aggregate for instance used in road construction.

  13. In-situ suspended aggregate microextraction of gold nanoparticles from water samples and determination by electrothermal atomic absorption spectrometry.

    Science.gov (United States)

    Choleva, Tatiana G; Kappi, Foteini A; Tsogas, George Z; Vlessidis, Athanasios G; Giokas, Dimosthenis L

    2016-05-01

    This work describes a new method for the extraction and determination of gold nanoparticles in environmental samples by means of in-situ suspended aggregate microextraction and electrothermal atomic absorption spectrometry. The method relies on the in-situ formation of a supramolecular aggregate phase through ion-association between a cationic surfactant and a benzene sulfonic acid derivative. Gold nanoparticles are physically entrapped into the aggregate phase which is separated from the bulk aqueous solution by vacuum filtration on the surface of a cellulose filter in the form of a thin film. The film is removed from the filter surface and is dissociated into an acidified methanolic solution which is used for analysis. Under the optimized experimental conditions, gold nanoparticles can be efficiently extracted from water samples with recovery rates between 81.0-93.3%, precision 5.4-12.0% and detection limits as low as 75femtomolL(-1) using only 20mL of sample volume. The satisfactory analytical features of the method along with the simplicity indicate the efficiency of this new approach to adequately collect and extract gold nanoparticle species from water samples. PMID:26946014

  14. Tunable emission properties by ferromagnetic coupling Mn(II) aggregates in Mn-doped CdS microbelts/nanowires

    Science.gov (United States)

    Arshad Kamran, Muhammad; Liu, Ruibin; Shi, Li-Jie; Li, Zi-An; Marzi, Thomas; Schöppner, Christian; Farle, Michael; Zou, Bingsuo

    2014-09-01

    Tunable optical emission properties from ferromagnetic semiconductors have not been well identified yet. In this work, high-quality Mn(II)-doped CdS nanowires and micrometer belts were prepared using a controlled chemical vapor deposition technique. The Mn doping could be controlled with time, precursor concentration and temperature. These wires or belts can produce both tunable redshifted emissions and ferromagnetic responses simultaneously upon doping. The strong emission bands at 572, 651, 693, 712, 745, 768, 787 and 803 nm, due to the Mn(II) 4T1(4G) → 6A1(6s) d-d transition, can be detected and accounted for by the aggregation of Mn ions at Cd sites in the CdS lattice at high temperature. These aggregates with ferromagnetism and shifted luminescence are related to the excitonic magnetic polaron (EMP) and localized EMP formations; this is verified by ab initio calculations. The correlation between aggregation-dependent optical emissions and ferromagnetic responses not only presents a new size effect for diluted magnetic semiconductors (DMSs), but also supplies a possible way to study or modulate the ferromagnetic properties of a DMS and to fabricate spin-related photonic devices in the future.

  15. Waste water treatment by flotation

    OpenAIRE

    Camelia Badulescu; Lorand Toth; Romulus Sarbu

    2005-01-01

    The flotation is succesfully applied as a cleaning method of waste water refineries, textile fabrics (tissues), food industry, paper plants, oils plants, etc. In the flotation process with the released air, first of all, the water is saturated with air compressed at pressures between 0,3 – 3 bar, followed by the relaxed phenomenon of the air-water solution in a flotation cell with slowly flowing. The supersaturation could be applied in the waste water treatment. In this case the waste water, ...

  16. Gemstone enhancement by radiation treatment

    International Nuclear Information System (INIS)

    Since the discovery of radioactivity, investigations on the effects of atomic rays on precious stones began and Crookes established that alpha rays from radium produced green colour in diamonds. Gamma rays, x-rays, electrons, neutrons, protons etc. are effective in producing colour in precious stone like topaz and corundum. Some of these also produce considerable amount of radioactivity which is not acceptable if the radioactivity exceeds permissible limits. Colour enhancement by radiation treatment, different radiations, safety of irradiated gem stones and market related aspects are discussed. (author)

  17. Determination of thermodynamic potentials and the aggregation number for micelles with the mass-action model by isothermal titration calorimetry: A case study on bile salts.

    Science.gov (United States)

    Olesen, Niels Erik; Westh, Peter; Holm, René

    2015-09-01

    The aggregation number (n), thermodynamic potentials (ΔG, ΔH, ΔS) and critical micelle concentration (CMC) for 6 natural bile salts were determined on the basis of both original and previously published isothermal titration calorimetry (ITC) data. Different procedures to estimate parameters of micelles with ITC were compared to a mass-action model (MAM) of reaction type: n⋅S⇌Mn. This analysis can provide guidelines for future ITC studies of systems behaving in accordance with this model such as micelles and proteins that undergo self-association to oligomers. Micelles with small aggregation numbers, as those of bile salts, are interesting because such small aggregates cannot be characterized as a separate macroscopic phase and the widely applied pseudo-phase model (PPM) is inaccurate. In the present work it was demonstrated that the aggregation number of micelles was constant at low concentrations enabling determination of the thermodynamic potentials by the MAM. A correlation between the aggregation number and the heat capacity was found, which implies that the dehydrated surface area of bile salts increases with the aggregation number. This is in accordance with Tanford's principles of opposing forces where neighbouring molecules in the aggregate are better able to shield from the surrounding hydrophilic environment when the aggregation number increases. PMID:25978555

  18. Investigation of cyclooxygenase and signaling pathways involved in human platelet aggregation mediated by synergistic interaction of various agonists.

    Science.gov (United States)

    Khan, Nadia; Farooq, Ahsana Dar; Sadek, Bassem

    2015-01-01

    In the present study, the mechanism(s) of synergistic interaction of various platelet mediators such as arachidonic acid (AA) when combined with 5-hydroxytryptamine (5-HT) or adenosine diphosphate (ADP) on human platelet aggregation were examined. The results demonstrated that 5-HT had no or negligible effect on aggregation but it did potentiate the aggregation response of AA. Similarly, the combination of subeffective concentrations of ADP and AA exhibited noticeable rise in platelet aggregation. Moreover, the observed synergistic effect of AA with 5-HT on platelets was inhibited by different cyclooxygenase (COX) inhibitors, namely ibuprofen and celecoxib, with half maximal inhibitory effect (IC50) values of 18.0 ± 1.8 and 15.6 ± 3.4 μmol/L, respectively. Interestingly, the synergistic effect observed for AA with 5-HT was, also, blocked by the 5-HT receptor blockers cyproheptadine (IC50=22.0 ± 7 μmol/L), ketanserin (IC50=152 ± 23 μmol/L), phospholipase C (PLC) inhibitor (U73122; IC50=6.1 ± 0.8 μmol/L), and mitogen activated protein kinase (MAPK) inhibitor (PD98059; IC50=3.8 ± 0.5 μmol/L). Likewise, the synergism of AA and ADP was, also, attenuated by COX inhibitors (ibuprofen; IC50=20 ± 4 μmol/L and celecoxib; IC50=24 ± 7 μmol/L), PLC inhibitor (U73122; IC50=3.7 ± 0.3 μmol/L), and MAPK inhibitor (PD98059; IC50=2.8 ± 1.1 μmol/L). Our observed data demonstrate that the combination of subthreshold concentrations of agonists amplifies platelet aggregation and that these synergistic effects largely depend on activation of COX/thromboxane A2, receptor-operated Ca(2+) channels, Gq/PLC, and MAPK signaling pathways. Moreover, our data revealed that inhibition of COX pathways by using both selective and/or non-selective COX inhibitors blocks not only AA metabolism and thromboxane A2 formation, but also its binding to Gq receptors and activation of receptor-operated Ca(2+) channels in platelets. Overall, our results show that PLC and MAPK inhibitors proved

  19. SILICON REFINING BY VACUUM TREATMENT

    Directory of Open Access Journals (Sweden)

    André Alexandrino Lotto

    2014-12-01

    Full Text Available This work aims to investigate the phosphorus removal by vacuum from metallurgical grade silicon (MGSi (98.5% to 99% Si. Melting experiments were carried out in a vacuum induction furnace, varying parameters such as temperature, time and relation area exposed to the vacuum / volume of molten silicon. The results of chemical analysis were obtained by inductively coupled plasma (ICP, and evaluated based on thermodynamic and kinetic aspects of the reaction of vaporization of the phosphorus in the silicon. The phosphorus was decreased from 33 to approximately 1.5 ppm after three hours of vacuum treatment, concluding that the evaporation step is the controlling step of the process for parameters of temperature, pressure and agitation used and refining by this process is technically feasible.

  20. Formation of rod-like nanostructure by aggregation of TiO2 nanoparticles with improved performances

    Indian Academy of Sciences (India)

    Weijuan Zhang; Wenkai Chang; Baozhen Cheng; Zenghe Li; Junhui Ji; Yang Zhao; Jun Nie

    2015-10-01

    To improve the performance of titanium dioxide (TiO2)-based devices, many efforts have been made to prepare nanostructures with composite of TiO2 nanoparticles and nanorods. In this work, a novel rod-like TiO2 nanostructure was obtained via a controllable hydrolysis process. Morphology and structure analysis showed that the rod-like nanostructure was a well-aligned aggregate of nearly spherical TiO2 nanoparticles. Rod-like TiO2 nanoparticle aggregates were fabricated on a primary TiO2 nanoparticle-based layer without the use of template, and formed a hierarchical TiO2 composite film together. The photocatalytic activity of the TiO2 film with rod-like nanoparticle aggregates was evaluated by the degradation of methylene blue. The antibacterial activity of fabricated hierarchical TiO2 film was assessed against Staphylococcus aureus. The photoelectrochemical property of this film as the photoanode in assemble dye-sensitized solar cell was also tested. Compared with randomly distributed nanoparticle-based TiO2 film, the hierarchical TiO2 film exhibited improved performance of photocatalysis, antibacterial activity and photoelectric conversion.

  1. Identification of intrinsic defects in SiC: Towards an understanding of defect aggregates by combining theoretical and experimental approaches

    Energy Technology Data Exchange (ETDEWEB)

    Bockstedte, Michel; Mattausch, Alexander; Pankratov, Oleg [Lehrstuhl fuer Theoretische Festkoerperphysik, Universitaet Erlangen-Nuernberg, Erlangen (Germany); Gali, Adam [Department of Atomic Physics, Budapest University of Technology and Economics, Budapest (Hungary); Steeds, John W. [Department of Physics, University of Bristol (United Kingdom)

    2008-07-15

    In SiC, mobile point defects may form thermally stable clusters and aggregates, such as di-vacancies or carbon interstitial complexes. Although predicted by theory, experimental evidence of such clusters became available only recently. Combining theoretical and experimental approaches, the unique identification of the di-vacancy, the carbon vacancy-antisite complex with the spin resonance centers P6/P7 and SI5 was recently achieved. In this way also the di-carbon and tri-carbon antisites with the photoluminiscence centers P-T and U, HT3 and HT4, respectively were identified. The two identified vacancy complexes show distinct properties: while the di-vacancy, like the silicon vacancy possesses a high-spin ground state, the carbon vacancy-antisite complex, like the carbon vacancy, is a Jahn-Teller center. These effects consistently explain the complex properties of the spin resonance spectra and are discussed in detail for the isolated vacancies. The aggregation of vacancies proved to be relevant in the explantation of the kinetic deactivation of nitrogen in co-implanted SiC. This and further evidence for defect aggregates underline the relevance of this notion. (copyright 2008 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Recycling of MSWI fly ash by means of cementitious double step cold bonding pelletization: Technological assessment for the production of lightweight artificial aggregates.

    Science.gov (United States)

    Colangelo, Francesco; Messina, Francesco; Cioffi, Raffaele

    2015-12-15

    In this work, an extensive study on the recycling of municipal solid waste incinerator fly ash by means of cold bonding pelletization is presented. The ash comes from an incineration plant equipped with rotary and stoker furnaces, in which municipal, hospital and industrial wastes are treated. Fly ash from waste incineration is classified as hazardous and cannot be utilized or even landfilled without prior treatment. The pelletization process uses cement, lime and coal fly ash as components of the binding systems. This process has been applied to several mixes in which the ash content has been varied from 50% (wt.%) up to a maximum of 70%. An innovative additional pelletization step with only cementitious binder has been performed in order to achieve satisfactory immobilization levels. The obtained lightweight porous aggregates are mostly suitable for recovery in the field of building materials with enhanced sustainability properties. Density, water absorption and crushing strength ranged from 1000 to 1600 kg/m(3), 7 to 16% and 1.3 to 6.2 MPa, respectively, and the second pelletization step increased stabilization efficiency. The feasibility of the process has been analyzed by testing also concrete specimens containing the artificial aggregates, resulting in lightweight concrete of average performance. PMID:26124064

  3. Organ Visualization by Photoscanning Using Micro- and Macro-Aggregates of Radioalbumin

    International Nuclear Information System (INIS)

    Micro aggregates (10 - 20 nm) of human serum albumin I131 are shown to be superior to other agents for liver-spleen photoscanning. Radiation exposure to these organs is minimized and the test agent can be prepared with relative ease and simplicity. Also, the heart, stomach and salivary glands may be clearly visualized with the same material. The techniques and physiological basis for performing and interpreting scans of these organs are described. Their diagnostic value is illustrated. The physiological basis for using macro albumin aggregates (1 - 10 μm) for visualization of the lungs is presented, along with typical scans in dogs. Toxicity studies and related pathophysiological investigations in animals demonstrate a wide margin of safety for using the large-particle test agents in man. Preliminary experiments in dogs indicate the feasibility of performing lung scans following the inhalation of an aerosol of the same material. This technique is simple, painless and entirely safe. Photoscans are presented from patients with a wide variety of pulmonary disorders. (author)

  4. Nitrosative stress mediated misfolded protein aggregation mitigated by Na-D-{beta}-hydroxybutyrate intervention

    Energy Technology Data Exchange (ETDEWEB)

    Kabiraj, Parijat; Pal, Rituraj [Department of Chemistry, University of Texas at El Paso, El Paso, TX (United States); Varela-Ramirez, Armando [Department of Biological Sciences, Border Biomedical Research Center, University of Texas at El Paso, El Paso, TX (United States); Miranda, Manuel [Department of Biological Sciences, University of Texas at El Paso, El Paso, TX (United States); Narayan, Mahesh, E-mail: mnarayan@utep.edu [Department of Chemistry, University of Texas at El Paso, El Paso, TX (United States)

    2012-09-28

    Highlights: Black-Right-Pointing-Pointer Rotenone is a model for inducing apoptosis and synphilin-1 accumulation in Parkinson Prime s studies. Black-Right-Pointing-Pointer The metabolite sodium betahydroxybutryate mitigates these effects in SHSY5Y cell lines. Black-Right-Pointing-Pointer Results reveal a novel and innate mechanism to prevent neurodegeneration/cell death. -- Abstract: Mitochondrial dysfunction, leading to elevated levels of reactive oxygen species, is associated with the pathogenesis of neurodegenerative disorders. Rotenone, a mitochondrial stressor induces caspase-9 and caspase-3 activation leading proteolytic cleavage of substrate nuclear poly(ADP-ribose) polymerase (PARP). PARP cleavage is directly related to apoptotic cell death. In this study, we have monitored the aggregation of green-fluorescent protein (GFP)-tagged synphilin-1, as a rotenone-induced Parkinsonia-onset biomarker. We report that the innate ketone body, Na-D-{beta}-hydroxybutyrate (Na{beta}HB) reduces markedly the incidence of synphilin-1 aggregation. Furthermore, our data reveal that the metabolic byproduct also prevents rotenone-induced caspase-activated apoptotic cell death in dopaminergic SH-SY5Y cells. Together, these results suggest that Na{beta}HB is neuroprotective; it attenuates effects originating from mitochondrial insult and can serve as a scaffold for the design and development of sporadic neuropathies.

  5. Enhancement of Chemotactic Cell Aggregation by Haptotactic Cell-To-Cell Interaction.

    Directory of Open Access Journals (Sweden)

    Tae-Goo Kwon

    Full Text Available The crawling of biological cell is a complex phenomenon involving various biochemical and mechanical processes. Some of these processes are intrinsic to individual cells, while others pertain to cell-to-cell interactions and to their responses to extrinsically imposed cues. Here, we report an interesting aggregation dynamics of mathematical model cells, when they perform chemotaxis in response to an externally imposed global chemical gradient while they influence each other through a haptotaxis-mediated social interaction, which confers intriguing trail patterns. In the absence of the cell-to-cell interaction, the equilibrium population density profile fits well to that of a simple Keller-Segal population dynamic model, in which a chemotactic current density [Formula: see text] competes with a normal diffusive current density [Formula: see text], where p and ρ refer to the concentration of chemoattractant and population density, respectively. We find that the cell-to-cell interaction confers a far more compact aggregation resulting in a much higher peak equilibrium cell density. The mathematical model system is applicable to many biological systems such as swarming microglia and neutrophils or accumulating ants towards a localized food source.

  6. High density flux of Co nanoparticles produced by a simple gas aggregation apparatus

    International Nuclear Information System (INIS)

    Gas aggregation is a well known method used to produce clusters of different materials with good size control, reduced dispersion, and precise stoichiometry. The cost of these systems is relatively high and they are generally dedicated apparatuses. Furthermore, the usual sample production speed of these systems is not as fast as physical vapor deposition devices posing a problem when thick samples are needed. In this paper we describe the development of a multipurpose gas aggregation system constructed as an adaptation to a magnetron sputtering system. The cost of this adaptation is negligible and its installation and operation are both remarkably simple. The gas flow for flux in the range of 60-130 SCCM (SCCM denotes cubic centimeter per minute at STP) is able to completely collimate all the sputtered material, producing spherical nanoparticles. Co nanoparticles were produced and characterized using electron microscopy techniques and Rutherford back-scattering analysis. The size of the particles is around 10 nm with around 75 nm/min of deposition rate at the center of a Gaussian profile nanoparticle beam.

  7. Stabilization/solidification of incinerator fly ash for the manufacture of artificial aggregate by cementitious granulation

    Energy Technology Data Exchange (ETDEWEB)

    Colangelo, F.; Cioffi, R. [Univ. Pathenope of Naples (Italy). Dept. of Technology; Montagnaro, F.; Santoro, L. [Univ. Federico 2 of Naples (Italy). Dept. of Chemistry; Di Giacomo, C.; Roncone, A. [Extra Group Co., Citta Sant' Angelo (Italy)

    2010-07-01

    This paper presented the results of a study in which municipal, hospital, and industrial waste ash from an incineration plant equipped with rotary and stoker furnaces was used in a stabilization/solidification granulation process with cement, lime, and coal fly ash as binder components. The ash from the incineration plant was classified as hazardous. The granulation process was conducted with a range of waste ash mixtures in order to determine the appropriate waste ash percentage for the safe manufacture of artificial aggregates. Waste ash content ranging from 50 to 70 per cent was incorporated within the binding matrix. A 2-step granulation process was then conducted with a pure binder in order to encapsulate the granules from the initial process within an outer shell. The granules obtained from the processes were tested to assess their physico-mechanical and leaching properties. Concrete mixtures were then prepared with some of the artificial aggregates made using the granulation process. Results of the study demonstrated that the granules were suitable for the manufacture of concrete blocks. 19 refs., 8 tabs., 1 fig.

  8. Credit, Money, and Aggregate Demand

    OpenAIRE

    Bernanke, Ben S.; Alan S. Blinder

    1988-01-01

    Standard models of aggregate demand treat money and credit asymmetrically; money is given a special status, while loans, bonds, and other debt instruments are lumped together in a "bond market" and suppressed by Walras' Law. This makes bank liabilities central to the monetary transmission mechanism, while giving no role to bank assets. We show how to modify a textbook IS-UI model so as to permit a more balanced treatment. As in Tobin (1969) and Brunner-Meltzer (1972), the key assumption is th...

  9. Thermal protein denaturation and protein aggregation in cells made thermotolerant by various chemicals: role of heat shock proteins.

    Science.gov (United States)

    Kampinga, H H; Brunsting, J F; Stege, G J; Burgman, P W; Konings, A W

    1995-08-01

    Thermotolerance (TT) induced by sodium arsenite (A-TT: 100 microM, 1 h, 37 degrees C) was compared to heat-induced thermotolerance (H-TT: 15 min, 44 degrees C) using HeLa S3 cells. All four pretreatments led to comparable levels of thermotolerance and also induced resistance to arsenite-, ethanol-, and diamide-induced toxicity (clonogenic ability). Stress-induced expression of the major heat shock proteins (hsp27, hsc70(p73), hsp70(p72), and hsp90) was generally highest in H-TT cells and lowest in A-TT cells. Interestingly, the four types of TT cells showed distinct differences in certain aspects of resistance against thermal protein damage. Thermal protein denaturation and aggregation determined in isolated cellular membrane fractions was found to be attenuated when they were isolated from H-TT and A-TT cells but not when isolated from E-TT and D-TT cells. The heat resistance in the proteins of the membrane fraction corresponded with elevated levels of hsp70(p72) associated with the isolated membrane fractions. In the nuclear fraction, only marginal (not significant) attenuation of the formation of protein aggregates (as determined by TX-100 (in)solubility) was observed. However, the postheat recovery from heat-induced protein aggregation in the nucleus was faster in H-TT, E-TT, and D-TT cells, but not in A-TT cells. Despite the fact that elevated levels of hsp27, hsp70(p73), and hsp70(p72) were found in the TX-100 insoluble nuclear fraction derived from all TT cells, no correlation was found with the degree of resistance in terms of the accelerated recovery from nuclear protein aggregation. The only correlation between accelerated recovery from nuclear protein aggregates was that with total cellular levels of hsp27. The data indicate that heat-induced loss of clonogenic ability may be a multitarget rather than a single target event. A threshold of damage may exist in cells after exposure to heat; multiple sets of proteins in (different compartments of) the cell

  10. Involvement of Nitric Oxide on Calcium Mobilization and Arachidonic Acid Pathway Activation during Platelet Aggregation with different aggregating agonists.

    Science.gov (United States)

    Banerjee, Debipriya; Mazumder, Sahana; Kumar Sinha, Asru

    2016-03-01

    Platelet aggregation by different aggregating agonists is essential in the normal blood coagulation process, the excess of which caused acute coronary syndrome (ACS). In all cases, the activation of arachidonic acid by cycloxygenase was needed for the synthesis of thromboxane A2 (TXA2) but the mechanism of arachidonic acid release in platelets remains obscure. Studies were conducted to determine the role of nitric oxide (NO), if any, on the release of arachidonic acid in platelets. The cytosolic Ca(2+) was visualized and quantitated by fluorescent spectroscopy by using QUIN-2. NO was measured by methemoglobin method. Arachidonic acid was determined by HPLC. TXA2 was measured as ThromboxaneB2 (TXB2) by ELISA. Treatment of platelets in platelet-rich plasma (PRP) with different aggregating agents resulted in the inhibition of nitric oxide synthase (NOS) which inhibited the production of NO synthesis and increased TXA2 synthesis. Furthermore, the treatment of washed PRP with different platelet aggregating agents resulted in the increase of [Ca(2+)] in nM ranges. In contrast, the pre-treatment of washed PRP with aspirin increased platelet NO level and inhibited the Ca(2+) mobilization and TXA2 synthesis. These results indicated that the aggregation of platelets by different aggregating agonists was caused by the cytosolic Ca(2+) mobilization due to the inhibition of NOS. PMID:27127451

  11. Human SOD2 modification by dopamine quinones affects enzymatic activity by promoting its aggregation: possible implications for Parkinson's disease.

    Directory of Open Access Journals (Sweden)

    Elisa Belluzzi

    Full Text Available Mitochondrial dysfunction and oxidative stress are considered central in dopaminergic neurodegeneration in Parkinson's disease (PD. Oxidative stress occurs when the endogenous antioxidant systems are overcome by the generation of reactive oxygen species (ROS. A plausible source of oxidative stress, which could account for the selective degeneration of dopaminergic neurons, is the redox chemistry of dopamine (DA and leads to the formation of ROS and reactive dopamine-quinones (DAQs. Superoxide dismutase 2 (SOD2 is a mitochondrial enzyme that converts superoxide radicals to molecular oxygen and hydrogen peroxide, providing a first line of defense against ROS. We investigated the possible interplay between DA and SOD2 in the pathogenesis of PD using enzymatic essays, site-specific mutagenesis, and optical and high-field-cw-EPR spectroscopies. Using radioactive DA, we demonstrated that SOD2 is a target of DAQs. Exposure to micromolar DAQ concentrations induces a loss of up to 50% of SOD2 enzymatic activity in a dose-dependent manner, which is correlated to the concomitant formation of protein aggregates, while the coordination geometry of the active site appears unaffected by DAQ modifications. Our findings support a model in which DAQ-mediated SOD2 inactivation increases mitochondrial ROS production, suggesting a link between oxidative stress and mitochondrial dysfunction.

  12. The Testing Strength Curves of Lightweight Aggregate Concrete by Rebound Method and Ultrasonic-rebound Combined Method

    Institute of Scientific and Technical Information of China (English)

    RONG Hui; QIAN Chunxiang; GAO Lixiong; HAN Jiande; WANG Caihui

    2011-01-01

    The strength curves of lightweight aggregate concrete (LWAC) were tested based on detecting LWAC with density of 1 400-1 900 kg/m3 and LWAC with strength grade of LCI5-LC50 by rebound method and ultrasonic-rebound combined method.The results show that the common measured strength curves tested by above two methods can not satisfy the required accuracy of LWAC strength test.In addition,specified compressive strength curves of testing LWAC by rebound method and ultrasonic-rebound combined method are obtained,respectively.

  13. An exact approach for aggregated formulations

    DEFF Research Database (Denmark)

    Gamst, Mette; Spoorendonk, Simon; Røpke, Stefan

    Aggregating formulations is a powerful approach for problems to take on tractable forms. Aggregation may lead to loss of information, i.e. the aggregated formulation may be an approximation of the original problem. In branch-and-bound context, aggregation can also complicate branching, e.g. when...... optimality cannot be guaranteed by branching on aggregated variables. We present a generic exact solution method to remedy the drawbacks of aggregation. It combines the original and aggregated formulations and applies Benders' decomposition. We apply the method to the Split Delivery Vehicle Routing Problem....

  14. Plastic shrinkage of mortars with shrinkage reducing admixture and lightweight aggregates studied by neutron tomography

    Energy Technology Data Exchange (ETDEWEB)

    Wyrzykowski, Mateusz, E-mail: mateusz.wyrzykowski@empa.ch [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Dübendorf (Switzerland); Lodz University of Technology, Department of Building Physics and Building Materials, Lodz (Poland); Trtik, Pavel [Paul Scherrer Institute, Laboratory for Neutron Scattering and Imaging, Villigen (Switzerland); Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Dübendorf (Switzerland); Münch, Beat [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Dübendorf (Switzerland); Weiss, Jason [Purdue University, School of Civil Engineering, West Lafayette (United States); Vontobel, Peter [Paul Scherrer Institute, Laboratory for Neutron Scattering and Imaging, Villigen (Switzerland); Lura, Pietro [Empa, Swiss Federal Laboratories for Materials Science and Technology, Concrete and Construction Chemistry Laboratory, Dübendorf (Switzerland); ETH Zurich, Institute for Building Materials (IfB), Zurich (Switzerland)

    2015-07-15

    Water transport in fresh, highly permeable concrete and rapid water evaporation from the concrete surface during the first few hours after placement are the key parameters influencing plastic shrinkage cracking. In this work, neutron tomography was used to determine both the water loss from the concrete surface due to evaporation and the redistribution of fluid that occurs in fresh mortars exposed to external drying. In addition to the reference mortar with a water to cement ratio (w/c) of 0.30, a mortar with the addition of pre-wetted lightweight aggregates (LWA) and a mortar with a shrinkage reducing admixture (SRA) were tested. The addition of SRA reduced the evaporation rate from the mortar at the initial stages of drying and reduced the total water loss. The pre-wetted LWA released a large part of the absorbed water as a consequence of capillary pressure developing in the fresh mortar due to evaporation.

  15. Plastic shrinkage of mortars with shrinkage reducing admixture and lightweight aggregates studied by neutron tomography

    International Nuclear Information System (INIS)

    Water transport in fresh, highly permeable concrete and rapid water evaporation from the concrete surface during the first few hours after placement are the key parameters influencing plastic shrinkage cracking. In this work, neutron tomography was used to determine both the water loss from the concrete surface due to evaporation and the redistribution of fluid that occurs in fresh mortars exposed to external drying. In addition to the reference mortar with a water to cement ratio (w/c) of 0.30, a mortar with the addition of pre-wetted lightweight aggregates (LWA) and a mortar with a shrinkage reducing admixture (SRA) were tested. The addition of SRA reduced the evaporation rate from the mortar at the initial stages of drying and reduced the total water loss. The pre-wetted LWA released a large part of the absorbed water as a consequence of capillary pressure developing in the fresh mortar due to evaporation

  16. The secondary and aggregation structural changes of BSA induced by trivalent chromium: A biophysical study

    International Nuclear Information System (INIS)

    Trivalent chromium Cr(III), which was originally considered to be innocuous as a nutriment, has been suspected to induce some abnormalities in human body recently. In the present work, the effects of Cr(III) on the structural state of BSA were comprehensively investigated through a series of appropriate methods in combination, including X-ray photoelectron spectroscopy (XPS), fourier transform infrared spectroscopy (FTIR), circular dichroism (CD), UV–vis absorption, synchronous fluorescence, fluorescence lifetime analysis, resonance light scattering (RLS), dynamic light scattering (DLS) and excitation–emission matrix spectroscopy (EEMS) methods. XPS accurately described the binding activity of Cr(III) with protein C, N and O atoms. The structural analysis according to FTIR and CD methods showed that the Cr(III) binding altered BSA conformation with a major reduction of α-helix. RLS and DLS analyses demonstrated that the presence of Cr(III) with low concentration could induce the aggregation structural changes of BSA. UV–vis absorption, EEMS and synchronous fluorescence suggested that the interaction between Cr(III) and BSA induced a slight unfolding of the polypeptide backbone and altered the microenvironments of Trp and Tyr residues in BSA. This research is helpful for understanding the structure-function relationship involved in metal ion-protein bioconjugate process. - Highlights: • The effect of Cr(III) on the conformational state of BSA was comprehensively studied. • XPS described the binding activity of Cr(III) with protein C, N and O atoms. • FTIR and CD data revealed secondary structural alteration in BSA. • Cr(III) complexation induced microenvironmental changes of Trp and Tyr. • RLS, DLS and EEMS presented the aggregational states of Cr(III)–BSA complex

  17. Morfologia de agregados do solo avaliada por meio de análise de imagens Morphology of soil aggregates evaluated by images analysis

    Directory of Open Access Journals (Sweden)

    N. Olszevski

    2004-10-01

    deterioration of soil physical properties, mainly due to modifications in the soil structure pattern. Once the structural changes could affect the morphology aggregates in different ways, the search for new methods of studying soil macro-morphological characteristics must be prioritized to allow the observation of modified characteristics in cultivated soils. Therefore, this study was carried out to adapt and test a digital method for a qualitative macro-morphological analysis of soil aggregates of Rodhic Haplustox in samples taken in 1998, aiming to detect morphological modifications caused by human activities. From an original set of eleven, five replicated treatments were selected: no till, cinzel plow, heavy disk harrow, disk plow and chisel plow, carried out annually. The shape of the different soil aggregates was from images obtained using a scanner (HP 6100C with 1200 dpi optical resolution which were then processed by the computer program UTHSCSA Image Tool. This program furnishes values of different aggregate indexes: roundness, compactness and lengthiness. The roundness index depends on the perimeter measurement (external roughness and the compactness and lengthiness indexes depend on the measurement of the length of the longest axle (long edges. Generally, the management systems used during three consecutive years did not modify the aggregate morphology of the clayey Rodhic Haplustox for the analyzed variables. Image analysis sensitively detected alterations in soil aggregate morphology promising considerable usefulness as a novel tool for on soil structure studies.

  18. A housing stock model of non-heating end-use energy in England verified by aggregate energy use data

    International Nuclear Information System (INIS)

    This paper proposes a housing stock model of non-heating end-use energy for England that can be verified using aggregate energy use data available for small areas. These end-uses, commonly referred to as appliances and lighting, are a rapidly increasing part of residential energy demand. This paper proposes a model that can be verified using aggregated data of electricity meters in small areas and census data on housing. Secondly, any differences that open up between major collections of housing could potentially be resolved by using data from frequently updated expenditure surveys. For the year 2008, the model overestimated domestic non-heating energy use at the national scale by 1.5%. This model was then used on the residential sector with various area classifications, which found that rural and suburban areas were generally underestimated by up to 3.3% and urban areas overestimated by up to 5.2% with the notable exception of “professional city life” classifications. The model proposed in this paper has the potential to be a verifiable and adaptable model for non-heating end-use energy in households in England for the future. - Highlights: ► Housing stock energy model was developed for end-uses outside of heating for UK context. ► This entailed changes to the building energy model that serves as the bottom of the stock model. ► The model is adaptable to reflect rapid changes in consumption between major housing surveys. ► Verification was done against aggregated consumption data and for the first time uses a measured size of the housing stock. ► The verification process revealed spatial variations in consumption patterns for future research.

  19. Investigation of cyclooxygenase and signaling pathways involved in human platelet aggregation mediated by synergistic interaction of various agonists

    Directory of Open Access Journals (Sweden)

    Khan N

    2015-07-01

    Full Text Available Nadia Khan,1,2 Ahsana Dar Farooq,1 Bassem Sadek21Dr Panjwani Center for Molecular Medicine and Drug Research, International Center for Chemical and Biological Sciences, University of Karachi, Karachi, Pakistan; 2Department of Pharmacology and Therapeutics, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab EmiratesAbstract: In the present study, the mechanism(s of synergistic interaction of various platelet mediators such as arachidonic acid (AA when combined with 5-hydroxytryptamine (5-HT or adenosine diphosphate (ADP on human platelet aggregation were examined. The results demonstrated that 5-HT had no or negligible effect on aggregation but it did potentiate the aggregation response of AA. Similarly, the combination of subeffective concentrations of ADP and AA exhibited noticeable rise in platelet aggregation. Moreover, the observed synergistic effect of AA with 5-HT on platelets was inhibited by different cyclooxygenase (COX inhibitors, namely ibuprofen and celecoxib, with half maximal inhibitory effect (IC50 values of 18.0±1.8 and 15.6±3.4 µmol/L, respectively. Interestingly, the synergistic effect observed for AA with 5-HT was, also, blocked by the 5-HT receptor blockers cyproheptadine (IC50=22.0±7 µmol/L, ketanserin (IC50=152±23 µmol/L, phospholipase C (PLC inhibitor (U73122; IC50=6.1±0.8 µmol/L, and mitogen activated protein kinase (MAPK inhibitor (PD98059; IC50=3.8±0.5 µmol/L. Likewise, the synergism of AA and ADP was, also, attenuated by COX inhibitors (ibuprofen; IC50=20±4 µmol/L and celecoxib; IC50=24±7 µmol/L, PLC inhibitor (U73122; IC50=3.7±0.3 µmol/L, and MAPK inhibitor (PD98059; IC50=2.8±1.1 µmol/L. Our observed data demonstrate that the combination of subthreshold concentrations of agonists amplifies platelet aggregation and that these synergistic effects largely depend on activation of COX/thromboxane A2, receptor-operated Ca2+ channels, Gq/PLC, and MAPK signaling

  20. Preventing Vomiting Caused by Cancer Treatment

    Science.gov (United States)

    ... by Cancer Treatment Request Permissions Print to PDF Preventing Vomiting Caused by Cancer Treatment November 2, 2015 ... Torisel) Topotecan (Hycamtin, Brakiva) Trastuzumab (Herceptin) Recommendations for preventing vomiting caused by chemotherapy and targeted therapy The ...

  1. Total organic carbon in aggregates as a soil recovery indicator

    Science.gov (United States)

    Luciene Maltoni, Katia; Rodrigues Cassiolato, Ana Maria; Amorim Faria, Glaucia; Dubbin, William

    2015-04-01

    The soil aggregation promotes physical protection of organic matter, preservation of which is crucial to improve soil structure, fertility and ensure the agro-ecosystems sustainability. The no-tillage cultivation system has been considered as one of the strategies to increase total soil organic carbono (TOC) contents and soil aggregation, both are closely related and influenced by soil management systems. The aim of this study was to evaluate the distribution of soil aggregates and the total organic carbon inside aggregates, with regard to soil recovery, under 3 different soil management systems, i.e. 10 and 20 years of no-tillage cultivation as compared with soil under natural vegetation (Cerrado). Undisturbed soils (0-5; 5-10; and 10-20 cm depth) were collected from Brazil, Central Region. The soils, Oxisols from Cerrado, were collected from a field under Natural Vegetation-Cerrado (NV), and from fields that were under conventional tillage since 1970s, and 10 and 20 years ago were changed to no-tillage cultivation system (NT-10; NT-20 respectively). The undisturbed samples were sieved (4mm) and the aggregates retained were further fractionated by wet sieving through five sieves (2000, 1000, 500, 250, and 50 μm) with the aggregates distribution expressed as percentage retained by each sieve. The TOC was determined, for each aggregate size, by combustion (Thermo-Finnigan). A predominance of aggregates >2000 μm was observed under NV treatment (92, 91, 82 %), NT-10 (64, 73, 61 %), and NT-20 (71, 79, 63 %) for all three depths (0-5; 5-10; 10-20 cm). In addition greater quantities of aggregates in sizes 1000, 500, 250 and 50 μm under NT-10 and NT-20 treatments, explain the lower aggregate stability under these treatments compared to the soil under NV. The organic C concentration for NV in aggregates >2000 μm was 24,4; 14,2; 8,7 mg/g for each depth (0-5; 5-10; 10-20 cm, respectively), higher than in aggregates sized 250-50 μm (7,2; 5,5; 4,4 mg/g) for all depths

  2. The effect of sterols on amphotericin b self-aggregation in a lipid bilayer as revealed by free energy simulations

    OpenAIRE

    Neumann A.; Baginski M.; Winczewski S.; Czub J.

    2013-01-01

    Amphotericin B (AmB) is an effective but toxic antifungal drug, known to increase the permeability of the cell membrane, presumably by assembling into transmembrane pores in a sterol-dependent manner. The aggregation of AmB molecules in a phospholipid bilayer is, thus, crucial for the drug’s activity. To provide an insight into the molecular nature of this process, here, we report an atomistic molecular dynamics simulation study of AmB head-to-head dimerization in a phospholipid bilayer, a po...

  3. Casein Aggregates Built Step-by-Step on Charged Polyelectrolyte Film Surfaces Are Calcium Phosphate-cemented*

    OpenAIRE

    Nagy, Krisztina; Pilbat, Ana-Maria; Groma, Géza; Szalontai, Balázs; Cuisinier, Frédéric J.G.

    2010-01-01

    The possible mechanism of casein aggregation and micelle buildup was studied in a new approach by letting α-casein adsorb from low concentration (0.1 mg·ml−1) solutions onto the charged surfaces of polyelectrolyte films. It was found that α-casein could adsorb onto both positively and negatively charged surfaces. However, only when its negative phosphoseryl clusters remained free, i.e. when it adsorbed onto a negative surface, could calcium phosphate (CaP) nanoclusters bind to the casein mole...

  4. Highly stable SERS pH nanoprobes produced by co-solvent controlled AuNP aggregation.

    Science.gov (United States)

    Wei, Haoran; Willner, Marjorie R; Marr, Linsey C; Vikesland, Peter J

    2016-08-15

    Production of gold nanoparticle (AuNP) surface-enhanced Raman spectroscopy (SERS) nanoprobes requires replicable aggregation to produce multimers with high signal intensity. Herein, we illustrate a novel, yet simple, approach to produce SERS nanoprobes through control of co-solvent composition. AuNP multimers were produced by mixing AuNP monomers in water : ethanol co-solvent for variable periods of time. By varying the water : ethanol ratio and the amount of 4-mercaptobenzoic acid (4-MBA) present, the aggregation rate can be systematically controlled. Thiolated poly(ethylene glycol) was then added to halt the aggregation process and provide steric stability. This approach was used to produce pH nanoprobes with excellent colloidal stability in high ionic strength environments and in complex samples. The pH probe exhibits broad pH sensitivity over the range 6-11 and we calculate that a single AuNP dimer in a 35 fL volume is sufficient to generate a detectable SERS signal. As a proof-of-concept, the probes were used to detect the intracellular pH of human prostate cancer cells (PC-3). The internalized probes exhibit a strong 4-MBA signal without any interfering bands from either the cells or the culture media and produce exceptionally detailed pH maps. pH maps obtained from 19 xy surface scans and 14 yz depth scans exhibit highly consistent intracellular pH in the range of 5 to 7, thus indicating the greater reliability and reproducibility of our pH probes compared with other probes previously reported in the literature. Our water : ethanol co-solvent production process is fast, simple, and efficient. Adjustment of solvent composition may become a powerful way to produce SERS tags or nanoprobes in the future. PMID:27143623

  5. Interannual Changes in Biomass Affect the Spatial Aggregations of Anchovy and Sardine as Evidenced by Geostatistical and Spatial Indicators.

    Directory of Open Access Journals (Sweden)

    Marco Barra

    Full Text Available Geostatistical techniques were applied and a series of spatial indicators were calculated (occupation, aggregation, location, dispersion, spatial autocorrelation and overlap to characterize the spatial distributions of European anchovy and sardine during summer. Two ecosystems were compared for this purpose, both located in the Mediterranean Sea: the Strait of Sicily (upwelling area and the North Aegean Sea (continental shelf area, influenced by freshwater. Although the biomass of anchovy and sardine presented high interannual variability in both areas, the location of the centres of gravity and the main spatial patches of their populations were very similar between years. The size of the patches representing the dominant part of the abundance (80% was mostly ecosystem- and species-specific. Occupation (area of presence appears to be shaped by the extent of suitable habitats in each ecosystem whereas aggregation patterns (how the populations are distributed within the area of presence were species-specific and related to levels of population biomass. In the upwelling area, both species showed consistently higher occupation values compared to the continental shelf area. Certain characteristics of the spatial distribution of sardine (e.g. spreading area, overlapping with anchovy differed substantially between the two ecosystems. Principal component analysis of geostatistical and spatial indicators revealed that biomass was significantly related to a suite of, rather than single, spatial indicators. At the spatial scale of our study, strong correlations emerged between biomass and the first principal component axis with highly positive loadings for occupation, aggregation and patchiness, independently of species and ecosystem. Overlapping between anchovy and sardine increased with the increase of sardine biomass but decreased with the increase of anchovy. This contrasting pattern was attributed to the location of the respective major patches

  6. The thiG Gene Is Required for Full Virulence of Xanthomonas oryzae pv. oryzae by Preventing Cell Aggregation.

    Directory of Open Access Journals (Sweden)

    Xiaoyue Yu

    Full Text Available Bacterial blight of rice is an important serious bacterial diseases of rice in many rice-growing regions, caused by Xanthomonas oryzae pv. oryzae (Xoo. The thiG gene from Xoo strain ZJ173, which is involved with thiazole moiety production in the thiamine biosynthesis pathway, is highly conserved among the members of Xanthomonas. The thiG deletion mutant displayed impaired virulence and growth in thiamine-free medium but maintained its normal growth rate in the rice tissues, indicating that the thiG gene is involved in Xoo virulence. Compared to the wild type strain, the formation of cell-cell aggregates was affected in thiG deletion mutants. Although biofilm formation was promoted, motility and migration in rice leaves were repressed in the thiG mutants, and therefore limited the expansion of pathogen infection in rice. Quorum sensing and extracellular substance are two key factors that contribute to the formation of cell-cell aggregates. Our study found that in the thiG mutant the expression of two genes, rpfC and rpfG, which form a two-component regulatory signal system involved in the regulation of biofilm formation by a second messenger cyclic di-GMP is down-regulated. In addition, our study showed that xanthan production was not affected but the expression of some genes associated with xanthan biosynthesis, like gumD, gumE, gumH and gumM, were up-regulated in thiG mutants. Taken together, these findings are the first to demonstrate the role of the thiazole biosynthsis gene, thiG, in virulence and the formation of aggregates in Xanthomonas oryzae pv. oryzae.

  7. Reduction of radiostrontium mobility in acid soils by carbonate treatment

    International Nuclear Information System (INIS)

    Development of chemical treatments to immobilize 90Sr in soil to prevent its leaching from radioactive waste disposed in shallow land burial sites is highly desirable. Six in situ carbonate-precipitating treatments, varying the amounts of carbonate, alkaline earth cation (Ca or Ba as chlorides), and order of addition were examined for their ability to immobilize radiostrontium in laboratory soil columns. The Na2CO3-followed by CaCl2-treatment was most consistently successful at reducing the leachability of radiostrontium by 0.05M CaCl2 from three low organic matter-acid soils, immobilizing as much as 53% of added radiostrontium. For the high organic matter-slightly acid soil, Na2CO3 alone, without supplemental Ca or Ba, resulted in the best immobilization (39%); dissolution of soil organic matter and the alkalinity-induced aggregate dispersion probably interfered with CaCO3 and/or BaCO3 precipitation. Success of the treatments is based primarily on their ability to generate, in situ, Ca(Sr,Mg)CO3 or Ba(Ca,Mg,Sr)CO3 precipitates that exchange radiostrontium very slowly with eluting Ca ions. Allied tests with 137Cs, which is commonly codisposed with 90Sr, indicated that the treatments describe did not interfere with the natural tendency of the selected soils to fix 137Cs strongly

  8. Effect of the Surfactant Tween 80 on the Detachment and Dispersal of Salmonella enterica Serovar Thompson Single Cells and Aggregates from Cilantro Leaves as Revealed by Image Analysis

    OpenAIRE

    Maria T Brandl; Huynh, Steven

    2014-01-01

    Salmonella enterica has the ability to form biofilms and large aggregates on produce surfaces, including on cilantro leaves. Aggregates of S. enterica serovar Thompson that remained attached to cilantro leaves after rigorous washing and that were present free or bound to dislodged leaf tissue in the wash suspension were observed by confocal microscopy. Measurement of S. Thompson population sizes in the leaf washes by plate counts failed to show an effect of 0.05% Tween 80 on the removal of th...

  9. Multiple scattering of a zero-order Bessel beam with arbitrary incidence by an aggregate of uniaxial anisotropic spheres

    Science.gov (United States)

    Li, Z. J.; Wu, Z. S.; Qu, T.; Shang, Q. C.; Bai, L.

    2016-01-01

    Based on the generalized multiparticle Mie theory, multiple scattering of an aggregate of uniaxial anisotropic spheres illuminated by a zero-order Bessel beam (ZOBB) with arbitrary propagation direction is investigated. The particle size and configuration are arbitrary. The arbitrary incident Bessel beam is expanded in terms of spherical vector wave functions (SVWFs). Utilizing the vector addition theorem of SVWFs, interactive and total scattering coefficients are derived through the continuous boundary conditions on which the interaction of the particles is considered. The accuracy of the theory and codes are verified by comparing results with those obtained for arbitrary plane wave incidence by CST simulation, and for ZOBB incidence by a numerical method. The effects of angle of incidence, pseudo-polarization angle, half-conical angle, beam center position, and permittivity tensor elements on the radar cross sections (RCSs) of several types of collective uniaxial anisotropic spheres, such as a linear chain, a 4×4×4 cube-shaped array, and other periodical structures consisting of massive spheres, are numerically analyzed. Selected results on the properties of typical particles such as TiO2, SiO2, or other particle lattices are calculated. This investigation could provide an effective test for further research on the scattering characteristics of an aggregate of anisotropic spheres by a high-order Bessel vortex beam. The results have important application in optical tweezers and particle manipulation.

  10. Effects of free iron oxyhydrates and soil organic matter on copper sorption-desorption behavior by size fractions of aggregates from two paddy soils

    Institute of Scientific and Technical Information of China (English)

    WANG Fang; PAN Genxing; LI Lianqing

    2009-01-01

    Effects of free iron oxyhydrates (Fed) and soil organic matter (SOM) on copper (Cu2+) sorption-desorption behavior by size fractions of aggregates from two typical paddy soils (Ferric-Accumulic Stagnic Anthrosol (Soil H) and Gleyic Stagnic Anthrosol (Soil W)) were investigated with and without treatment of dithionite-citrate-bicarbonate and of H2O2. The size fractions of aggregates were obtained from the undisturbed bulk topsoil using a low energy ultrasonic dispersion procedure. Experiments of equilibrium sorption and subsequent desorption were conducted at soil water ratio of 1:20, 25℃. For Soil H, Cu2+ sorption capacity of the DCB-treated size fractions was decreased by 5.9% for fine sand fraction, by 40.4% for coarse sand fraction, in comparison to 2.9% for the bulk sample. However, Cu2+ sorption capacities of the H2O2-treated fractions were decreased by over 80% for the coarse sand fraction and by 15% for the clay-sized fraction in comparison to 88% for bulk soil. For Soil W, Cu2+ sorption capacity of the DCB-treated size fraction was decreased by 30% for the coarse sand fraction and by over 75% for silt sand fraction in comparison to 44.5% for the bulk sample. Cu2+ sorption capacities of the H2O2-treated fractions were decreased by only 2.0% for the coarse sand fraction and by 15% for the fine sand fraction in comparison to by 3.4% for bulk soil. However, Cu2+ desorption rates were increased much in H2O2-treated samples by over 80% except the clay-sized fraction (only 9.5%) for Soil H. While removal of SOM with H2O2 tendend to increase desorption rate, DCB- and H2O2-treatments caused decrease in Cu2+ retention capacity of size fractions. Particularly, there hardly remained Cu2+ retention capacity by size fractions from Soil H after H2O2 treatment except for clay-sized fraction. These findings supported again the dominance of the coarse sand fraction in sorption of metals and the preference of absorbed metals bound to SOM in differently stabilized status

  11. Comparative Use of a Caribbean Mesophotic Coral Ecosystem and Association with Fish Spawning Aggregations by Three Species of Shark

    Science.gov (United States)

    Pickard, Alexandria E.; Vaudo, Jeremy J.; Wetherbee, Bradley M.; Nemeth, Richard S.; Blondeau, Jeremiah B.; Kadison, Elizabeth A.; Shivji, Mahmood S.

    2016-01-01

    Understanding of species interactions within mesophotic coral ecosystems (MCEs; ~ 30–150 m) lags well behind that for shallow coral reefs. MCEs are often sites of fish spawning aggregations (FSAs) for a variety of species, including many groupers. Such reproductive fish aggregations represent temporal concentrations of potential prey that may be drivers of habitat use by predatory species, including sharks. We investigated movements of three species of sharks within a MCE and in relation to FSAs located on the shelf edge south of St. Thomas, United States Virgin Islands. Movements of 17 tiger (Galeocerdo cuvier), seven lemon (Negaprion brevirostris), and six Caribbean reef (Carcharhinus perezi) sharks tagged with acoustic transmitters were monitored within the MCE using an array of acoustic receivers spanning an area of 1,060 km2 over a five year period. Receivers were concentrated around prominent grouper FSAs to monitor movements of sharks in relation to these temporally transient aggregations. Over 130,000 detections of telemetered sharks were recorded, with four sharks tracked in excess of 3 years. All three shark species were present within the MCE over long periods of time and detected frequently at FSAs, but patterns of MCE use and orientation towards FSAs varied both spatially and temporally among species. Lemon sharks moved over a large expanse of the MCE, but concentrated their activities around FSAs during grouper spawning and were present within the MCE significantly more during grouper spawning season. Caribbean reef sharks were present within a restricted portion of the MCE for prolonged periods of time, but were also absent for long periods. Tiger sharks were detected throughout the extent of the acoustic array, with the MCE representing only portion of their habitat use, although a high degree of individual variation was observed. Our findings indicate that although patterns of use varied, all three species of sharks repeatedly utilized the MCE

  12. Comparative Use of a Caribbean Mesophotic Coral Ecosystem and Association with Fish Spawning Aggregations by Three Species of Shark.

    Directory of Open Access Journals (Sweden)

    Alexandria E Pickard

    Full Text Available Understanding of species interactions within mesophotic coral ecosystems (MCEs; ~ 30-150 m lags well behind that for shallow coral reefs. MCEs are often sites of fish spawning aggregations (FSAs for a variety of species, including many groupers. Such reproductive fish aggregations represent temporal concentrations of potential prey that may be drivers of habitat use by predatory species, including sharks. We investigated movements of three species of sharks within a MCE and in relation to FSAs located on the shelf edge south of St. Thomas, United States Virgin Islands. Movements of 17 tiger (Galeocerdo cuvier, seven lemon (Negaprion brevirostris, and six Caribbean reef (Carcharhinus perezi sharks tagged with acoustic transmitters were monitored within the MCE using an array of acoustic receivers spanning an area of 1,060 km2 over a five year period. Receivers were concentrated around prominent grouper FSAs to monitor movements of sharks in relation to these temporally transient aggregations. Over 130,000 detections of telemetered sharks were recorded, with four sharks tracked in excess of 3 years. All three shark species were present within the MCE over long periods of time and detected frequently at FSAs, but patterns of MCE use and orientation towards FSAs varied both spatially and temporally among species. Lemon sharks moved over a large expanse of the MCE, but concentrated their activities around FSAs during grouper spawning and were present within the MCE significantly more during grouper spawning season. Caribbean reef sharks were present within a restricted portion of the MCE for prolonged periods of time, but were also absent for long periods. Tiger sharks were detected throughout the extent of the acoustic array, with the MCE representing only portion of their habitat use, although a high degree of individual variation was observed. Our findings indicate that although patterns of use varied, all three species of sharks repeatedly

  13. Comparative Use of a Caribbean Mesophotic Coral Ecosystem and Association with Fish Spawning Aggregations by Three Species of Shark.

    Science.gov (United States)

    Pickard, Alexandria E; Vaudo, Jeremy J; Wetherbee, Bradley M; Nemeth, Richard S; Blondeau, Jeremiah B; Kadison, Elizabeth A; Shivji, Mahmood S

    2016-01-01

    Understanding of species interactions within mesophotic coral ecosystems (MCEs; ~ 30-150 m) lags well behind that for shallow coral reefs. MCEs are often sites of fish spawning aggregations (FSAs) for a variety of species, including many groupers. Such reproductive fish aggregations represent temporal concentrations of potential prey that may be drivers of habitat use by predatory species, including sharks. We investigated movements of three species of sharks within a MCE and in relation to FSAs located on the shelf edge south of St. Thomas, United States Virgin Islands. Movements of 17 tiger (Galeocerdo cuvier), seven lemon (Negaprion brevirostris), and six Caribbean reef (Carcharhinus perezi) sharks tagged with acoustic transmitters were monitored within the MCE using an array of acoustic receivers spanning an area of 1,060 km2 over a five year period. Receivers were concentrated around prominent grouper FSAs to monitor movements of sharks in relation to these temporally transient aggregations. Over 130,000 detections of telemetered sharks were recorded, with four sharks tracked in excess of 3 years. All three shark species were present within the MCE over long periods of time and detected frequently at FSAs, but patterns of MCE use and orientation towards FSAs varied both spatially and temporally among species. Lemon sharks moved over a large expanse of the MCE, but concentrated their activities around FSAs during grouper spawning and were present within the MCE significantly more during grouper spawning season. Caribbean reef sharks were present within a restricted portion of the MCE for prolonged periods of time, but were also absent for long periods. Tiger sharks were detected throughout the extent of the acoustic array, with the MCE representing only portion of their habitat use, although a high degree of individual variation was observed. Our findings indicate that although patterns of use varied, all three species of sharks repeatedly utilized the MCE and

  14. Aggregation on heterogeneous surface

    Institute of Scientific and Technical Information of China (English)

    Lu Hang-Jun; Wu Feng-Min; Fang Yun-Zhang

    2004-01-01

    Chessboard-like substrates are introduced in this paper, in order to study the diffusion-limited aggregation (DLA)and the motion of poly-atoms on heterogeneous surfaces. The effect of morphology of such substrates upon the cluster aggregation is investigated using the Monte Carlo simulation. It is found that the growth process and the cluster morphology are governed by the energetic topography of the substrates. Our simulation also indicate that the island density and the fractal dimension of the clusters depend strongly on the substrate topography and the activation energy.

  15. Membrane aggregation and perturbation induced by antimicrobial peptide of S-thanatin

    International Nuclear Information System (INIS)

    Thanatin, a 21-residue peptide, is an inducible insect peptide. In our previous study, we have identified a novel thanatin analog of S-thanatin, which exhibited a broad antimicrobial activity against bacteria and fungi with low hemolytic activity. This study was aimed to delineate the antimicrobial mechanism of S-thanatin and identify its interaction with bacterial membranes. In this study, membrane phospholipid was found to be the target for S-thanatin. In the presence of vesicles, S-thanatin interestingly led to the aggregation of anionic vesicles and sonicated bacteria. Adding S-thanatin to Escherichia coli suspension would result in the collapse of membrane and kill bacteria. The sensitivity assay of protoplast elucidated the importance of outer membrane (OM) for S-thanatin's antimicrobial activity. Compared with other antimicrobial peptide, S-thanatin produced chaotic membrane morphology and cell debris in electron microscopic appearance. These results supported our hypothesis that S-thanatin bound to negatively charged LPS and anionic lipid, impeded membrane respiration, exhausted the intracellular potential, and released periplasmic material, which led to cell death.

  16. MLL5 maintains spindle bipolarity by preventing aberrant cytosolic aggregation of PLK1.

    Science.gov (United States)

    Zhao, Wei; Liu, Jie; Zhang, Xiaoming; Deng, Lih-Wen

    2016-03-28

    Faithful chromosome segregation with bipolar spindle formation is critical for the maintenance of genomic stability. Perturbation of this process often leads to severe mitotic failure, contributing to tumorigenesis. MLL5 has been demonstrated to play vital roles in cell cycle progression and the maintenance of genomic stability. Here, we identify a novel interaction between MLL5 and PLK1 in the cytosol that is crucial for sustaining spindle bipolarity during mitosis. Knockdown of MLL5 caused aberrant PLK1 aggregation that led to acentrosomal microtubule-organizing center (aMTOC) formation and subsequent spindle multipolarity. Further molecular studies revealed that the polo-box domain (PBD) of PLK1 interacted with a binding motif on MLL5 (Thr887-Ser888-Thr889), and this interaction was essential for spindle bipolarity. Overexpression of wild-type MLL5 was able to rescue PLK1 mislocalization and aMTOC formation in MLL5-KD cells, whereas MLL5 mutants incapable of interacting with the PBD failed to do so. We thus propose that MLL5 preserves spindle bipolarity through maintaining cytosolic PLK1 in a nonaggregated form. PMID:27002166

  17. Dispersion/Aggregation of polymer grafted nanorods in a polymer matrix studied by Dissipative Particle Dynamics

    Science.gov (United States)

    Maia, Joao; Khani, Shaghayegh

    2015-03-01

    Nanorods are incorporated into polymer matrices for fabricating composite materials with enhanced physical and mechanical properties.The final macroscopic properties of the composites are directly related to the dispersion and organization of the nanoparticles in the matrix. For instance, a significant improvement in the mechanical properties of the nanorod-polymer composites is observed upon formation of a percolating network. One way of controlling the assembly of nanorods in the polymer medium is adjusting the chemical interactions which is done through grafting polymer chains on the surface of the rods. The recent developments in the computational techniques have paved the road for further understanding of the controlled dispersion and aggregation of nanorods in polymer matrices. In this study, Dissipative Particle Dynamics (DPD) is employed in order to investigate the effect of enthalpic and entopic variables on the phase behavior of the abovementioned nanocomposites. In DPD, the interaction parameter between the components of the systems can be mapped onto the Flory-Huggins χ-parameter via well-known Groot-Warren expression. This works studies the effect of the enthalpic and entropic variables on phase transitions. The main goal is to provide a phase diagram than can be used to guide the experiments in designing new materials.

  18. Membrane aggregation and perturbation induced by antimicrobial peptide of S-thanatin

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Guoqiu, E-mail: guoqiuwu@163.com [Center of Clinical Laboratory Medicine of Zhongda Hospital, Southeast University, Nanjing (China); Wu, Hongbin; Li, Linxian; Fan, Xiaobo; Ding, Jiaxuan; Li, Xiaofang; Xi, Tao [Biotechnology Center, Department of Life Science and Biotechnology, China Pharmaceutical University, Nanjing 210009 (China); Shen, Zilong, E-mail: Zilongshen@sina.com [Biotechnology Center, Department of Life Science and Biotechnology, China Pharmaceutical University, Nanjing 210009 (China)

    2010-04-23

    Thanatin, a 21-residue peptide, is an inducible insect peptide. In our previous study, we have identified a novel thanatin analog of S-thanatin, which exhibited a broad antimicrobial activity against bacteria and fungi with low hemolytic activity. This study was aimed to delineate the antimicrobial mechanism of S-thanatin and identify its interaction with bacterial membranes. In this study, membrane phospholipid was found to be the target for S-thanatin. In the presence of vesicles, S-thanatin interestingly led to the aggregation of anionic vesicles and sonicated bacteria. Adding S-thanatin to Escherichia coli suspension would result in the collapse of membrane and kill bacteria. The sensitivity assay of protoplast elucidated the importance of outer membrane (OM) for S-thanatin's antimicrobial activity. Compared with other antimicrobial peptide, S-thanatin produced chaotic membrane morphology and cell debris in electron microscopic appearance. These results supported our hypothesis that S-thanatin bound to negatively charged LPS and anionic lipid, impeded membrane respiration, exhausted the intracellular potential, and released periplasmic material, which led to cell death.

  19. In vitro platelet activation, aggregation and platelet-granulocyte complex formation induced by surface modified single-walled carbon nanotubes.

    Science.gov (United States)

    Fent, János; Bihari, Péter; Vippola, Minnamari; Sarlin, Essi; Lakatos, Susan

    2015-08-01

    Surface modification of single-walled carbon nanotubes (SWCNTs) such as carboxylation, amidation, hydroxylation and pegylation is used to reduce the nanotube toxicity and render them more suitable for biomedical applications than their pristine counterparts. Toxicity can be manifested in platelet activation as it has been shown for SWCNTs. However, the effect of various surface modifications on the platelet activating potential of SWCNTs has not been tested yet. In vitro platelet activation (CD62P) as well as the platelet-granulocyte complex formation (CD15/CD41 double positivity) in human whole blood were measured by flow cytometry in the presence of 0.1mg/ml of pristine or various surface modified SWCNTs. The effect of various SWCNTs was tested by whole blood impedance aggregometry, too. All tested SWCNTs but the hydroxylated ones activate platelets and promote platelet-granulocyte complex formation in vitro. Carboxylated, pegylated and pristine SWCNTs induce whole blood aggregation as well. Although pegylation is preferred from biomedical point of view, among the samples tested by us pegylated SWCNTs induced far the most prominent activation and a well detectable aggregation of platelets in whole blood. PMID:25956790

  20. Superhydrophobic Surfaces with Very Low Hysteresis Prepared by Aggregation of Silica Nanoparticles During In Situ Urea-Formaldehyde Polymerization.

    Science.gov (United States)

    Diwan, Anubhav; Jensen, David S; Gupta, Vipul; Johnson, Brian I; Evans, Delwyn; Telford, Clive; Linford, Matthew R

    2015-12-01

    We present a new method for the preparation of superhydrophobic materials by in situ aggregation of silica nanoparticles on a surface during a urea-formaldehyde (UF) polymerization. This is a one-step process in which a two-tier topography is obtained. The polymerization is carried out for 30, 60, 120, 180, and 240 min on silicon shards. Silicon surfaces are sintered to remove the polymer. SEM and AFM show both an increase in the area covered by the nanoparticles and their aggregation with increasing polymerization time. Chemical vapor deposition of a fluorinated silane in the presence of a basic catalyst gives these surfaces hydrophobicity. Deposition of this low surface energy silane is confirmed by the F 1s signal in XPS. The surfaces show advancing water contact angles in excess of 160 degrees with very low hysteresis (< 7) after 120 min and 60 min polymerization times for 7 nm and 14 nm silica, respectively. Depositions are successfully demonstrated on glass substrates after they are primed with a UF polymer layer. Superhydrophobic surfaces can also be prepared on unsintered substrates. PMID:26682448

  1. Heparin binding by murine recombinant prion protein leads to transient aggregation and formation of RNA-resistant species.

    Science.gov (United States)

    Vieira, Tuane C R G; Reynaldo, Daniel P; Gomes, Mariana P B; Almeida, Marcius S; Cordeiro, Yraima; Silva, Jerson L

    2011-01-19

    The conversion of cellular prion protein (PrP(C)) into the pathological conformer PrP(Sc) requires contact between both isoforms and probably also requires a cellular factor, such as a nucleic acid or a glycosaminoglycan (GAG). Little is known about the structural features implicit in the GAG-PrP interaction. In the present work, light scattering, fluorescence, circular dichroism, and nuclear magnetic resonance (NMR) spectroscopy were used to describe the chemical and physical properties of the murine recombinant PrP 23-231 interaction with low molecular weight heparin (LMWHep) at pH 7.4 and 5.5. LMWHep interacts with rPrP 23-231, thereby inducing transient aggregation. The interaction between murine rPrP and heparin at pH 5.5 had a stoichiometry of 2:1 (LMWHep:rPrP 23-231), in contrast to a 1:1 binding ratio at pH 7.4. At binding equilibrium, NMR spectra showed that rPrP complexed with LMWHep had the same general fold as that of the free protein, even though the binding can be indicated by significant changes in few residues of the C-terminal domain, especially at pH 5.5. Notably, the soluble LMWHep:rPrP complex prevented RNA-induced aggregation. We also investigated the interaction between LMWHep and the deletion mutants rPrP Δ51-90 and Δ32-121. Heparin did not bind these constructs at pH 7.4 but was able to interact at pH 5.5, indicating that this glycosaminoglycan binds the octapeptide repeat region at pH 7.4 but can also bind other regions of the protein at pH 5.5. The interaction at pH 5.5 was dependent on histidine residues of the murine rPrP 23-231. Depending on the cellular milieu, the PrP may expose different regions that can bind GAG. These results shed light on the role of GAGs in PrP conversion. The transient aggregation of PrP may explain why some GAGs have been reported to induce the conversion into the misfolded, scrapie conformation, whereas others are thought to protect against conversion. The acquired resistance of the complex against RNA

  2. Molecular Dynamics Study on the Inhibition Mechanisms of Drugs CQ1-3 for Alzheimer Amyloid-β40 Aggregation Induced by Cu(2.).

    Science.gov (United States)

    Dong, Mingyan; Li, Haoyue; Hu, Dingkun; Zhao, Wei; Zhu, Xueying; Ai, Hongqi

    2016-05-18

    The aggregation of amyloid-β (Aβ) peptide induced by Cu(2+) is a key factor in development of Alzheimer's disease (AD), and metal ion chelation therapy enables treatment of AD. Three CQi (i = 1, 2, and 3 with R = H, Cl, and NO2, respectively) drugs had been verified experimentally to be much stronger inhibitors than the pioneer clioquinol (CQ) in both disaggregation of Aβ40 aggregate and reduction of toxicity induced by Cu(2+) binding at low pH. Due to the multiple morphologies of Cu(2+)-Aβ40 complexes produced at different pH states, we performed a series of molecular dynamics simulations to explain the structural changes and morphology characteristics as well as intrinsic disaggregation mechanisms of three Cu(2+)-Aβ40 models in the presence of any of the three CQi drugs at both low and high pH states. Three inhibition mechanisms for CQi were proposed as "insertion", "semi-insertion", and "surface" mechanisms, based on the morphologies of CQi-model x (CQi-x, x = 1, 2, and 3) and the strengths of binding between CQi and the corresponding model x. The insertion mechanism was characterized by the morphology with binding strength of more than 100 kJ/mol and by CQi being inserted or embedded into the hydrophobic cavity of model x. In those CQi-x morphologies with lower binding strength, CQi only attaches on the surface or inserts partly into Aβ peptide. Given the evidence that the binding strength is correlated positively with the effectiveness of drug to inhibit Aβ aggregation and thus to reduce toxicity, the data of binding strength presented here can provide a reference for one to screen drugs. From the point of view of binding strength, CQ2 is the best drug. Because of the special role of Asp23 in both Aβ aggregation and stabilizing the Aβ fibril, the generation of a H-bond between CQ3 and Asp23 of the Aβ40 peptide is believed to be responsible for CQ3 having the strongest disaggregation capacity. Therefore, besides strong binding, stronger propensity to

  3. Naringin administration inhibits platelet aggregation and release by reducing blood cholesterol levels and the cytosolic free calcium concentration in hyperlipidemic rabbits

    OpenAIRE

    Xiao, Yang; LI, LAI-LAI; Guo, Jing-Jing; XU, WEN-PING; Wang, Yan-Yan; Wang, Yi

    2014-01-01

    This study investigated the effects of naringin on platelet aggregation and release in hyperlipidemic rabbits, and the underlying mechanisms. The safety of naringin was also investigated. The rabbits were orally administered 60, 30 or 15 mg/kg of naringin once a day for 14 days after being fed a high fat/cholesterol diet for four weeks. Following the two weeks of drug administration, the degree of platelet aggregation induced by arachidonic acid, adenosine diphosphate and collagen was signifi...

  4. Whey protein isolate modified by transglutaminase aggregation and emulsion gel properties

    Science.gov (United States)

    Qi, Weiwei; Chen, Chong; Liu, Mujun; Yu, Guoping; Cai, Xinghang; Guo, Peipei; Yao, Yuxiu; Mei, Sijie

    2015-07-01

    Whey protein isolate and commercial soybean salad oil were used to produce the WPI emulsion dispersions. The properties of TG-catalyzed emulsion gelation produced from WPI emulsion dispersions were investigated by the amount of TG, temperature, pH and reaction time. Specifically, the texture properties (hardness and springiness), water-holding capacity and rheological properties (G' and G") were assessed. The result of Orthogonal tests showed WPI emulsion can form better hardness and springiness gel when the ratio of TG and WPI was 20U/g, pH 7.5, treatment temperature and time were 50°C and 3 h, respectively. The microstructure of TG emulsion gels was more compact, gel pore is smaller, distribution more uniform, the oil droplets size smaller compared with untreated emulsion gels. Compared to the control of rheological properties, G' and G" were significantly increased and G' > G", results showed that the gel was solid state, and TG speeded up the process of gelation.

  5. Identification of small molecule inhibitors of Tau aggregation by targeting monomeric Tau as a potential therapeutic approach for Tauopathies

    Science.gov (United States)

    Pickhardt, Marcus; Neumann, Thomas; Schwizer, Daniel; Callaway, Kari; Vendruscolo, Michele; Schenk, Dale; George-Hyslop, Peter; Mandelkow, Eva M.; Dobson, Christopher M.; McConlogue, Lisa; Mandelkow, Eckhard; Tóth, Gergely

    2016-01-01

    A potential strategy to alleviate the aggregation of intrinsically disordered proteins (IDPs) is to maintain the native functional state of the protein by small molecule binding. However, the targeting of the native state of IDPs by small molecules has been challenging due to their heterogeneous conformational ensembles. To tackle this challenge, we applied a high-throughput chemical microarray surface plasmon resonance imaging screen to detect the binding between small molecules and monomeric full-length Tau, a protein linked with the onset of a range of Tauopathies. The screen identified a novel set of drug-like fragment and lead-like compounds that bound to Tau. We verified that the majority of these hit compounds reduced the aggregation of different Tau constructs in vitro and in N2a cells. These results demonstrate that Tau is a viable receptor of drug-like small molecules. The drug discovery approach that we present can be applied to other IDPs linked to other misfolding diseases such as Alzheimer’s and Parkinson’s diseases. PMID:26510979

  6. Towards Better Understanding of Concrete Containing Recycled Concrete Aggregate

    OpenAIRE

    Hisham Qasrawi; Iqbal Marie

    2013-01-01

    The effect of using recycled concrete aggregates (RCA) on the basic properties of normal concrete is studied. First, recycled aggregate properties have been determined and compared to those of normal aggregates. Except for absorption, there was not a significant difference between the two. Later, recycled aggregates were introduced in concrete mixes. In these mixes, natural coarse aggregate was partly or totally replaced by recycled aggregates. Results show that the use of recycled aggregates...

  7. Evaluation of the effects of amyloid β aggregation from seaweed extracts by a microliter-scale high-throughput screening system with a quantum dot nanoprobe.

    Science.gov (United States)

    Ogara, Toshiki; Takahashi, Tomohito; Yasui, Hajime; Uwai, Koji; Tokuraku, Kiyotaka

    2015-07-01

    Inhibitors of amyloid β (Aβ) aggregation have the potential to serve as lead compounds for anti-Alzheimer's disease (AD) agents because Aβ aggregation is a key step in AD pathogenesis. Recently, we developed a novel microliter-scale high-throughput screening (MSHTS) system for Aβ aggregation inhibitors that applied fluorescence microscopic analysis with quantum dot nanoprobes, and attempted to comprehensively screen the inhibitors from spices using this system (Ishigaki et al., PLoS One, 8, e72992, 2013). In this study, we tried to evaluate the inhibitory activities of 11 seaweed extracts on Aβ aggregation using the MSHTS system. The half-maximal effective concentration (EC50) of the ethanolic extracts from all seaweeds exceeded 4.9 mg/ml, indicating that the extracts inhibit Aβ aggregation although this activity was significantly lower than that displayed by members of the Lamiaceae, a family of herbal spices that showed highest activity among 52 spices tested in our 2013 study. On the other hand, the EC50 of boiling water extracts was 0.013-0.42 mg/ml which was comparable with the EC50 of the extracts from the Lamiaceae family. These results suggest that the extraction efficiency of the inhibitors by boiling water extraction was higher than that by ethanolic extraction. Moreover, analysis of fluorescence micrographs, which were obtained from the MSHTS system, revealed that the morphology of the Aβ aggregates coincubated with boiling water extracts differed from control aggregates, suggesting that the MSHTS system is also useful for screening substances that affect the morphology of aggregates. PMID:25534595

  8. WASTEWATER TREATMENT BY ARTIFICIAL WETLANDS

    Science.gov (United States)

    Studies of artificial wetlands at Santee, California demonstrated the capacity of wetlands systems for integrated secondary and advanced treatment of municipal wastewaters. When receiving a blend of primary and secondary wastewaters at a blend ratio of 1:2 (6 cm per day: 12 cm pe...

  9. Erythrocyte aggregation in flowing blood

    International Nuclear Information System (INIS)

    This paper addresses the issue of whether nonionic contrast media (CM) promote thrombosis by the formation of large, irregular red blood cell aggregates with videomicroscopy and a flow chamber, red blood cell aggregates adjacent to an endothelial cell monolayer were imaged at 17 sec-1 in dilute suspensions (hematocrit, --8) at 370C in plasma with 20% CM by non-red blood cell volume. All aggregates were rouleaux (<100 μm) readily dispersed at higher shear rates. Aggregate length in eight experiments was increased 11% by ioxaglate (320 mg of iodine per milliliter), decreased 58% by diatrizoate (370 mg of iodine per milliliter) but reduced similarly (16%) by iohexol (350 mg of iodine per milliliter) and saline. Iohexol did not enhance platelet aggregation on injured monolayers

  10. Upgrading the quality of mixed recycled aggregates from construction and demolition waste by using near-infrared sorting technology

    OpenAIRE

    Vegas, Iñigo; Broos, Kris; Nielsen, Peter; Lambertz, Oliver; Lisbona, Amaia

    2015-01-01

    Recycled aggregates of high-purity, guaranteeing optimal technical and environmental performance, are required for high-grade construction applications such as concrete. The main problem constituents causing a decrease in the quality of recycled aggregates to be used in high grade applications are: organic material, gypsum and autoclaved aerated concrete (AAC). This paper studies the potential of Near Infrared (NIR) sorting technology to improve the quality of mixed recycled aggregates. Tests...

  11. Diffusion in aggregated soil.

    NARCIS (Netherlands)

    Rappoldt, C.

    1992-01-01

    The structure of an aggregated soil is characterized by the distribution of the distance from an arbitrary point in the soil to the nearest macropore or crack. From this distribution an equivalent model system is derived to which a diffusion model can be more easily applied. The model system consist

  12. Probe Intracellular Trafficking of a Polymeric DNA Delivery Vehicle by Functionalization with an Aggregation-Induced Emissive Tetraphenylethene Derivative.

    Science.gov (United States)

    Han, Xiongqi; Chen, Qixian; Lu, Hongguang; Ma, Jianbiao; Gao, Hui

    2015-12-30

    Characteristic aggregation-induced quenching of π-fluorophores imposed substantial hindrance to their utilization in nanomedicine for insight into microscopic intracellular trafficking of therapeutic payload. To address this obstacle, we attempted to introduce a novel aggregation-induced emission (AIE) fluorophore into the cationic polymer, which was further used for formulation of a gene delivery carrier. Note that the selective restriction of the intramolecular rotation of the AIE fluorophore through its covalent bond to the polymer conduced to immense AIE. Furthermore, DNA payload labeled with the appropriate fluorophore as the Förster resonance energy transfer (FRET) acceptor verified a facile strategy to trace intracellular DNA releasing activity relying on the distance limitation requested by FRET (AIE fluorophore as FRET donor). Moreover, the hydrophobic nature of the AIE fluorophore appeared to promote colloidal stability of the constructed formulation. Together with other chemistry functionalization strategies (including endosome escape), the ultimate formulation exerted dramatic gene transfection efficiency. Hence, this report manifested a first nanomedicine platform combining AIE and FRET for microscopic insight into DNA intracellular trafficking activity. PMID:26634294

  13. Characterization of two second-site mutations preventing wild type protein aggregation caused by a dominant negative PMA1 mutant.

    Directory of Open Access Journals (Sweden)

    Pilar Eraso

    Full Text Available The correct biogenesis and localization of Pma1 at the plasma membrane is essential for yeast growth. A subset of PMA1 mutations behave as dominant negative because they produce aberrantly folded proteins that form protein aggregates, which in turn provoke the aggregation of the wild type protein. One approach to understand this dominant negative effect is to identify second-site mutations able to suppress the dominant lethal phenotype caused by those mutant alleles. We isolated and characterized two intragenic second-site suppressors of the PMA1-D378T dominant negative mutation. We present here the analysis of these new mutations that are located along the amino-terminal half of the protein and include a missense mutation, L151F, and an in-frame 12bp deletion that eliminates four residues from Cys409 to Ala412. The results show that the suppressor mutations disrupt the interaction between the mutant and wild type enzymes, and this enables the wild type Pma1 to reach the plasma membrane.

  14. Properties of Ferrofluid Nanoparticles Prepared by Coprecipitation and Acid Treatment

    International Nuclear Information System (INIS)

    A new stable acid water-based CoFe2O4 ferrofluid is prepared by coprecipitation and acid treatment. The properties of the nanoparticles forming the ferrofluid are examined by means of X-ray diffraction, vibrating sample magnetometer, scanning tunneling microscopy, transmission electron microscopy and annihilation technique. The results show that the particles are cubic CoFe2O4 nanoparticles, which have an average diameter of 12.2 nm and are coated with a low density porous amorphous layer. The CoFe2O4 particles in an acid aqueous medium exist in two kinds of forms, one is a single spherical particle and another is an aggregation of several spherical particles

  15. Properties of Ferrofluid Nanoparticles Prepared by Coprecipitation and Acid Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Li Jian [Southwest China Normal University, Physics Department (China); Dai Dalin [Southwest China Normal University, Life-Science Department (China); Zhao Baogang; Lin Yueqiang; Liu Cenye [Southwest China Normal University, Physics Department (China)

    2002-06-15

    A new stable acid water-based CoFe{sub 2}O{sub 4} ferrofluid is prepared by coprecipitation and acid treatment. The properties of the nanoparticles forming the ferrofluid are examined by means of X-ray diffraction, vibrating sample magnetometer, scanning tunneling microscopy, transmission electron microscopy and annihilation technique. The results show that the particles are cubic CoFe{sub 2}O{sub 4} nanoparticles, which have an average diameter of 12.2 nm and are coated with a low density porous amorphous layer. The CoFe{sub 2}O{sub 4} particles in an acid aqueous medium exist in two kinds of forms, one is a single spherical particle and another is an aggregation of several spherical particles.

  16. Sewage water treatment by irradiation

    International Nuclear Information System (INIS)

    Irradiation of the outlet wastewater from Adra Plant shows that radiation sensitivity for the total count of the microorganism, fungi, and pathogenic microorganism were 0.328, 0.327, 0.305 kGy respectively at 3.4 kGy/h. No Ascaris Lumbricoides eggs were found. These results show that radiation technology in wastewater treatment at Adra Plant for reuse in irrigation safely from microbial point of view can be applied. (author)

  17. Topics in Probabilistic Judgment Aggregation

    Science.gov (United States)

    Wang, Guanchun

    2011-01-01

    This dissertation is a compilation of several studies that are united by their relevance to probabilistic judgment aggregation. In the face of complex and uncertain events, panels of judges are frequently consulted to provide probabilistic forecasts, and aggregation of such estimates in groups often yield better results than could have been made…

  18. Recycled aggregates concrete: aggregate and mix properties

    Directory of Open Access Journals (Sweden)

    González-Fonteboa, B.

    2005-09-01

    Full Text Available This study of structural concrete made with recycled concrete aggregate focuses on two issues: 1. The characterization of such aggregate on the Spanish market. This involved conducting standard tests to determine density, water absorption, grading, shape, flakiness and hardness. The results obtained show that, despite the considerable differences with respect to density and water absorption between these and natural aggregates, on the whole recycled aggregate is apt for use in concrete production. 2. Testing to determine the values of basic concrete properties: mix design parameters were established for structural concrete in non-aggressive environments. These parameters were used to produce conventional concrete, and then adjusted to manufacture recycled concrete aggregate (RCA concrete, in which 50% of the coarse aggregate was replaced by the recycled material. Tests were conducted to determine the physical (density of the fresh and hardened material, water absorption and mechanical (compressive strength, splitting tensile strength and modulus of elasticity properties. The results showed that, from the standpoint of its physical and mechanical properties, concrete in which RCA accounted for 50% of the coarse aggregate compared favourably to conventional concrete.

    Se aborda el estudio de hormigones estructurales fabricados con áridos reciclados procedentes de hormigón, incidiéndose en dos aspectos: 1. Caracterización de tales áridos, procedentes del mercado español. Para ello se llevan a cabo ensayos de densidad, absorción, granulometría, coeficiente de forma, índice de lajas y dureza. Los resultados obtenidos han puesto de manifiesto que, a pesar de que existen diferencias notables (sobre todo en cuanto a densidad y absorción con los áridos naturales, las características de los áridos hacen posible la fabricación de hormigones. 2. Ensayos sobre propiedades básicas de los hormigones: se establecen parámetros de dosificaci

  19. The database for aggregate analysis of ClinicalTrials.gov (AACT and subsequent regrouping by clinical specialty.

    Directory of Open Access Journals (Sweden)

    Asba Tasneem

    Full Text Available BACKGROUND: The ClinicalTrials.gov registry provides information regarding characteristics of past, current, and planned clinical studies to patients, clinicians, and researchers; in addition, registry data are available for bulk download. However, issues related to data structure, nomenclature, and changes in data collection over time present challenges to the aggregate analysis and interpretation of these data in general and to the analysis of trials according to clinical specialty in particular. Improving usability of these data could enhance the utility of ClinicalTrials.gov as a research resource. METHODS/PRINCIPAL RESULTS: The purpose of our project was twofold. First, we sought to extend the usability of ClinicalTrials.gov for research purposes by developing a database for aggregate analysis of ClinicalTrials.gov (AACT that contains data from the 96,346 clinical trials registered as of September 27, 2010. Second, we developed and validated a methodology for annotating studies by clinical specialty, using a custom taxonomy employing Medical Subject Heading (MeSH terms applied by an NLM algorithm, as well as MeSH terms and other disease condition terms provided by study sponsors. Clinical specialists reviewed and annotated MeSH and non-MeSH disease condition terms, and an algorithm was created to classify studies into clinical specialties based on both MeSH and non-MeSH annotations. False positives and false negatives were evaluated by comparing algorithmic classification with manual classification for three specialties. CONCLUSIONS/SIGNIFICANCE: The resulting AACT database features study design attributes parsed into discrete fields, integrated metadata, and an integrated MeSH thesaurus, and is available for download as Oracle extracts (.dmp file and text format. This publicly-accessible dataset will facilitate analysis of studies and permit detailed characterization and analysis of the U.S. clinical trials enterprise as a whole. In

  20. Mechanics of fire ant aggregations

    Science.gov (United States)

    Tennenbaum, Michael; Liu, Zhongyang; Hu, David; Fernandez-Nieves, Alberto

    2016-01-01

    Fire ants link their bodies to form aggregations; these can adopt a variety of structures, they can drip and spread, or withstand applied loads. Here, by using oscillatory rheology, we show that fire ant aggregations are viscoelastic. We find that, at the lowest ant densities probed and in the linear regime, the elastic and viscous moduli are essentially identical over the spanned frequency range, which highlights the absence of a dominant mode of structural relaxation. As ant density increases, the elastic modulus rises, which we interpret by alluding to ant crowding and subsequent jamming. When deformed beyond the linear regime, the aggregation flows, exhibiting shear-thinning behaviour with a stress load that is comparable to the maximum load the aggregation can withstand before individual ants are torn apart. Our findings illustrate the rich, collective mechanical behaviour that can arise in aggregations of active, interacting building blocks.

  1. Production of lightweight aggregate from industrial waste and carbon dioxide.

    Science.gov (United States)

    Gunning, Peter J; Hills, Colin D; Carey, Paula J

    2009-10-01

    The concomitant recycling of waste and carbon dioxide emissions is the subject of developing technology designed to close the industrial process loop and facilitate the bulk-re-use of waste in, for example, construction. The present work discusses a treatment step that employs accelerated carbonation to convert gaseous carbon dioxide into solid calcium carbonate through a reaction with industrial thermal residues. Treatment by accelerated carbonation enabled a synthetic aggregate to be made from thermal residues and waste quarry fines. The aggregates produced had a bulk density below 1000 kg/m(3) and a high water absorption capacity. Aggregate crushing strengths were between 30% and 90% stronger than the proprietary lightweight expanded clay aggregate available in the UK. Cast concrete blocks containing the carbonated aggregate achieve compressive strengths of 24 MPa, making them suitable for use with concrete exposed to non-aggressive service environments. The energy intensive firing and sintering processes traditionally required to produce lightweight aggregates can now be augmented by a cold-bonding, low energy method that contributes to the reduction of green house gases to the atmosphere. PMID:19577916

  2. Spatial aggregation of soil predictions over pre-defined areas of interest for better use by local land managers.

    Science.gov (United States)

    Vaysse, Kévin; Heuvelink, Gerard B. M.; Lagacherie, Philippe

    2015-04-01

    The GlobalSoilMap project aims to provide global soil property predictions and associated uncertainties at multiple depths at fine spatial resolution (100mx100m grid). This product is specifically tailored for agro-environmental modellers that produce results at global scales over large regions. However, local land managers are less interested in fine resolution maps because they need to make decisions for much larger areas of interest, such as provinces, districts, watersheds or farm territories. To serve their need, we propose a spatial aggregation approach that uses the GlobalSoilMap prediction maps as input and derives from these linear as well as non-linear spatial aggregates, such as the spatial mean, the spatial median or any other quantile, or the proportion of land within the area of interest that satisfies a pre-specified criterion (e.g. pH 400g/kg). The method must also be able to quantify the uncertainty in the spatial aggregate. For this reason, we employed a spatial stochastic simulation approach. We tested the method in the Languedoc-Roussillon region (27,236 km2), by first applying regression kriging using legacy soil profile observations (Vaysse and Lagacherie, 2015). Next we predicted the proportion of land for all districts within the region (average size 18 km2) that is suitable with regard to a threshold applied to three different soil properties: pH, organic carbon and clay content at 5-15 cm interval of depth. This procedure comprises four different steps: i) empirical reproduction of the joint conditional probability distribution of the soil properties at all grid cells in the district by means of sequential Gaussian simulation applied to a regression kriging model (Goovaerts, 2001); ii) calculation of the indicator (0 or 1, depending on whether the thresholds are met) for each simulation and each grid cell; iii) calculation of the proportion of "suitable" land area by zonal statistics of the indicator variable over the district for each

  3. Mechanism of fiber assembly; treatment of Aβ-peptide aggregation with a coarse-grained united-residue force field

    OpenAIRE

    Rojas, Ana; Liwo, Adam; Browne, Dana; Scheraga, Harold A.

    2010-01-01

    The mechanism of growth of fibrils of the β-amyloid peptide (Aβ) was studied by means of a physics-based coarse-grained united-residue (UNRES) model and molecular dynamics (MD) simulations. To identify the mechanism of monomer addition to an Aβ1–40 fibril, an unstructured monomer was placed at a 20 Å distance from a fibril template, and allowed to interact freely with it. The monomer was not biased towards the fibril conformation, by either the force field or the MD algorithm. By using a coar...

  4. Single-crystal-like NiO colloidal nanocrystal-aggregated microspheres with mesoporous structure: Synthesis and enhanced electrochemistry, photocatalysis and water treatment properties

    International Nuclear Information System (INIS)

    A new microwave-assisted hydrothermal synthetic route based on the self-assembly and subsequently controlled thermal decomposition process is proposed to fabricate nickel oxide colloidal nanocrystal aggregated microspheres (CNAMs) with mesoporous structure. XRD, EDS, SEM, TEM. FTIR, and N2 adsorption and desorption isotherm techniques are employed for morphology and structure characterizations. The as-prepared nickel oxide CNAMs, which has a high surface area (234 m2/g) with narrow pore distribution at around 3.25 nm, are composed of numerous hexagonal mesoporous nanocrystals of approximately 50–60 nm in size, and present a single-crystal-like characteristic. The experimental results also demonstrated that the CNAMs showed outstanding performance in electrochemistry, photocatalysis and waste water treatment due to their special hierarchical and mesoporous structure, presenting the promising candidate for catalysis and catalysis support materials. - Graphical abstract: CNAMs with mesoporous structure synthesized via a simple microwave-assisted hydrothermal method was applied in electrochemistry and catalysis and exhibited enhanced performance. Display Omitted - Highlights: • CNAMs with mesoporous structure are achieved via a simple microwave-assisted hydrothermal method. • Morphology, structure and pore distribution of sample particles is specifically controlled. • The samples show enhanced properties in electrochemistry and catalysis due to hierarchical structure

  5. Uncovering the Mechanism of Aggregation of Human Transthyretin*

    OpenAIRE

    Saelices, Lorena; Johnson, Lisa M.; Liang, Wilson Y.; Sawaya, Michael R.; Cascio, Duilio; Ruchala, Piotr; Whitelegge, Julian; Jiang, Lin; Riek, Roland; Eisenberg, David S.

    2015-01-01

    Background: Transthyretin (TTR) aggregation is associated with systemic amyloidosis. Results: Residue replacements on the F and H strands hinder TTR aggregation. Conclusion: The F and H strands are aggregation-driving segments of TTR. The binding of designed peptides inhibits protein aggregation. Significance: We point the way to new therapeutic approaches against TTR aggregation by using peptides to block amyloid segments.

  6. Particulate emissions by a small non-road diesel engine: Biodiesel and diesel characterization and mass measurements using the extended idealized aggregates theory

    Science.gov (United States)

    Chung, A.; Lall, A. A.; Paulson, S. E.

    Particulate emissions from a 4.8-kW diesel generator running on ultra-low sulfur diesel and biodiesel fuels are characterized as a function of engine load. Number distributions measured by a scanning mobility particle sizer (SMPS) show that particle mobility diameters rise with increasing engine loads. The elemental carbon (EC) to organic carbon (OC) ratio, measured by thermo-optical transmission evolved gas analysis, with careful attention to avoid OC sampling artifacts, increases from about 0.5 at idle load to 3.8 at 100% load when using diesel fuel. Transmission electron microscopy (TEM) images of the particles showed that at idle, the particles were liquid droplets together with a few aggregates. When a load was applied, the droplets were replaced by chain aggregates, which had a mean primary particle size of 29±9 nm at 100% load. Fractal dimension averaged 1.63±0.13, consistent with much larger diesel engines emissions reported in the literature. The use of biofuel (B100) results in emissions of particles that are compact, irregular, and lack the clearly defined primary particles of diesel aggregates, and yet at maximum load they have similar EC and OC content as diesel particles. The accuracy of the idealized aggregate (IA) theory correction and its extension to the transition regime [Lall, A.A., Friedlander, S.K., 2006. On-line measurement of ultrafine aggregate surface area and volume distributions by electrical mobility analysis: 1. Theoretical analysis. Journal of Aerosol Science 37, 260-271] was tested as a method to obtain mass distributions for diesel aggregates using and SMPS. The total mass concentrations calculated from the SMPS measurements using the extended IA theory are in good agreement with the mass concentrations obtained from gravimetric and EC/OC measurements. The loss of aggregates in the TSI SMPS inlet impactor is also discussed.

  7. Changes on aggregation in mine waste amended with biochar and marble mud

    Science.gov (United States)

    Ángeles Muñoz, María; Guzmán, Jose; Zornoza, Raúl; Moreno-Barriga, Fabián; Faz, Ángel; Lal, Rattan

    2016-04-01

    treatment because macro aggregate stability is largely responsible for macro-porosity. The decrease in bulk density may be an indication of a positive effect for mine waste reclamation. Conversely, no differences were observed among treatments in micro-aggregate stability. Apparently, low organic matter contents in MW needed to be co-amended with labile organic amendments to effectively increase soil aggregation. Furthermore, the presence of Fe hydroxides could also increase the micro-aggregation. Additional research is needed to understand the mechanisms of mine soil reclamation. Acknowledgement : This work has been funded by Fundación Séneca (Agency of Science and Technology of the Region of Murcia, Spain

  8. Mechanism of fiber assembly: treatment of Aβ peptide aggregation with a coarse-grained united-residue force field.

    Science.gov (United States)

    Rojas, Ana; Liwo, Adam; Browne, Dana; Scheraga, Harold A

    2010-12-01

    The growth mechanism of β-amyloid (Aβ) peptide fibrils was studied by a physics-based coarse-grained united-residue model and molecular dynamics (MD) simulations. To identify the mechanism of monomer addition to an Aβ(1-40) fibril, we placed an unstructured monomer at a distance of 20 Å from a fibril template and allowed it to interact freely with the latter. The monomer was not biased towards fibril conformation by either the force field or the MD algorithm. With the use of a coarse-grained model with replica-exchange molecular dynamics, a longer timescale was accessible, making it possible to observe how the monomers probe different binding modes during their search for the fibril conformation. Although different assembly pathways were seen, they all follow a dock-lock mechanism with two distinct locking stages, consistent with experimental data on fibril elongation. Whereas these experiments have not been able to characterize the conformations populating the different stages, we have been able to describe these different stages explicitly by following free monomers as they dock onto a fibril template and to adopt the fibril conformation (i.e., we describe fibril elongation step by step at the molecular level). During the first stage of the assembly ("docking"), the monomer tries different conformations. After docking, the monomer is locked into the fibril through two different locking stages. In the first stage, the monomer forms hydrogen bonds with the fibril template along one of the strands in a two-stranded β-hairpin; in the second stage, hydrogen bonds are formed along the second strand, locking the monomer into the fibril structure. The data reveal a free-energy barrier separating the two locking stages. The importance of hydrophobic interactions and hydrogen bonds in the stability of the Aβ fibril structure was examined by carrying out additional canonical MD simulations of oligomers with different numbers of chains (4-16 chains), with the fibril

  9. Molecular aggregation of humic substances

    Science.gov (United States)

    Wershaw, R. L.

    1999-01-01

    Humic substances (HS) form molecular aggregates in solution and on mineral surfaces. Elucidation of the mechanism of formation of these aggregates is important for an understanding of the interactions of HS in soils arid natural waters. The HS are formed mainly by enzymatic depolymerization and oxidation of plant biopolymers. These reactions transform the aromatic and lipid plant components into amphiphilic molecules, that is, molecules that consist of separate hydrophobic (nonpolar) and hydrophilic (polar) parts. The nonpolar parts of the molecules are composed of relatively unaltered segments of plant polymers and the polar parts of carboxylic acid groups. These amphiphiles form membrane-like aggregates on mineral surfaces and micelle-like aggregates in solution. The exterior surfaces of these aggregates are hydrophilic, and the interiors constitute separate hydrophobic liquid-like phases.

  10. DRAG ON SUBMICRON NANOPARTICLE AGGREGATES

    Institute of Scientific and Technical Information of China (English)

    F.; Einar; Kruis

    2005-01-01

    A new procedure was developed for estimating the effective collision diameter of an aggregate composed of primary particles of any size. The coagulation coefficient of two oppositely charged particles was measured experimentally and compared with classic Fuchs theory, including a new method to account for particle non-sphericity. A second set of experiments were performed on well-defined nanoparticle aggregates at different stages of sintering, i.e. from the aggregate to the fully sintered stage. Here, electrical mobility was used to characterize the particle drag. The aggregates are being built from two different size-fractionated nanoparticle aerosols, the non-aggregated particles are discarded by an electrofilter and then they are passed through a furnace at concentrations low enough not to induce coagulation.

  11. Dispersion and Functionalization of Nanoparticles Synthesized by Gas Aggregation Source: Opening New Routes Toward the Fabrication of Nanoparticles for Biomedicine.

    Science.gov (United States)

    Oprea, B; Martínez, L; Román, E; Vanea, E; Simon, S; Huttel, Y

    2015-12-29

    The need to find new nanoparticles for biomedical applications is pushing the limits of the fabrication methods. New techniques with versatilities beyond the extended chemical routes can provide new insight in the field. In particular, gas aggregation sources offer the possibility to fabricate nanoparticles with controlled size, composition, and structure out of thermodynamics. In this context, the milestone is the optimization of the dispersion and functionalization processes of nanoparticles once fabricated by these routes as they are generated in the gas phase and deposited on substrates in vacuum or ultra-high vacuum conditions. In the present work we propose a fabrication route in ultra-high vacuum that is compatible with the subsequent dispersion and functionalization of nanoparticles in aqueous media and, which is more remarkable, in one single step. In particular, we will present the fabrication of nanoparticles with a sputter gas aggregation source using a Fe50B50 target and their further dispersion and functionalization with polyethyleneglycol (PEG). Characterization of these nanoparticles is carried out before and after PEG functionalization. During functionalization, significant boron dissolution occurs, which facilitates nanoparticle dispersion in the aqueous solution. The use of different complementary techniques allows us to prove the PEG attachment onto the surface of the nanoparticles, creating a shell to make them biocompatible. The result is the formation of nanoparticles with a structure mainly composed by a metallic Fe core and an iron oxide shell, surrounded by a second PEG shell dispersed in aqueous solution. Relaxivity measurements of these PEG-functionalized nanoparticles assessed their effectiveness as contrast agents for magnetic resonance imaging (MRI) analysis. Therefore, this new fabrication route is a reliable alternative for the synthesis of nanoparticles for biomedicine. PMID:26640032

  12. Hierarchical nitrogen and cobalt co-doped TiO2 prepared by an interface-controlled self-aggregation process

    International Nuclear Information System (INIS)

    Highlights: •N–Co-codoped TiO2 was prepared by hydrothermal method at vapor–liquid interface. •Hierarchical N–Co-codoped TiO2 was synthesized. •Growth mechanism of N–Co-codoped TiO2 was discussed. •Ferromagnetism was found on the titanate N–Co-codoped TiO2 at room temperature. •Light absorption edge of N–Co-codoped TiO2 was shifted to visible light region. -- Abstract: Hierarchical N and Co co-doped TiO2 (NCT) self-aggregates were prepared by the interfacial self-aggregation in an autoclave, where a mixed Ti(SO4)2 and Co(NO3)2 solution reacted with polyacrylate-controlled-releasing ammonia at the vapor–liquid interface. The SEM images show that the typical hierarchical NCT self-aggregates were composed of perpendicular nanosheets on the top, granule aggregates in the middle, and flower-like nanosheets at the bottom. A possible mechanism of their formation has been proposed on the basis of a series of experiments. We found that the morphology and crystal structure of the NCT self-aggregates can be controlled by adjusting reaction temperature, reaction time, and the amount of ammonia solution. The demonstration of hysteresis loops in the magnetization curves indicates that the NCT self-aggregate samples prepared at 150 °C were ferromagnetic at room temperature. The absorption spectra of the samples prepared at 150 °C showed evident absorption in the visible region. These NCT self-aggregates may be potentially useful in photoelectrochemical and magneto-electronic applications

  13. Ultrafast fluorescent decay induced by metal-mediated dipole-dipole interaction in two-dimensional molecular aggregates

    CERN Document Server

    Hu, Qing; Nam, Sang Hoon; Xiao, Jun; Liu, Yongmin; Zhang, Xiang; Fang, Nicholas X

    2016-01-01

    Two-dimensional molecular aggregate (2DMA), a thin sheet of strongly interacting dipole molecules self-assembled at close distance on an ordered lattice, is a fascinating fluorescent material. It is distinctively different from the single or colloidal dye molecules or quantum dots in most previous research. In this paper, we verify for the first time that when a 2DMA is placed at a nanometric distance from a metallic substrate, the strong and coherent interaction between the dipoles inside the 2DMA dominates its fluorescent decay at picosecond timescale. Our streak-camera lifetime measurement and interacting lattice-dipole calculation reveal that the metal-mediated dipole-dipole interaction shortens the fluorescent lifetime to about one half and increases the energy dissipation rate by ten times than expected from the noninteracting single-dipole picture. Our finding can enrich our understanding of nanoscale energy transfer in molecular excitonic systems and may designate a new direction for developing fast a...

  14. Optimization of measurement angles for soot aggregate sizing by elastic light scattering, through design-of-experiment theory

    International Nuclear Information System (INIS)

    In multiangle elastic light scattering (MAELS) experiments, the morphology of aerosolized particles is inferred by shining collimated radiation through the aerosol and then measuring the scattered light intensity over a set of angles. In the case of soot-laden-aerosols MAELS can, in principle, be used to recover the size distribution of soot aggregates, although this involves solving an ill-posed inverse problem. This paper presents a design-of-experiment methodology for identifying the set of angles that maximizes the information content of the angular scattering measurements, thereby minimizing the ill-posedness of the underlying inverse problem. While the optimized angles highlight the physical significance of the scattering regimes, they do not improve the accuracy of size distributions reconstructed from simulated experimental data.

  15. Non-aggregating tau phosphorylation by cyclin-dependent kinase 5 contributes to motor neuron degeneration in spinal muscular atrophy.

    Science.gov (United States)

    Miller, Nimrod; Feng, Zhihua; Edens, Brittany M; Yang, Ben; Shi, Han; Sze, Christie C; Hong, Benjamin Taige; Su, Susan C; Cantu, Jorge A; Topczewski, Jacek; Crawford, Thomas O; Ko, Chien-Ping; Sumner, Charlotte J; Ma, Long; Ma, Yong-Chao

    2015-04-15

    Mechanisms underlying motor neuron degeneration in spinal muscular atrophy (SMA), the leading inherited cause of infant mortality, remain largely unknown. Many studies have established the importance of hyperphosphorylation of the microtubule-associated protein tau in various neurodegenerative disorders, including Alzheimer's and Parkinson's diseases. However, tau phosphorylation in SMA pathogenesis has yet to be investigated. Here we show that tau phosphorylation on serine 202 (S202) and threonine 205 (T205) is increased significantly in SMA motor neurons using two SMA mouse models and human SMA patient spinal cord samples. Interestingly, phosphorylated tau does not form aggregates in motor neurons or neuromuscular junctions (NMJs), even at late stages of SMA disease, distinguishing it from other tauopathies. Hyperphosphorylation of tau on S202 and T205 is mediated by cyclin-dependent kinase 5 (Cdk5) in SMA disease condition, because tau phosphorylation at these sites is significantly reduced in Cdk5 knock-out mice; genetic knock-out of Cdk5 activating subunit p35 in an SMA mouse model also leads to reduced tau phosphorylation on S202 and T205 in the SMA;p35(-/-) compound mutant mice. In addition, expression of the phosphorylation-deficient tauS202A,T205A mutant alleviates motor neuron defects in a zebrafish SMA model in vivo and mouse motor neuron degeneration in culture, whereas expression of phosphorylation-mimetic tauS202E,T205E promotes motor neuron defects. More importantly, genetic knock-out of tau in SMA mice rescues synapse stripping on motor neurons, NMJ denervation, and motor neuron degeneration in vivo. Altogether, our findings suggest a novel mechanism for SMA pathogenesis in which hyperphosphorylation of non-aggregating tau by Cdk5 contributes to motor neuron degeneration. PMID:25878277

  16. Deviant by Design: Risks Associated with Aggregating Deviant Peers into Group Prevention and Treatment Programs

    Science.gov (United States)

    Dishion, Thomas J.; Dodge, Kenneth A.; Lansford, Jennifer E.

    2008-01-01

    While delinquency has multiple causes, deviant peer affiliation is one of the strongest. In fact, a high proportion of violence, drug use, and other deviant behaviors are committed in groups, rather than in isolation. This article explores how practices within educational, mental health, juvenile justice, and community programs can lead to deviant…

  17. Mechanisms of browning development in aggregates of marine organic matter formed under anoxic conditions: A study by mid-infrared and near-infrared spectroscopy

    Science.gov (United States)

    Mecozzi, Mauro; Acquistucci, Rita; Nisini, Laura; Conti, Marcelo Enrique

    2014-03-01

    In this paper we analyze some chemical aspects concerning the browning development associated to the aggregation of marine organic matter (MOM) occurring in anoxic conditions. Organic matter samples obtained by the degradation of different algal samples were daily taken to follow the evolution of the aggregation process and the associated browning process. These samples were examined by Fourier transform mid infrared (FTIR) and Fourier transform near infrared (FTNIR) spectroscopy and the colour changes occurring during the above mentioned aggregation process were measured by means of Colour Indices (CIs). Spectral Cross Correlation Analysis (SCCA) was applied to correlate changes in CI values to the structural changes of MOM observed by FTIR and FTNIR spectra which were also submitted to Two-Dimensional Hetero Correlation Analysis (2HDCORR). SCCA results showed that all biomolecules present in MOM aggregates such as carbohydrates, proteins and lipids are involved in the browning development. In particular, SCCA results of algal mixtures suggest that the observed yellow-brown colour can be linked to the development of non enzymatic (i.e. Maillard) browning reactions. SCCA results for MOM furthermore suggest that aggregates coming from brown algae also showed evidence of browning related to enzymatic reactions. In the end 2HDCORR results indicate that hydrogen bond interactions among different molecules of MOM can play a significant role in the browning development.

  18. Effect of CO2 on the properties and sinking velocity of aggregates of the coccolithophore Emiliania huxleyi

    Science.gov (United States)

    Biermann, A.; Engel, A.

    2010-03-01

    Coccolithophores play an important role in organic matter export due to their production of the mineral calcite that can act as ballast. Recent studies indicated that calcification in coccolithophores may be affected by changes in seawater carbonate chemistry. We investigated the influence of CO2 on the aggregation and sinking behaviour of the coccolithophore Emiliania huxleyi (PML B92/11) during a laboratory experiment. The coccolithophores were grown under low (~180 μatm), medium (~380 μatm), and high (~750 μatm) CO2 conditions. Aggregation of the cells was promoted using roller tables. Size and settling velocity of aggregates were determined during the incubation using video image analysis. Our results indicate that aggregate properties are sensitive to changes in the degree of ballasting, as evoked by ocean acidification. Average sinking velocity was highest for low CO2 aggregates (~1292 m d-1) that also had the highest particulate inorganic to particulate organic carbon (PIC/POC) ratio. Lowest PIC/POC ratios and lowest sinking velocity (~366 m d-1) at comparable sizes were observed for aggregates of the high CO2 treatment. Aggregates of the high CO2 treatment showed a 4-fold lower excess density (~4.2×10-4 g cm-3) when compared to aggregates from the medium and low CO2 treatments (~1.7 g×10-3 cm-3). We also observed that more aggregates formed in the high CO2 treatment, and that those aggregates contained more bacteria than aggregates in the medium and low CO2 treatment. If applicable to the future ocean, our findings suggest that a CO2 induced reduction of the calcite content of aggregates could weaken the deep export of organic matter in the ocean, particularly in areas dominated by coccolithophores.

  19. Aggregated Computational Toxicology Resource (ACTOR)

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Aggregated Computational Toxicology Resource (ACTOR) is a database on environmental chemicals that is searchable by chemical name and other identifiers, and by...

  20. Consistent Trade Policy Aggregation

    OpenAIRE

    Anderson, James E.

    2008-01-01

    Much empirical work requires the aggregation of policies. This paper provides methods of policy aggregation that are consistent with two common objectives of empirical work. One is to preserve real income. The other is to preserve the real volume of activity in one or more parts of the economy. Trade policy aggregation is an acute example of the aggregation problem with thousands of highly dispersed trade barriers to be aggregated. An application to India shows that the standard atheoretic me...

  1. Consistency in Aggregation

    OpenAIRE

    Ludwig Auer

    2004-01-01

    In empirical economic research, individual prices are often aggregated into average prices of sub-aggregates. Then, these average prices are aggregated to produce the average price of the total aggregate. Often, such two stage procedures help to illuminate the underlying forces driving the overall result. Since price data are usually published as price changes, this two stage aggregation is typically based on some price index formula. In this paper, various screening devices are introduced wh...

  2. Information-aggregation bias

    OpenAIRE

    Goodfriend, Marvin

    1991-01-01

    Aggregation in the presence of data-processing lags distorts the information content of data, violating orthogonality restrictions that hold at the individual level. Though the phenomenon is general, it is illustrated here for the life-cycle-permanent-income model. Cross-section and pooled-panel data induce information-aggregation bias akin to that in aggregate time series. Calculations show that information aggregation can seriously bias tests of the life-cycle model on aggregate time series...

  3. A kinetic and structural study of two-step aggregation and fusion of neutral phospholipid vesicles promoted by serum albumin at low pH.

    Science.gov (United States)

    Schenkman, S; Soares de Araujo, P; Sesso, A; Quina, F H; Chaimovich, H

    1981-03-01

    The addition of bovine serum albumin (BSA) to 25 +/- 5 nm diameter single bilayer phosphatidylcholine (PC) vesicles (SBV) (pH 3.5) gives rise to readily visible transient turbidity. Studies of this system, employing a series of techniques, including time-dependent turbidity changes, membrane filtration, centrifugation, Sepharose chromatography and freeze fracture electron microscopy demonstrated that the process involves aggregation and fusion of the vesicles. At least three distinct time-dependent steps have been characterized: (1) the rapid initial formation (in approx. 5 min) of large aggregates (responsible for the visible turbidity) composed of SBV interconnected by BSA in its F form. The formation of these aggregates may be reversed by raising the pH or adding excess BSA to the system at this stage; (2) spontaneous collapse of these large aggregates, in an irreversible step, to form a heterogeneous population of vesicles; (3) fusion produces as the final product of the process, a relatively homogeneous population of larger (50 +/- 10 nm diamter) vesicles. This system serves as a convenient and simple model system for the detailed study of protein-mediated aggregation and fusion of membranes at the molecular level. PMID:7194154

  4. Work Function Modification in P3HT H/J Aggregate Nanostructures Revealed by Kelvin Probe Force Microscopy and Photoluminescence Imaging.

    Science.gov (United States)

    Baghgar, Mina; Barnes, Michael D

    2015-07-28

    We show that surface electronic properties of poly-3-hexylthiophene (P3HT) crystalline nanofibers as probed by Kelvin probe force microscopy (KPFM) depends sensitively on the degree of polymer packing order and dominant coupling type (e.g., H- or J-aggregate) as signaled by absorption or photoluminescence spectroscopy. Nominal HOMO energies between high molecular weight (J-aggregate) nanofibers and low-molecular weight (H-aggregate) nanofibers differ by ≈160 meV. This is consistent with shifts expected from H-type charge-transfer (CT) interactions that lower HOMO energies according to registration between thiophene moieties on adjacent polymer chains. These results show how KPFM combined with wavelength-resolved photoluminescence imaging can be used to extract information on "dark" (CT) interactions in polymer assemblies. PMID:26095304

  5. 28 CFR 2.5 - Sentence aggregation.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Sentence aggregation. 2.5 Section 2.5 Judicial Administration DEPARTMENT OF JUSTICE PAROLE, RELEASE, SUPERVISION AND RECOMMITMENT OF PRISONERS... aggregation. When multiple sentences are aggregated by the Bureau of Prisons pursuant to 18 U.S.C. 4161...

  6. Aggregated Authentication (AMAC) Using Universal Hash Functions

    Science.gov (United States)

    Znaidi, Wassim; Minier, Marine; Lauradoux, Cédric

    Aggregation is a very important issue to reduce the energy consumption in Wireless Sensors Networks (WSNs). There is currently a lack of cryptographic primitives for authentication of aggregated data. The theoretical background for Aggregated Message Authentication Codes (AMACs) has been proposed by Chan and Castelluccia at ISIT 08.

  7. Potentiation of Amyotrophic Lateral Sclerosis (ALS)-associated TDP-43 Aggregation by the Proteasome-targeting Factor, Ubiquilin 1*S⃞

    OpenAIRE

    Kim, Sang Hwa; Shi, Yuling; Hanson, Keith A.; Williams, Leah M.; Sakasai, Ryo; Bowler, Michael J.; Tibbetts, Randal S.

    2009-01-01

    TDP-43 (43-kDa TAR DNA-binding domain protein) is a major constituent of ubiquitin-positive cytoplasmic aggregates present in neurons of patients with fronto-temporal lobular dementia and amyotrophic lateral sclerosis (ALS). The pathologic significance of TDP-43 aggregation is not known; however, dominant mutations in TDP-43 cause a subset of ALS cases, suggesting that misfolding and/or altered trafficking of TDP-43 is relevant to the disease process. Here, we show tha...

  8. Diagnostic and analysis of aggregation stability of magnetic fluids for biomedical applications by small-angle neutron scattering

    International Nuclear Information System (INIS)

    Diagnostics of aggregation and determination of the aggregation regimes and their control in biocompatible magnetic fluids are necessary for their development in biomedical applications. Small-angle neutron scattering (SANS) method was applied in the structure analysis of various types of magnetic fluids for biomedical applications. Additionally the interaction characteristics between surfactant/polymer molecules used in stabilization of magnetic fluids were investigated, which is very important for understanding the synthesis procedure of highly stable magnetic fluids with controllable properties.

  9. Quantitative characterization of agglomerates and aggregates of pyrogenic and precipitated amorphous silica nanomaterials by transmission electron microscopy

    OpenAIRE

    De Temmerman Pieter-Jan; Van Doren Elke; Verleysen Eveline; Van der Stede Yves; Francisco Michel Abi; Mast Jan

    2012-01-01

    Abstract Background The interaction of a nanomaterial (NM) with a biological system depends not only on the size of its primary particles but also on the size, shape and surface topology of its aggregates and agglomerates. A method based on transmission electron microscopy (TEM), to visualize the NM and on image analysis, to measure detected features quantitatively, was assessed for its capacity to characterize the aggregates and agglomerates of precipitated and pyrogenic synthetic amorphous ...

  10. Utilization Possibility of Natural Aggregate Resources in Central Town of Tokat as Concrete Aggregate

    Directory of Open Access Journals (Sweden)

    S. I. Tutmaz

    2010-01-01

    Full Text Available In this study, aggregates of three quarries sampled from Tokat Province were tested to evaluate their suitability for concrete production. The aggregates were supplied from Yesilirmak River, and largely used in agricultural structures constructed in Tokat. Standard aggregate tests approved by Turkish Standards Institute were carried out to analyze the samples. Granulation, unit weight, specific weight, water absorption rate, resistance to frost, resistance against abrasion, ratio of fine materials, organic material contents and, mineralogical analysis of aggregates sampled from aggregate quarries were determined. Pressure resistance tests were conducted on concrete prepared by the aggregates. The results indicated that the aggregate granulation distribution of aggregate quarries evaluated was not suitable however other parameters determined were appropriate for concrete production. The resultant concrete had sufficient pressure resistance. The possible solutions to improve the improper characteristics of aggregates used in concrete were also determined and introduced with this study.

  11. Cathodoluminescence microscopy and petrographic image analysis of aggregates in concrete pavements affected by alkali–silica reaction

    International Nuclear Information System (INIS)

    Various microscopic techniques (cathodoluminescence, polarizing and electron microscopy) were combined with image analysis with the aim to determine a) the modal composition and degradation features within concrete, and b) the petrographic characteristics and the geological types (rocks, and their provenance) of the aggregates. Concrete samples were taken from five different portions of Highway Nos. D1, D11, and D5 (the Czech Republic). Coarse and fine aggregates were found to be primarily composed of volcanic, plutonic, metamorphic and sedimentary rocks, as well as of quartz and feldspar aggregates of variable origins. The alkali–silica reaction was observed to be the main degradation mechanism, based upon the presence of microcracks and alkali–silica gels in the concrete. Use of cathodoluminescence enabled the identification of the source materials of the quartz aggregates, based upon their CL characteristics (i.e., color, intensity, microfractures, deformation, and zoning), which is difficult to distinguish only employing polarizing and electron microscopy. - Highlights: ► ASR in concrete pavements on the Highways Nos. D1, D5 and D11 (Czech Republic). ► Cathodoluminescence was combined with various microscopic techniques and image analysis. ► ASR was attributed to aggregates. ► Source materials of aggregates were identified based on cathodoluminescence characteristics. ► Quartz comes from different volcanic, plutonic and metamorphic parent rocks.

  12. Cathodoluminescence microscopy and petrographic image analysis of aggregates in concrete pavements affected by alkali-silica reaction

    Energy Technology Data Exchange (ETDEWEB)

    Stastna, A., E-mail: astastna@gmail.com [Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Praha 2 (Czech Republic); Sachlova, S.; Pertold, Z.; Prikryl, R. [Institute of Geochemistry, Mineralogy and Mineral Resources, Faculty of Science, Charles University in Prague, Albertov 6, 128 43 Praha 2 (Czech Republic); Leichmann, J. [Department of Geological Sciences, Faculty of Science, Masaryk University in Brno, Kotlarska 267/2, 611 37 Brno (Czech Republic)

    2012-03-15

    Various microscopic techniques (cathodoluminescence, polarizing and electron microscopy) were combined with image analysis with the aim to determine a) the modal composition and degradation features within concrete, and b) the petrographic characteristics and the geological types (rocks, and their provenance) of the aggregates. Concrete samples were taken from five different portions of Highway Nos. D1, D11, and D5 (the Czech Republic). Coarse and fine aggregates were found to be primarily composed of volcanic, plutonic, metamorphic and sedimentary rocks, as well as of quartz and feldspar aggregates of variable origins. The alkali-silica reaction was observed to be the main degradation mechanism, based upon the presence of microcracks and alkali-silica gels in the concrete. Use of cathodoluminescence enabled the identification of the source materials of the quartz aggregates, based upon their CL characteristics (i.e., color, intensity, microfractures, deformation, and zoning), which is difficult to distinguish only employing polarizing and electron microscopy. - Highlights: Black-Right-Pointing-Pointer ASR in concrete pavements on the Highways Nos. D1, D5 and D11 (Czech Republic). Black-Right-Pointing-Pointer Cathodoluminescence was combined with various microscopic techniques and image analysis. Black-Right-Pointing-Pointer ASR was attributed to aggregates. Black-Right-Pointing-Pointer Source materials of aggregates were identified based on cathodoluminescence characteristics. Black-Right-Pointing-Pointer Quartz comes from different volcanic, plutonic and metamorphic parent rocks.

  13. The aggregation and neurotoxicity of TDP-43 and its ALS-associated 25 kDa fragment are differentially affected by molecular chaperones in Drosophila.

    Directory of Open Access Journals (Sweden)

    Jenna M Gregory

    Full Text Available Almost all cases of sporadic amyotrophic lateral sclerosis (ALS, and some cases of the familial form, are characterised by the deposition of TDP-43, a member of a family of heteronuclear ribonucleoproteins (hnRNP. Although protein misfolding and deposition is thought to be a causative feature of many of the most prevalent neurodegenerative diseases, a link between TDP-43 aggregation and the dysfunction of motor neurons has yet to be established, despite many correlative neuropathological studies. We have investigated this relationship in the present study by probing the effect of altering TDP-43 aggregation behaviour in vivo by modulating the levels of molecular chaperones in a Drosophila model. More specifically, we quantify the effect of either pharmacological upregulation of the heat shock response or specific genetic upregulation of a small heat shock protein, CG14207, on the neurotoxicity of both TDP-43 and of its disease associated 25 kDa fragment (TDP-25 in a Drosophila model. Inhibition of the aggregation of TDP-43 by either method results in a partial reduction of its neurotoxic effects on both photoreceptor and motor neurons, whereas inhibition of the aggregation of TDP-25 results not only in a complete suppression of its toxicity but also its clearance from the brain in both neuronal subtypes studied. The results demonstrate, therefore, that aggregation plays a crucial role in mediating the neurotoxic effects of both full length and truncated TDP-43, and furthermore reveal that the in vivo propensity of these two proteins to aggregate and their susceptibility to molecular chaperone mediated clearance are quite distinct.

  14. Quantifying Pb and Cd complexation by alginates and the role of metal binding on macromolecular aggregation

    OpenAIRE

    Lamelas, Cristina; Avaltroni, F; Benedetti, Marc,; Wilkinson, Kevin J; Slaveykova, Vera

    2005-01-01

    The Pb and Cd binding capacity of alginates were quantified by the determination of their complex stability constants and the concentration of complexing sites using H+, Pb2+, or Cd2+ selective electrodes in both static and dynamic titrations. Centrifugation filter devices (30 kDa filter cutoff), followed by inductively coupled plasma mass spectrometry (ICP-MS) measurements of lead or cadmium in the filtrates, were used to validate the results. The influence of ionic strength, pH, and the met...

  15. Overestimation of Yield Loss of Tobacco Caused by the Aggregated Spatial Pattern of Meloidogyne incognita

    OpenAIRE

    Noe, J. P.; Barker, K. R.

    1985-01-01

    Overestimation of yield loss caused by Meloidogyne incognita on tobacco was calculated as a function of the statistical frequency distribution of sample counts. Sampling frequency distributions were described by a negative binomial model, with parameter k, and the resulting probability generating function was used to calculate discrete damage probabilities. Negative binomial damage predictions were compared to mean-density estimates of damage. Predictions based on mean density alone overestim...

  16. Optical properties of petal-like aggregated nanocrystalline zinc oxide synthesized by laser ablation

    International Nuclear Information System (INIS)

    Highlights: ► Petal like ZnO nanocrystals are synthesized by high frequency laser ablation in water. ► Optical band gap of ZnO nanocrystals was tunable by changing the laser pulse energy. ► Nonlinear optical properties and limiting threshold were obtained by Z-scan technique. -- Abstract: The results of the investigations carried out on the third-order nonlinearity in zinc oxide (ZnO) nanocrystals (NCs) by Z-scan technique are included in this paper. ZnO NCs show negative nonlinearity and good nonlinear absorption behavior at 532 nm. The third-order optical susceptibility χ(3) increases with enlargement of NCs due to the size dependent enhancement of exciton oscillator strength. The synthesis of ZnO NCs was performed by laser ablation from a high-purity metallic target of Zn in distilled water medium. For the ablation process, a high frequency pulsed Nd:YAG laser was employed operating at 532 nm with 100 ns pulse duration. UV–vis absorption spectroscopy illustrated the enhancement of the size of ZnO NCs upon increasing the laser pulse energy applied in ablation process. Accordingly the corresponding optical band gap (Eg) decrease by increasing the size of NCs. X-ray diffraction (XRD) associated with transmission electron microscopy (TEM) was utilized to characterize the crystalline phase and also for determining the ZnO NCs morphology.

  17. Crossover from the coffee-ring effect to the uniform deposit caused by irreversible cluster-cluster aggregation

    Science.gov (United States)

    Crivoi, A.; Zhong, X.; Duan, Fei

    2015-09-01

    The coffee-ring effect for particle deposition near the three-phase line after drying a pinned sessile colloidal droplet has been suppressed or attenuated in many recent studies. However, there have been few attempts to simulate the mitigation of the effect in the presence of strong particle-particle attraction forces. We develop a three-dimensional stochastic model to investigate the drying process of a pinned colloidal sessile droplet by considering the sticking between particles, which was observed in the experiments. The Monte Carlo simulation results show that by solely promoting the particle-particle attraction in the model, the final deposit shape is transformed from the coffee ring to the uniform film deposition. This phenomenon is modeled using the colloidal aggregation technique and explained by the "Tetris principle," meaning that unevenly shaped or branched particle clusters rapidly build up a sparse structure spanning throughout the entire domain in the drying process. The influence of the controlled parameters is analyzed as well. The simulation is reflected by the drying patterns of the nanofluid droplets through the surfactant control in the experiments.

  18. Significance of detection of the monocyte CD14+CD16+ subsets and monocyte-platelet aggregates in patients with cerebral infarction by FCM

    International Nuclear Information System (INIS)

    Objective: To investigate the mononuclear cell subsets distribution and monocyte-platelet aggregates of the peripheral blood in patients with cerebral infarction and its clinical significance. Methods: In 48 patients with cerebral infarction and 31 normal controls, the expression levels of CD14, CD16, CD41 were measured by flow cytometry. Results: The expression levels of CD14, Cr16 and CD41 on monocyte in group of cerebral infarction patients were significant difference than those in normal control (P+CD16+ subsets and the monocyte-platelet aggregates (PMAs) were helpful for the early diagnosis in patients with cerebral infarction. (authors)

  19. MAGNIFY NETWORK LIFETIME IN WSN BY REDUCING DATA AGGREGATION DISTANCE OF WEAK NODES

    Directory of Open Access Journals (Sweden)

    Prashant Katoch

    2015-12-01

    Full Text Available Energy efficient protocols have always played a vital role in conservation of energy in Wireless Sensor Network. One of the major introduced protocols is LEACH a cluster based protocol. To improve its performance, an algorithm named as Maximizing the Network Lifetime of Clustered-based WSN Using Probability of Residual Energy is introduced. This protocol improved the Cluster Head selection process of LEACH by using the concept of residual energy. In the proposed paper, further improvement is done by enhancing the data transmission process. This process heightens the lifetime of the nodes having very less energy left by reducing their data transmission distance. Implemented results in MATLAB shows increase in the stability and lifetime of the network..

  20. Investigation of the effect of aggregates' morphology on concrete creep properties by numerical simulations

    International Nuclear Information System (INIS)

    Prestress losses due to creep of concrete is a matter of interest for long-term operations of nuclear power plants containment buildings. Experimental studies by Granger (1995) have shown that concretes with similar formulations have different creep behaviors. The aim of this paper is to numerically investigate the effect of size distribution and shape of elastic inclusions on the long-term creep of concrete. Several microstructures with prescribed size distribution and spherical or polyhedral shape of inclusions are generated. By using the 3D numerical homogenization procedure for viscoelastic microstructures proposed by Šmilauer and Bažant (2010), it is shown that the size distribution and shape of inclusions have no measurable influence on the overall creep behavior. Moreover, a mean-field estimate provides close predictions. An Interfacial Transition Zone was introduced according to the model of Nadeau (2003). It is shown that this feature of concrete's microstructure can explain differences between creep behaviors