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Sample records for nanoparticles induces transient

  1. A dual role of transient receptor potential melastatin 2 channel in cytotoxicity induced by silica nanoparticles

    PubMed Central

    Yu, Peilin; Li, Jin; Jiang, Jialin; Zhao, Zunquan; Hui, Zhaoyuan; Zhang, Jun; Zheng, Yifan; Ling, Daishun; Wang, Lie; Jiang, Lin-Hua; Luo, Jianhong; Zhu, Xinqiang; Yang, Wei

    2015-01-01

    Silica nanoparticles (NPs) have remarkable applications. However, accumulating evidence suggests NPs can cause cellular toxicity by inducing ROS production and increasing intracellular Ca2+ ([Ca2+]i), but the underlying molecular mechanism is largely unknown. Transient receptor potential melastatin 2 (TRPM2) channel is known to be a cellular redox potential sensor that provides an important pathway for increasing the [Ca2+]i under oxidative stress. In this study, we examined the role of TRPM2 channel in silica NPs-induced oxidative stress and cell death. By quantitation of cell viability, ROS production, [Ca2+]i, and protein identification, we showed that TRPM2 channel is required for ROS production and Ca2+ increase induced by silica NPs through regulating NADPH oxidase activity in HEK293 cells. Strikingly, HEK293 cells expressing low levels of TRPM2 were more susceptible to silica NPs than those expressing high levels of TRPM2. Macrophages from young mice showed significantly lower TRPM2 expression than those from senescent mice and had significantly lower viability after silica NPs exposure than those from senescent ones. Taken together, these findings demonstrate for the first time that TRPM2 channel acts as an oxidative stress sensor that plays a dual role in silica NPs-induced cytotoxicity by differentially regulating the NADPH oxidase activity and ROS generation. PMID:26656285

  2. Binding of biological effectors on magnetic nanoparticles measured by a magnetically induced transient birefringence experiment

    NASA Astrophysics Data System (ADS)

    Wilhelm, C.; Gazeau, F.; Roger, J.; Pons, J. N.; Salis, M. F.; Perzynski, R.; Bacri, J. C.

    2002-03-01

    We have investigated the relaxation of the magnetically induced birefringence in a suspension of magnetic nanoparticles in order to detect the binding reaction of polyclonal antibodies on the particle surface. The birefringence relaxation is driven by the rotational diffusion of the complex formed by the magnetic nanoparticles bound to the antibody and thus is directly related to the hydrodynamic size of this complex. Birefringence relaxations are well described by stretched exponential laws revealing a polydisperse distribution of hydrodynamic diameters. Comparing the size distribution of samples with different initial ratios of immunoglobuline added per magnetic nanoparticles, we evidence the graft of an antibody on particle and eventually the onset of particles agregation. Measurements on samples separated in size by gel filtration demonstrate the robustness of our experiment for the determination of size distribution and its modification due to the adsorption of a macromolecule. The immunoglobuline binding assay is performed comparatively for ionic magnetic nanoparticles with different coatings.

  3. Internalization of mesoporous silica nanoparticles induces transient but not sufficient osteogenic signals in human mesenchymal stem cells

    SciTech Connect

    Huang, D.-M. Chung, T.-H.; Hung, Y.; Lu, F.; Wu, S.-H.; Mou, C.-Y.; Yao, M.; Chen, Y.-C.

    2008-09-01

    The biocompatibility of nanoparticles is the prerequisite for their applications in biomedicine but can be misleading due to the absence of criteria for evaluating the safety and toxicity of those nanomaterials. Recent studies indicate that mesoporous silica nanoparticles (MSNs) can easily internalize into human mesenchymal stem cells (hMSCs) without apparent deleterious effects on cellular growth or differentiation, and hence are emerging as an ideal stem cell labeling agent. The objective of this study was to thoroughly investigate the effect of MSNs on osteogenesis induction and to examine their biocompatibility in hMSCs. Uptake of MSNs into hMSCs did not affect the cell viability, proliferation and regular osteogenic differentiation of the cells. However, the internalization of MSNs indeed induced actin polymerization and activated the small GTP-bound protein RhoA. The MSN-induced cellular protein responses as believed to cause osteogenesis of hMSCs did not result in promotion of regular osteogenic differentiation as analyzed by cytochemical stain and protein activity assay of alkaline phosphatase (ALP). When the effect of MSNs on ALP gene expression was further examined by reverse transcriptase polymerase chain reaction, MSN-treated hMSCs were shown to have significantly higher mRNA expression than control cells after 1-hour osteogenic induction. The induction of ALP gene expression by MSNs, however, was absent in cells after 1-day incubation with osteogenic differentiation. Together our results show that the internalization of MSNs had a significant effect on the transient protein response and osteogenic signal in hMSCs, thereby suggesting that the effects of nanoparticles on diverse aspects of cellular activities should be carefully evaluated even though the nanoparticles are generally considered as biocompatible at present.

  4. Transient Uncoupling Induces Synchronization.

    PubMed

    Schröder, Malte; Mannattil, Manu; Dutta, Debabrata; Chakraborty, Sagar; Timme, Marc

    2015-07-31

    Finding conditions that support synchronization is a fertile and active area of research with applications across multiple disciplines. Here we present and analyze a scheme for synchronizing chaotic dynamical systems by transiently uncoupling them. Specifically, systems coupled only in a fraction of their state space may synchronize even if fully coupled they do not. While for many standard systems coupling strengths need to be bounded to ensure synchrony, transient uncoupling removes this bound and thus enables synchronization in an infinite range of effective coupling strengths. The presented coupling scheme therefore opens up the possibility to induce synchrony in (biological or technical) systems whose parameters are fixed and cannot be modified continuously. PMID:26274420

  5. Transient Uncoupling Induces Synchronization

    NASA Astrophysics Data System (ADS)

    Schröder, Malte; Mannattil, Manu; Dutta, Debabrata; Chakraborty, Sagar; Timme, Marc

    2015-07-01

    Finding conditions that support synchronization is a fertile and active area of research with applications across multiple disciplines. Here we present and analyze a scheme for synchronizing chaotic dynamical systems by transiently uncoupling them. Specifically, systems coupled only in a fraction of their state space may synchronize even if fully coupled they do not. While for many standard systems coupling strengths need to be bounded to ensure synchrony, transient uncoupling removes this bound and thus enables synchronization in an infinite range of effective coupling strengths. The presented coupling scheme therefore opens up the possibility to induce synchrony in (biological or technical) systems whose parameters are fixed and cannot be modified continuously.

  6. Transient induced drag

    NASA Technical Reports Server (NTRS)

    Weihs, D.; Katz, J.

    1986-01-01

    In the present treatment of the calculation of forces on a wing that is suddenly brought into motion at a constant speed, attention is given to the unsteady potential's contribution to the force balance. Total bound vorticity is produced at the initial impulse. The results obtained are independent of wing aspect ratio; as time increases, this effect on the drag force becomes smaller as the vortex emanating from the trailing edge is left behind. The second contributor to induced drag is the spanwise vorticity shedding that results from the spanwise load distribution of three-dimensional wings. This contribution grows with time as the length of the wake grows.

  7. Transient electron energy distribution in supported Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Merschdorf, M.; Kennerknecht, C.; Willig, K.; Pfeiffer, W.

    2002-11-01

    The electron relaxation in Ag nanoparticles supported on graphite is investigated by time-resolved multiphoton photoemission spectroscopy. The photoemission spectra map the transient electron energy distribution in the nanoparticles and reveal the internal thermalization and cooling of the electron gas. The excess energy stored in the electron gas is calculated using the free-electron model. In contrast to the behaviour of isolated nanoparticles the energy loss rate from the electron gas increases with the pump fluence. This indicates that the electron gas equilibration in Ag nanoparticles on graphite is modified by excited electron transport.

  8. Transient magnetic birefringence for determining magnetic nanoparticle diameters in dense, highly light scattering media.

    PubMed

    Köber, Mariana; Moros, Maria; Grazú, Valeria; de la Fuente, Jesus M; Luna, Mónica; Briones, Fernando

    2012-04-20

    The increasing use of biofunctionalized magnetic nanoparticles in biomedical applications calls for further development of characterization tools that allow for determining the interactions of the nanoparticles with the biological medium in situ. In cell-incubating conditions, for example, nanoparticles may aggregate and serum proteins adsorb on the particles, altering the nanoparticles' performance and their interaction with cell membranes. In this work we show that the aggregation of spherical magnetite nanoparticles can be detected with high sensitivity in dense, highly light scattering media by making use of magnetically induced birefringence. Moreover, the hydrodynamic particle diameter distribution of anisometric nanoparticle aggregates can be determined directly in these media by monitoring the relaxation time of the magnetically induced birefringence. As a proof of concept, we performed measurements on nanoparticles included in an agarose gel, which scatters light in a similar way as a more complex biological medium but where particle-matrix interactions are weak. Magnetite nanoparticles were separated by agarose gel electrophoresis and the hydrodynamic diameter distribution was determined in situ. For the different particle functionalizations and agarose concentrations tested, we could show that gel electrophoresis did not yield a complete separation of monomers and small aggregates, and that the electrophoretic mobility of the aggregates decreased linearly with the hydrodynamic diameter. Furthermore, the rotational particle diffusion was not clearly affected by nanoparticle-gel interactions. The possibility to detect nanoparticle aggregates and their hydrodynamic diameters in complex scattering media like cell tissue makes transient magnetic birefringence an interesting technique for biological applications. PMID:22456180

  9. Transient magnetic birefringence for determining magnetic nanoparticle diameters in dense, highly light scattering media

    NASA Astrophysics Data System (ADS)

    Köber, Mariana; Moros, Maria; Grazú, Valeria; de la Fuente, Jesus M.; Luna, Mónica; Briones, Fernando

    2012-04-01

    The increasing use of biofunctionalized magnetic nanoparticles in biomedical applications calls for further development of characterization tools that allow for determining the interactions of the nanoparticles with the biological medium in situ. In cell-incubating conditions, for example, nanoparticles may aggregate and serum proteins adsorb on the particles, altering the nanoparticles’ performance and their interaction with cell membranes. In this work we show that the aggregation of spherical magnetite nanoparticles can be detected with high sensitivity in dense, highly light scattering media by making use of magnetically induced birefringence. Moreover, the hydrodynamic particle diameter distribution of anisometric nanoparticle aggregates can be determined directly in these media by monitoring the relaxation time of the magnetically induced birefringence. As a proof of concept, we performed measurements on nanoparticles included in an agarose gel, which scatters light in a similar way as a more complex biological medium but where particle-matrix interactions are weak. Magnetite nanoparticles were separated by agarose gel electrophoresis and the hydrodynamic diameter distribution was determined in situ. For the different particle functionalizations and agarose concentrations tested, we could show that gel electrophoresis did not yield a complete separation of monomers and small aggregates, and that the electrophoretic mobility of the aggregates decreased linearly with the hydrodynamic diameter. Furthermore, the rotational particle diffusion was not clearly affected by nanoparticle-gel interactions. The possibility to detect nanoparticle aggregates and their hydrodynamic diameters in complex scattering media like cell tissue makes transient magnetic birefringence an interesting technique for biological applications.

  10. Transient-induced climate drift

    SciTech Connect

    Johansson, A.; Reinhold, B.; Saha, S. )

    1993-05-01

    The climate drift of various quantities associated with deep, planetary-scale, equilibrated, transient Rossby waves are estimated for the Southern Hemisphere extratropical summer as revealed by the DERF II (Dynamical Extended Range Forecasting) dataset. It is found that the vertical structures of these waves systematically become too baroclinic during the course of integration. There are two time scales associated with this climate drift. There is one very short time scale, estimated to be of the order of one day, when the waves become more barotropic. It is followed by a period when the wave baroclinicity monotonically increases, and after roughly 10 days the model structures appear to have reached their statistically equilibrated state. In the meantime, the kinetic energy of the transient waves decreases substantially to roughly half the observed value. After this initial drop, however, the transient kinetic energy increases again, and it is not clear if an equilibrium value has been reached after 30 days, which is the limit of the DERF II dataset. This third time scale is not found in the quantities directly associated with the vertical structures per se, but it is hypothesized to be a consequence of these errors. A theory is utilized that in a simplified way takes into account the processes that determine the vertical structure of baroclinic waves as well as their robustness as a means of understanding the processes leading to these errors. The implications from this theory are that the formulation and magnitude of the dissipative and diffusive processes in the model are the most likely problem, but there are other possibilities. 37 refs., 10 figs.

  11. Plasmonic Nanobubbles as Transient Vapor Nanobubbles Generated Around Plasmonic Nanoparticles

    PubMed Central

    Lukianova-Hleb, Ekaterina; Hu, Ying; Latterini, Loredana; Tarpani, Luigi; Lee, Seunghyun; Drezek, Rebekah A.; Hafner, Jason H.; Lapotko, Dmitri O.

    2010-01-01

    We have used short laser pulses to generate transient vapor nanobubbles around plasmonic nanoparticles. The photothermal, mechanical and optical properties of such bubbles were found to be different from those of plasmonic nanoparticle and vapor bubbles as well. This phenomena was considered as a new complex nanosystem – plasmonic nanobubble (PNB). Mechanical and optical scattering properties of PNB depended upon the nanoparticle surface and heat capacity, clusterization state, and the optical pulse length. The generation of the PNB required much higher laser pulse fluence thresholds than the explosive boiling level, and was characterized by the relatively high lower threshold of the minimal size (lifetime) of PNB. Optical scattering by PNB and its diameter (measured as the lifetime) has been varied with the fluence of laser pulse and this has demonstrated the tunable nature of PNB. PMID:20307085

  12. Plasmonic nanobubbles as transient vapor nanobubbles generated around plasmonic nanoparticles.

    PubMed

    Lukianova-Hleb, Ekaterina; Hu, Ying; Latterini, Loredana; Tarpani, Luigi; Lee, Seunghyun; Drezek, Rebekah A; Hafner, Jason H; Lapotko, Dmitri O

    2010-04-27

    We have used short laser pulses to generate transient vapor nanobubbles around plasmonic nanoparticles. The photothermal, mechanical, and optical properties of such bubbles were found to be different from those of plasmonic nanoparticle and vapor bubbles, as well. This phenomenon was considered as a new complex nanosystem-plasmonic nanobubble (PNB). Mechanical and optical scattering properties of PNB depended upon the nanoparticle surface and heat capacity, clusterization state, and the optical pulse length. The generation of the PNB required much higher laser pulse fluence thresholds than the explosive boiling level and was characterized by the relatively high lower threshold of the minimal size (lifetime) of PNB. Optical scattering by PNB and its diameter (measured as the lifetime) has been varied with the fluence of laser pulse, and this has demonstrated the tunable nature of PNB. PMID:20307085

  13. A transient molecular probe for characterizing the surface properties of TiO II nanoparticle in colloidal solution

    NASA Astrophysics Data System (ADS)

    Weng, Yu-Xiang; Du, Lu-Chao; Zhang, Qing-Li

    2006-08-01

    A transient molecular probe for characterization of the surface properties of TiO II nanoparticles in colloidal solution has been developed recently in our laboratory. The probe molecule is all-trans-retinoic acid (ATRA) adsorbed on the TiO2 nanoparticle surface. After photoexcitation, the photoinduced interfacial charge recombination would generate ATRA triplet state (ATRA T) with a substantial quantum yield. While the quantum yield of triplet ATRA generated in the solution phase is substantially low, which renders the interfacial-charge-recombination generated triplet ATRA being a transient probe molecule specific only to the interface. It is found that the triplet-triplet absorption spectrum of ATRA adsorbed molecule is sensitive to its binding form with the surface Ti atom through the carboxylic group, as well as to the polarity of the medium. Especially the apparent lifetime of ATRA T at the TiO II surface changes substantially when the local polarity around the TiO II nanoparticle changes. We found that the ATRAT monolayer adsorbed at the TiO II surface can be used as a transient molecular probe for the surface binding forms, coordination state of the surface Ti atoms and the light-induced wettability change of the TiO II nanoparticle. TiO II nanoparticle, all-trans-retinoic acid, molecular probe, interfacial charge recombination, surface binding form, light-induced wettability change.

  14. Laser-induced transient grating setup with continuously tunable period

    SciTech Connect

    Vega-Flick, A.; Eliason, J. K.; Maznev, A. A.; Nelson, K. A.; Khanolkar, A.; Abi Ghanem, M.; Boechler, N.; Alvarado-Gil, J. J.

    2015-12-15

    We present a modification of the laser-induced transient grating setup enabling continuous tuning of the transient grating period. The fine control of the period is accomplished by varying the angle of the diffraction grating used to split excitation and probe beams. The setup has been tested by measuring dispersion of bulk and surface acoustic waves in both transmission and reflection geometries. The presented modification is fully compatible with optical heterodyne detection and can be easily implemented in any transient grating setup.

  15. Transient studies of capillary-induced flow

    NASA Technical Reports Server (NTRS)

    Reagan, M. K.; Bowman, W. J.

    1993-01-01

    This paper presents the numerical and experimental results of a study performed on the transient rise of fluid in a capillary tube. The capillary tube problem provides an excellent mechanism from which to launch an investigation into the transient flow of a fluid in a porous wick structure where capillary forces must balance both adverse gravitational effects and frictional losses. For the study, a capillary tube, initially charged with a small volume of water, was lowered into a pool of water. The behavior of the column of fluid during the transient that followed as more water entered the tube from the pool was both numerically and experimentally studied.

  16. Transient light absorption induced in glassby femtosecond laser pulses

    SciTech Connect

    Blonskii, I V; Kadan, V N; Pavlov, I A; Kryuchkov, N N; Shpotyuk, O I

    2009-10-31

    The dynamics of the transient light absorption induced in K8 optical glass by filamented femtosecond laser pulses have been studied using time-resolved transmitted-light microscopy at wavelengths from 450 to 700 nm. The transient absorption measured as a function of probe beam wavelength is compared to that predicted by the Drude plasma model. We conclude that, just 450 fs after a pump pulse, the transient absorption is dominated by transient electronic states, presumably, self-trapped excitons, with an excitation energy of 2.6 - 2.7 eV. These states are filled with free-carriers from a long-lived plasma, which acts as a 'carrier reservoir'. The relaxation of transient absorption has two components. The slow component, with {tau}{sub 1} {approx} 17-17.5 ps, is governed by the plasma thermalisation time, whereas the second, with {tau}{sub 1} >> 300 ps, is determined by the plasma lifetime. (nonlinear optical phenomena)

  17. Charge Carrier Dynamics of Quantum Confined Semiconductor Nanoparticles Analyzed via Transient Absorption Spectroscopy

    NASA Astrophysics Data System (ADS)

    Thibert, Arthur Joseph, III

    Semiconductor nanoparticles are tiny crystalline structures (typically range from 1 - 100 nm) whose shape in many cases can be dictated through tailored chemical synthesis with atomic scale precision. The small size of these nanoparticles often results in quantum confinement (spatial confinement of wave functions), which imparts the ability to manipulate band-gap energies thus allowing them to be optimally engineered for different applications (i.e., photovoltaics, photocatalysis, imaging). However, charge carriers excited within these nanoparticles are often involved in many different processes: trapping, trap migration, Auger recombination, non-radiative relaxation, radiative relaxation, oxidation / reduction, or multiple exciton generation. Broadband ultrafast transient absorption laser spectroscopy is used to spectrally resolve the fate of excited charge carriers in both wavelength and time, providing insight as to what synthetic developments or operating conditions will be necessary to optimize their efficiency for certain applications. This thesis outlines the effort of resolving the dynamics of excited charge carriers for several Cd and Si based nanoparticle systems using this experimental technique. The thesis is organized into five chapters and two appendices as indicated below. Chapter 1 provides a brief introduction to the photophysics of semiconductor nanoparticles. It begins by defining what nanoparticles, semiconductors, charge carriers, and quantum confinement are. From there it details how the study of charge carrier dynamics within nanoparticles can lead to increased efficiency in applications such as photocatalysis. Finally, the experimental methodology associated with ultrafast transient absorption spectroscopy is introduced and its power in mapping charge carrier dynamics is established. Chapter 2 (JPCC, 19647, 2011) introduces the first of the studied samples: water-solubilized 2D CdSe nanoribbons (NRs), which were synthesized in the Osterloh

  18. Unusual transient absorption dynamics of silver nanoparticles in solutions of carboxylated amine complexons

    NASA Astrophysics Data System (ADS)

    Shevchenko, G. P.; Zhuravkov, V. A.; Tretyak, E. V.; Tikhomirov, S. A.; Buganov, O. V.; Ponyavina, A. N.; Pham, Hong Minh; Do, Hoang Tung; Duong Pham, Van; Nguyen, Dai Hung

    2016-09-01

    We present the results of research on fast relaxation dynamics in the electronic excitation of silver nanoparticles synthesized in the presence of carboxylated amine complexons (NTA, Na2EDTA, DTPA) without any reductant or polymeric stabilizer. Unusual transient absorption dynamics in these objects after femtosecond laser irradiation was found, manifesting as the appearance of an additional long-lived bleaching band. The effect may be assigned to the inhomogeneous and porous shell of silver nanoparticles synthesized by such a procedure, as the consequence of a partial fragmentation of this shell due to heating under femtosecond laser excitation of plasmonic nanoparticles and subsequent electron–phonon energy relaxation.

  19. Acute transient hemiparesis induced by lightning strike.

    PubMed

    Rahmani, Seyed Hesam; Faridaalaee, Gholamreza; Jahangard, Samira

    2015-07-01

    According to data from the National Oceanic and Atmospheric Administration,in the years from 1959 to 1994, lightning was responsible for more than 3000 deaths and nearly 10,000 casualties. The most important characteristic features of lightning injuries are multisystem involvement and widely variable severity. Lightning strikes are primarily a neurologic injury that affects all 3 components of the nervous system: central, autonomic,and peripheral. Neurologic complications of lightning strikes vary from transient benign symptoms to permanent disability. Many patients experience a temporary paralysis called keraunoparalysis. Here we reported a 22-year-old mountaineer man with complaining of left sided hemiparesis after being hit by a lightning strike in the mountain 3 hours ago. There was no loss of consciousness at hitting time. On arrival the patient was alert, awake and hemodynamically stable. In neurologic examination cranial nerves were intact, left sided upper and lower extremity muscle force was I/V with a combination of complete sensory loss, and right-sided muscle force and sensory examination were normal. There is not any evidence of significant vascular impairment in the affected extremities. Brain MRI and CT scan and cervical MRI were normal. During 2 days of admission, with intravenous hydration, heparin 5000 unit SC q12hr and physical therapy of the affected limbs, motor and sensory function improved and was normal except mild paresthesia. He was discharged 1 day later for outpatient follow up while vitamin B1 100mg orally was prescribed.Paresthesia improved after 3 days without further sequels. PMID:25650360

  20. Stress-Induced Nanoparticle Crystallization

    PubMed Central

    2015-01-01

    We demonstrate for the first time a new mechanical annealing method that can significantly improve the structural quality of self-assembled nanoparticle arrays by eliminating defects at room temperature. Using in situ high-pressure small-angle X-ray scattering, we show that deformation of nanoparticle assembly in the presence of gigapascal level stress rebalances interparticle forces within nanoparticle arrays and transforms the nanoparticle film from an amorphous assembly with defects into a quasi-single crystalline superstructure. Our results show that the existence of the hydrostatic pressure field makes the transformation both thermodynamically and kinetically possible/favorable, thus providing new insight for nanoparticle self-assembly and integration with enhanced mechanical performance. PMID:24829089

  1. Ultraviolet converter transients induced by electrons

    NASA Technical Reports Server (NTRS)

    Kernell, R. L.; Becher, J.; Reft, C. S.

    1984-01-01

    The output of ultraviolet converters typically used in satellite astronomy was monitored during irradiation with electrons from a sealed SR-90 source which approximated the peak flux in earth's outer electron belt. The signal induced by irradiation was attributed to two mechanisms: (1) photoelectrons resulting from photons created in the MgF2 window and (2) the direct impact of electrons on the phosphor. For irradiation at about 1 x 10 to the 7th e/sq cm sec, these two effects produced signals which were, in order of magnitude, the same as those produced by an incident UV flux (254 nm) of 10 to the 8th and 10 to the 7th photons/sq cm sec, respectively. In addition, the induced signal was investigated as a function of electron energy by irradiating another converter with 0.4-1.8-MeV electrons from a Van de Graaff. These results suggest that the dominant contribution to the electron-induced signal is Cerenkov photon production in the MgF2 window.

  2. Spectral Induced Polarization of Goethite Nanoparticles

    NASA Astrophysics Data System (ADS)

    Huisman, J. A.; Moradi, S.; Zimmermann, E.; Bosch, J.; Vereecken, H.

    2014-12-01

    Goethite nanoparticles are being considered as a tool to enhance in situ remediation of aquifers contaminated with aromatic hydrocarbons. Injection of goethite nanoparticles into the plume is expected to enhance microbial iron reduction and associated beneficial oxidation of hydrocarbons in a cost-effective manner. Amongst others, current challenges associated with this novel approach are the monitoring of nanoparticle delivery and the nanoparticle and contaminant concentration dynamics over time. Obviously, non-invasive monitoring of these properties would be highly useful. In this study, we aim to evaluate whether spectral induced polarization (SIP) measurements of the complex electrical conductivity are suitable for such non-invasive characterization. In principle, this is not unreasonable because the electrical double layers of the goethite nanoparticles are expected to affect electrical polarization and thus the imaginary part of the complex electrical conductivity. In a first set of measurements, we determined the complex electrical conductivity of goethite nanoparticle suspensions with different nanoparticle concentrations, pH, and ionic strength in the mHz to kHz frequency range. In a second set of measurements, mixtures of sand and different concentrations of goethite nanoparticles and variable pH and ionic strengths were analyzed. Finally, flow experiments were monitored with SIP in a 1-m long laboratory column to investigate dynamic effects associated with goethite nanoparticle injection and delivery. The results showed that the imaginary part of the electrical conductivity was only affected in the high frequency range (Hz - kHz), which is expected from the small size of the goethite nanoparticles. Overall, we found that the goethite nanoparticles are associated with a small increase in the imaginary electrical conductivity at 1 kHz that can be measured in situ using recently improved borehole electrical impedance tomography measurement equipment that

  3. Microscopic heat pulses induce contraction of cardiomyocytes without calcium transients

    SciTech Connect

    Oyama, Kotaro; Mizuno, Akari; Shintani, Seine A.; Itoh, Hideki; Serizawa, Takahiro; Fukuda, Norio; Suzuki, Madoka

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer Infra-red laser beam generates microscopic heat pulses. Black-Right-Pointing-Pointer Heat pulses induce contraction of cardiomyocytes. Black-Right-Pointing-Pointer Ca{sup 2+} transients during the contraction were not detected. Black-Right-Pointing-Pointer Skinned cardiomyocytes in free Ca{sup 2+} solution also contracted. Black-Right-Pointing-Pointer Heat pulses regulated the contractions without Ca{sup 2+} dynamics. -- Abstract: It was recently demonstrated that laser irradiation can control the beating of cardiomyocytes and hearts, however, the precise mechanism remains to be clarified. Among the effects induced by laser irradiation on biological tissues, temperature change is one possible effect which can alter physiological functions. Therefore, we investigated the mechanism by which heat pulses, produced by infra-red laser light under an optical microscope, induce contractions of cardiomyocytes. Here we show that microscopic heat pulses induce contraction of rat adult cardiomyocytes. The temperature increase, {Delta}T, required for inducing contraction of cardiomyocytes was dependent upon the ambient temperature; that is, {Delta}T at physiological temperature was lower than that at room temperature. Ca{sup 2+} transients, which are usually coupled to contraction, were not detected. We confirmed that the contractions of skinned cardiomyocytes were induced by the heat pulses even in free Ca{sup 2+} solution. This heat pulse-induced Ca{sup 2+}-decoupled contraction technique has the potential to stimulate heart and skeletal muscles in a manner different from the conventional electrical stimulations.

  4. An Unexpected Transient Breakdown of the Blood Brain Barrier Triggers Passage of Large Intravenously Administered Nanoparticles

    PubMed Central

    Smith, Nicole M.; Gachulincova, Ivana; Ho, Diwei; Bailey, Charlotte; Bartlett, Carole A.; Norret, Marck; Murphy, John; Buckley, Alysia; Rigby, Paul J.; House, Michael J.; St. Pierre, Timothy; Fitzgerald, Melinda; Iyer, K. Swaminathan; Dunlop, Sarah A.

    2016-01-01

    The highly restrictive blood-brain barrier (BBB) plays a critically important role in maintaining brain homeostasis and is pivotal for proper neuronal function. The BBB is currently considered the main limiting factor restricting the passage of large (up to 200 nm) intravenously administered nanoparticles to the brain. Breakdown of the barrier occurs as a consequence of cerebrovascular diseases and traumatic brain injury. In this article, we report that remote injuries in the CNS are also associated with BBB dysfunction. In particular, we show that a focal partial transection of the optic nerve triggers a previously unknown transient opening of the mammalian BBB that occurs in the visual centres. Importantly, we demonstrate that this transient BBB breakdown results in a dramatic change in the biodistribution of intravenously administered large polymeric nanoparticles which were previously deemed as BBB-impermeable. PMID:26940762

  5. An Unexpected Transient Breakdown of the Blood Brain Barrier Triggers Passage of Large Intravenously Administered Nanoparticles

    NASA Astrophysics Data System (ADS)

    Smith, Nicole M.; Gachulincova, Ivana; Ho, Diwei; Bailey, Charlotte; Bartlett, Carole A.; Norret, Marck; Murphy, John; Buckley, Alysia; Rigby, Paul J.; House, Michael J.; St. Pierre, Timothy; Fitzgerald, Melinda; Iyer, K. Swaminathan; Dunlop, Sarah A.

    2016-03-01

    The highly restrictive blood-brain barrier (BBB) plays a critically important role in maintaining brain homeostasis and is pivotal for proper neuronal function. The BBB is currently considered the main limiting factor restricting the passage of large (up to 200 nm) intravenously administered nanoparticles to the brain. Breakdown of the barrier occurs as a consequence of cerebrovascular diseases and traumatic brain injury. In this article, we report that remote injuries in the CNS are also associated with BBB dysfunction. In particular, we show that a focal partial transection of the optic nerve triggers a previously unknown transient opening of the mammalian BBB that occurs in the visual centres. Importantly, we demonstrate that this transient BBB breakdown results in a dramatic change in the biodistribution of intravenously administered large polymeric nanoparticles which were previously deemed as BBB-impermeable.

  6. Transient light-induced intracellular oxidation revealed by redox biosensor

    SciTech Connect

    Kolossov, Vladimir L.; Beaudoin, Jessica N.; Hanafin, William P.; DiLiberto, Stephen J.; Kenis, Paul J.A.; Rex Gaskins, H.

    2013-10-04

    Highlights: •Time-resolved live cell imaging revealed light-induced oxidation. •Only the roGFP probe fused with glutaredoxin reveals photooxidation. •The transient oxidation is rapidly reduced by the cytosolic antioxidant system. •Intracellular photooxidation is media-dependent. •Oxidation is triggered exclusively by exposure to short wavelength excitation. -- Abstract: We have implemented a ratiometric, genetically encoded redox-sensitive green fluorescent protein fused to human glutaredoxin (Grx1-roGFP2) to monitor real time intracellular glutathione redox potentials of mammalian cells. This probe enabled detection of media-dependent oxidation of the cytosol triggered by short wavelength excitation. The transient nature of light-induced oxidation was revealed by time-lapse live cell imaging when time intervals of less than 30 s were implemented. In contrast, transient ROS generation was not observed with the parental roGFP2 probe without Grx1, which exhibits slower thiol-disulfide exchange. These data demonstrate that the enhanced sensitivity of the Grx1-roGFP2 fusion protein enables the detection of short-lived ROS in living cells. The superior sensitivity of Grx1-roGFP2, however, also enhances responsiveness to environmental cues introducing a greater likelihood of false positive results during image acquisition.

  7. Cocaine-induced vasospasm causing spinal cord transient ischemia.

    PubMed

    Gorelik, N; Tampieri, D

    2012-07-01

    A 25-year-old woman developed a spinal cord infarction leading to quadriplegia and respiratory insufficiency after consuming cocaine and vodka for several days. Within five months, she regained full motor and respiratory function. A literature review revealed 11 cases of cocaine-induced spinal cord infarction. A complete recovery from quadriplegia and respiratory failure following cocaine abuse has never been reported to date. The value of diffusion-weighted imaging in cocaine-induced spinal cord infarction is here presented and discussed. The literature proposes several mechanisms for cocaine-induced infarction including vasospasm, arteritis, and thrombosis. In this case, the imaging studies and the full recovery suggest that the spinal cord ischemia was secondary to a transient vasospasm of the anterior spinal artery. PMID:24028991

  8. Transient radiation-induced absorption in laser materials

    NASA Astrophysics Data System (ADS)

    Brannon, Paul J.

    1994-06-01

    Transient radiation-induced absorption losses in laser materials have been measured using a pulsed nuclear reactor. Reactor pulse widths of 70 to 90 microsecond(s) and absorbed doses of 1 to 7.5 krad have been used. Transmission recovery times and peak absorption coefficients are given. Materials tested include LiNbO3, GSGG, silica substrates, and filter glasses used in the laser cavity. The filter glasses are tested at discrete wavelengths in the range 440 - 750 nm. Lithium niobate, MgO-doped LiNbO3, GSGG, and the silica substrates are tested at 1061 nm.

  9. Accelerator-induced transients in Accelerator Driven Subcritical Reactors

    NASA Astrophysics Data System (ADS)

    Ahmad, Ali; Lindley, Benjamin A.; Parks, Geoffrey T.

    2012-12-01

    Achieving higher particles energies and beam powers have long been the main focus of research in accelerator technology. Since Accelerator Driven Subcritical Reactors (ADSRs) have become the subject of increasing interest, accelerator reliability and modes of operation have become important matters that require further research and development in order to accommodate the engineering and economic needs of ADSRs. This paper focuses on neutronic and thermo-mechanical analyses of accelerator-induced transients in an ADSR. Such transients fall into three main categories: beam interruptions (trips), pulsed-beam operation, and beam overpower. The concept of a multiple-target ADSR is shown to increase system reliability and to mitigate the negative effects of beam interruptions, such as thermal cyclic fatigue in the fuel cladding and the huge financial cost of total power loss. This work also demonstrates the effectiveness of the temperature-to-reactivity feedback mechanisms in ADSRs. A comparison of shutdown mechanisms using control rods and beam cut-off highlights the intrinsic safety features of ADSRs. It is evident that the presence of control rods is crucial in an industrial-scale ADSR. This paper also proposes a method to monitor core reactivity online using the repetitive pattern of beam current fluctuations in a pulsed-beam operation mode. Results were produced using PTS-ADS, a computer code developed specifically to study the dynamic neutronic and thermal responses to beam transients in subcritical reactor systems.

  10. Heavy Ion and Proton Induced Single Event Transients in Linear Devices

    NASA Technical Reports Server (NTRS)

    Nichols, D. K.; Coss, J. R.; Miyahira, T.; Schwartz, H. R.

    1996-01-01

    This paper presents a display of heavy-ion and proton-induced single event transients for selected linear devices. The transient vital signs are serious; low LET threshold, high voltage amplitude and extended pulse duration (microsecs.).

  11. HEMP-induced transients in electric power substations. Final report

    SciTech Connect

    Wiggins, C.M.; Thomas, D.E.; Salas, T.M.

    1992-02-01

    A nuclear detonation in or above the earth`s atmosphere produces an intense electromagnetic pulse (EMP). A large portion of the EMP electromagnetic energy is within the RF spectrum. A detonation at high altitudes above 40 km produces an EMP called high-altitude EMP (HEMP). HEMP is a steep-front short duration transient with a rise time on the order of a few nanoseconds which decays to near zero in less than a microsecond. A single high-altitude burst can subject much of the continental United States to intense HEMP electric fields on the order of tens of kilovolts per meter. The intense transient HEMP will induce fast transients in high-voltage transmission lines and bus structures, instrumentation cables, and control wires in power transmission and distribution (T & D) substations. A system of traveling wave coupling models for a 500 kV substation, including models for the high voltage primary bus, components (circuit breakers, disconnect switches, power transformers, and current and voltage instrument transformers), low voltage control wiring circuits, and a number of conducted and radiated interference coupling modes, had been developed earlier by EPRI. These EPRI served as the baseline for the present HEMP coupling investigations. The HEMP effects on protective relays were assessed for a nominal HEMP environment using several new field coupling models merged with the switching transient data. It is found that a representative solid state relay is unlikely to be damaged or to misoperate by the nominal HEMP threat with a peak field strength of 50 kV/m. However, it is possible for both DC control wires to flash over to ground simultaneously, causing fuses to blow and placing the relay in an inoperative state.

  12. HEMP-induced transients in electric power substations

    SciTech Connect

    Wiggins, C.M.; Thomas, D.E.; Salas, T.M. )

    1992-02-01

    A nuclear detonation in or above the earth's atmosphere produces an intense electromagnetic pulse (EMP). A large portion of the EMP electromagnetic energy is within the RF spectrum. A detonation at high altitudes above 40 km produces an EMP called high-altitude EMP (HEMP). HEMP is a steep-front short duration transient with a rise time on the order of a few nanoseconds which decays to near zero in less than a microsecond. A single high-altitude burst can subject much of the continental United States to intense HEMP electric fields on the order of tens of kilovolts per meter. The intense transient HEMP will induce fast transients in high-voltage transmission lines and bus structures, instrumentation cables, and control wires in power transmission and distribution (T D) substations. A system of traveling wave coupling models for a 500 kV substation, including models for the high voltage primary bus, components (circuit breakers, disconnect switches, power transformers, and current and voltage instrument transformers), low voltage control wiring circuits, and a number of conducted and radiated interference coupling modes, had been developed earlier by EPRI. These EPRI served as the baseline for the present HEMP coupling investigations. The HEMP effects on protective relays were assessed for a nominal HEMP environment using several new field coupling models merged with the switching transient data. It is found that a representative solid state relay is unlikely to be damaged or to misoperate by the nominal HEMP threat with a peak field strength of 50 kV/m. However, it is possible for both DC control wires to flash over to ground simultaneously, causing fuses to blow and placing the relay in an inoperative state.

  13. Understanding charge carrier relaxation processes in terbium arsenide nanoparticles using transient absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Vanderhoef, Laura R.

    Erbium arsenide nanoparticles epitaxially grown within III-V semiconductors have been shown to improve the performance of devices for applications ranging from thermoelectrics to THz pulse generation. The small size of rare-earth nanoparticles suggests that interesting electronic properties might emerge as a result of both spatial confinement and surface states. However, ErAs nanoparticles do not exhibit any signs of quantum confinement or an emergent bandgap, and these experimental observations are understood from theory. The incorporation of other rare-earth monopnictide nanoparticles into III-V hosts is a likely path to engineering carrier excitation, relaxation and transport dynamics for optoelectronic device applications. However, the electronic structure of these other rare-earth monopnictide nanoparticles remains poorly understood. The objective of this research is to explore the electronic structure and optical properties of III-V materials containing novel rare-earth monopnictides. We use ultrafast pump-probe spectroscopy to investigate the electronic structure of TbAs nanoparticles in III-V hosts. We start with TbAs:GaAs, which was expected to be similar to ErAs:GaAs. We study the dynamics of carrier relaxation into the TbAs states using optical pump terahertz probe transient absorption spectroscopy. By analyzing how the carrier relaxation rates depend on pump fluence and sample temperature, we conclude that the TbAs states are saturable. Saturable traps suggest the existence of a bandgap for TbAs nanoparticles, in sharp contrast with previous results for ErAs. We then apply the same experimental technique to two samples of TbAs nanoparticles in InGaAs with different concentrations of TbAs. We observe similar relaxation dynamics associated with trap saturation, though the ability to resolve these processes is contingent upon a high enough TbAs concentration in the sample. We have also constructed an optical pump optical probe transient absorption

  14. Influence of laser parameters on nanoparticle-induced membrane permeabilization

    NASA Astrophysics Data System (ADS)

    Yao, Cuiping; Qu, Xiaochao; Zhang, Zhenxi; Hüttmann, Gereon; Rahmanzadeh, Ramtin

    2009-09-01

    Light-absorbing nanoparticles that are heated by short laser pulses can transiently increase membrane permeability. We evaluate the membrane permeability by flow cytometry assaying of propidium iodide and fluorescein isothiocyanate dextran (FITC-D) using different laser sources. The dependence of the transfection efficiency on laser parameters such as pulse duration, irradiant exposure, and irradiation mode is investigated. For nano- and also picosecond irradiation, we show a parameter range where a reliable membrane permeabilization is achieved for 10-kDa FITC-D. Fluorescent labeled antibodies are able to penetrate living cells that are permeabilized using these parameters. More than 50% of the cells are stained positive for a 150-kDa IgG antibody. These results suggest that the laser-induced permeabilization approach constitutes a promising tool for targeted delivery of larger exogenous molecules into living cells.

  15. Transient cefuroxime/metronidazole treatment induced factor V antibodies

    PubMed Central

    Van den Berg, Sjoerd Adrianus Antonius; Verwer, Patricia E; Idema, René N; Van Guldener, Coen

    2014-01-01

    A 29-year-old patient presented with an appendicular infiltrate, initially treated with intravenous antibiotics, but later requiring percutaneous drainage. Both prothrombin time (PT) and activated partial thromboplastin time (aPTT) were prolonged on 3 days of antibiotic treatment and unresponsive to vitamin K or prothrombin complex concentrate. Laboratory investigation ultimately showed reduced factor V activity and factor V antibodies. In contrast to previously described cases of factor V antibodies, PT and aPTT were only mildly prolonged and residual factor V activity was still >20%. Draining of the abscess did not induce significant bleeding. Afterwards, no haemostatic medication was required. The patient was discharged from the hospital without complications. One week after cessation of the antibiotic treatment, PT and aPTT were within normal range again, with a factor V activity level of 36%. In conclusion, we present a patient with transient factor V antibodies, induced by antibiotics, without clinical bleeding tendency. PMID:25139922

  16. Visualizing interfacial charge transfer in dye sensitized nanoparticles using x-ray transient absorption spectroscopy.

    SciTech Connect

    Zhang, X. Y.; Smolentsev, G.; Guo, J.; Attenkofer, K.; Kurtz, C.; Jennings, G.; Lockard, J. V.; Stickrath, A. B.; Chen, L. X.

    2011-01-01

    A molecular level understanding of the structural reorganization accompanying interfacial electron transfer is important for rational design of solar cells. Here we have applied XTA (X-ray transient absorption) spectroscopy to study transient structures in a heterogeneous interfacial system mimicking the charge separation process in dye-sensitized solar cell (DSSC) with Ru(dcbpy){sub 2}(NCS){sub 2} (RuN3) dye adsorbed to TiO{sub 2} nanoparticle surfaces. The results show that the average Ru-NCS bond length reduces by 0.06 {angstrom}, whereas the average Ru-N(dcbpy) bond length remains nearly unchanged after the electron injection. The differences in bond-order change and steric hindrance between two types of ligands are attributed to their structural response in the charge separation. This study extends the application of XTA into optically opaque hybrid interfacial systems relevant to the solar energy conversion.

  17. Nanoparticle-mediated monitoring of carbohydrate-lectin interactions using Transient Magnetic Birefringence.

    PubMed

    Köber, Mariana; Moros, Maria; Franco Fraguas, Laura; Grazú, Valeria; de la Fuente, Jesus M; Luna, Mónica; Briones, Fernando

    2014-12-16

    The development of sensitive and easy-to-use biosensors that allow an adequate characterization of specific weak biological interactions like carbohydrate-lectin interactions still remains challenging today. Nanoparticles functionalized with carbohydrates are one of the most powerful systems for studying carbohydrate-lectin interactions, because they mimic the multivalent presentation of carbohydrates encountered in nature, for example when viruses and bacteria bind to cells. On the basis of the model system glucose-Concanavalin A (ConA), we explore the application of Transient Magnetic Birefringence (TMB) to study these weak interactions, using glucose-functionalized colloidal magnetite nanoparticles (NPs) as probes. We demonstrate that the binding dynamics can be monitored and derive a model to obtain the apparent cooperativity. For our studies, we use nanoparticles of 6 and 8 nm in diameter. The ConA-generated response shows apparent cooperativity, due to the cross-linking of nanoparticles by the ConA tetramer which has four binding sites. Cooperativity is higher for 6 nm NPs, possibly due to a better accessibility of all four ConA binding sites on smaller NPs, enhancing cross-linking. For this system, we find a detection limit of 3-23 nM. PMID:25417550

  18. Parametric analysis of transient skin heating induced by terahertz radiation.

    PubMed

    Zilberti, Luca; Arduino, Alessandro; Bottauscio, Oriano; Chiampi, Mario

    2014-07-01

    This paper investigates the effect of relevant physical parameters on transient temperature elevation induced in human tissues by electromagnetic waves in the terahertz (THz) band. The problem is defined by assuming a plane wave, which, during a limited time interval, normally impinges on the surface of a 3-layer model of the human body, causing a thermal transient. The electromagnetic equations are solved analytically, while the thermal ones are handled according to the finite element method. A parametric analysis is performed with the aim of identifying the contribution of each parameter, showing that the properties of the first skin layer (except blood flow) play a major role in the computation of the maximum temperature rise for the considered exposure situation. Final results, obtained by combining all relevant parameters together, show that the deviation from the reference solution of the maximum temperature elevation in skin is included in the coverage intervals from -30% to +10% at 0.1 THz and from -33% to +18% at 1 THz (with 95% confidence level). These data allow bounding the possible temperature increase against the spread of tissue properties that could be reasonably used for dosimetric simulations. PMID:24510310

  19. Thermally induced optical nonlinearity during transient heating of thin films

    SciTech Connect

    Chen, G. ); Tien, C.L. )

    1994-05-01

    This work studies the temperature field and the optical response of weakly absorbing thin films with thermally induced optical nonlinearity during picosecond to nanosecond pulsed-laser heating. A one-dimensional model is presented that examines the effects of the temperature dependent optical constants and the nonuniform absorption caused by interference. The energy equation is solved numerically, coupled with the matrix method in optical multilayer theory. Both cadmium sulfide (CdS) thin films and a zinc selenide (ZnSe) interference filter are considered. The computational results compare favorably with available experimental data on the ZnSe interference filter. This study shows that the transient temperature distributions in the films are highly nonuniform. Such nonuniformity yields Airy's formulae for calculating the thin-film reflectance and transmittance inapplicable. Applications of the work include optical bistability, localized change of the film structure, and measurement of the thermal diffusivity of thin films. 31 refs., 7 figs., 1 tab.

  20. Laser-induced stress transients: applications for molecular delivery

    NASA Astrophysics Data System (ADS)

    Flotte, Thomas J.; Lee, Shun; Zhang, Hong; McAuliffe, Daniel J.; Douki, Tina; Doukas, Apostolos G.

    1995-05-01

    Lasers can be used to enhance the delivery of a number of molecules. Other investigators have demonstrated local release of molecules from liposomes following laser irradiation, microbeam disruption of the cell membrane to increase cell transport, microbeam ablation of the zona pellucida surrounding the ovum to increase the chances of fertilization, and increased transcutaneous transport following ablation of the stratum corneum. Our experiments have shown that laser-induced stress transients can be utilized as a vector for intracellular delivery of molecules that may or may not normally cross the cell membrane. These two conditions have been tested with Photofrin and DNA. This technology may have applications in cell and molecular biology, cancer therapy, gene therapy, and others.

  1. Workshop on Transient Induced Insulator Flashover in Vacuum

    NASA Astrophysics Data System (ADS)

    A workshop to discuss the state-of-the-art in transient induced insulator flashover in vacuum was convened at the Pleasanton Hilton at the Club Hotel on August 24-25, 1988. The workshop was attended by 39 participants. Flashover of vacuum-insulator surfaces is the limiting factor in virtually all well designed high voltage, pulsed systems where such interfaces are needed. They are critical to many LLNL present and future applications. The workshop participants attempted via presentations and lively discussions to summarize the state-of-the-art in the field and to outline the critical research topics which could lead to advances in understanding and applications. Several new results were presented at the workshop and an intense discussion session resulted in the formulation of a set of research recommendations and priorities.

  2. Pacemaker-induced transient asynchrony suppresses heart failure progression.

    PubMed

    Kirk, Jonathan A; Chakir, Khalid; Lee, Kyoung Hwan; Karst, Edward; Holewinski, Ronald J; Pironti, Gianluigi; Tunin, Richard S; Pozios, Iraklis; Abraham, Theodore P; de Tombe, Pieter; Rockman, Howard A; Van Eyk, Jennifer E; Craig, Roger; Farazi, Taraneh G; Kass, David A

    2015-12-23

    Uncoordinated contraction from electromechanical delay worsens heart failure pathophysiology and prognosis, but restoring coordination with biventricular pacing, known as cardiac resynchronization therapy (CRT), improves both. However, not every patient qualifies for CRT. We show that heart failure with synchronous contraction is improved by inducing dyssynchrony for 6 hours daily by right ventricular pacing using an intracardiac pacing device, in a process we call pacemaker-induced transient asynchrony (PITA). In dogs with heart failure induced by 6 weeks of atrial tachypacing, PITA (starting on week 3) suppressed progressive cardiac dilation as well as chamber and myocyte dysfunction. PITA enhanced β-adrenergic responsiveness in vivo and normalized it in myocytes. Myofilament calcium response declined in dogs with synchronous heart failure, which was accompanied by sarcomere disarray and generation of myofibers with severely reduced function, and these changes were absent in PITA-treated hearts. The benefits of PITA were not replicated when the same number of right ventricular paced beats was randomly distributed throughout the day, indicating that continuity of dyssynchrony exposure is necessary to trigger the beneficial biological response upon resynchronization. These results suggest that PITA could bring the benefits of CRT to the many heart failure patients with synchronous contraction who are not CRT candidates. PMID:26702095

  3. Pacemaker-Induced Transient Asynchrony Suppresses Heart Failure Progression

    PubMed Central

    Kirk, Jonathan A.; Chakir, Khalid; Lee, Kyoung Hwan; Karst, Edward; Holewinski, Ronald J.; Pironti, Gianluigi; Tunin, Richard S.; Pozios, Iraklis; Abraham, Theodore P.; de Tombe, Pieter; Rockman, Howard A.; Van Eyk, Jennifer E.; Craig, Roger; Farazi, Taraneh G.; Kass, David A.

    2016-01-01

    Uncoordinated contraction from electromechanical delay worsens heart failure pathophysiology and prognosis, but restoring coordination with bi-ventricular pacing, known as cardiac resynchronization therapy (CRT) improves both. Not every patient, however, qualifies for CRT. Here we show that heart failure with synchronous contraction is improved by inducing dyssynchrony for 6 hours daily by right-ventricular pacing using an intracardiac pacing device, in a process we call pacemaker-induced transient asynchrony (PITA). In dogs with heart failure induced by 6 weeks of atrial tachypacing, PITA (starting on week 3) suppressed progressive cardiac dilation as well as chamber and myocyte dysfunction. PITA enhanced β-adrenergic responsiveness in vivo and normalized it in myocytes. Myofilament calcium response declined in dogs with synchronous heart failure, which was accompanied by sarcomere disarray and generation of myofibers with severely reduced function, and these changes were absent in PITA-treated hearts. The benefits of PITA were not replicated when the same number of RV-paced beats was randomly distributed throughout the day, indicating that continuity of dyssynchrony exposure is necessary to trigger the beneficial biological response upon resynchronization. These results suggest PITA could bring the benefits of CRT to the many heart failure patients with synchronous contraction that are not CRT candidates. PMID:26702095

  4. Transient laser annealing of zinc oxide nanoparticle inks to fabricate zinc oxide thin film transistors

    NASA Astrophysics Data System (ADS)

    Willemann, Michael

    Display technology, which relies exclusively on amorphous silicon as the active material for driver electronics, has reached multiple impasses that limit future progress. In order to deliver higher resolutions, higher refresh rates, new display technologies, and innovative form factors, driver electronics must transition to higher performance materials like amorphous oxide semiconductors (AOSs). Transient laser annealing offers an attractive means to maximize performance while minimizing thermal budget, making it compatible with flexible back plane materials and roll-to-roll processing. This research investigates the deposition and annealing of zinc oxide nanoparticle inks to form fully densified crystalline and amorphous zinc oxide films. Processing routes for nanoparticle annealing, including ligand removal, calcining, and excimer pulse laser sintering on the nanosecond time scale, will be introduced that minimize defect formation and suppress the anomalous n-conductivity which is a major challenge to zinc oxide processing. Resistivities as high as 6 x 107 O-cm have been demonstrated. Laser processing on longer millisecond time scales can control defect formation to produce ZnO films without extrinsic doping which have low resistivity for intrinsic oxides, in the range of 10-1 - 10-2 O-cm. Finally, a viable process for the production of backgated ZnO transistors with promising characteristics is presented and the future implications for AOSs and transient thermal processing will be discussed.

  5. Dual Transient Bleaching of Au/PbS Hybrid Core/Shell Nanoparticles.

    PubMed

    Kobayashi, Yoichi; Nonoguchi, Yoshiyuki; Wang, Li; Kawai, Tsuyoshi; Tamai, Naoto

    2012-05-01

    We examined the optical response of hybrid Au/PbS core/shell nanoparticles (NPs) using transient absorption spectroscopy. Finite-difference time-domain (FDTD) calculations and transient absorption measurements show that Au/PbS NPs have unique two extinction peaks: the peak at the longer wavelength (∼700 nm) is originated from the plasmon, and that at the shorter wavelength (550 nm) is from the local maximum of the refractive index of PbS. The transient absorption dynamics of Au/PbS NPs excited at 400 nm have clear oscillation behavior, which is assigned to the breathing mode of whole particle. We observed a weak excitation-wavelength dependence of the plasmon band. The time constant of electron-phonon coupling of Au/PbS NPs was obtained by changing the excitation intensity. We show that spectral properties of Au/PbS NPs are strongly altered by the hybrid formations, while their dynamics differ only minimally compared with those of Au NPs. PMID:26288045

  6. Ultrafast transient absorption studies of hematite nanoparticles: the effect of particle shape on exciton dynamics.

    PubMed

    Fitzmorris, Bob C; Patete, Jonathan M; Smith, Jacqueline; Mascorro, Xiomara; Adams, Staci; Wong, Stanislaus S; Zhang, Jin Z

    2013-10-01

    Much progress has been made in using hematite (α-Fe2 O3 ) as a potentially practical and sustainable material for applications such as solar-energy conversion and photoelectrochemical (PEC) water splitting; however, recent studies have shown that the performance can be limited by a very short charge-carrier diffusion length or exciton lifetime. In this study, we performed ultrafast studies on hematite nanoparticles of different shapes to determine the possible influence of particle shape on the exciton dynamics. Nanorice, multifaceted spheroidal nanoparticles, faceted nanocubes, and faceted nanorhombohedra were synthesized and characterized by using SEM and XRD techniques. Their exciton dynamics were investigated by using femtosecond transient absorption (TA) spectroscopy. Although the TA spectral features differ for the four samples studied, their decay profiles are similar, which can be fitted with time constants of 1-3 ps, approximately 25 ps, and a slow nanosecond component extending beyond the experimental time window that was measured (2 ns). The results indicate that the overall exciton lifetime is weakly dependent on the shape of the hematite nanoparticles, even though the overall optical absorption and scattering are influenced by the particle shape. This study suggests that other strategies need to be developed to increase the exciton lifetime or to lengthen the exciton diffusion length in hematite nanostructures. PMID:24058060

  7. Fertilization Induces a Transient Exposure of Phosphatidylserine in Mouse Eggs

    PubMed Central

    Curia, Claudio A.; Ernesto, Juan I.; Stein, Paula; Busso, Dolores; Schultz, Richard M.; Cuasnicu, Patricia S.; Cohen, Débora J.

    2013-01-01

    Phosphatidylserine (PS) is normally localized to the inner leaflet of the plasma membrane and the requirement of PS translocation to the outer leaflet in cellular processes other than apoptosis has been demonstrated recently. In this work we investigated the occurrence of PS mobilization in mouse eggs, which express flippase Atp8a1 and scramblases Plscr1 and 3, as determined by RT-PCR; these enzyme are responsible for PS distribution in cell membranes. We find a dramatic increase in binding of flouresceinated-Annexin-V, which specifically binds to PS, following fertilization or parthenogenetic activation induced by SrCl2 treatment. This increase was not observed when eggs were first treated with BAPTA-AM, indicating that an increase in intracellular Ca2+ concentration was required for PS exposure. Fluorescence was observed over the entire egg surface with the exception of the regions overlying the meiotic spindle and sperm entry site. PS exposure was also observed in activated eggs obtained from CaMKIIγ null females, which are unable to exit metaphase II arrest despite displaying Ca2+ spikes. In contrast, PS exposure was not observed in TPEN-activated eggs, which exit metaphase II arrest in the absence of Ca2+ release. PS exposure was also observed when eggs were activated with ethanol but not with a Ca2+ ionophore, suggesting that the Ca2+ source and concentration are relevant for PS exposure. Last, treatment with cytochalasin D, which disrupts microfilaments, or jasplakinolide, which stabilizes microfilaments, prior to egg activation showed that PS externalization is an actin-dependent process. Thus, the Ca2+ rise during egg activation results in a transient exposure of PS in fertilized eggs that is not associated with apoptosis. PMID:23951277

  8. Transient radiation-induced absorption in the materials for a GSGG laser

    NASA Astrophysics Data System (ADS)

    Brannon, P. J.

    1993-11-01

    Materials used in the optical elements of a 1,061 m GSGG (gadolinium scandium gallium garnet) laser have been tested for transient radiation-induced absorption. The transient radiation-induced absorption in KK1, Schott S7005 and S7010, and M382 glasses have been determined for discrete wavelengths in the range 440-750 nm. Also, the transient radiation-induced absorption in 'pure' and MgO doped LiNbO3 has been measured at 1,061 nm. Mathematical expressions composed of exponentials are fitted to the data.

  9. Induced transients in substation cables: Measurements and models

    SciTech Connect

    Thomas, D.E.; Wiggins, C.M.; Salas, T.M.; Nickel, F.S. ); Wright, S.E. )

    1994-10-01

    An extensive set of switching transient EMI response measurements on several types of substation cables and internal cable wires in described in this paper. Measured and predicted cable/wire current and voltage transients at both air-insulated substations (AIS) and gas-insulated substations (GIS) are presented, for system voltages ranging from 115 kV to 500 kV.. The maximum peak-to-peak amplitudes of measured wire transients are found to vary from around 1 A to almost 20 A (current in amperes), and from 0.3 kV to almost 7 kV (voltage in kilovolts). Predictive models for field-driven coupling, as well as for direct-driven coupling via current transformers or capacitively-coupled voltage transformers (CT's/CCVT's), are presented. Model predictions are compared to and validated against measured wire transients.

  10. Transient studies of G-induced capillary dryout and rewet

    NASA Technical Reports Server (NTRS)

    Reagan, M. K.; Bowman, W. J.

    1995-01-01

    A transient, one-dimensional numerical code is developed to model the liquid motion in an axial groove with square cross section. Axial variation in liquid level, shear stress and heat transfer between the groove wall and the liquid, evaporation and transient body forces are accounted for in the model. Dryout and rewet of the groove are allowed; the front location is determined numerically using conservation of mass and linear extrapolation. Several numerical test results are presented and discussed.

  11. Effect of laser-induced temperature field on the characteristics of laser-sintered silver nanoparticle ink.

    PubMed

    Lee, D G; Kim, D K; Moon, Y J; Moon, S-J

    2013-07-01

    Laser sintering of metal nanoparticles is a key technology for high-performance printed electronics fabricated on heat-sensitive substrates such as glass or plastic. Although laser-sintered electronic devices have been successfully fabricated, the role of the induced temperature field in the laser sintering process has not been reported thus far. In this work, the effect of temperature on the laser sintering process is described for the first time using a two-dimensional transient heat conduction equation for inkjet-printed silver nanoparticle ink. The in situ electrical resistance was measured to estimate the transient thermal conductivity and hence the temperature of the sintered ink during the laser sintering process. To verify the estimated laser sintering temperature, the morphology of furnace-sintered silver nanoparticle ink was compared with that of laser-sintered ink. The electrical characteristics and surface morphology of laser-sintered ink are found to be related to the process temperature. PMID:23732285

  12. Quenching of chlorophyll fluorescence induced by silver nanoparticles.

    PubMed

    Queiroz, A M; Mezacasa, A V; Graciano, D E; Falco, W F; M'Peko, J-C; Guimarães, F E G; Lawson, T; Colbeck, I; Oliveira, S L; Caires, A R L

    2016-11-01

    The interaction between chlorophyll (Chl) and silver nanoparticles (AgNPs) was evaluated by analyzing the optical behavior of Chl molecules surrounded by different concentrations of AgNPs (10, 60, and 100nm of diameter). UV-Vis absorption, steady state and time-resolved fluorescence measurements were performed for Chl in the presence and absence of these nanoparticles. AgNPs strongly suppressed the Chl fluorescence intensity at 678nm. The Stern-Volmer constant (KSV) showed that fluorescence suppression is driven by the dynamic quenching process. In particular, KSV was nanoparticle size-dependent with an exponential decrease as a function of the nanoparticle diameter. Finally, changes in the Chl fluorescence lifetime in the presence of nanoparticles demonstrated that the fluorescence quenching may be induced by the excited electron transfer from the Chl molecules to the metal nanoparticles. PMID:27280858

  13. Weakly Charged Cationic Nanoparticles Induce DNA Bending and Strand Separation

    SciTech Connect

    Railsback, Justin; Singh, Abhishek; Pearce, Ryan; McKnight, Timothy E; Collazo, Ramon; Sitar, Zlatko; Yingling, Yaroslava; Melechko, Anatoli Vasilievich

    2012-01-01

    The understanding of interactions between double stranded (ds) DNA and charged nanoparticles will have a broad bearing on many important applications from drug delivery [ 1 4 ] to DNAtemplated metallization. [ 5 , 6 ] Cationic nanoparticles (NPs) can bind to DNA, a negatively charged molecule, through a combination of electrostatic attraction, groove binding, and intercalation. Such binding events induce changes in the conformation of a DNA strand. In nature, DNA wraps around a cylindrical protein assembly (diameter and height of 6 nm) [ 7 ] with an 220 positive charge, [ 8 ] creating the complex known as chromatin. Wrapping and bending of DNA has also been achieved in the laboratory through the binding of highly charged species such as molecular assemblies, [ 9 , 10 ] cationic dendrimers, [ 11 , 12 ] and nanoparticles. [ 13 15 ] The charge of a nanoparticle plays a crucial role in its ability to induce DNA structural changes. If a nanoparticle has a highly positive surface charge density, the DNA is likely to wrap and bend upon binding to the nanoparticle [ 13 ] (as in the case of chromatin). On the other hand, if a nanoparticle is weakly charged it will not induce dsDNA compaction. [ 9 , 10 , 15 ] Consequently, there is a transition zone from extended to compact DNA conformations which depends on the chemical nature of the nanoparticle and occurs for polycations with charges between 5 and 10. [ 9 ] While the interactions between highly charged NPs and DNA have been extensively studied, the processes that occur within the transition zone are less explored.

  14. Epstein-Barr Virus Induced Epigenetic Alterations Following Transient Infection

    PubMed Central

    Queen, Krista J.; Shi, Mingxia; Zhang, Fangfang; Cvek, Urska; Scott, Rona S.

    2012-01-01

    Epstein-Barr virus (EBV) is a known tumor virus associated with an increasing array of malignancies; however, the association of the virus with certain malignancies is often erratic. To determine EBV’s contributions to tumorigenesis in a setting of incomplete association, a transient model of infection was established where a clonal CCL185 carcinoma cell line infected with recombinant EBV was allowed to lose viral genomes by withdrawal of selection pressure. Global gene expression comparing EBV-negative, transiently infected clones to uninfected controls identified expression changes in over 1000 genes. Among downregulated genes, several genes known to be DNA methylated in cancer were identified including E-cadherin and PYCARD. A cadherin switch, increased motility and enhanced cellular invasiveness present in EBV-positive cells were retained following viral loss indicating an epigenetic effect. Repression of PYCARD expression was due to increased promoter CpG methylation, whereas loss of E-cadherin expression after transient EBV infection did not correlate with increased DNA methylation of the E-cadherin promoter. Rather, repression of E-cadherin was consistent with formation of a repressive chromatin state. Decreased histone 3 or 4 acetylation at the promoter and 5’ end of the E-cadherin gene was observed in an EBV-negative, transiently infected clone relative to the uninfected controls. These results suggest that EBV can stably alter gene expression in a heritable fashion in formerly infected cells, while its own contribution to the oncogenic process is masked. PMID:23047626

  15. Marek's disease virus induced transient paralysis--a closer look

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Marek’s Disease (MD) is a lymphoproliferative disease of domestic chickens caused by a highly cell-associated alpha herpesvirus, Marek’s disease virus (MDV). Clinical signs of MD include depression, crippling, weight loss, and transient paralysis (TP). TP is a disease of the central nervous system...

  16. Osmotic equilibrium of colloidal nanoparticles transiently confined in an optical trap

    NASA Astrophysics Data System (ADS)

    Fu, Jinxin; Ou-Yang, H. Daniel

    2015-03-01

    Equilibrium number density profile of colloidal particles in a potential force field depends on the particle number density, the force field and interactions between the particles. Einstein described the particle number density profile by an osmotic equilibrium equation relating colloidal osmotic pressure and the potential force in his 1905 paper on the Brownian motion. For a dilute suspension of colloids, when particle interactions are negligible, the osmotic equilibrium equation can be used to determine unknown potential energy profiles from the Boltzmann distribution of the particle number density. Using a known potential energy profile, one can determine the colloidal osmotic pressure as a function of particle density, i.e., the osmotic equation of state, from the density profiles of interacting colloids. We use particle density profiles determined by confocal imaging of fluorescent polystyrene nanoparticles transiently confined in an optical trap to determine the colloidal osmotic equation of state for colloids in the presence of KCl and neutral polymers. The osmotic compressibility and chemical potentials of the colloids are calculated from the osmotic equation of state to predict colloidal stability and phase transitions. This project is supported in part by funds from NSF DMR 0923299, Lehigh Center for Optical Technologies and the Emulsion Polymers Institute.

  17. Paramagnetic Nanoparticles Leave Their Mark on Nuclear Spins of Transiently Adsorbed Proteins.

    PubMed

    Zanzoni, Serena; Pedroni, Marco; D'Onofrio, Mariapina; Speghini, Adolfo; Assfalg, Michael

    2016-01-13

    The successful application of nanomaterials in biosciences necessitates an in-depth understanding of how they interface with biomolecules. Transient associations of proteins with nanoparticles (NPs) are accessible by solution NMR spectroscopy, albeit with some limitations. The incorporation of paramagnetic centers into NPs offers new opportunities to explore bio-nano interfaces. We propose NMR paramagnetic relaxation enhancement as a new tool to detect NP-binding surfaces on proteins with increased sensitivity, also extending the applicability of NMR investigations to heterogeneous biomolecular mixtures. The adsorption of ubiquitin on gadolinium-doped fluoride-based NPs produced residue-specific NMR line-broadening effects mapping to a contiguous area on the surface of the protein. Importantly, an identical paramagnetic fingerprint was observed in the presence of a competing protein-protein association equilibrium, exemplifying possible interactions taking place in crowded biological media. The interaction was further characterized using isothermal titration calorimetry and upconversion emission measurements. The data indicate that the used fluoride-based NPs are not biologically inert but rather are capable of biomolecular recognition. PMID:26683352

  18. Application of confocal microscopy on glutamate-induced intracellular calcium transient in neurons

    NASA Astrophysics Data System (ADS)

    Zhu, Geng; Zhou, Wei; Zhang, Yuan; Liu, Xiuli; Wu, Yuxiang; Luo, Qingming

    2006-02-01

    Intracellular calcium, as an important second messenger, plays a significant role in cell signaling transduction and metabolism. Glutamate can induce the intracellular calcium transient through triggering diverse signaling pathways. To test the effect of glutamate to neurons, we loaded Fluo-3/Am in cultured rat hippocampal neurons, and then acquired two-dimensional fluorescent image by confocal microscopy and the analyzed fluorescent intensity. In cultured neurons, we observed two types of neurons that have different morphology: bipolar-type and pyramidal-type. Inducing [Ca 2+] i transient by glutamate, we found the amplitude and time constant of the response curves of bipolar neurons are larger than those of pyramidal neurons. Further, we induced [Ca 2+] ii transient under different concentrations of glutamate. Two different types of kinetic of the [Ca 2+] i transient have been found, corresponded to the two kinds of neuron. The amplitude of [Ca 2+] i transient increased when applying higher concentration of glutamate in pyramidal neurons; while it decreased in bipolar ones. Responses of neurons bathing in calcium-free extracellular solution to glutamate were different from those bathing in normal solution. [Ca 2+] i transient of pyramidal neurons caused by any concentration were totally blocked; while [Ca 2+] i transient in bipolar neurons caused by high concentration of glutamate (500μM) were partly inhibited. All of the phenomena suggest that different types of cultured hippocampal neurons may have different mechanism of the response to glutamate.

  19. Conductivity affects nanosecond electrical pulse induced pressure transient formation

    NASA Astrophysics Data System (ADS)

    Roth, Caleb C.; Barnes, Ronald A.; Ibey, Bennett L.; Beier, Hope T.; Glickman, Randolph D.

    2016-03-01

    Nanoporation occurs in cells exposed to high amplitude short duration (< 1μs) electrical pulses. The biophysical mechanism(s) responsible for nanoporation is unknown although several theories exist. Current theories focus exclusively on the electrical field, citing electrostriction, water dipole alignment and/or electrodeformation as the primary mechanisms for pore formation. Our group has shown that mechanical forces of substantial magnitude are also generated during nsEP exposures. We hypothesize that these mechanical forces may contribute to pore formation. In this paper, we report that alteration of the conductivity of the exposure solution also altered the level of mechanical forces generated during a nsEP exposure. By reducing the conductivity of the exposure solutions, we found that we could completely eliminate any pressure transients normally created by nsEP exposure. The data collected for this proceeding does not definitively show that the pressure transients previously identified contribute to nanoporation; however; it indicates that conductivity influences both survival and pressure transient formation.

  20. Coherence-population-trapping transients induced by an ac magnetic field

    NASA Astrophysics Data System (ADS)

    Margalit, L.; Rosenbluh, M.; Wilson-Gordon, A. D.

    2012-06-01

    Coherent-population-trapping transients induced by an ac magnetic field are investigated theoretically for a realistic three-level Λ system in the D1 line of 87Rb. The contributions to the transient probe absorption from the various subsystems that compose the realistic atomic system are examined and the absorption of each Λ subsystem is compared to that of a simple Λ system. The population redistribution due to optical pumping is shown to be the dominant cause of the difference between the contributions of the various subsystems to the oscillatory character of the probe absorption. We also discuss the series of transients that reappear every half-cycle time of a modulated magnetic field when the system is in two-photon resonance, and we study the transient behavior as a function of the probe detuning. The effect of a buffer gas on the amplitude and shape of the transients is considered.

  1. Aggregation in charged nanoparticles solutions induced by different interactions

    NASA Astrophysics Data System (ADS)

    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.

  2. Manganese ferrite-based nanoparticles induce ex vivo, but not in vivo, cardiovascular effects

    PubMed Central

    Nunes, Allancer DC; Ramalho, Laylla S; Souza, Álvaro PS; Mendes, Elizabeth P; Colugnati, Diego B; Zufelato, Nícholas; Sousa, Marcelo H; Bakuzis, Andris F; Castro, Carlos H

    2014-01-01

    Magnetic nanoparticles (MNPs) have been used for various biomedical applications. Importantly, manganese ferrite-based nanoparticles have useful magnetic resonance imaging characteristics and potential for hyperthermia treatment, but their effects in the cardiovascular system are poorly reported. Thus, the objectives of this study were to determine the cardiovascular effects of three different types of manganese ferrite-based magnetic nanoparticles: citrate-coated (CiMNPs); tripolyphosphate-coated (PhMNPs); and bare magnetic nanoparticles (BaMNPs). The samples were characterized by vibrating sample magnetometer, X-ray diffraction, dynamic light scattering, and transmission electron microscopy. The direct effects of the MNPs on cardiac contractility were evaluated in isolated perfused rat hearts. The CiMNPs, but not PhMNPs and BaMNPs, induced a transient decrease in the left ventricular end-systolic pressure. The PhMNPs and BaMNPs, but not CiMNPs, induced an increase in left ventricular end-diastolic pressure, which resulted in a decrease in a left ventricular end developed pressure. Indeed, PhMNPs and BaMNPs also caused a decrease in the maximal rate of left ventricular pressure rise (+dP/dt) and maximal rate of left ventricular pressure decline (−dP/dt). The three MNPs studied induced an increase in the perfusion pressure of isolated hearts. BaMNPs, but not PhMNPs or CiMNPs, induced a slight vasorelaxant effect in the isolated aortic rings. None of the MNPs were able to change heart rate or arterial blood pressure in conscious rats. In summary, although the MNPs were able to induce effects ex vivo, no significant changes were observed in vivo. Thus, given the proper dosages, these MNPs should be considered for possible therapeutic applications. PMID:25031535

  3. Transient cardio-respiratory responses to visually induced tilt illusions

    NASA Technical Reports Server (NTRS)

    Wood, S. J.; Ramsdell, C. D.; Mullen, T. J.; Oman, C. M.; Harm, D. L.; Paloski, W. H.

    2000-01-01

    Although the orthostatic cardio-respiratory response is primarily mediated by the baroreflex, studies have shown that vestibular cues also contribute in both humans and animals. We have demonstrated a visually mediated response to illusory tilt in some human subjects. Blood pressure, heart and respiration rate, and lung volume were monitored in 16 supine human subjects during two types of visual stimulation, and compared with responses to real passive whole body tilt from supine to head 80 degrees upright. Visual tilt stimuli consisted of either a static scene from an overhead mirror or constant velocity scene motion along different body axes generated by an ultra-wide dome projection system. Visual vertical cues were initially aligned with the longitudinal body axis. Subjective tilt and self-motion were reported verbally. Although significant changes in cardio-respiratory parameters to illusory tilts could not be demonstrated for the entire group, several subjects showed significant transient decreases in mean blood pressure resembling their initial response to passive head-up tilt. Changes in pulse pressure and a slight elevation in heart rate were noted. These transient responses are consistent with the hypothesis that visual-vestibular input contributes to the initial cardiovascular adjustment to a change in posture in humans. On average the static scene elicited perceived tilt without rotation. Dome scene pitch and yaw elicited perceived tilt and rotation, and dome roll motion elicited perceived rotation without tilt. A significant correlation between the magnitude of physiological and subjective reports could not be demonstrated.

  4. Environmentally-induced discharge transient coupling to spacecraft

    NASA Technical Reports Server (NTRS)

    Viswanathan, R.; Barbay, G.; Stevens, N. J.

    1985-01-01

    The Hughes SCREENS (Space Craft Response to Environments of Space) technique was applied to generic spin and 3-axis stabilized spacecraft models. It involved the NASCAP modeling for surface charging and lumped element modeling for transients coupling into a spacecraft. A differential voltage between antenna and spun shelf of approx. 400 V and current of 12 A resulted from discharge at antenna for the spinner and approx. 3 kv and 0.3 A from a discharge at solar panels for the 3-axis stabilized Spacecraft. A typical interface circuit response was analyzed to show that the transients would couple into the Spacecraft System through ground points, which are most vulnerable. A compilation and review was performed on 15 years of available data from electron and ion current collection phenomena. Empirical models were developed to match data and compared with flight data of Pix-1 and Pix-2 mission. It was found that large space power systems would float negative and discharge if operated at or above 300 V. Several recommendations are given to improve the models and to apply them to large space systems.

  5. Coupling of transient near infrared photonic with magnetic nanoparticle for potential dissipation-free biomedical application in brain.

    PubMed

    Sagar, Vidya; Atluri, V S R; Tomitaka, A; Shah, P; Nagasetti, A; Pilakka-Kanthikeel, S; El-Hage, N; McGoron, A; Takemura, Y; Nair, M

    2016-01-01

    Combined treatment strategies based on magnetic nanoparticles (MNPs) with near infrared ray (NIR) biophotonic possess tremendous potential for non-invasive therapeutic approach. Nonetheless, investigations in this direction have been limited to peripheral body region and little is known about the potential biomedical application of this approach for brain. Here we report that transient NIR exposure is dissipation-free and has no adverse effect on the viability and plasticity of major brain cells in the presence or absence superparamagnetic nanoparticles. The 808 nm NIR laser module with thermocouple was employed for functional studies upon NIR exposure to brain cells. Magnetic nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic laser scattering (DLS), and vibrating sample magnetometer (VSM). Brain cells viability and plasticity were analyzed using electric cell-substrate impedance sensing system, cytotoxicity evaluation, and confocal microscopy. When efficacious non-invasive photobiomodulation and neuro-therapeutical targeting and monitoring to brain remain a formidable task, the discovery of this dissipation-free, transient NIR photonic approach for brain cells possesses remarkable potential to add new dimension. PMID:27465276

  6. Coupling of transient near infrared photonic with magnetic nanoparticle for potential dissipation-free biomedical application in brain

    PubMed Central

    Sagar, Vidya; Atluri, V. S. R.; Tomitaka, A.; Shah, P.; Nagasetti, A.; Pilakka-Kanthikeel, S.; El-Hage, N.; McGoron, A.; Takemura, Y.; Nair, M.

    2016-01-01

    Combined treatment strategies based on magnetic nanoparticles (MNPs) with near infrared ray (NIR) biophotonic possess tremendous potential for non-invasive therapeutic approach. Nonetheless, investigations in this direction have been limited to peripheral body region and little is known about the potential biomedical application of this approach for brain. Here we report that transient NIR exposure is dissipation-free and has no adverse effect on the viability and plasticity of major brain cells in the presence or absence superparamagnetic nanoparticles. The 808 nm NIR laser module with thermocouple was employed for functional studies upon NIR exposure to brain cells. Magnetic nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic laser scattering (DLS), and vibrating sample magnetometer (VSM). Brain cells viability and plasticity were analyzed using electric cell-substrate impedance sensing system, cytotoxicity evaluation, and confocal microscopy. When efficacious non-invasive photobiomodulation and neuro-therapeutical targeting and monitoring to brain remain a formidable task, the discovery of this dissipation-free, transient NIR photonic approach for brain cells possesses remarkable potential to add new dimension. PMID:27465276

  7. Coupling of transient near infrared photonic with magnetic nanoparticle for potential dissipation-free biomedical application in brain

    NASA Astrophysics Data System (ADS)

    Sagar, Vidya; Atluri, V. S. R.; Tomitaka, A.; Shah, P.; Nagasetti, A.; Pilakka-Kanthikeel, S.; El-Hage, N.; McGoron, A.; Takemura, Y.; Nair, M.

    2016-07-01

    Combined treatment strategies based on magnetic nanoparticles (MNPs) with near infrared ray (NIR) biophotonic possess tremendous potential for non-invasive therapeutic approach. Nonetheless, investigations in this direction have been limited to peripheral body region and little is known about the potential biomedical application of this approach for brain. Here we report that transient NIR exposure is dissipation-free and has no adverse effect on the viability and plasticity of major brain cells in the presence or absence superparamagnetic nanoparticles. The 808 nm NIR laser module with thermocouple was employed for functional studies upon NIR exposure to brain cells. Magnetic nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), dynamic laser scattering (DLS), and vibrating sample magnetometer (VSM). Brain cells viability and plasticity were analyzed using electric cell-substrate impedance sensing system, cytotoxicity evaluation, and confocal microscopy. When efficacious non-invasive photobiomodulation and neuro-therapeutical targeting and monitoring to brain remain a formidable task, the discovery of this dissipation-free, transient NIR photonic approach for brain cells possesses remarkable potential to add new dimension.

  8. The containment set approach to digital system tolerance of lightning-induced transient faults

    NASA Technical Reports Server (NTRS)

    Masson, G. M.; Glaser, R. E.

    1982-01-01

    A fault model and a system model are necessary to assess the tolerance or resilience of a digital system to lightning-induced transients. It is noted that these models are usually developed separately. A new approach is outlined here for this assessment problem which combines the fault and system models into an overall model. With this approach, referred to as the containment set approach, an assessment of the effects of lightning-induced transients can be made in terms of a state transition matrix. This matrix can be generated by means of fault injection experiments. In addition, certain nonredundancy-oriented design alternatives to the achievement of lightning-induced transient tolerance in digital systems are indicated by the containment set approach.

  9. Transient photoacoustic effects induced in liquids by pulsed erbium lasers

    NASA Astrophysics Data System (ADS)

    Frenz, Martin; Pratisto, Hans; Ith, Michael; Asshauer, Thomas; Rink, Klaus; Delacretaz, Guy P.; Romano, Valerio; Salathe, Rene-Paul; Weber, Heinz P.

    1994-08-01

    The intense interest in the investigation of erbium laser radiation in medicine is due to the fact that radiation at 3 micrometers is very strongly absorbed by water, which is present in all biological tissue. As a consequence of this high absorption the interaction of pulsed radiation is characterized by an explosive process with a low ablation threshold and a thin coagulation zone along the laser incisions. Erbium lasers, therefore, have a wide field of potential medical applications which become even more attractive with the availability of reliable delivery systems. An interesting situation arises in orthopaedics and angioplasty, where a precise cutting instrument is needed in a liquid environment. For this reason, we experimentally investigated the interaction mechanism of fiber transmitted, pulsed, free-running and Q- switched Erbium:YSGG ((lambda) equals 2.79 micrometers ) and Erbium:YAG ((lambda) equals 2.94 micrometers ) laser radiation with liquid water. The dynamics of the bubble formation and the propagation of shockwaves in water was studied and visualized by flash photography. Acoustic transients of a few hundreds of bars accompanying the ablation process were measured with a needle hydrophone. A clear correlation between the spikes of the laser pulse and those of the pressure signal was observed. Additionally, strong pressure transients were measured after the end of the laser pulse, which could be associated with the collapse of the vapor bubble and further collapses after multiple rebounds. The influence of pulse energy, fiber size and pulse duration on the formation and the amplitude of the pressure waves is demonstrated.

  10. The significance of nanoparticles in particle-induced pulmonary fibrosis

    PubMed Central

    Byrne, James D; Baugh, John A

    2008-01-01

    Exposure to airborne nanoparticles contributes to many chronic pulmonary diseases. Nanoparticles, classified as anthropogenic and natural particles, and fibers of diameters less than 100 nm, have unrestricted access to most areas of the lung due to their size. Size relates to the deposition efficiency of the particle, with particles in the nano-range having the highest efficiencies. The deposition of nanoparticles in the lung can lead to chronic inflammation, epithelial injury, and further to pulmonary fibrosis. Cases of particle-induced pulmonary fibrosis, namely pneumoconiosis, are mostly occupationally influenced, and continue to be documented around the world. The tremendous growth of nanotechnology, however, has spurred fears of increased rates of pulmonary diseases, especially fibrosis. The severity of toxicological consequences warrants further examination of the effects of nanoparticles in humans, possible treatments and increased regulatory measures. PMID:18523535

  11. Transient Current of Nematic Liquid Crystals with Negative Dielectric Anisotropy Induced by Step-Voltage Excitation

    NASA Astrophysics Data System (ADS)

    Iwata, Yosuke; Naito, Hiroyoshi; Inoue, Masaru; Ichinose, Hideo; Klasen-Memmer, Melanie; Tarumi, Kazuaki

    2004-12-01

    A simple theory for measuring the rotational viscosity has been proposed from the analysis of transient current, induced by step-voltage excitation, in nematic liquid crystal cells (NLCs) with positive dielectric anisotropy [M. Imai et al.: Jpn. J. Appl. Phys. 33 (1994) L119]. The applicability of the theory to NLCs with negative dielectric anisotropy has been examined. It is found that the transient current shape of NLCs with negative dielectric anisotropy is different from that of NLCs with positive dielectric anisotropy, and hence, the theory cannot directly be applied to the analysis of the transient current of NLCs with negative dielectric anisotropy. Computer simulation shows that the transient current of NLCs with negative dielectric anisotropy is successfully reproduced by taking into account the flow effects with an appropriate boundary condition and that the flow effects play a key role in eliciting a faster electrooptic response in vertically aligned NLC displays.

  12. Nanoparticle-Mediated, Light-Induced Phase Separations.

    PubMed

    Neumann, Oara; Neumann, Albert D; Silva, Edgar; Ayala-Orozco, Ciceron; Tian, Shu; Nordlander, Peter; Halas, Naomi J

    2015-12-01

    Nanoparticles that both absorb and scatter light, when dispersed in a liquid, absorb optical energy and heat a reduced fluid volume due to the combination of multiple scattering and optical absorption. This can induce a localized liquid-vapor phase change within the reduced volume without the requirement of heating the entire fluid. For binary liquid mixtures, this process results in vaporization of the more volatile component of the mixture. When subsequently condensed, these two steps of vaporization and condensation constitute a distillation process mediated by nanoparticles and driven by optical illumination. Because it does not require the heating of a large volume of fluid, this process requires substantially less energy than traditional distillation using thermal sources. We investigated nanoparticle-mediated, light-induced distillation of ethanol-H2O and 1-propanol-H2O mixtures, using Au-SiO2 nanoshells as the absorber-scatterer nanoparticle and nanoparticle-resonant laser irradiation to drive the process. For ethanol-H2O mixtures, the mole fraction of ethanol obtained in the light-induced process is substantially higher than that obtained by conventional thermal distillation, essentially removing the ethanol-H2O azeotrope that limits conventional distillation. In contrast, for 1-propanol-H2O mixtures the distillate properties resulting from light-induced distillation were very similar to those obtained by thermal distillation. In the 1-propanol-H2O system, a nanoparticle-mediated, light-induced liquid-liquid phase separation was also observed. PMID:26535465

  13. New transient absorption observed in the spectrum of colloidal CdSe nanoparticles pumped with high-power femtosecond pulses

    SciTech Connect

    Burda, C.; Link, S.; Green, T.C.; El-Sayed, M.A.

    1999-12-09

    The power dependence of the transient absorption spectrum of CdSe nanoparticle colloids with size distribution of 4.0 {+-} 0.4 nm diameter is studied with femtosecond pump-probe techniques. At the lowest pump laser power, the absorption bleaching (negative spectrum) characteristic of the exciton spectrum is observed with maxima at 560 and 480 nm. As the pump laser power increases, two new transient absorptions at 510 and 590 nm with unresolved fast rise (<100 fs) and long decay times ({much{underscore}gt}150 ps) are observed. The energy of each of the positive absorption is red shifted from that of the bleach bands by {approximately}120 MeV. The origin of this shift is discussed in terms of the effect of the internal electric field of the many electron-hole pairs formed within the quantum dot at the high pump intensity, absorption from a metastable excited state or the formation of biexcitons.

  14. Transient altitude-induced compartment syndrome associated with fiberglass casts using waterproof cast padding.

    PubMed

    Kadzielski, John; Bae, Donald S

    2013-01-01

    Changes in aircraft cabin pressure and its interplay with a fixed diameter fiberglass cylindrical cast and the closed air cells in waterproof cast padding may cause a transient altitude-induced compartment syndrome. In this case series, 2 patients reported transient compartment syndromes that resolved with aircraft decent. As proof of concept, this work displays photographic and video evidence showing the difference in air cell volume from experimental data in a vacuum chamber as well as real-world volume changes at cruise altitude in a commercial airliner. Transient altitude-induced compartment syndromes associated with fiberglass casts using waterproof cast padding are real and surgeons and patients should be advised of this potentially devastating complication. PMID:23431541

  15. Implantation induced extended defects and transient enhanced diffusion in silicon

    SciTech Connect

    Chen, J.; Liu, J.; Listebarger, J.; Krishnamoorthy, W.; Zhang, L.; Jones, K.S.

    1995-08-01

    Transient enhanced diffusion (TED) of dopant in silicon caused by point defects during annealing of implanted. Si has become one of the essential concerns in miniaturization of silicon device technology. In order to control and minimize the TED effect, a fundamental understanding of the evolution of the point defects upon annealing and the interaction between point defects and extended defects and their effects on dopant diffusion is necessary. Our studies were carried out by two parts; (1) For understanding the evolution of <311> and <110> defects, B{sup +} and Si{sup +} implantation at energies (from 5 keV to 40 keV) and doses in the range from 5 x 10{sup 12} to 1 x 10{sup 14}/cm{sup 2} were used. The annealing kinetics were investigated using a N{sub 2} ambient with temperatures for time ranging from 500{degrees}C to 1100{degrees}C for time ranging from 3 min to 3 hours. A matrix of implant energy vs. dose on formation threshold of <311> and <110> defect, interstitials napped and dissolved condition were obtained. (2) For Understanding the interaction between Type II dislocation loop and point defect a B doped buried marker layer was used. The oxidation of silicon surface used as a interstitials injection source and a buried type II loop layer as a point defect detector used to quantify the flux of interstitials injected. Combining the flux measured by loops and dopant diffusion the D{sub I} C{sub I} was determined. The diffusion limited kinetics was concluded. The TED from <311> and EOR (End of Range) <110> defect was studied using 8keV B{sup +} implanted Si to a dose of the le14 and 190keV Ge{sub +} implanted to a dose of le15. Subsequent anneals are done for 5 min and 30 min, respectively, These defects affect dopant diffusion by trapping and releasing point defects.

  16. Quantification of laser local hyperthermia induced by gold plasmonic nanoparticles.

    PubMed

    Yakunin, Alexander N; Avetisyan, Yuri A; Tuchin, Valery V

    2015-05-01

    This paper discusses one of the key problems of laser-induced tissue/cell hyperthermia mediated by gold nanoparticles, namely, quantifying and precise prediction of the light exposure to provide a controllable local heating impact on living organisms. The distributions of such parameters as an efficiency factor of absorption, differential and integral absorbing power of a nanoparticle, temperature increment, and Arrhenius damage integral were used to quantify nanoparticle effectiveness in the two-dimensional coordinate space “laser wavelength (λ) × radius of gold nanoparticles (R).” It was found that the fulfillment of required spatial and temporal characteristics of temperature fields in the vicinity of nanoparticle determines the optimal λ and R. As a result, the area in the space (λ × R) with a minimal criticality to alterations of the local hyperthermia may be significantly displaced from the position of the plasmonic resonance. The aspects of generalization of the proposed methodology for the analysis of local hyperthermia using nanoparticles of different shapes (nanoshells, nanorods, nanostars) and short pulse laser radiation are discussed. PMID:25629389

  17. In Caenorhabditis elegans Nanoparticle-Bio-Interactions Become Transparent: Silica-Nanoparticles Induce Reproductive Senescence

    PubMed Central

    Bossinger, Olaf; von Mikecz, Anna

    2009-01-01

    While expectations and applications of nanotechnologies grow exponentially, little is known about interactions of engineered nanoparticles with multicellular organisms. Here we propose the transparent roundworm Caenorhabditis elegans as a simple but anatomically and biologically well defined animal model that allows for whole organism analyses of nanoparticle-bio-interactions. Microscopic techniques showed that fluorescently labelled nanoparticles are efficiently taken up by the worms during feeding, and translocate to primary organs such as epithelial cells of the intestine, as well as secondary organs belonging to the reproductive tract. The life span of nanoparticle-fed Caenorhabditis elegans remained unchanged, whereas a reduction of progeny production was observed in silica-nanoparticle exposed worms versus untreated controls. This reduction was accompanied by a significant increase of the ‘bag of worms’ phenotype that is characterized by failed egg-laying and usually occurs in aged wild type worms. Experimental exclusion of developmental defects suggests that silica-nanoparticles induce an age-related degeneration of reproductive organs, and thus set a research platform for both, detailed elucidation of molecular mechanisms and high throughput screening of different nanomaterials by analyses of progeny production. PMID:19672302

  18. Resveratrol-loaded Nanoparticles Induce Antioxidant Activity against Oxidative Stress

    PubMed Central

    Kim, Jae-Hwan; Park, Eun-Young; Ha, Ho-Kyung; Jo, Chan-Mi; Lee, Won-Jae; Lee, Sung Sill; Kim, Jin Wook

    2016-01-01

    Resveratrol acts as a free radical scavenger and a potent antioxidant in the inhibition of numerous reactive oxygen species (ROS). The function of resveratrol and resveratrol-loaded nanoparticles in protecting human lung cancer cells (A549) against hydrogen peroxide was investigated in this study. The 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid (ABTS) assay was performed to evaluate the antioxidant properties. Resveratrol had substantially high antioxidant capacity (trolox equivalent antioxidant capacity value) compared to trolox and vitamin E since the concentration of resveratrol was more than 50 μM. Nanoparticles prepared from β-lactoglobulin (β-lg) were successfully developed. The β-lg nanoparticle showed 60 to 146 nm diameter in size with negatively charged surface. Non-cytotoxicity was observed in Caco-2 cells treated with β-lg nanoparticles. Fluorescein isothiocynate-conjugated β-lg nanoparticles were identified into the cell membrane of Caco-2 cells, indicating that nanoparticles can be used as a delivery system. Hydrogen peroxide caused accumulation of ROS in a dose- and time-dependent manner. Resveratrol-loaded nanoparticles restored H2O2-induced ROS levels by induction of cellular uptake of resveratrol in A549 cells. Furthermore, resveratrol activated nuclear factor erythroid 2-related factor 2-Kelch ECH associating protein 1 (Nrf2-Keap1) signaling in A549 cells, thereby accumulation of Nrf2 abundance, as demonstrated by western blotting approach. Overall, these results may have implications for improvement of oxidative stress in treatment with nanoparticles as a biodegradable and non-toxic delivery carrier of bioactive compounds. PMID:26732454

  19. Cationic nanoparticles induce nanoscale disruption in living cell plasma membranes.

    PubMed

    Chen, Jiumei; Hessler, Jessica A; Putchakayala, Krishna; Panama, Brian K; Khan, Damian P; Hong, Seungpyo; Mullen, Douglas G; Dimaggio, Stassi C; Som, Abhigyan; Tew, Gregory N; Lopatin, Anatoli N; Baker, James R; Holl, Mark M Banaszak; Orr, Bradford G

    2009-08-13

    It has long been recognized that cationic nanoparticles induce cell membrane permeability. Recently, it has been found that cationic nanoparticles induce the formation and/or growth of nanoscale holes in supported lipid bilayers. In this paper, we show that noncytotoxic concentrations of cationic nanoparticles induce 30-2000 pA currents in 293A (human embryonic kidney) and KB (human epidermoid carcinoma) cells, consistent with a nanoscale defect such as a single hole or group of holes in the cell membrane ranging from 1 to 350 nm(2) in total area. Other forms of nanoscale defects, including the nanoparticle porating agents adsorbing onto or intercalating into the lipid bilayer, are also consistent; although the size of the defect must increase to account for any reduction in ion conduction, as compared to a water channel. An individual defect forming event takes 1-100 ms, while membrane resealing may occur over tens of seconds. Patch-clamp data provide direct evidence for the formation of nanoscale defects in living cell membranes. The cationic polymer data are compared and contrasted with patch-clamp data obtained for an amphiphilic phenylene ethynylene antimicrobial oligomer (AMO-3), a small molecule that is proposed to make well-defined 3.4 nm holes in lipid bilayers. Here, we observe data that are consistent with AMO-3 making approximately 3 nm holes in living cell membranes. PMID:19606833

  20. Inducing Transient Charge State of a Single Water Cluster on Cu(111) Surface.

    PubMed

    Guo, Yang; Ding, Zijing; Sun, Lihuan; Li, Jianmei; Meng, Sheng; Lu, Xinghua

    2016-04-26

    The hydrated electron on solid surface is a crucial species to interfacial chemistry. We present a joint low-temperature scanning tunneling microscopy and density functional theory investigation to explore the existence of a transient hydrated electron state induced by injecting tunneling electrons into a single water nonamer cluster on Cu(111) surface. The directional diffusion of water cluster under the Coulomb repulsive potential has been observed as evidence for the emergence of the transient hydrated electron. A critical structure transformation in water cluster for the emergence of hydrated electron has been identified. A charging mechanism has been proposed based on density functional theory calculation and scanning tunneling microscope results. PMID:27007702

  1. Compensation of the Kerr effect for transient optomechanically induced transparency in a silica microsphere.

    PubMed

    Shen, Zhen; Dong, Chun-Hua; Chen, Yuan; Xiao, Yun-Feng; Sun, Fang-Wen; Guo, Guang-Can

    2016-03-15

    We have studied the Kerr effect in silica microspheres and demonstrated compensation of the Kerr effect for transient optomechanically induced transparency (OMIT). Due to the Kerr effect of the temporal strong driving pulse, an asymmetric transparency dip is observed during the transient OMIT experiment when the laser frequency is locked at one mechanical frequency, ω(m), below the whispering gallery mode resonance using a weak locking pulse. For compensation of the Kerr effect, we lock the laser at a lower frequency and show the symmetric transparency window. These results are important for studying photon-phonon interconversion, especially in systems with strong driving power. PMID:26977681

  2. Significance of Persistent Inflammation in Respiratory Disorders Induced by Nanoparticles

    PubMed Central

    Morimoto, Yasuo; Izumi, Hiroto; Kuroda, Etsushi

    2014-01-01

    Pulmonary inflammation, especially persistent inflammation, has been found to play a key role in respiratory disorders induced by nanoparticles in animal models. In inhalation studies and instillation studies of nanomaterials, persistent inflammation is composed of neutrophils and alveolar macrophages, and its pathogenesis is related to chemokines such as the cytokine-induced neutrophil chemoattractant (CINC) family and macrophage inflammatory protein-1α and oxidant stress-related genes such as heme oxygenase-1 (HO-1). DNA damages occur chemically or physically by nanomaterials. Chemical and physical damage are associated with point mutation by free radicals and double strand brake, respectively. The failure of DNA repair and accumulation of mutations might occur when inflammation is prolonged, and finally normal cells could become malignant. These free radicals can not only damage cells but also induce signaling molecules containing immunoreaction. Nanoparticles and asbestos also induce the production of free radicals. In allergic responses, nanoparticles act as Th2 adjuvants to activate Th2 immune responses such as activation of eosinophil and induction of IgE. Taken together, the presence of persistent inflammation may contribute to the pathogenesis of a variety of diseases induced by nanomaterials. PMID:25097864

  3. X-ray Detection of Transient Magnetic Moments Induced by a Spin Current in Cu.

    PubMed

    Kukreja, R; Bonetti, S; Chen, Z; Backes, D; Acremann, Y; Katine, J A; Kent, A D; Dürr, H A; Ohldag, H; Stöhr, J

    2015-08-28

    We have used a MHz lock-in x-ray spectromicroscopy technique to directly detect changes in magnetic moment of Cu due to spin injection from an adjacent Co layer. The elemental and chemical specificity of x rays allows us to distinguish two spin current induced effects. We detect the creation of transient magnetic moments of 3×10^{-5}μ_{B} on Cu atoms within the bulk of the 28 nm thick Cu film due to spin accumulation. The moment value is compared to predictions by Mott's two current model. We also observe that the hybridization induced existing magnetic moments at the Cu interface atoms are transiently increased by about 10% or 4×10^{-3}μ_{B} per atom. This reveals the dominance of spin-torque alignment over Joule heat induced disorder of the interfacial Cu moments during current flow. PMID:26371670

  4. X-ray Detection of Transient Magnetic Moments Induced by a Spin Current in Cu

    NASA Astrophysics Data System (ADS)

    Kukreja, R.; Bonetti, S.; Chen, Z.; Backes, D.; Acremann, Y.; Katine, J. A.; Kent, A. D.; Dürr, H. A.; Ohldag, H.; Stöhr, J.

    2015-08-01

    We have used a MHz lock-in x-ray spectromicroscopy technique to directly detect changes in magnetic moment of Cu due to spin injection from an adjacent Co layer. The elemental and chemical specificity of x rays allows us to distinguish two spin current induced effects. We detect the creation of transient magnetic moments of 3 ×10-5μB on Cu atoms within the bulk of the 28 nm thick Cu film due to spin accumulation. The moment value is compared to predictions by Mott's two current model. We also observe that the hybridization induced existing magnetic moments at the Cu interface atoms are transiently increased by about 10% or 4 ×10-3μB per atom. This reveals the dominance of spin-torque alignment over Joule heat induced disorder of the interfacial Cu moments during current flow.

  5. X-ray detection of transient magnetic moments induced by a spin current in Cu

    SciTech Connect

    Kukreja, R.; Bonetti, S.; Chen, Z.; Backes, D.; Acremann, Y.; Katine, J.; Kent, A. D.; Durr, H. A.; Ohldag, H.; Stohr, J.

    2015-08-24

    We have used a MHz lock-in x-ray spectromicroscopy technique to directly detect changes in magnetic moment of Cu due to spin injection from an adjacent Co layer. The elemental and chemical specificity of x rays allows us to distinguish two spin current induced effects. We detect the creation of transient magnetic moments of 3×10–5μB on Cu atoms within the bulk of the 28 nm thick Cu film due to spin accumulation. The moment value is compared to predictions by Mott’s two current model. We also observe that the hybridization induced existing magnetic moments at the Cu interface atoms are transiently increased by about 10% or 4×10–3μB per atom. As a result, this reveals the dominance of spin-torque alignment over Joule heat induced disorder of the interfacial Cu moments during current flow.

  6. A study of transient induced voltages on a MAGLEV train coil system

    SciTech Connect

    Ametani, A.; Kato, R.; Nishinaga, H.; Okai, M.

    1995-07-01

    The paper discusses transient induced voltages to a coil system of a magnetic-levitation (MAGLEV) train planned in Japan from an overhead ground wire (GW) which protects the coil system from a lightning stroke. A simplified lumped-circuit coil model is developed based on a two-port theory of an L equivalent circuit of a distributed-parameter line. Its impedances are evaluated from the impedance and admittance matrices of an overhead multiconductor system, which represents a coil, using the EMTP CABLE CONSTANTS. Calculated results of transient induced voltages by the proposed coil model agree satisfactorily with experimental results. It is made clear that the greater the ground resistance and the smaller the separation between the coil and the GW and the span length of grounding, the greater the induced voltage.

  7. Distinguishing cells by their first-order transient motion response under an optically induced dielectrophoretic force field

    NASA Astrophysics Data System (ADS)

    Zhao, Yuliang; Liang, Wenfeng; Zhang, Guanglie; Mai, John D.; Liu, Lianqing; Lee, Gwo-Bin; Li, Wen J.

    2013-10-01

    This letter reports our characterization of the transient motion of cells under an optically induced dielectrophoresis (ODEP) force field. Different types of human cells repeatably undergo a first-order transient motion response when subjected to a specific ODEP force field. A kernel function is derived to describe this transient motion. This function can be generally matched to experimental data for Raji cells and red blood cells by measuring two parameters: the initial velocity and the transient time-constant. They are uniquely different for Raji cells and RBCs. Support vector machine is used to distinguish between them based on their transient response characteristics.

  8. Transient Cardiomyopathy and Quadriplegia Induced by Ephedrine Decongestant

    PubMed Central

    Kurklinsky, Andrew K.; Chirila, Razvan

    2015-01-01

    Ephedrine decongestant products are widely used. Common side effects include palpitations, nervousness, and headache. More severe adverse reactions include cardiomyopathy and vasospasm. We report the case of an otherwise healthy 37-year-old woman who presented with acute-onset quadriplegia and heart failure. She had a normal chest radiograph on admission, but developed marked pulmonary edema and bilateral effusions the next day. Echocardiography revealed a left ventricular ejection fraction of 0.18 and no obvious intrinsic pathologic condition such as foramen narrowing on spinal imaging. Laboratory screening was positive for methamphetamines in the urine, and the patient admitted to having used, over the past several weeks, multiple ephedrine-containing products for allergy-symptom relief. She was ultimately diagnosed with an acute catecholamine-induced cardiomyopathy and spinal artery vasospasm consequential to excessive use of decongestants. Her symptoms resolved completely with supportive care and appropriate heart-failure management. An echocardiogram 2 weeks after admission showed improvement of the left ventricular ejection fraction to 0.33. Ten months after the event, the patient was entirely asymptomatic and showed further improvement of her ejection fraction to 0.45. To our knowledge, ours is the first report of spinal artery vasospasm resulting in quadriplegia in a human being after ephedrine ingestion. PMID:26664316

  9. Nanoparticle-induced twist-grain boundary phase

    NASA Astrophysics Data System (ADS)

    Trček, Maja; Cordoyiannis, George; Tzitzios, Vassilios; Kralj, Samo; Nounesis, George; Lelidis, Ioannis; Kutnjak, Zdravko

    2014-09-01

    By means of high-resolution ac calorimetry and polarizing optical microscopy, it is demonstrated that surface-functionalized spherical CdSSe nanoparticles induce a twist-grain boundary phase when dispersed in a chiral liquid crystal. These nanoparticles can effectively stabilize the one-dimensional lattice of screw dislocations, thus establishing the twist-grain boundary order between the cholesteric and the smectic-A phases. A Landau-de Gennes-Ginzburg model is used to analyze the impact of nanoparticles on widening the temperature range of molecular organizations possessing a lattice of screw dislocations. We show that in addition to the defect-core-replacement mechanism, the saddle-splay elasticity may also play a significant role.

  10. Nanoparticle-induced twist-grain boundary phase.

    PubMed

    Trček, Maja; Cordoyiannis, George; Tzitzios, Vassilios; Kralj, Samo; Nounesis, George; Lelidis, Ioannis; Kutnjak, Zdravko

    2014-09-01

    By means of high-resolution ac calorimetry and polarizing optical microscopy, it is demonstrated that surface-functionalized spherical CdSSe nanoparticles induce a twist-grain boundary phase when dispersed in a chiral liquid crystal. These nanoparticles can effectively stabilize the one-dimensional lattice of screw dislocations, thus establishing the twist-grain boundary order between the cholesteric and the smectic-A phases. A Landau-de Gennes-Ginzburg model is used to analyze the impact of nanoparticles on widening the temperature range of molecular organizations possessing a lattice of screw dislocations. We show that in addition to the defect-core-replacement mechanism, the saddle-splay elasticity may also play a significant role. PMID:25314459

  11. Superior neuroprotective effects of cerebrolysin in nanoparticle-induced exacerbation of hyperthermia-induced brain pathology.

    PubMed

    Sharma, Aruna; Muresanu, Dafin Fior; Mössler, Herbert; Sharma, Hari Shanker

    2012-02-01

    In recent years, the incidence of heat stroke and associated brain pathology are increasing Worldwide. More than half of the world's population are living in areas associated with high environmental heat especially during the summer seasons. Thus, new research is needed using novel drug targets to achieve neuroprotection in heat-induced brain pathology. Previous research from our laboratory showed that the pathophysiology of brain injuries following heat stroke are exacerbated by chronic intoxication of engineered nanoparticles of small sizes (50-60 nm) following identical heat exposure in rats. Interestingly, in nanoparticle-intoxicated animals the known neuroprotective agents in standard doses failed to induce effective neuroprotection. This suggests that the dose-response of the drugs either requires modification or new therapeutic agents are needed to provide better neuroprotection in nanoparticle-intoxicated animals after heat stroke. This review is focused on the use of cerebrolysin, a mixture of several neurotrophic factors and active peptide fragments, in relation to other neuroprotective agents normally used to treat ischemic stroke in clinics in nanoparticle-induced exacerbation of brain damage in heat stroke. It appears that cerebrolysin exerts the most superior neuroprotective effects in heat stress as compared to other neuroprotective agents on brain pathology in normal rats. Interestingly, to induce effective neuroprotection in nanoparticle-induced exacerbation of brain pathology a double dose of cerebrolysin is needed. On the other hand, double doses of the other drugs were quite ineffective in reducing brain damage. These observations suggest that the drug type and doses are important factors in attenuating nanoparticle-induced exacerbation of brain pathology in heat stroke. The functional significance and possible mechanisms of drug-induced neuroprotection in nanoparticle-treated, heat-stressed rats are discussed. PMID:22229316

  12. Simulation of thermal-transient-induced-pipe-flow stratification using COMMIX-2

    SciTech Connect

    Shah, V.L.; Domanus, H.M.; Miao, C.C.; Schmitt, R.C.; Sha, W.T.

    1982-01-01

    At low-flow (high Richardson number) in a piping system with thermal transient, thermal-buoyancy-induced secondary flows exist. Three-dimensional computer codes are, therefore, necessary to model correctly the non-axisymmetric, thermally stratified flow through a piping system. This paper presents the results of the numerical simulation of thermal-hydraulic behavior in a pipe during a thermal transient. The particular transient considered was the experimental test No. PIPE2, and carried out at the Mixing Components Test Facility (MCTF). The numerical simulation was performed using COMMIX-2. COMMIX-2 is a computer code for steady/unsteady, three-dimensional, two-phase thermal-hydraulic analysis of reactor components under normal and off-normal operating conditions. The results of simulation are compared with the experimental measurements and they are in reasonable agreement with experimental data.

  13. Heat-induced spinodal decomposition of Ag-Cu nanoparticles.

    PubMed

    Sopoušek, Jiří; Zobač, Ondřej; Buršík, Jiří; Roupcová, Pavla; Vykoukal, Vít; Brož, Pavel; Pinkas, Jiří; Vřešt'ál, Jan

    2015-11-14

    Solvothermal synthesis was used for Ag-Cu nanoparticle (NP) preparation from metallo-organic precursors. The detailed NP characterization was performed to obtain information about nanoparticle microstructure and both phase and chemical compositions. The resulting nanoparticles exhibited chemical composition inside a FCC_Ag + FCC_Cu two-phase region. The microstructure study was performed by various methods of electron microscopy including high-resolution transmission electron microscopy (HRTEM) at an atomic scale. The HRTEM and X-ray diffraction studies showed that the prepared nanoparticles form the face centred cubic (FCC) crystal lattice where the silver atoms are randomly mixed with copper. The CALPHAD approach was used for predicting the phase diagram of the Ag-Cu system in both macro- and nano-scales. The predicted spinodal decomposition of the metastable Ag-Cu nanoparticles was experimentally induced by heating on an X-ray powder diffractometer (HT XRD). The nucleation of the Cu-rich phase was detected and its growth was studied. Changes in the Ag-rich phase were observed in situ by X-ray diffraction under vacuum. The heat treatment was conducted at different maximum temperatures up to 450 °C and the resulting particle product was analysed. The experiments were complemented by differential scanning calorimetry (DSC) measurements up to liquidus temperature. The start temperatures of the spinodal phase transformation and particle aggregation were evaluated. PMID:25929324

  14. Nanoparticles induced multiferroicity in liquid crystal

    NASA Astrophysics Data System (ADS)

    Ganguly, Prasun; Kumar, Ajay; Muralidhar, K.; Biradar, A. M.

    2016-05-01

    Soft multiferroic character has been observed in a ferroelectric liquid crystal (FLC) dispersed with nickel nanoparticles (Ni NPs). A suitable amount of ferromagnetic Ni NPs has been added into FLC material, and the co-existence of ferroelectric and ferromagnetic ordering is examined using P-E and M-H hysteresis measurements. The magnitude of ferromagnetic order is found to depend strongly on the concentration of Ni NPs. Our theoretical approach indicated a strong dependence of helical pitch of FLC on the doping concentration of Ni NPs. We proposed that the intrinsic magnetic field of Ni NPs has been coupled with that of director field of the FLC molecules to result in the observed multiferroic behavior.

  15. Surface spin polarization induced ferromagnetic Ag nanoparticles

    NASA Astrophysics Data System (ADS)

    Shih, Po-Hsun; Li, Wen-Hsien; Wu, Sheng Yun

    2016-05-01

    We report on the observation of ferromagnetic spin polarized moments in 4.5 nm Ag nanoparticles. Both ferromagnetic and diamagnetic responses to an applied magnetic field were detected. The spin polarized moments shown under non-linear thermoinduced magnetization appeared on the surface atoms, rather than on all the atoms in particles. The saturation magnetization departed substantially from the Bloch T3/2-law, showing the existence of magnetic anisotropy. The Heisenberg ferromagnetic spin wave model for Ha-aligned moments was then employed to identify the magnetic anisotropic energy gap of ~0.12 meV. Our results may be understood by assuming the surface magnetism model, in which the surface atoms give rise to polarized moments while the core atoms produce diamagnetic responses.

  16. Investigations of the ultrafast laser induced melt dynamics by means of transient quantitative phase microscopy (TQPm)

    NASA Astrophysics Data System (ADS)

    Mingareev, Ilya; Horn, Alexander

    2008-05-01

    Modifications of bulk aluminum irradiated well above ablation threshold (F < 300 J.cm-2) have been investigated in situ by means of shadowgraphy and transient quantitative phase microscopy (TQPm) using ultrafast laser radiation (tp=80 fs, λ=800 nm). This novel pump-probe technique enables quantitative time-resolved measurements of object's properties, e.g. dimensions of melt droplets and layer thickness or transient refractive index changes. A series of time-resolved phase images of vaporized material and/or melt, which are induced by n=1..8 pulses on an aluminum target, are obtained using TQPm. Dynamics and characteristics of melting, dependence of the ablated material volume on process parameters and thereby induced structural modifications have been studied. An increase of material ejection rate is observed at delay time of approximately τ=300 ns and τ>800 ns after the incident pulse. Transient refractive index modifications have been investigated in technical glass (Schott D263) by means of TQPm. By using high-repetition rate ultra-short pulsed laser radiation (tp=400 fs, λ=1045 nm, frep=1 MHz) focused by a microscope objective (w0 ~ 4 μm) heat accumulation and thereby glass melting as well as welding is enabled. Transient optical phase variation has been measured up to τ=2.1 μs after the incident pulse and can be attributed to the generation of free charge carriers and compression forces inside glass.

  17. Cerium oxide nanoparticle treatment ameliorates peritonitis-induced diaphragm dysfunction

    PubMed Central

    Asano, Shinichi; Arvapalli, Ravikumar; Manne, Nandini DPK; Maheshwari, Mani; Ma, Bing; Rice, Kevin M; Selvaraj, Vellaisamy; Blough, Eric R

    2015-01-01

    The severe inflammation observed during sepsis is thought to cause diaphragm dysfunction, which is associated with poor patient prognosis. Cerium oxide (CeO2) nanoparticles have been posited to exhibit anti-inflammatory and antioxidative activities suggesting that these particles may be of potential use for the treatment of inflammatory disorders. To investigate this possibility, Sprague Dawley rats were randomly assigned to the following groups: sham control, CeO2 nanoparticle treatment only (0.5 mg/kg iv), sepsis, and sepsis+CeO2 nanoparticles. Sepsis was induced by the introduction of cecal material (600 mg/kg) directly into the peritoneal cavity. Nanoparticle treatment decreased sepsis-associated impairments in diaphragmatic contractile (Po) function (sham: 25.6±1.6 N/cm2 vs CeO2: 23.4±0.8 N/cm2 vs Sep: 15.9±1.0 N/cm2 vs Sep+CeO2: 20.0±1.0 N/cm2, P<0.05). These improvements in diaphragm contractile function were accompanied by a normalization of protein translation signaling (Akt, FOXO-1, and 4EBP1), diminished proteolysis (caspase 8 and ubiquitin levels), and decreased inflammatory signaling (Stat3 and iNOS). Histological analysis suggested that nanoparticle treatment was associated with diminished sarcolemma damage and diminished inflammatory cell infiltration. These data indicate CeO2 nanoparticles may improve diaphragmatic function in the septic laboratory rat. PMID:26491293

  18. Heavy Ion Microbeam- and Broadbeam-Induced Transients in SiGe HBTs

    NASA Technical Reports Server (NTRS)

    Pellish, Jonathan A.; Reed, Robert A.; McMorrow, Dale; Vizkelethy, Gyorgy; Ferlet-Cavrois, Veronique; Baggio, Jacques; Duhamel, Olivier; Moen, Kurt A.; Phillips, Stanley D.; Diestelhorst, Ryan M.; Cressler, John D.; Sutton, Akil K.; Raman, Ashok; Turowski, Marek; Dodd, Paul E.; Alles, Michael L.; Schrimpf, Ronald D.; Marshall, Paul W.; LaBel, Kenneth A.

    2009-01-01

    SiGe HBT heavy ion-induced current transients are measured using Sandia National Laboratories microbeam and high- and low-energy broadbeam sources at the Grand Accelerateur National d'Ions Lourds and the University of Jyvaskyla. The data were captured using a custom broadband IC package and real-time digital phosphor oscilloscopes with at least 16 GHz of analog bandwidth. These data provide detailed insight into the effects of ion strike location, range, and LET.

  19. Laser-induced plasma generation and evolution in a transient spray.

    PubMed

    Kawahara, Nobuyuki; Tsuboi, Kazuya; Tomita, Eiji

    2014-01-13

    The behaviors of laser-induced plasma and fuel spray were investigated by visualizing images with an ultra-high-speed camera. Time-series images of laser-induced plasma in a transient spray were visualized using a high-speed color camera. The effects of a shockwave generated from the laser-induced plasma on the evaporated spray behavior were investigated. The interaction between a single droplet and the laser-induced plasma was investigated using a single droplet levitated by an ultrasonic levitator. Two main conclusions were drawn from these experiments: (1) the fuel droplets in the spray were dispersed by the shockwave generated from the laser-induced plasma; and (2) the plasma position may have shifted due to breakdown of the droplet surface and the lens effect of droplets. PMID:24921999

  20. Transient radiation-induced absorption in materials for the DOI laser

    SciTech Connect

    Brannon, P.J.

    1995-01-01

    This is the final report on a series of experiments concerned with transient radiation-induced absorption in materials for a Cr,Nd:GSGG laser. Both the Sandia National Laboratories SPR III pulsed reactor and the Hermes III pulsed X-ray machine are used as radiation sources. The time dependence and the magnitude of the induced absorption in filter glasses and in doped and undoped LiNbO{sub 3} Q-switch materials have been measured. Gain has been observed in Cr,Nd:GSGG, the laser medium, when it is irradiated by X-rays.

  1. Transient radiation-induced absorption in materials for the DOI laser

    NASA Astrophysics Data System (ADS)

    Brannon, P. J.

    1994-11-01

    This is the final report on a series of experiments concerned with transient radiation-induced absorption in materials for a Cr,Nd:GSGG laser. Both the Sandia National Laboratories SPR III pulsed reactor and the Hermes III pulsed X-ray machine are used as radiation sources. The time dependence and the magnitude of the induced absorption in filter glasses and in doped and undoped LiNbO3 Q-switch materials have been measured. Gain has been observed in Cr,Nd:GSGG, the laser medium, when it is irradiated by X-rays.

  2. Solvent-induced desorption of alkanethiol ligands from Au nanoparticles.

    PubMed

    Huang, Yuanyuan; Liu, Wei; Cheng, Hao; Yao, Tao; Yang, Lina; Bao, Jie; Huang, Ting; Sun, Zhihu; Jiang, Yong; Wei, Shiqiang

    2016-06-21

    Removing surfactants from a colloidal metal nanoparticle surface is necessary for their realistic applications, and how they could be stripped is a subject of active investigation. Here, we report a solvent-induced desorption of dodecanethiol ligands from the gold nanoparticle surface, and traced this desorption process using a combination of in situ X-ray absorption fine structure (XAFS) and Raman spectroscopic techniques. In situ analysis results reveal that the solvent exchange of ethanol with tetrahydrofuran (THF) can effectively remove dodecanethiol ligands while keeping the particle morphology unchanged. Upon increasing the THF/ethanol ratio from 0 : 1 to 5 : 1, the surface coverage of thiol on the Au surface is reduced from 0.47 to 0.07, suggesting the depletion of ligands first from the nanoparticle facet sites, then from the edge sites, while the ligands at the corner sites are intact. This work enriches our knowledge on surfactant removal and may pave the way towards preparing surface-clean nanoparticles for practical applications. PMID:27241025

  3. Transient variation of a cross-sectional area of inkjet-printed silver nanoparticle ink during furnace sintering

    NASA Astrophysics Data System (ADS)

    Kim, Dongkeun; Lee, Iksang; Yoo, Youngbum; Moon, Yoon-Jae; Moon, Seung-Jae

    2014-06-01

    In this work, the transient variation of a cross-sectional area of inkjet-printed silver nanoparticle ink was monitored as a function of temperature. The ink was composed of 34 wt% silver nanoparticles with an average grain size of 50 nm. In order to determine the relationship between shrinkage and electrical properties, the cross-sectional area and specific resistance change were measured with various sintering temperatures and times. The samples were sintered at 150, 200, and 250 °C for 60, 120, 300, 600, 1200, and 3000 s. The cross-sectional profile was investigated in order to calculate the cross-sectional area of the ink using a surface profiler. To examine the mass transfer in a conductive line with various sintering temperatures and times, the surface morphology was investigated via field-emission scanning electron microscopy. As the temperature increased, the shrinkage ratio of the ink's cross-sectional area increased. By investigating the relationship between specific resistance and shrinkage, the sintering mechanisms can be determined.

  4. Lineage conversion induced by pluripotency factors involves transient passage through an iPS cell stage

    PubMed Central

    Bar-Nur, Ori; Verheul, Cassandra; Sommer, Andreia Gianotti; Brumbaugh, Justin; Schwarz, Benjamin A.; Lipchina, Inna; Huebner, Aaron J.; Mostoslavsky, Gustavo; Hochedlinger, Konrad

    2016-01-01

    Brief expression of pluripotency-associated factors such as Oct4, Klf4, Sox2 and c-Myc (OKSM), in combination with differentiation-inducing signals, was reported to trigger transdifferentiation of fibroblasts into other cell types. Here we show that OKSM expression in mouse fibroblasts gives rise to both induced pluripotent stem cells (iPSCs) and induced neural stem cells (iNSCs) under conditions previously shown to induce only iNSCs. Fibroblast-derived iNSC colonies silenced retroviral transgenes and reactivated silenced X chromosomes, both hallmarks of pluripotent stem cells. Moreover, lineage tracing with an Oct4-CreER labeling system demonstrated that virtually all iNSC colonies originated from cells transiently expressing Oct4, whereas ablation of Oct4+ cells prevented iNSC formation. Lastly, an alternative transdifferentiation cocktail that lacks Oct4 and was reportedly unable to support induced pluripotency yielded iPSCs and iNSCs carrying the Oct4-CreER-derived lineage label. Together, these data suggest that iNSC generation from fibroblasts using OKSM and other pluripotency-related reprogramming factors requires passage through a transient iPSC state. PMID:26098450

  5. Iron Oxide Nanoparticles Induce Autophagosome Accumulation through Multiple Mechanisms: Lysosome Impairment, Mitochondrial Damage, and ER Stress.

    PubMed

    Zhang, Xudong; Zhang, Hongqiu; Liang, Xin; Zhang, Jinxie; Tao, Wei; Zhu, Xianbing; Chang, Danfeng; Zeng, Xiaowei; Liu, Gan; Mei, Lin

    2016-07-01

    Magnetite (iron oxide, Fe3O4) nanoparticles have been widely used for drug delivery and magnetic resonance imaging (MRI). Previous studies have shown that many metal-based nanoparticles including Fe3O4 nanoparticles can induce autophagosome accumulation in treated cells. However, the underlying mechanism is still not clear. To investigate the biosafety of Fe3O4 and PLGA-coated Fe3O4 nanoparticles, some experiments related to the mechanism of autophagy induction by these nanoparticles have been investigated. In this study, the results showed that Fe3O4, PLGA-coated Fe3O4, and PLGA nanoparticles could be taken up by the cells through cellular endocytosis. Fe3O4 nanoparticles extensively impair lysosomes and lead to the accumulation of LC3-positive autophagosomes, while PLGA-coated Fe3O4 nanoparticles reduce this destructive effect on lysosomes. Moreover, Fe3O4 nanoparticles could also cause mitochondrial damage and ER and Golgi body stresses, which induce autophagy, while PLGA-coated Fe3O4 nanoparticles reduce the destructive effect on these organelles. Thus, the Fe3O4 nanoparticle-induced autophagosome accumulation may be caused by multiple mechanisms. The autophagosome accumulation induced by Fe3O4 was also investigated. The Fe3O4, PLGA-coated Fe3O4, and PLGA nanoparticle-treated mice were sacrificed to evaluate the toxicity of these nanoparticles on the mice. The data showed that Fe3O4 nanoparticle treated mice would lead to the extensive accumulation of autophagosomes in the kidney and spleen in comparison to the PLGA-coated Fe3O4 and PLGA nanoparticles. Our data clarifies the mechanism by which Fe3O4 induces autophagosome accumulation and the mechanism of its toxicity on cell organelles and mice organs. These findings may have an important impact on the clinical application of Fe3O4 based nanoparticles. PMID:27287467

  6. Plasmon-induced hot carriers in metallic nanoparticles.

    PubMed

    Manjavacas, Alejandro; Liu, Jun G; Kulkarni, Vikram; Nordlander, Peter

    2014-08-26

    Plasmon-induced hot carrier formation is attracting an increasing research interest due to its potential for applications in photocatalysis, photodetection and solar energy harvesting. However, despite very significant experimental effort, a comprehensive theoretical description of the hot carrier generation process is still missing. In this work we develop a theoretical model for the plasmon-induced hot carrier process and apply it to spherical silver nanoparticles and nanoshells. In this model, the conduction electrons of the metal are described as free particles in a finite spherical potential well, and the plasmon-induced hot carrier production is calculated using Fermi’s golden rule. We show that the inclusion of many-body interactions has only a minor influence on the results. Using the model we calculate the rate of hot carrier generation, finding that it closely follows the spectral profile of the plasmon. Our analysis reveals that particle size and hot carrier lifetime play a central role in determining both the production rate and the energy distribution of the hot carriers. Specifically, larger nanoparticle sizes and shorter lifetimes result in higher carrier production rates but smaller energies, and vice versa. We characterize the efficiency of the hot carrier generation process by introducing a figure of merit that measures the number of high energy carriers generated per plasmon. Furthermore, we analyze the spatial distribution and directionality of these excitations. The results presented here contribute to the basic understanding of plasmon-induced hot carrier generation and provide insight for optimization of the process. PMID:24960573

  7. Wounding Induces the Rapid and Transient Activation of a Specific MAP Kinase Pathway.

    PubMed Central

    Bogre, L.; Ligterink, W.; Meskiene, I.; Barker, P. J.; Heberle-Bors, E.; Huskisson, N. S.; Hirt, H.

    1997-01-01

    Mechanical injury in plants induces responses that are involved not only in healing but also in defense against a potential pathogen. To understand the intracellular signaling mechanism of wounding, we have investigated the involvement of protein kinases. Using specific antibodies, we showed that wounding alfalfa leaves specifically induces the transient activation of the p44MMK4 kinase, which belongs to the family of mitogen-activated protein kinases. Whereas activation of the MMK4 pathway is a post-translational process and was not blocked by [alpha]-amanitin and cycloheximide, inactivation depends on de novo transcription and translation of a protein factor(s). After wound-induced activation, the MMK4 pathway was subject to a refractory period of 25 min, during which time restimulation was not possible, indicating that the inactivation mechanism is only transiently active. After activation of the p44MMK4 kinase by wounding, transcript levels of the MMK4 gene increased, suggesting that the MMK4 gene may be a direct target of the MMK4 pathway. In contrast, transcripts of the wound-inducible MsWIP gene, encoding a putative proteinase inhibitor, were detected only several hours after wounding. Abscisic acid, methyl jasmonic acid, and electrical activity are known to mediate wound signaling in plants. However, none of these factors was able to activate the p44MMK4 kinase in the absence of wounding, suggesting that the MMK4 pathway acts independently of these signals. PMID:12237344

  8. Transient energy deficit induced by exercise increases 24-h fat oxidation in young trained men.

    PubMed

    Iwayama, Kaito; Kawabuchi, Ryosuke; Park, Insung; Kurihara, Reiko; Kobayashi, Masashi; Hibi, Masanobu; Oishi, Sachiko; Yasunaga, Koichi; Ogata, Hitomi; Nabekura, Yoshiharu; Tokuyama, Kumpei

    2015-01-01

    Whole body fat oxidation increases during exercise. However, 24-h fat oxidation on a day with exercise often remains similar to that of sedentary day, when energy intake is increased to achieve an energy-balanced condition. The present study aimed to examine a possibility that time of the day when exercise is performed makes differences in 24-h fat oxidation. As a potential mechanism of exercise affecting 24-h fat oxidation, its relation to exercise-induced transient energy deficit was examined. Nine young male endurance athletes underwent three trials of indirect calorimetry using a metabolic chamber, in which they performed a session of 100 min of exercise before breakfast (AM), after lunch (PM), or two sessions of 50 min of exercise before breakfast and after lunch (AM/PM) at 65% of maximal oxygen uptake. Experimental meals were designed to achieve individual energy balance. Twenty-four-hour energy expenditure was similar among the trials, but 24-h fat oxidation was 1,142 ± 97, 809 ± 88, and 608 ± 46 kcal/24 h in descending order of its magnitude for AM, AM/PM, and PM, respectively (P < 0.05). Twenty-four-hour carbohydrate oxidation was 2,558 ± 110, 2,374 ± 114, and 2,062 ± 96 kcal/24 h for PM, AM/PM, and AM, respectively. In spite of energy-balanced condition over 24 h, exercise induced a transient energy deficit, the magnitude of which was negatively correlated with 24-h fat oxidation (r = -0.72, P < 0.01). Similarly, transient carbohydrate deficit after exercise was negatively correlated with 24-h fat oxidation (r = -0.40, P < 0.05). The time of the day when exercise is performed affects 24-h fat oxidation, and the transient energy/carbohydrate deficit after exercise is implied as a factor affecting 24-h fat oxidation. PMID:25554797

  9. Transient photoconductivity in CdSe nanoparticles and nanocrystalline TiO2 as measured by time-resolved terahertz spectroscopy

    NASA Astrophysics Data System (ADS)

    Schmuttenmaer, Charles A.; Turner, Gordon M.; Beard, Matthew C.

    2003-12-01

    The transient photoconductivity of dye-sensitized nanocrystalline colloidal TiO2 has been measured time-resolved THz spectroscopy (TRTS), a non-contact electrical probe with sub-picosecond temporal resolution. The photoconductivity deviates strongly from Drude behavior and is explained by disorder-induced carrier localization and/or backscattering of the photogenerated carriers. In addition, the carriers are found to thermally equilibrate with the lattice in roughly 300 femtoseconds. The size-dependent photoconductivity of CdSe nanoparticles ranging from 2.54 nm up to >25 nm has also been measured using TRTS. The measured change in the frequency-dependent optical density and change in phase of the transmitted THz pulse fall into three distinct groupings as a function of size and can be classified for diameters smaller than the Bohr exciton radius, diameters greater than the Bohr exciton radius but smaller than the bulk mean free path, and diameters greater than the bulk mean free path. The underlying cause of the grouping is a size-dependent mobility (or carrier scattering rate).

  10. Relapse induced by cues predicting cocaine depends on rapid, transient synaptic potentiation

    PubMed Central

    Gipson, Cassandra D.; Kupchik, Yonatan M.; Shen, Haowei; Reissner, Kathryn J.; Thomas, Charles A.; Kalivas, Peter W.

    2013-01-01

    Summary Cocaine addiction is characterized by long-lasting vulnerability to relapse arising because neutral environmental stimuli become associated with drug use and then act as cues that induce relapse. It is not known how cues elicit cocaine seeking, and why cocaine seeking is more difficult to regulate than seeking a natural reward. We found that cocaine-associated cues initiate cocaine seeking by inducing a rapid, transient increase in dendritic spine size and synaptic strength in the nucleus accumbens. These changes required neural activity in the prefrontal cortex. This is not the case when identical cues were associated with obtaining sucrose, which did not elicit changes in spine size or synaptic strength. The marked cue-induced synaptic changes in the accumbens were correlated with the intensity of cocaine, but not sucrose seeking, and may explain the difficulty addicts experience in managing relapse to cocaine use. PMID:23473317

  11. An Optimized Nanoparticle Separator Enabled by Electron Beam Induced Deposition

    SciTech Connect

    Fowlkes, Jason Davidson; Doktycz, Mitchel John; Rack, P. D.

    2010-01-01

    Size based separations technologies will inevitably benefit from advances in nanotechnology. Direct write nanofabrication provides a useful mechanism to deposit/etch nanoscale elements in environments otherwise inaccessible to conventional nanofabrication techniques. Here, electron beam induced deposition (EBID) was used to deposit an array of nanoscale features in a 3D environment with minimal material proximity effects outside the beam interaction region (BIR). Specifically, the membrane component of a nanoparticle separator was fabricated by depositing a linear array of sharply tipped nanopillars, with a singular pitch, designed for sub 50nm nanoparticle permeability. The nanopillar membrane was used in a dual capacity to control the flow of nanoparticles in the transaxial direction of the array while facilitating the sealing of the cellular sized compartment in the paraxial direction. An optimized growth recipe resulted which (1) maximized the growth efficiency of the membrane (which minimizes proximity effects), (2) preserved the fidelity of spacing between nanopillars (which maximizes the size based gating quality of the membrane) while (3) maintaining sharp nanopillar apexes for impaling an optically transparent polymeric lid critical for device sealing.

  12. An optimized nanoparticle separator enabled by electron beam induced deposition.

    PubMed

    Fowlkes, J D; Doktycz, M J; Rack, P D

    2010-04-23

    Size-based separations technologies will inevitably benefit from advances in nanotechnology. Direct-write nanofabrication provides a useful mechanism for depositing/etching nanoscale elements in environments otherwise inaccessible to conventional nanofabrication techniques. Here, electron beam induced deposition was used to deposit an array of nanoscale features in a 3D environment with minimal material proximity effects outside the beam-interaction region. Specifically, the membrane component of a nanoparticle separator was fabricated by depositing a linear array of sharply tipped nanopillars, with a singular pitch, designed for sub-50 nm nanoparticle permeability. The nanopillar membrane was used in a dual capacity to control the flow of nanoparticles in the transaxial direction of the array while facilitating the sealing of the cellular-sized compartment in the paraxial direction. An optimized growth recipe resulted which (1) maximized the growth efficiency of the membrane (which minimizes proximity effects) and (2) preserved the fidelity of the spacing between nanopillars (which maximizes the size-based gating quality of the membrane) while (3) maintaining sharp nanopillar apexes for impaling an optically transparent polymeric lid critical for device sealing. PMID:20351412

  13. Transient photocurrent and photovoltage studies on charge transport in dye sensitized solar cells made from the composites of TiO2 nanofibers and nanoparticles

    NASA Astrophysics Data System (ADS)

    Wang, Xiaoxu; Karanjit, Sudeep; Zhang, Lifeng; Fong, Hao; Qiao, Qiquan; Zhu, Zhengtao

    2011-02-01

    Herein, we report the transient photocurrent and photovoltage studies on the charge transport in dye sensitized solar cells (DSSCs) made from the composites of electrospun titanium oxide (TiO2) nanofibers, and conventional TiO2 nanoparticles. The results on charge transport parameters (including the charge recombination lifetime, the electron transport lifetime, and the diffusion length) indicated that the addition of TiO2 nanofibers into composite photoanodes led to substantial improvement on the efficiency of charge collection, suggesting that the composites of nanoparticles and one-dimensional nanostructures are promising materials for the development of DSSCs with high efficiency.

  14. The performance of cable braids and terminations to lightning induced transients

    NASA Technical Reports Server (NTRS)

    Crofts, David

    1991-01-01

    The latest specification detailing the test waveforms for indirect lightning transients as applied to aircraft wiring systems specify very high voltages and currents. Although considerable data exists for measuring cable screen leakage using such methods as surface transfer impedance and bulk cable injection, there is little data on the likely core transient level that is likely to be induced from these threats. In particular, the new Waveform 5 at very high current levels (10 kA) is reputed to cause severe cable damage. A range of representative cables were made with various screen termination techniques and screening levels. These were tested first to determine their relative screening performance and then they were subjected to lightning transient testing to all the specified waveforms. Core voltages were measured for each test. Tests were also performed on bundles with fewer wires to determine the failure criteria with Waveform 5 and these tests also include flat conductor cables. The test showed that correctly terminated cable bundles performed well in all the tests and would provide a high level of protection to the electronic systems. The use of overbraides, provided the individual screens are well terminated, appears to be unnecessary.

  15. Dual-reporter in vivo imaging of transient and inducible heat-shock promoter activation

    PubMed Central

    Fortin, Pierre-Yves; Genevois, Coralie; Chapolard, Mathilde; Santalucía, Tomàs; Planas, Anna M.; Couillaud, Franck

    2014-01-01

    Gene promoter activity can be studied in vivo by molecular imaging methods using reporter gene technology. Transcription of the reporter and the reported genes occurs simultaneously. However, imaging depends on reporter protein translation, stability, and cellular fate that may differ among the various proteins. A double transgenic mouse strain expressing the firefly luciferase (lucF) and fluorescent mPlum protein under the transcriptional control of the thermo-inducible heat-shock protein (Hspa1b) promoter was generated allowing to follow up the reporter proteins by different and complementary in vivo imaging technologies. These mice were used for in vivo imaging by bioluminescence and epi fluorescence reflectance imaging (BLI & FRI) and as a source of embryonic fibroblast (MEF) for in vitro approaches. LucF, mPlum and endogenous Hsp70 mRNAs were transcribed simultaneously. The increase in mRNA was transient, peaking at 3 h and then returning to the basal level about 6 h after the thermal stimulations. The bioluminescent signal was transient and initiated with a 3 h delay versus mRNA expression. The onset of mPlum fluorescence was more delayed, increasing slowly up to 30 h after heat-shock and remaining for several days. This mouse allows for both bioluminescence imaging (BLI) and fluorescence reflectance imaging (FRI) of Hsp70 promoter activation showing an early and transient lucF activity and a retrospective and persistent mPlum fluorescence. This transgenic mouse will allow following the transient local induction of Hsp-70 promoter beyond its induction time-frame and relate into subsequent dynamic biological effects of the heat-shock response. PMID:24575340

  16. Dual-reporter in vivo imaging of transient and inducible heat-shock promoter activation.

    PubMed

    Fortin, Pierre-Yves; Genevois, Coralie; Chapolard, Mathilde; Santalucía, Tomàs; Planas, Anna M; Couillaud, Franck

    2014-02-01

    Gene promoter activity can be studied in vivo by molecular imaging methods using reporter gene technology. Transcription of the reporter and the reported genes occurs simultaneously. However, imaging depends on reporter protein translation, stability, and cellular fate that may differ among the various proteins. A double transgenic mouse strain expressing the firefly luciferase (lucF) and fluorescent mPlum protein under the transcriptional control of the thermo-inducible heat-shock protein (Hspa1b) promoter was generated allowing to follow up the reporter proteins by different and complementary in vivo imaging technologies. These mice were used for in vivo imaging by bioluminescence and epi fluorescence reflectance imaging (BLI & FRI) and as a source of embryonic fibroblast (MEF) for in vitro approaches. LucF, mPlum and endogenous Hsp70 mRNAs were transcribed simultaneously. The increase in mRNA was transient, peaking at 3 h and then returning to the basal level about 6 h after the thermal stimulations. The bioluminescent signal was transient and initiated with a 3 h delay versus mRNA expression. The onset of mPlum fluorescence was more delayed, increasing slowly up to 30 h after heat-shock and remaining for several days. This mouse allows for both bioluminescence imaging (BLI) and fluorescence reflectance imaging (FRI) of Hsp70 promoter activation showing an early and transient lucF activity and a retrospective and persistent mPlum fluorescence. This transgenic mouse will allow following the transient local induction of Hsp-70 promoter beyond its induction time-frame and relate into subsequent dynamic biological effects of the heat-shock response. PMID:24575340

  17. Ion beam induced effects on the ferromagnetism in Pd nanoparticles

    SciTech Connect

    Kulriya, P. K.; Mehta, B. R.; Agarwal, D. C.; Agarwal, Kanika; Kumar, Praveen; Shivaprasad, S. M.; Avasthi, D. K.

    2012-06-05

    Present study demonstrates the role of metal-insulator interface and ion irradiation induced defects on the ferromagnetic properties of the non-magnetic materials. Magnetic properties of the Pd nanoparticles(NPs) embedded in the a-silica matrix synthesized using atom beam sputtering technique, were determined using SQUID magnetometry measurements which showed that ferromagnetic response of Pd increased by 3.5 times on swift heavy ion(SHI) irradiation. The ferromagnetic behavior of the as-deposited Pd NPs is due to strain induced by the surrounding matrix and modification in the electronic structure at the Pd-silica interface as revealed by insitu XRD and XPS investigations, respectively. The defects created by the SHI bombardment are responsible for enhancement of the magnetization in the Pd NPs.

  18. Discrete nanoparticles induce loss of Legionella pneumophila biofilms from surfaces.

    PubMed

    Raftery, Tara D; Kerscher, Petra; Hart, Ashley E; Saville, Steven L; Qi, Bin; Kitchens, Christopher L; Mefford, Olin Thompson; McNealy, Tamara L

    2014-08-01

    Nanoparticles (NPs) have been shown to induce dispersal events in microbial biofilms but the mechanism of the dispersal is unknown. Biofilms contaminate many man-made aquatic systems such as cooling towers, spas and dental lines. Within these biofilms, Legionella pneumophila is a primary pathogen, leading to these environments serving as sources for disease outbreaks. Here we show a reduction in biofilm bio-volume upon treatment with citrate-coated 6-nm platinum NPs, polyethylene glycol (PEG)-coated 11-nm gold NPs, and PEG-coated 8-nm iron oxide NPs. Treatment with citrate-coated 8-nm silver NPs, however, did not reduce biomass. The synthesis of NPs that remain dispersed and resist irreversible aggregation in the exposure media appears to be a key factor in the ability of NPs to induce biofilm dispersal. PMID:23586422

  19. TiO2 Nanoparticles Induced Hippocampal Neuroinflammation in Mice

    PubMed Central

    Ze, Xiao; Yu, Xiaohong; Pan, Xiaoyu; Lin, Anan; Zhao, Yue; Zhang, Chi; Zhou, Qiuping; Wang, Ling; Hong, Fashui

    2014-01-01

    Titanium dioxide nanoparticles (TiO2 NPs) have been used in various medical and industrial areas. However, the impacts of these nanoparticles on neuroinflammation in the brain are poorly understood. In this study, mice were exposed to 2.5, 5, or 10 mg/kg body weight TiO2 NPs for 90 consecutive days, and the TLRs/TNF-α/NF-κB signaling pathway associated with the hippocampal neuroinflammation was investigated. Our findings showed titanium accumulation in the hippocampus, neuroinflammation and impairment of spatial memory in mice following exposure to TiO2 NPs. Furthermore, TiO2 NPs significantly activated the expression of Toll-like receptors (TLR2, TLR4), tumor necrosis factor-α, nucleic IκB kinase, NF-κB-inducible kinase, nucleic factor–κB, NF-κB2(p52), RelA(p65), and significantly suppressed the expression of IκB and interleukin-2. These findings suggest that neuroinflammation may be involved in TiO2 NP-induced alterations of cytokine expression in mouse hippocampus. Therefore, more attention should be focused on the application of TiO2 NPs in the food industry and their long-term exposure effects, especially in the human central nervous system. PMID:24658543

  20. Functionalized nanoparticles for AMF-induced gene and drug delivery

    NASA Astrophysics Data System (ADS)

    Biswas, Souvik

    The properties and broad applications of nano-magnetic colloids have generated much interest in recent years. Specially, Fe3O4 nanoparticles have attracted a great deal of attention since their magnetic properties can be used for hyperthermia treatment or drug targeting. For example, enhanced levels of intracellular gene delivery can be achieved using Fe3O4 nano-vectors in the presence of an external magnetic field, a process known as 'magnetofection'. The low cytotoxicity, tunable particle size, ease of surface functionalization, and ability to generate thermal energy using an external alternating magnetic field (AMF) are properties have propelled Fe3O4 research to the forefront of nanoparticle research. The strategy of nanoparticle-mediated, AMF-induced heat generation has been used to effect intracellular hyperthermia. One application of this 'magnetic hyperthermia' is heat activated local delivery of a therapeutic effector (e.g.; drug or polynucleotide). This thesis describes the development of a magnetic nano-vector for AMF-induced, heat-activated pDNA and small molecule delivery. The use of heat-inducible vectors, such as heat shock protein ( hsp) genes, is a promising mode of gene therapy that would restrict gene expression to a local region by focusing a heat stimulus only at a target region. We thus aimed to design an Fe3O4 nanoparticle-mediated gene transfer vehicle for AMF-induced localized gene expression. We opted to use 'click' oximation techniques to assemble the magnetic gene transfer vector. Chapter 2 describes the synthesis, characterization, and transfection studies of the oxime ether lipid-based nano-magnetic vectors MLP and dMLP. The synthesis and characterization of a novel series of quaternary ammonium aminooxy reagents (2.1--2.4) is described. These cationic aminooxy compounds were loaded onto nanoparticles for ligation with carbonyl groups and also to impart a net positive charge on the nanoparticle surface. Our studies indicated that the

  1. Reorientation of Seedlings in the Earth's Gravitational Field Induces Cytosolic Calcium Transients1

    PubMed Central

    Plieth, Christoph; Trewavas, Anthony J.

    2002-01-01

    The gravitational field controls plant growth, morphology, and development. However, the underlying transduction mechanisms are not well understood. Much indirect evidence has implicated the cytoplasmic free calcium concentration ([Ca2+]c) as an important factor, but direct evidence for changes in [Ca2+]c is currently lacking. We now have made measurements of [Ca2+]c in groups of young seedlings of Arabidopsis expressing aequorin in the cytoplasm and reconstituted in vivo with cp-coelenterazine, a synthetic high-affinity luminophore. Distinct [Ca2+]c signaling occurs in response to gravistimulation with kinetics very different from [Ca2+]c transients evoked by other mechanical stimuli (e.g. movement and wind). [Ca2+]c changes produced in response to gravistimulation are transient but with a duration of many minutes and dependent on stimulus strength (i.e. the angle of displacement). The auxin transport blockers 2,3,5-tri-iodo benzoic acid and N-(1-naphthyl) phthalamic acid interfere with gravi-induced [Ca2+]c responses and addition of methyl indole-3-acetic acid to whole seedlings induces long-lived [Ca2+]c transients, suggesting that changes in auxin transport may interact with [Ca2+]c. Permanent nonaxial rotation of seedlings on a two-dimensional clinostat, however, produced a sustained elevation of the [Ca2+]c level. This probably reflects permanent displacement of gravity-sensing cellular components and/or disturbance of cytoskeletal tension. It is concluded that [Ca2+]c is part of the gravity transduction mechanism in young Arabidopsis seedlings. PMID:12068119

  2. Transient Expression of Candidatus Liberibacter Asiaticus Effector Induces Cell Death in Nicotiana benthamiana

    PubMed Central

    Pitino, Marco; Armstrong, Cheryl M.; Cano, Liliana M.; Duan, Yongping

    2016-01-01

    Candidatus Liberibacter asiaticus “Las” is a phloem-limited bacterial plant pathogen, and the most prevalent species of Liberibacter associated with citrus huanglongbing (HLB), a devastating disease of citrus worldwide. Although, the complete sequence of the Las genome provides the basis for studying functional genomics of Las and molecular mechanisms of Las-plant interactions, the functional characterization of Las effectors remains a slow process since remains to be cultured. Like other plant pathogens, Las may deliver effector proteins into host cells and modulate a variety of host cellular functions for their infection progression. In this study, we identified 16 putative Las effectors via bioinformatics, and transiently expressed them in Nicotiana benthamiana. Diverse subcellular localization with different shapes and aggregation patterns of the effector candidates were revealed by UV- microscopy after transient expression in leaf tissue. Intriguingly, one of the 16 candidates, Las5315mp (mature protein), was localized in the chloroplast and induced cell death at 3 days post inoculation (dpi) in N. benthamiana. Moreover, Las5315mp induced strong callose deposition in plant cells. This study provides new insights into the localizations and potential roles of these Las effectors in planta. PMID:27458468

  3. Transient Expression of Candidatus Liberibacter Asiaticus Effector Induces Cell Death in Nicotiana benthamiana.

    PubMed

    Pitino, Marco; Armstrong, Cheryl M; Cano, Liliana M; Duan, Yongping

    2016-01-01

    Candidatus Liberibacter asiaticus "Las" is a phloem-limited bacterial plant pathogen, and the most prevalent species of Liberibacter associated with citrus huanglongbing (HLB), a devastating disease of citrus worldwide. Although, the complete sequence of the Las genome provides the basis for studying functional genomics of Las and molecular mechanisms of Las-plant interactions, the functional characterization of Las effectors remains a slow process since remains to be cultured. Like other plant pathogens, Las may deliver effector proteins into host cells and modulate a variety of host cellular functions for their infection progression. In this study, we identified 16 putative Las effectors via bioinformatics, and transiently expressed them in Nicotiana benthamiana. Diverse subcellular localization with different shapes and aggregation patterns of the effector candidates were revealed by UV- microscopy after transient expression in leaf tissue. Intriguingly, one of the 16 candidates, Las5315mp (mature protein), was localized in the chloroplast and induced cell death at 3 days post inoculation (dpi) in N. benthamiana. Moreover, Las5315mp induced strong callose deposition in plant cells. This study provides new insights into the localizations and potential roles of these Las effectors in planta. PMID:27458468

  4. Induced regulatory T cells in allograft tolerance via transient mixed chimerism

    PubMed Central

    Hotta, Kiyohiko; Aoyama, Akihiro; Oura, Tetsu; Yamada, Yohei; Tonsho, Makoto; Huh, Kyu Ha; Kawai, Kento; Schoenfeld, David; Allan, James S.; Madsen, Joren C.; Benichou, Gilles; Smith, Rex-Neal; Colvin, Robert B.; Sachs, David H.; Cosimi, A. Benedict; Kawai, Tatsuo

    2016-01-01

    Successful induction of allograft tolerance has been achieved in nonhuman primates (NHPs) and humans via induction of transient hematopoietic chimerism. Since allograft tolerance was achieved in these recipients without durable chimerism, peripheral mechanisms are postulated to play a major role. Here, we report our studies of T cell immunity in NHP recipients that achieved long-term tolerance versus those that rejected the allograft (AR). All kidney, heart, and lung transplant recipients underwent simultaneous or delayed donor bone marrow transplantation (DBMT) following conditioning with a nonmyeloablative regimen. After DBMT, mixed lymphocyte culture with CFSE consistently revealed donor-specific loss of CD8+ T cell responses in tolerant (TOL) recipients, while marked CD4+ T cell proliferation in response to donor antigens was found to persist. Interestingly, a significant proportion of the proliferated CD4+ cells were FOXP3+ in TOL recipients, but not in AR or naive NHPs. In TOL recipients, CD4+FOXP3+ cell proliferation against donor antigens was greater than that observed against third-party antigens. Finally, the expanded Tregs appeared to be induced Tregs (iTregs) that were converted from non-Tregs. These data provide support for the hypothesis that specific induction of iTregs by donor antigens is key to long-term allograft tolerance induced by transient mixed chimerism. PMID:27446989

  5. Mechanisms of Nanoparticle-Induced Oxidative Stress and Toxicity

    PubMed Central

    Wang, Liying

    2013-01-01

    The rapidly emerging field of nanotechnology has offered innovative discoveries in the medical, industrial, and consumer sectors. The unique physicochemical and electrical properties of engineered nanoparticles (NP) make them highly desirable in a variety of applications. However, these novel properties of NP are fraught with concerns for environmental and occupational exposure. Changes in structural and physicochemical properties of NP can lead to changes in biological activities including ROS generation, one of the most frequently reported NP-associated toxicities. Oxidative stress induced by engineered NP is due to acellular factors such as particle surface, size, composition, and presence of metals, while cellular responses such as mitochondrial respiration, NP-cell interaction, and immune cell activation are responsible for ROS-mediated damage. NP-induced oxidative stress responses are torch bearers for further pathophysiological effects including genotoxicity, inflammation, and fibrosis as demonstrated by activation of associated cell signaling pathways. Since oxidative stress is a key determinant of NP-induced injury, it is necessary to characterize the ROS response resulting from NP. Through physicochemical characterization and understanding of the multiple signaling cascades activated by NP-induced ROS, a systemic toxicity screen with oxidative stress as a predictive model for NP-induced injury can be developed. PMID:24027766

  6. Regulation of particulate matter-induced mucin secretion by transient receptor potential vanilloid 1 receptors.

    PubMed

    Yu, Hongmei; Li, Qi; Kolosov, Victor P; Perelman, Juliy M; Zhou, Xiangdong

    2012-12-01

    Exposure to airborne particulate matter (PM) is a worldwide health problem. Previous studies have reported that PMs induced depolarizing currents and increased intracellular Ca(2+) in human bronchial epithelial cells. Ca(2+) plays important role in the regulation of mucus exocytosis, and mucin hypersecretion is a key pathological feature of inflammatory respiratory diseases. To explore more mechanisms underlying PM toxicity, we measured PM-induced mucin secretion in human bronchial epithelial (16HBE) cells. MUC5AC secretion and cyclic adenosine monophosphate (cAMP) level were detected by ELISA. Transient receptor potential vanilloid (TRPV)1 inward currents were examined by electrophysiology. Ca(2+) concentration was assessed by laser scanning confocal microscope. Exposure of PMs to 16HBE cells was found to induce mucin secretion, as a consequence of sustained Ca(2+) influx and cAMP increase through TRPV1 receptors. Mucin secretion was completely inhibited by TRPV1 receptor antagonist capsazepine. Removal of Ca(2+) by Ca(2+) chelator BAPTA or inhibition of protein kinase A (PKA) by the PKA inhibitors H-89 each partially reduced PC(2)s-induced mucin secretion. The combination of BAPTA and H-89 completely prevented mucin secretion mediated by PMs. These results suggest that PM induces mucin secretion through Ca(2+) influx and cAMP/PKA pathway by TRPV1 receptors in human bronchial epithelial cells, thereby providing a potential mechanism to reduce PM toxicity. PMID:22829138

  7. Transient axonal glycoprotein-1 induces apoptosis-related gene expression without triggering apoptosis in U251 glioma cells

    PubMed Central

    Chang, Haigang; Song, Shanshan; Chen, Zhongcan; Wang, Yaxiao; Yang, Lujun; Du, Mouxuan; Ke, Yiquan; Xu, Ruxiang; Jin, Baozhe; Jiang, Xiaodan

    2014-01-01

    Previous studies show that transient axonal glycoprotein-1, a ligand of amyloid precursor protein, increases the secretion of amyloid precursor protein intracellular domain and is involved in apoptosis in Alzheimer's disease. In this study, we examined the effects of transient axonal glycoprotein-1 on U251 glioma cells. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay showed that transient axonal glycoprotein-1 did not inhibit the proliferation of U251 cells, but promoted cell viability. The terminal deoxynucleotidyl transferase dUTP nick end labeling assay showed that transient axonal glycoprotein-1 did not induce U251 cell apoptosis. Real-time PCR revealed that transient axonal glycoprotein-1 substantially upregulated levels of amyloid precursor protein intracellular C-terminal domain, and p53 and epidermal growth factor receptor mRNA expression. Thus, transient axonal glycoprotein-1 increased apoptosis-related gene expression in U251 cells without inducing apoptosis. Instead, transient axonal glycoprotein-1 promoted the proliferation of these glioma cells. PMID:25206849

  8. Cell-specific transmembrane injection of molecular cargo with gold nanoparticle-generated transient plasmonic nanobubbles.

    PubMed

    Lukianova-Hleb, Ekaterina Y; Wagner, Daniel S; Brenner, Malcolm K; Lapotko, Dmitri O

    2012-07-01

    Optimal cell therapies require efficient, selective and rapid delivery of molecular cargo into target cells without compromising their viability. Achieving these goals ex vivo in bulk heterogeneous multi-cell systems such as human grafts is impeded by low selectivity and speed of cargo delivery and by significant damage to target and non-target cells. We have developed a cell level approach for selective and guided transmembrane injection of extracellular cargo into specific target cells using transient plasmonic nanobubbles (PNB) as cell-specific nano-injectors. As a technical platform for this method we developed a laser flow cell processing system. The PNB injection method and flow system were tested in heterogeneous cell suspensions of target and non-target cells for delivery of Dextran-FITC dye into squamous cell carcinoma HN31 cells and transfection of human T-cells with a green fluorescent protein-encoding plasmid. In both models the method demonstrated single cell type selectivity, high efficacy of delivery (96% both for HN31 cells T-cells), speed of delivery (nanoseconds) and viability of treated target cells (96% for HN31 cells and 75% for T-cells). The PNB injection method may therefore be beneficial for real time processing of human grafts without removal of physiologically important cells. PMID:22521612

  9. Curcumin Attenuates Hepatotoxicity Induced by Zinc Oxide Nanoparticles in Rats

    PubMed Central

    Khorsandi, Layasadat; Mansouri, Esrafil; Orazizadeh, Mahmoud; Jozi, Zahra

    2016-01-01

    Background: Zinc oxide nanoparticles (NZnO) are increasingly used in modern life. Most metal nanoparticles have adverse effects on the liver. Aims: To explore the protective action of curcumin (Cur) against hepatotoxicity induced by NZnO in rats. Study Design: Animal experimentation. Methods: Control group animals received normal saline, while the Cur group animals were treated with 200 mg/kg of Cur orally for 21 days. NZnO-intoxicated rats received 50 mg/kg of NZnO for 14 days by gavage method. In the NZnO+Cur group, rats were pretreated with Cur for 7 days before NZnO administration. Plasma activities of Alanine aminotransferase (ALT), aspartate aminotransferase (AST) and alkaline phosphatase (ALP) were measured as biomarkers of hepatotoxicity. Hepatic levels of malondialdehyde (MDA) and superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities were measured for detection of oxidative stress in liver tissue. Histological changes and apoptosis in liver tissue were studied by using Hematoxylin-eosin staining and the transferase dUTP nick end labeling (TUNEL) method. Results: NZnO induced a significant increase in plasma AST (2.8-fold), ALT (2.7-fold) and ALP (1.97-fold) activity in comparison to the control group (p<0.01). NZnO increased MDA content and reduced SOD and GPx activities. NZnO caused liver damage including centrilobular necrosis and microvesicular steatosis. The percentage of apoptosis in hepatocytes was increased in NZnO-treated rats (p<0.01). Pre-treatment of Cur significantly reduced lipid peroxidation (39%), increased SOD (156%) and GPx (26%) activities, and attenuated ALT (47%), AST (41%) and ALP (30%) activities. Pre-treatment with Cur also decreased the histology changes and apoptotic index of hepatocytes (p<0.05). Conclusion: These findings indicate that Cur effectively protects against NZnO-induced hepatotoxicity in rats. However, future studies are required to propose Cur as a potential protective agent against hepatotoxicity

  10. Ultrastructural hepatocytic alterations induced by silver nanoparticle toxicity.

    PubMed

    Almansour, Mansour; Sajti, Laszlo; Melhim, Walid; Jarrar, Bashir M

    2016-01-01

    Silver nanoparticles (SNPs) are widely used in nanomedicine and consuming products with potential risk to human health. While considerable work was carried out on the molecular, biochemical, and physiological alterations induced by these particles, little is known of the ultrastructural pathological alterations that might be induced by nanosilver materials. The aim of the present work is to investigate the hepatocyte ultrastructural alterations that might be induced by SNP exposure. Male rats were subjected to a daily single dose (2 mg/kg) of SNPs (15-35 nm diameter) for 21 days. Liver biopsies from all rats under study were processed for transmission electron microscopy examination. The following hepatic ultrastructural alterations were demonstrated: mitochondria swelling and crystolysis, endoplasmic reticulum disruption, cytoplasmic vacuolization, lipid droplets accumulation, glycogen depletion, karyopyknosis, apoptosis, sinusoidal dilatation, Kupffer cells activation, and myelin figures formation. The current findings may indicate that SNPs can induce hepatocyte organelles alteration, leading to cellular damage that may affect the function of the liver. These findings might indicate that SNPs potentially trigger heptocyte ultrastructural alterations that may affect the function of the liver with potential risk on human health in relation to numerous applications of these particles. More work is needed to elucidate probable ultrastructural alterations in the vital organs that might result from nanosilver toxicity. PMID:26934218

  11. Therapeutic effect of apatinib-loaded nanoparticles on diabetes-induced retinal vascular leakage

    PubMed Central

    Jeong, Ji Hoon; Nguyen, Hong Khanh; Lee, Jung Eun; Suh, Wonhee

    2016-01-01

    Apatinib, a novel and selective inhibitor of vascular endothelial growth factor (VEGF) receptor 2, has been demonstrated recently to exhibit anticancer efficacy by inhibiting the VEGF signaling pathway. Given the importance of VEGF in retinal vascular leakage, the present study was designed to investigate whether apatinib-loaded polymeric nanoparticles inhibit VEGF-mediated retinal vascular hyperpermeability and block diabetes-induced retinal vascular leakage. For the delivery of water-insoluble apatinib, the drug was encapsulated in nanoparticles composed of human serum albumin (HSA)-conjugated polyethylene glycol (PEG). In vitro paracellular permeability and transendothelial electric resistance assays showed that apatinib-loaded HSA-PEG (Apa-HSA-PEG) nanoparticles significantly inhibited VEGF-induced endothelial hyperpermeability in human retinal microvascular endothelial cells. In addition, they substantially reduced the VEGF-induced junctional loss and internalization of vascular endothelial-cadherin, a major component of endothelial junction complexes. In vivo intravitreal injection of Apa-HSA-PEG nanoparticles in mice blocked VEGF-induced retinal vascular leakage. These in vitro and in vivo data indicated that Apa-HSA-PEG nanoparticles efficiently blocked VEGF-induced breakdown of the blood–retinal barrier. In vivo experiments with streptozotocin-induced diabetic mice showed that an intravitreal injection of Apa-HSA-PEG nanoparticles substantially inhibited diabetes-induced retinal vascular leakage. These results demonstrated, for the first time, that apatinib-loaded nanoparticles may be a promising therapeutic agent for the prevention and treatment of diabetes-induced retinal vascular disorders. PMID:27462154

  12. Therapeutic effect of apatinib-loaded nanoparticles on diabetes-induced retinal vascular leakage.

    PubMed

    Jeong, Ji Hoon; Nguyen, Hong Khanh; Lee, Jung Eun; Suh, Wonhee

    2016-01-01

    Apatinib, a novel and selective inhibitor of vascular endothelial growth factor (VEGF) receptor 2, has been demonstrated recently to exhibit anticancer efficacy by inhibiting the VEGF signaling pathway. Given the importance of VEGF in retinal vascular leakage, the present study was designed to investigate whether apatinib-loaded polymeric nanoparticles inhibit VEGF-mediated retinal vascular hyperpermeability and block diabetes-induced retinal vascular leakage. For the delivery of water-insoluble apatinib, the drug was encapsulated in nanoparticles composed of human serum albumin (HSA)-conjugated polyethylene glycol (PEG). In vitro paracellular permeability and transendothelial electric resistance assays showed that apatinib-loaded HSA-PEG (Apa-HSA-PEG) nanoparticles significantly inhibited VEGF-induced endothelial hyperpermeability in human retinal microvascular endothelial cells. In addition, they substantially reduced the VEGF-induced junctional loss and internalization of vascular endothelial-cadherin, a major component of endothelial junction complexes. In vivo intravitreal injection of Apa-HSA-PEG nanoparticles in mice blocked VEGF-induced retinal vascular leakage. These in vitro and in vivo data indicated that Apa-HSA-PEG nanoparticles efficiently blocked VEGF-induced breakdown of the blood-retinal barrier. In vivo experiments with streptozotocin-induced diabetic mice showed that an intravitreal injection of Apa-HSA-PEG nanoparticles substantially inhibited diabetes-induced retinal vascular leakage. These results demonstrated, for the first time, that apatinib-loaded nanoparticles may be a promising therapeutic agent for the prevention and treatment of diabetes-induced retinal vascular disorders. PMID:27462154

  13. Electric-field-induced weakly chaotic transients in ferroelectric liquid crystals.

    PubMed

    Śliwa, I; Jeżewski, W; Kuczyński, W

    2016-01-01

    Nonlinear dynamics induced in surface stabilized ferroelectric liquid crystals by strong alternating external electric fields is studied both theoretically and experimentally. As has already been shown, molecular reorientations induced by sufficiently strong fields of high-enough frequencies can reveal a long transient behavior that has a weakly chaotic character. The resulting complex dynamics of ferroelectric liquid crystals can be considered not only as a consequence of irregular motions of particular molecules but also as a repercussion of a surface-enforced partial decorrelation of nonlinear molecular motions within smectic layers. To achieve more insight into the nature of this phenomenon and to show that the underlying complex field-induced behavior of smectic liquid crystals is not exceptional, ranges of system parameters for which the chaotic behavior occurs are determined. It is proved that there exists a large enough set of initial phase trajectory points, for which weakly chaotic long-time transitory phenomena occur, and, thereby, it is demonstrated that such a chaotic behavior can be regarded as being typical for strongly field-driven thin liquid crystal systems. Additionally, the influence of low-amplitude random noise on the duration of the transient processes is numerically studied. The strongly nonlinear contribution to the electro-optic response, experimentally determined for liquid crystal samples at frequencies lower than the actual field frequency, is also analyzed for long-time signal sequences. Using a statistical approach to distinguish numerically response signals of samples from noise generated by measuring devices, it is shown that the distribution of sample signals distinctly differs from the device noise. This evidently corroborates the occurrence of the nonlinear low-frequency effect, found earlier for different surface stabilized liquid crystal samples. PMID:26871130

  14. Propacetamol-Induced Injection Pain Is Associated with Activation of Transient Receptor Potential Vanilloid 1 Channels.

    PubMed

    Schillers, Florian; Eberhardt, Esther; Leffler, Andreas; Eberhardt, Mirjam

    2016-10-01

    Propacetamol (PPCM) is a prodrug of paracetamol (PCM), which was generated to increase water solubility of PCM for intravenous delivery. PPCM is rapidly hydrolyzed by plasma esterases to PCM and diethylglycine and shares some structural and metabolic properties with lidocaine. Although PPCM is considered to be comparable to PCM regarding its analgesic properties, injection pain is a common side effect described for PPCM but not PCM. Injection pain is a frequent and unpleasant side effect of numerous drugs in clinical use, and previous reports have indicated that the ligand gated ion channels transient receptor potential ankyrin 1 (TRPA1) and transient receptor potential vanilloid 1 (TRPV1) can mediate this effect on sensory neurons. This study aimed to investigate molecular mechanisms by which PPCM, in contrast to PCM, causes injection pain. Therefore, human TRPV1 and TRPA1 receptors were expressed in human embryonic kidney 293 cells and investigated by means of whole-cell patch clamp and ratiometric calcium imaging. PPCM (but not PCM) activated TRPV1, sensitized heat-induced currents, and caused an increase in intracellular calcium. In TRPA1-expressing cells however, both PPCM and PCM evoked calcium responses but failed to induce inward currents. Intracutaneous injection of PPCM, but not of PCM, in human volunteers induced an intense and short-lasting pain and an increase in superficial blood flow, indicating activation of nociceptive C fibers and subsequent neuropeptide release. In conclusion, activation of human TRPV1 by PPCM seems to be a relevant mechanism for induction of pain upon intracutaneous injection and thus also for pain reported as an adverse side effect upon intravenous administration. PMID:27457427

  15. Gravity-induced swirl of nanoparticles in microfluidics.

    PubMed

    Zhao, Chao; Oztekin, Alparslan; Cheng, Xuanhong

    2013-04-01

    Parallel flows of two fluids in microfluidic devices are used for miniaturized chemistry, physics, biology and bioengineering studies, and the streams are often considered to remain parallel. However, as the two fluids do not always have the same density, interface reorientation induced by density stratification is unavoidable. In this paper, flow characteristics of an aqueous polystyrene nanofluid and a sucrose-densified aqueous solution flowing parallel in microchannels are examined. Nanoparticles 100 nm in diameter are used in the study. The motion of the nanoparticles is simulated using the Lagrangian description and directly observed by a confocal microscope. Matched results are obtained from computational and empirical analysis. Although solution density homogenizes rapidly resulting from a fast diffusion of sucrose in water, the nanofluid is observed to rotate for an extended period. Angular displacement of the nanofluid depends on the ratio of gravitational force to viscous force, Re/Fr (2), where Re is the Reynolds number and Fr is the Froude number. In the developing region at the steady state, the angular displacement is related to y/D h, the ratio between distance from the inlet and the hydraulic diameter of the microfluidic channel. The development of nanofluid flow feature also depends on h/w, the ratio of microfluidic channel's height to width. The quantitative description of the angular displacement of nanofluid will aid rational designs of microfluidic devices utilizing multistream, multiphase flows. PMID:24563612

  16. Gravity-induced swirl of nanoparticles in microfluidics

    PubMed Central

    Zhao, Chao; Oztekin, Alparslan

    2013-01-01

    Parallel flows of two fluids in microfluidic devices are used for miniaturized chemistry, physics, biology and bioengineering studies, and the streams are often considered to remain parallel. However, as the two fluids do not always have the same density, interface reorientation induced by density stratification is unavoidable. In this paper, flow characteristics of an aqueous polystyrene nanofluid and a sucrose-densified aqueous solution flowing parallel in microchannels are examined. Nanoparticles 100 nm in diameter are used in the study. The motion of the nanoparticles is simulated using the Lagrangian description and directly observed by a confocal microscope. Matched results are obtained from computational and empirical analysis. Although solution density homogenizes rapidly resulting from a fast diffusion of sucrose in water, the nanofluid is observed to rotate for an extended period. Angular displacement of the nanofluid depends on the ratio of gravitational force to viscous force, Re/Fr2, where Re is the Reynolds number and Fr is the Froude number. In the developing region at the steady state, the angular displacement is related to y/Dh, the ratio between distance from the inlet and the hydraulic diameter of the microfluidic channel. The development of nanofluid flow feature also depends on h/w, the ratio of microfluidic channel’s height to width. The quantitative description of the angular displacement of nanofluid will aid rational designs of microfluidic devices utilizing multistream, multiphase flows. PMID:24563612

  17. Oxide nanoparticles synthesis via laser-induced plasma in liquid

    NASA Astrophysics Data System (ADS)

    Goto, Taku; Weihs, Hansel; Honda, Mitsuhiro; Kulinich, Sergei; Shimizu, Yoshiki; Ito, Tsuyohito

    2014-10-01

    Laser ablation in fluids has recently attracted a lot of attention as one of synthetic techniques to prepare new attractive nanomaterials, with the ability to control both product chemistry and morphology in many systems. In this study, we generated laser-induced plasma in H2O - ethanol mixtures, while ablating metal targets to produce oxide nanoparticles and to study the effect of the medium on their properties. The ablated targets used in this study were Zn or Sn plates. A nanosecond Nd:YAG laser with the wavelength of 532 nm (10 Hz, 20--30 mJ/pulse) was applied to irradiate the targets. The liquid media were maintained at 0.1 to 30 MPa to study the effect of pressure. We found that the H2O/ethanol ratio (at atmospheric pressure) can control the properties of the produced ZnO nanoparticles, such as defects and oxidation degree. The properties were examined by photoluminescence (PL) spectroscopy, X-ray diffraction, electron microscopies, and so on. More details will be presented at the symposium.

  18. Numerical Simulation of Roughness-Induced Transient Growth in a Laminar Boundary Layer

    NASA Technical Reports Server (NTRS)

    Fischer, Paul; Choudhari, Meelan

    2004-01-01

    Numerical simulations are used to examine the roughness-induced transient growth in a laminar boundary-layer flow. Based on the spectral element method, these simulations model the stationary disturbance field associated with a nonsmooth roughness geometry, such as the spanwise periodic array of circular disks used by White and co-workers during a series of wind tunnel experiments at Case Western Reserve University. Besides capturing the major trends from the recent measurements by White and Ergin, the simulations provide additional information concerning the relative accuracy of the experimental findings derived from two separate wall-finding procedures. The paper also explores the dependence of transient growth on geometric characteristics of the roughness distribution, including the height and planform shape of the roughness element and the ratio of roughness due to spacing between an adjacent pair of elements. Results are used for a preliminary assessment of the differences between recently reported theoretical results of Tumin and Reshotko and the measurements by White and Ergin.

  19. Silver nanoparticles induce endoplasmatic reticulum stress response in zebrafish

    SciTech Connect

    Christen, Verena; Capelle, Martinus; Fent, Karl

    2013-10-15

    Silver nanoparticles (AgNPs) find increasing applications, and therefore humans and the environment are increasingly exposed to them. However, potential toxicological implications are not sufficiently known. Here we investigate effects of AgNPs (average size 120 nm) on zebrafish in vitro and in vivo, and compare them to human hepatoma cells (Huh7). AgNPs are incorporated in zebrafish liver cells (ZFL) and Huh7, and in zebrafish embryos. In ZFL cells AgNPs lead to induction of reactive oxygen species (ROS), endoplasmatic reticulum (ER) stress response, and TNF-α. Transcriptional alterations also occur in pro-apoptotic genes p53 and Bax. The transcriptional profile differed in ZFL and Huh7 cells. In ZFL cells, the ER stress marker BiP is induced, concomitant with the ER stress marker ATF-6 and spliced XBP-1 after 6 h and 24 h exposure to 0.5 g/L and 0.05 g/L AgNPs, respectively. This indicates the induction of different pathways of the ER stress response. Moreover, AgNPs induce TNF-α. In zebrafish embryos exposed to 0.01, 0.1, 1 and 5 mg/L AgNPs hatching was affected and morphological defects occurred at high concentrations. ER stress related gene transcripts BiP and Synv are significantly up-regulated after 24 h at 0.1 and 5 mg/L AgNPs. Furthermore, transcriptional alterations occurred in the pro-apoptotic genes Noxa and p21. The ER stress response was strong in ZFL cells and occurred in zebrafish embryos as well. Our data demonstrate for the first time that AgNPs lead to induction of ER stress in zebrafish. The induction of ER stress can have several consequences including the activation of apoptotic and inflammatory pathways. - Highlights: • Effects of silver nanoparticles (120 nm AgNPs) are investigated in zebrafish. • AgNPs induce all ER stress reponses in vitro in zebrafish liver cells. • AgNPs induce weak ER stress in zebrafish embryos. • AgNPs induce oxidative stress and transcripts of pro-apoptosis genes.

  20. Soft-shear induced phase-separated nanoparticle string-structures in polymer thin films.

    PubMed

    Zhang, Ren; Lee, Bongjoon; Bockstaller, Michael R; Al-Enizi, Abdullah M; Elzatahry, Ahmed; Berry, Brian C; Karim, Alamgir

    2016-04-12

    Application of shear stress has been shown to unidirectionally orient the microstructures of block copolymers and polymer blends. In the present work, we study the phase separation of a novel nanoparticle (NP)-polymer blend thin film system under shear using a soft-shear dynamic zone annealing (DZA-SS) method. The nanoparticles are densely grafted with polymer chains of chemically dissimilar composition from the matrix polymer, which induces phase separation upon thermal annealing into concentrated nanoparticle domains. We systematically examine the influence of DZA-SS translation speed and thus the effective shear rate on nanoparticle domain elongation and compare this with the counterpart binary polymer blend behavior. Unidirectionally aligned nanoparticle string-domains are fabricated in the presence of soft-shear in confined thin film geometry. We expect this DZA-SS method to be applicable to various NP-polymer blends towards unidirectionally aligned nanoparticle structures, which are important to functional nanoparticle structure fabrication. PMID:26814827

  1. Water-soluble core/shell nanoparticles for proton therapy through particle-induced radiation

    NASA Astrophysics Data System (ADS)

    Park, Jeong Chan; Jung, Myung-Hwan; Kim, Maeng Jun; Kim, Kye-Ryung

    2015-02-01

    Metallic nanoparticles have been used in biomedical applications such as magnetic resonance imaging (MRI), therapy, and drug delivery systems. Metallic nanoparticles as therapeutic tools have been demonstrated using radio-frequency magnetic fields or near-infrared light. Recently, therapeutic applications of metallic nanomaterials combined with proton beams have been reported. Particle-induced radiation from metallic nanoparticles, which can enhance the therapeutic effects of proton therapy, was released when the nanoparticles were bombarded by a high-energy proton beam. Core/shell nanoparticles, especially Au-coated magnetic nanoparticles, have drawn attention in biological applications due to their attractive characteristics. However, studies on the phase transfer of organic-ligand-based core/shell nanoparticles into water are limited. Herein, we demonstrated that hydrophobic core/shell structured nanomaterials could be successfully dispersed in water through chloroform/surfactant mixtures. The effects of the core/shell nanomaterials and the proton irradiation on Escherichia coli (E. coli) were also explored.

  2. Surfactant-induced postsynthetic modulation of Pd nanoparticle crystallinity.

    SciTech Connect

    Liu, Y.; Wang, C.; Wei, Y.; Zhu, L.; Li, D.; Jiang, J. S.; Markovic, N. M.; Stamenkovic, V. R.; Sun, S.

    2011-02-01

    Modulation of Pd nanoparticle (NP) crystallinity is achieved by switching the surfactants of different binding strengths. Pd NPs synthesized in the presence of weak binding surfactants such as oleylamine possess polyhedral shapes and a polycrystalline nature. When oleylamine is substituted by trioctylphosphine, a much stronger binding surfactant, the particles become spherical and their crystallinity decreases significantly. Moreover, the Pd NPs reconvert their polycrystalline structure when the surfactant is switched back to oleylamine. Through control experiments and molecular dynamics simulation, we propose that this unusual nanocrystallinity transition induced by surfactant exchange was resulted from a counterbalance between the surfactant binding energy and the nanocrystal adhesive energy. The findings represent a novel postsynthetic approach to tailoring the structure and corresponding functional performance of nanomaterials.

  3. DNA melting and genotoxicity induced by silver nanoparticles and graphene.

    PubMed

    Ivask, Angela; Voelcker, Nicolas H; Seabrook, Shane A; Hor, Maryam; Kirby, Jason K; Fenech, Michael; Davis, Thomas P; Ke, Pu Chun

    2015-05-18

    We have revealed a connection between DNA-nanoparticle (NP) binding and in vitro DNA damage induced by citrate- and branched polyethylenimine-coated silver nanoparticles (c-AgNPs and b-AgNPs) as well as graphene oxide (GO) nanosheets. All three types of nanostructures triggered an early onset of DNA melting, where the extent of the melting point shift depends upon both the type and concentration of the NPs. Specifically, at a DNA/NP weight ratio of 1.1/1, the melting temperature of lambda DNA dropped from 94 °C down to 76 °C, 60 °C, and room temperature for GO, c-AgNPs and b-AgNPs, respectively. Consistently, dynamic light scattering revealed that the largest changes in DNA hydrodynamic size were also associated with the binding of b-AgNPs. Upon introduction to cells, b-AgNPs also exhibited the highest cytotoxicity, at the half-maximal inhibitory (IC50) concentrations of 3.2, 2.9, and 5.2 mg/L for B and T-lymphocyte cell lines and primary lymphocytes, compared to the values of 13.4, 12.2, and 12.5 mg/L for c-AgNPs and 331, 251, and 120 mg/L for GO nanosheets, respectively. At cytotoxic concentrations, all NPs elicited elevated genotoxicities via the increased number of micronuclei in the lymphocyte cells. However, b-AgNPs also induced micronuclei at subtoxic concentrations starting from 0.1 mg/L, likely due to their stronger cellular adhesion and internalization, as well as their subsequent interference with normal DNA synthesis or chromosome segregation during the cell cycle. This study facilitates our understanding of the effects of NP chemical composition, surface charge, and morphology on DNA stability and genotoxicity, with implications ranging from nanotoxicology to nanobiotechnology and nanomedicine. PMID:25781053

  4. Increases of Catalase and Glutathione Peroxidase Expressions by Lacosamide Pretreatment Contributes to Neuroprotection Against Experimentally Induced Transient Cerebral Ischemia.

    PubMed

    Choi, Hyun Young; Park, Joon Ha; Chen, Bai Hui; Shin, Bich Na; Lee, Yun Lyul; Kim, In Hye; Cho, Jeong-Hwi; Lee, Tae-Kyeong; Lee, Jae-Chul; Won, Moo-Ho; Ahn, Ji Hyeon; Tae, Hyun-Jin; Yan, Bing Chun; Hwang, In Koo; Cho, Jun Hwi; Kim, Young-Myeong; Kim, Sung Koo

    2016-09-01

    Lacosamide is a new antiepileptic drug which is widely used to treat partial-onset seizures. In this study, we examined the neuroprotective effect of lacosamide against transient ischemic damage and expressions of antioxidant enzymes such as Zn-superoxide dismutase (SOD1), Mn-superoxide dismutase (SOD2), catalase (CAT) and glutathione peroxidase (GPX) in the hippocampal cornu ammonis 1 (CA1) region following 5 min of transient global cerebral ischemia in gerbils. We found that pre-treatment with 25 mg/kg lacosamide protected CA1 pyramidal neurons from transient global cerebral ischemic insult using hematoxylin-eosin staining and neuronal nuclear antigen immunohistochemistry. Transient ischemia dramatically changed expressions of SOD1, SOD2 and GPX, not CAT, in the CA1 pyramidal neurons. Lacosamide pre-treatment increased expressions of CAT and GPX, not SOD1 and 2, in the CA1 pyramidal neurons compared with controls, and their expressions induced by lacosamide pre-treatment were maintained after transient cerebral ischemia. In brief, pre-treatment with lacosamide protected hippocampal CA1 pyramidal neurons from ischemic damage induced by transient global cerebral ischemia, and the lacosamide-mediated neuroprotection may be closely related to increases of CAT and GPX expressions by lacosamide pre-treatment. PMID:27209305

  5. Laser induced mechanisms controlling the size distribution of metallic nanoparticles.

    PubMed

    Liu, Zeming; Vitrant, Guy; Lefkir, Yaya; Bakhti, Said; Destouches, Nathalie

    2016-09-21

    This paper describes a model to simulate changes in the size distribution of metallic nanoparticles (NPs) in TiO2 films upon continuous wave light excitation. Interrelated laser induced physical and chemical processes initiated directly by photon absorption or by plasmon induced thermal heating are considered. Namely the model takes into account the NP coalescence, Ostwald ripening, the reduction of silver ions and the oxidation of metallic NPs, competitive mechanisms that can lead to counter-intuitive behaviors depending on the exposure conditions. Theoretical predictions are compared successfully to the experimental results deduced from a thorough analysis of scanning transmission electron microscopy (STEM) pictures of Ag:TiO2 films processed with a scanning visible laser beam at different speeds. Ag:TiO2 systems are considered for many applications in solar energy conversion, photocatalysis or secured data printing. Numerical investigations of such a system provide a better understanding of light induced growth and shrinking processes and open up prospects for designing more efficient photocatalytic devices based on metal NP doped TiO2 or for improving the size homogeneity in self-organized metallic NP patterns, for instance. PMID:27539293

  6. Rare earth nanoparticles prevent retinal degeneration induced by intracellular peroxides:

    NASA Astrophysics Data System (ADS)

    Chen, Junping; Patil, Swanand; Seal, Sudipta; McGinnis, James F.

    2006-11-01

    Photoreceptor cells are incessantly bombarded with photons of light, which, along with the cells' high rate of oxygen metabolism, continuously exposes them to elevated levels of toxic reactive oxygen intermediates (ROIs). Vacancy-engineered mixed-valence-state cerium oxide nanoparticles (nanoceria particles) scavenge ROIs. Our data show that nanoceria particles prevent increases in the intracellular concentrations of ROIs in primary cell cultures of rat retina and, in vivo, prevent loss of vision due to light-induced degeneration of photoreceptor cells. These data indicate that the nanoceria particles may be effective in inhibiting the progression of ROI-induced cell death, which is thought to be involved in macular degeneration, retinitis pigmentosa and other blinding diseases, as well as the ROI-induced death of other cell types in diabetes, Alzheimer's disease, atherosclerosis, stroke and so on. The use of nanoceria particles as a direct therapy for multiple diseases represents a novel strategy and suggests that they may represent a unique platform technology.

  7. [A case of transient ischemic attack of hemodynamic origin induced by postprandial hypotension].

    PubMed

    Sakima, Hirokuni; Isa, Katsunori; Nakachi, Koh; Shiroma, Kanako; Tokashiki, Takashi; Ohya, Yusuke

    2014-01-01

    An 82-year-old man had a transient ischemic attack (TIA) with symptoms of consciousness disturbance and right hemiparesis while resting in a sitting position after breakfast. His symptoms improved around 1 h after onset when he lied in a supine position and received intravenous hydration. Duplex carotid ultrasonography revealed severe stenosis of the left common carotid artery. A decrease in the brain perfusion reserve was confirmed by acetazolamide-stress brain perfusion scintigraphy. Moreover, ambulatory blood pressure monitoring revealed a reduction in systolic blood pressure below 90 mmHg after each meal, indicating postprandial hypotension (PPH). The PPH was improved by oral administration of α-glucosidase inhibitor without any subsequent recurrences of TIA. The patient was diagnosed with TIA of hemodynamic origin that was induced by PPH and exhibited severe carotid stenosis. PPH is common in elderly people, and it should be recognized as a significant trigger for ischemic cerebrovascular disease. PMID:24583593

  8. Cerium dioxide nanoparticles do not modulate the lipopolysaccharide-induced inflammatory response in human monocytes

    PubMed Central

    Hussain, Salik; Al-Nsour, Faris; Rice, Annette B; Marshburn, Jamie; Ji, Zhaoxia; Zink, Jeffery I; Yingling, Brenda; Walker, Nigel J; Garantziotis, Stavros

    2012-01-01

    Background Cerium dioxide (CeO2) nanoparticles have potential therapeutic applications and are widely used for industrial purposes. However, the effects of these nanoparticles on primary human cells are largely unknown. The ability of nanoparticles to exacerbate pre-existing inflammatory disorders is not well documented for engineered nanoparticles, and is certainly lacking for CeO2 nanoparticles. We investigated the inflammation-modulating effects of CeO2 nanoparticles at noncytotoxic concentrations in human peripheral blood monocytes. Methods CD14+ cells were isolated from peripheral blood samples of human volunteers. Cells were exposed to either 0.5 or 1 μg/mL of CeO2 nanoparticles over a period of 24 or 48 hours with or without lipopolysaccharide (10 ng/mL) prestimulation. Modulation of the inflammatory response was studied by measuring secreted tumor necrosis factor-alpha, interleukin-1beta, macrophage chemotactic protein-1, interferon-gamma, and interferon gamma-induced protein 10. Results CeO2 nanoparticle suspensions were thoroughly characterized using dynamic light scattering analysis (194 nm hydrodynamic diameter), zeta potential analysis (−14 mV), and transmission electron microscopy (irregular-shaped particles). Transmission electron microscopy of CD14+ cells exposed to CeO2 nanoparticles revealed that these nanoparticles were efficiently internalized by monocytes and were found either in vesicles or free in the cytoplasm. However, no significant differences in secreted cytokine profiles were observed between CeO2 nanoparticle-treated cells and control cells at noncytotoxic doses. No significant effects of CeO2 nanoparticle exposure subsequent to lipopolysaccharide priming was observed on cytokine secretion. Moreover, no significant difference in lipopolysaccharide-induced cytokine production was observed after exposure to CeO2 nanoparticles followed by lipopolysaccharide exposure. Conclusion CeO2 nanoparticles at noncytotoxic concentrations neither

  9. Transient overexpression of TGFBR3 induces apoptosis in human nasopharyngeal carcinoma CNE-2Z cells

    PubMed Central

    Zheng, Fangfang; He, Kaiwen; Li, Xin; Zhao, Dan; Sun, Fei; Zhang, Yu; Nie, Dan; Li, Xingda; Chu, Wenfeng; Sun, Yan; Lu, Yanjie

    2013-01-01

    NPC (nasopharyngeal carcinoma) is a common malignancy in southern China without defined aetiology. Recent studies have shown that TGFBR3 (transforming growth factor type III receptor, also known as betaglycan), exhibits anticancer activities. This study was to investigate the effects of TGFBR3 on NPC growth and the mechanisms for its actions. Effects of TGFBR3 overexpression on cell viability and apoptosis were measured by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide], AO/EB (acridine orange/ethidium bromide) staining and electron microscopy in human NPC CNE-2Z cells. The expression of apoptosis-related proteins, p-Bad, Bad, XIAP (X-linked inhibitor of apoptosis), AIF (apoptosis-inducing factor), Bax and Bcl-2, was determined by Western blot or immunofluorescence analysis. Caspase 3 activity was measured by caspase 3 activity kit and [Ca2+]i (intracellular Ca2+ concentration) was detected by confocal microscopy. Transfection of TGFBR3 containing plasmid DNA at concentrations of 0.5 and 1 μg/ml reduced viability and induced apoptosis in CNE-2Z in concentration- and time-dependent manners. Forced expression of TGFBR3 up-regulated pro-apoptotic Bad and Bax protein, and down-regulated anti-apoptotic p-Bad, Bcl-2 and XIAP protein. Furthermore, transient overexpression of TGFBR3 also enhanced caspase 3 activity, increased [Ca2+]i and facilitated AIF redistribution from the mitochondria to the nucleus in CNE-2Z cells, which is independent of the caspase 3 pathway. These events were associated with TGFBR3-regulated multiple targets involved in CNE-2Z proliferation. Therefore transient overexpression of TGFBR3 may be a novel strategy for NPC prevention and therapy. PMID:23387308

  10. Transient and persistent pain induced connectivity alterations in pediatric complex regional pain syndrome.

    PubMed

    Linnman, Clas; Becerra, Lino; Lebel, Alyssa; Berde, Charles; Grant, P Ellen; Borsook, David

    2013-01-01

    Evaluation of pain-induced changes in functional connectivity was performed in pediatric complex regional pain syndrome (CRPS) patients. High field functional magnetic resonance imaging was done in the symptomatic painful state and at follow up in the asymptomatic pain free/recovered state. Two types of connectivity alterations were defined: (1) Transient increases in functional connectivity that identified regions with increased cold-induced functional connectivity in the affected limb vs. unaffected limb in the CRPS state, but with normalized connectivity patterns in the recovered state; and (2) Persistent increases in functional connectivity that identified regions with increased cold-induced functional connectivity in the affected limb as compared to the unaffected limb that persisted also in the recovered state (recovered affected limb versus recovered unaffected limb). The data support the notion that even after symptomatic recovery, alterations in brain systems persist, particularly in amygdala and basal ganglia systems. Connectivity analysis may provide a measure of temporal normalization of different circuits/regions when evaluating therapeutic interventions for this condition. The results add emphasis to the importance of early recognition and management in improving outcome of pediatric CRPS. PMID:23526938

  11. Transient and Persistent Pain Induced Connectivity Alterations in Pediatric Complex Regional Pain Syndrome

    PubMed Central

    Linnman, Clas; Becerra, Lino; Lebel, Alyssa; Berde, Charles; Grant, P. Ellen; Borsook, David

    2013-01-01

    Evaluation of pain-induced changes in functional connectivity was performed in pediatric complex regional pain syndrome (CRPS) patients. High field functional magnetic resonance imaging was done in the symptomatic painful state and at follow up in the asymptomatic pain free/recovered state. Two types of connectivity alterations were defined: (1) Transient increases in functional connectivity that identified regions with increased cold-induced functional connectivity in the affected limb vs. unaffected limb in the CRPS state, but with normalized connectivity patterns in the recovered state; and (2) Persistent increases in functional connectivity that identified regions with increased cold-induced functional connectivity in the affected limb as compared to the unaffected limb that persisted also in the recovered state (recovered affected limb versus recovered unaffected limb). The data support the notion that even after symptomatic recovery, alterations in brain systems persist, particularly in amygdala and basal ganglia systems. Connectivity analysis may provide a measure of temporal normalization of different circuits/regions when evaluating therapeutic interventions for this condition. The results add emphasis to the importance of early recognition and management in improving outcome of pediatric CRPS. PMID:23526938

  12. Ultrasensitive detection of target analyte-induced aggregation of gold nanoparticles using laser-induced nanoparticle Rayleigh scattering.

    PubMed

    Lin, Jia-Hui; Tseng, Wei-Lung

    2015-01-01

    Detection of salt- and analyte-induced aggregation of gold nanoparticles (AuNPs) mostly relies on costly and bulky analytical instruments. To response this drawback, a portable, miniaturized, sensitive, and cost-effective detection technique is urgently required for rapid field detection and monitoring of target analyte via the use of AuNP-based sensor. This study combined a miniaturized spectrometer with a 532-nm laser to develop a laser-induced Rayleigh scattering technique, allowing the sensitive and selective detection of Rayleigh scattering from the aggregated AuNPs. Three AuNP-based sensing systems, including salt-, thiol- and metal ion-induced aggregation of the AuNPs, were performed to examine the sensitivity of laser-induced Rayleigh scattering technique. Salt-, thiol-, and metal ion-promoted NP aggregation were exemplified by the use of aptamer-adsorbed, fluorosurfactant-stabilized, and gallic acid-capped AuNPs for probing K(+), S-adenosylhomocysteine hydrolase-induced hydrolysis of S-adenosylhomocysteine, and Pb(2+), in sequence. Compared to the reported methods for monitoring the aggregated AuNPs, the proposed system provided distinct advantages of sensitivity. Laser-induced Rayleigh scattering technique was improved to be convenient, cheap, and portable by replacing a diode laser and a miniaturized spectrometer with a laser pointer and a smart-phone. Using this smart-phone-based detection platform, we can determine whether or not the Pb(2+) concentration exceed the maximum allowable level of Pb(2+) in drinking water. PMID:25476277

  13. T-type Ca2+ channels mediate propagation of odor-induced Ca2+ transients in rat olfactory receptor neurons.

    PubMed

    Gautam, S H; Otsuguro, K-I; Ito, S; Saito, T; Habara, Y

    2007-01-19

    Propagation of odor-induced Ca(2+) transients from the cilia/knob to the soma in mammalian olfactory receptor neurons (ORNs) is thought to be mediated exclusively by high-voltage-activated Ca(2+) channels. However, using confocal Ca(2+) imaging and immunocytochemistry we identified functional T-type Ca(2+) channels in rat ORNs. Here we show that T-type Ca(2+) channels in ORNs also mediate propagation of odor-induced Ca(2+) transients from the knob to the soma. In the presence of the selective inhibitor of T-type Ca(2+) channels mibefradil (10-15 microM) or Ni(2+) (100 microM), odor- and forskolin/3-isobutyl-1-methyl-xanthine (IBMX)-induced Ca(2+) transients in the soma and dendrite were either strongly inhibited or abolished. The percentage of inhibition of the Ca(2+) transients in the knob, however, was 40-50% less than that in the soma. Ca(2+) transients induced by 30 mM K(+) were partially inhibited by mibefradil, but without a significant difference in the extent of inhibition between the knob and soma. Furthermore, an increase of as little as 2.5 mM in the extracellular K(+) concentration (7.5 mM K(+)) was found to induce Ca(2+) transients in ORNs, and such responses were completely inhibited by mibefradil or Ni(2+). Total replacement of extracellular Na(+) with N-methyl-d-glutamate inhibited none of the odor-, forskolin/IBMX- or 7.5 mM K(+)-induced Ca(2+) transients. Positive immunoreactivity to the Ca(v)3.1, Ca(v)3.2 and Ca(v)3.3 subunits of the T-type Ca(2+) channel was observed throughout the soma, dendrite and knob. These data suggest that involvement of T-type Ca(2+) channels in the propagation of odor-induced Ca(2+) transients in ORNs may contribute to signal transduction and odor sensitivity. PMID:17110049

  14. Dual-responsive aggregation-induced emission-active supramolecular nanoparticles for gene delivery and bioimaging.

    PubMed

    Dong, Ruijiao; Ravinathan, Screenath P; Xue, Lizhe; Li, Nan; Zhang, Yingjian; Zhou, Linzhu; Cao, Chengxi; Zhu, Xinyuan

    2016-06-28

    Dual-responsive aggregation-induced emission-active supramolecular fluorescent nanoparticles are reported, which have the ability to undergo a unique morphological transition combining with a cooperative optical variation in response to pH and light stimuli. The dynamic supramolecular nanoparticles show excellent biocompatibility and effective plasmid DNA condensation capability, further achieving efficient in vitro gene delivery and bioimaging. PMID:27251637

  15. Transiently enhanced LPS-induced fever following hyperthermic stress in rabbits

    NASA Astrophysics Data System (ADS)

    Shibata, Masaaki; Uno, Tadashi; Riedel, Walter; Nishimaki, Michiyo; Watanabe, Kaori

    2005-11-01

    Hyperthermia has been shown to induce an enhanced febrile response to the bacterial-derived endotoxin lipopolysaccharide (LPS). The aim of the present study was to test the hypothesis that the enhanced LPS-induced fever seen in heat stressed (HS) animals is caused by leakage of intestinal bacterial LPS into the circulation. Male rabbits were rendered transiently hyperthermic (a maximum rectal temperature of 43°C) and divided into three groups. They were then allowed to recover in a room at 24°C for 1, 2 or 3 days post-HS. One day after injection with LPS, the post-HS rabbits exhibited significantly higher fevers than the controls, though this was not seen in rabbits at either 2 or 3 days post-HS. The plasma levels of endogenous LPS were significantly increased during the HS as compared to those seen in normothermic rabbits prior to HS. LPS fevers were not induced in these animals. One day post-HS, rabbits that had been pretreated with oral antibiotics exhibited significantly attenuated LPS levels. When challenged with human recombinant interleukin-1β instead of LPS, the 1-day post-HS rabbits did not respond with enhanced fevers. The plasma levels of TNFα increased similarly during LPS-induced fevers in both the control and 1-day post-HS rabbits, while the plasma levels of corticosterone and the osmolality of the 1-day post-HS rabbits showed no significant differences to those seen prior to the HS. These results suggest that the enhanced fever in the 1-day post-HS rabbits is LPS specific, and may be caused by increased leakage of intestinal endotoxin into blood circulation.

  16. Transient Lipopolysaccharide-Induced Resistance to Aerosolized Bacillus anthracis in New Zealand White Rabbits

    PubMed Central

    Yee, Steven B; Dyer, David N; Twenhafel, Nancy A; Pitt, M Louise M

    2013-01-01

    Previous studies have demonstrated that prior infection by various bacterial pathogens induces nonspecific resistance to subsequent infection by other gram-negative and gram-positive bacterial pathogens. In the present study, we evaluated whether underlying inflammation enhanced host resistance to inhalational Bacillus anthracis infection in New Zealand White rabbits (SPF; Bordetella- and Pasteurella-free). Accordingly, rabbits were pretreated with either the inflammagen bacterial LPS (60,000 EU/kg), a component of the outer membrane of gram-negative bacteria, or saline (vehicle). Administration of LPS resulted in brief pyrexia and a significant increase in the proinflammatory cytokine TNFα, thus confirming LPS-induced inflammation. At 24 h after LPS treatment, rabbits were exposed to aerosolized B. anthracis spores (Ames strain; approximately 300 LD50). Blood samples collected at various times after challenge were cultured. Compared with their saline-pretreated counterparts, LPS-pretreated, B. anthracis-challenged rabbits exhibited delays in 2 biomarkers of B. anthracis infection—anthrax-induced pyrexia (25 h versus 66 h after challenge, respectively) and bacteremia (26 h versus 63 h, respectively)—and survived longer (41 h versus 90 h, respectively). Similar to control animals, all LPS-pretreated, B. anthracis-challenged rabbits exhibited pathology consistent with inhalational anthrax. Taken together, these results suggest that prior or underlying stimulation of the innate immune system induces transient host resistance to subsequent B. anthracis infection in SPF New Zealand white rabbits. In particular, our results emphasize the importance of using animals that are free of underlying infections to prevent confounding data in studies for inhalational anthrax characterization and medical countermeasure evaluation. PMID:23759528

  17. Prostaglandin F2 alpha-induced calcium transient in ovine large luteal cells: II. Modulation of the transient and resting cytosolic free calcium alters progesterone secretion.

    PubMed

    Wegner, J A; Martinez-Zaguilan, R; Gillies, R J; Hoyer, P B

    1991-02-01

    A previous study demonstrated that prostaglandin F2 alpha (PGF2 alpha) stimulates a transient increase in cytosolic free Ca2+ levels [( Ca2+]i) in ovine large luteal cells. In the present study, the magnitude of the PGF2 alpha (0.5 microM)-induced calcium transient in Hanks' medium (87 +/- 2 nM increase above resting levels) was reduced (P less than 0.05) but not completely eliminated in fura-2 loaded large luteal cells incubated in Ca2(+)-free or phosphate- and carbonate-free medium (10 +/- 1 nM, 32 +/- 6 nM, above resting levels; respectively). Preincubation for 2 min with 1 mM LaCl3 (calcium antagonist) eliminated the PGF2 alpha-induced calcium transient. The inhibitory effect of PGF2 alpha on secretion of progesterone was reduced in Ca2(+)-free medium or medium plus LaCl3. Resting [Ca2+]i levels and basal secretion of progesterone were both reduced (P less than 0.05) in large cells incubated in Ca2(+)-free medium (27 +/- 4 nM; 70 +/- 6% control, respectively) or with 5 microM 5,5'-dimethyl bis-(O-aminophenoxy)ethane-N,N,N'N'-tetraacetic acid (40 +/- 2 nM; 49 +/- 1% control; respectively). In addition, secretion of progesterone was inhibited (P less than 0.05) by conditions that increased (P less than 0.05) [Ca2+]i; that is LaCl3 ([Ca2+]i, 120 +/- 17 nM; progesterone, 82 +/- 8% control) and PGF2 alpha ([Ca2+]i, 102 +/- 10 nM; progesterone, 82 +/- 3% control). In small luteal cells, resting [Ca2+]i levels and secretion of progesterone were reduced by incubation in Ca2(+)-free Hanks ([Ca2+]i, 28 +/- 2 nM; progesterone, 71 +/- 6% control), however, neither LaCl3 nor PGF2 alpha increased [Ca2+]i levels or inhibited secretion of progesterone. The findings presented here provide evidence that extracellular as well as intracellular calcium contribute to the PGF2 alpha-induced [Ca2+]i transient in large cells. Furthermore, whereas an adequate level of [Ca2+]i is required to support progesterone production in both small and large cells, optimal progesterone production in

  18. Electrically induced birefringence in nanoparticle dispersions for electrorheological applications

    NASA Astrophysics Data System (ADS)

    Pochylski, Mikolaj; Calandra, Pietro; Aliotta, Francesco; Ponterio, Rosina C.

    2014-11-01

    Recently, the observation of an anomalously large electrorheological effect in the dispersion of nanosized particles of titania in octanoid acid has been reported. Such an enhanced effect was not observed in the similar dispersion of micrometric particles or in more conventional suspensions of silica in silicon oil. It was suggested that this effect could be promoted by the formation of a thin layer of solvent molecules on the surface of the titania particles. We propose the measurement of electrically induced optical birefringence as a suitable independent method for testing this working hypothesis. In this paper, we report the results from the investigations of the dilute dispersions of 32 nm TiO2 particles in two insulating fluids: silicone oil and octanoic acid. A comparison of the experimental birefringence data with the theoretical predictions suggests that TiO2 nanoparticles behave like permanent electric dipoles, although induced dipoles are expected in the case of the titania material. The source of such behaviour has been individuated at the particle/solvent interface and the different possibilities of the permanent dipole origin are discussed. The lower value of the dipole moment observed in octanoic acid dispersion is explained in terms of a specific particle/solvent interaction leading to the formation of a solvent coating around the particle. The results highlight that electro-optical properties are related to electrorheological performance and that both methods can be considered as supportive for testing electrically driven phenomena in complex fluids.

  19. Nanoparticle-Mediated Mitochondrial Damage Induces Apoptosis in Cancer.

    PubMed

    Mallick, Abhik; More, Piyush; Syed, Muhammed Muazzam Kamil; Basu, Sudipta

    2016-06-01

    Detouring of conventional DNA damaging anticancer drugs into mitochondria to damage mitochondrial DNA is evolving as a promising strategy in chemotherapy. Inhibiting single target in mitochondria would eventually lead to the emergence of drug resistance. Moreover, targeting mitochondria selectively in cancer cells, keeping them intact in healthy cells, remains a major challenge. Herein, triphenylphosphine (TPP)-coated positively charged 131.6 nm spherical nanoparticles (NPs) comprised of α-tocopheryl succinate (TOS, inhibitor of complex II in electron transport chain) and obatoclax (Obt, inhibitor of Bcl-2) were engineered. The TOS-TPP-Obt-NPs entered into acidic lysosomes via macropinocytosis, followed by lysosomal escape and finally homed into mitochondria over a period of 24 h. Subsequently, these TOS-TPP-Obt-NPs triggered mitochondrial outer membrane permeabilization (MOMP) by inhibiting antiapoptotic Bcl-2, leading to Cytochrome C release. These TOS-TPP-Obt-NPs mediated mitochondrial damage induced cellular apoptosis through caspase-9 and caspase-3 cleavage to show improved efficacy in HeLa cells. Moreover, TOS-TPP-Obt-NPs induced MOMP in drug-resistant triple negative breast cancer cells (MDA-MB-231), leading to remarkable efficacy, compared to the combination of free drugs in higher drug concentrations. Results presented here clearly stimulate the usage of multiple drugs to perturb simultaneously diverse targets, selectively in mitochondria, as next-generation cancer therapeutics. PMID:27160664

  20. Extraordinary Light-Induced Local Angular Momentum near Metallic Nanoparticles.

    PubMed

    Alabastri, Alessandro; Yang, Xiao; Manjavacas, Alejandro; Everitt, Henry O; Nordlander, Peter

    2016-04-26

    The intense local field induced near metallic nanostructures provides strong enhancements for surface-enhanced spectroscopies, a major focus of plasmonics research over the past decade. Here we consider that plasmonic nanoparticles can also induce remarkably large electromagnetic field gradients near their surfaces. Sizeable field gradients can excite dipole-forbidden transitions in nearby atoms or molecules and provide unique spectroscopic fingerprinting for chemical and bimolecular sensing. Specifically, we investigate how the local field gradients near metallic nanostructures depend on geometry, polarization, and wavelength. We introduce the concept of the local angular momentum (LAM) vector as a useful figure of merit for the design of nanostructures that provide large field gradients. This quantity, based on integrated fields rather than field gradients, is particularly well-suited for optimization using numerical grid-based full wave electromagnetic simulations. The LAM vector has a more compact structure than the gradient matrix and can be straightforwardly associated with the angular momentum of the electromagnetic field incident on the plasmonic structures. PMID:27045994

  1. Plasmon-induced Hot Carriers in Metallic Nanoparticles

    NASA Astrophysics Data System (ADS)

    Liu, Jun; Manjavacas, Alejandro; Kulkarni, Vikram; Nordlander, Peter; LANP Team

    2015-03-01

    Plasmon-induced hot carrier formation is attracting an increasing research interest due to its potential for applications in photocatalysis, photodetection and solar energy harvesting. Here we develop a theoretical model for the plasmon-induced hot carrier process and apply it to spherical silver nanoparticles and nanoshells. We show that the inclusion of many-body interactions has only a minor influence on the results. Using the model we calculate the rate of hot carrier generation, finding that it closely follows the spectral profile of the plasmon. Our analysis reveals that particle size and hot carrier lifetime play a central role in determining both the production rate and the energy distribution of the hot carriers. We characterize the efficiency of the hot carrier generation process by introducing a figure of merit that measures the number of high energy carriers generated per plasmon. Furthermore, we analyze the spatial distribution and directionality of these excitations. A. M. acknowledges financial support from the Welch foundation through the J. Evans Attwell-Welch Postdoctoral Fellowship Program of the Smalley Institute of Rice University (Grant No. L-C-004).

  2. Nonsolvents-induced swelling of poly(methyl methacrylate) nanoparticles.

    PubMed

    Shundo, Atsuomi; Hori, Koichiro; Penaloza, David P; Yoshihiro, Kazuki; Annaka, Masahiko; Tanaka, Keiji

    2013-10-21

    Polymer nanoparticles have been used in a wide variety of applications. In most of these applications, they are generally dispersed in a non-solvent. However, the effect of the non-solvent on the structure, physical properties and function of the nanoparticles has not yet ever taken into account. In this study, monodispersed poly(methyl methacrylate) (PMMA) nanoparticles were prepared by a surfactant-free emulsion polymerization. The PMMA nanoparticles were dispersed in water and in methanol, both typical non-solvents for PMMA, so that we could discuss the effect of the non-solvent on the nanoparticles. Dynamic light scattering measurements revealed that the hydrodynamic radius of the PMMA nanoparticles in methanol was larger than the same PMMA dispersed in water. Their DLS values were also larger than the radius of the nanoparticles measured by atomic force microscopy. When pyrene was dispersed in methanol with the PMMA nanoparticles, it was incorporated into the nanoparticles. These results clearly indicate that non-solvent molecules can be sorbed into polymer nanoparticles because the area of the interface, where polymer segments might be dissolved into liquid phases, as the total volume is quite larger for such nanoparticles. Therefore, based on our findings, it can be arguably established that the present assumption for a polymer not to be swollen in its non-solvent is not necessarily true. PMID:23955567

  3. Tissue differentiation using laser-induced shock waves by detection of acoustic transients through an optical wave-guide

    NASA Astrophysics Data System (ADS)

    Tschepe, Johannes; Ahrens, Thomas; Helfmann, Juergen; Mueller, Gerhard J.; Gapontsev, Valentin P.

    1993-05-01

    Some physical phenomena which occur during the fragmentation of calculi by laser induced optical break down are presented. With in vitro experiments it could be shown that the energy of the laser induced plasma and of the cavitation bubble (induced by the plasma) depends by the nature of the tissue. The laser induced plasma and the cavitation bubble generate shock waves. These sound waves are transferred via the laser fiber and detected with a piezo- electrical sensor at the proximal end. The acoustic signal contains information on the potential energy of the bubble, which depends on the energy of the plasma. The possibility of measuring the energy dependent acoustic transients allows to distinguish between hard and soft tissue and by this it is suitable for controlling the laser lithotripsy process. The transmission of acoustic transients through silica glass fibers is investigated by theoretical calculations. It shows the feasibility of silica glass fibers as an acoustic wave guide.

  4. Zinc-induced Neurotoxicity Mediated by Transient Receptor Potential Melastatin 7 Channels*

    PubMed Central

    Inoue, Koichi; Branigan, Deborah; Xiong, Zhi-Gang

    2010-01-01

    Transient receptor potential melastatin 7 (TRPM7) channels are novel Ca2+-permeable non-selective cation channels ubiquitously expressed. Activation of TRPM7 channels has been shown to be involved in cellular Mg2+ homeostasis, diseases caused by abnormal magnesium absorption, and in Ca2+-mediated neuronal injury under ischemic conditions. Here we show strong evidence suggesting that TRPM7 channels also play an important role in cellular Zn2+ homeostasis and in Zn2+-mediated neuronal injury. Using a combination of fluorescent Zn2+ imaging, small interfering RNA, pharmacological analysis, and cell injury assays, we show that activation of TRPM7 channels augmented Zn2+-induced injury of cultured mouse cortical neurons. The Zn2+-mediated neurotoxicity was inhibited by nonspecific TRPM7 blockers Gd3+ or 2-aminoethoxydiphenyl borate, and by knockdown of TRPM7 channels with small interfering RNA. In addition, Zn2+-mediated neuronal injury under oxygen-glucose deprivation conditions was also diminished by silencing TRPM7. Furthermore, we show that overexpression of TRPM7 channels in HEK293 cells increased intracellular Zn2+ accumulation and Zn2+-induced cell injury, while silencing TRPM7 by small interfering RNA attenuated the Zn2+-mediated cell toxicity. Thus, TRPM7 channels may represent a novel target for neurological disorders where Zn2+ toxicity plays an important role. PMID:20048154

  5. Upregulation of Transient Receptor Potential Canonical Channels Contributes to Endotoxin-Induced Pulmonary Arterial Stenosis

    PubMed Central

    Chen, Gui-Lan; Jiang, Hongni; Zou, Fangdong

    2016-01-01

    Background Septic shock is a pathologic condition caused by endotoxin-producing bacteria, and often associated with severe pulmonary hypertension. Inflammation is a major systemic response to endotoxin; however, it is unknown whether endotoxin has a direct impact on pulmonary arteries that contributes to pathogenesis of pulmonary hypertension. Material/Methods Rat pulmonary arteries and primary pulmonary arterial smooth muscle cells (PASMCs) were cultured in vitro and treated with lipopolysaccharide (LPS) and blockers of transient receptor potential canonical (TRPC) channels. Neointimal growth and arterial stenosis were observed on cryosections of cultured pulmonary arteries. Proliferation of PASMCs was examined by a WST-1 (water-soluble tetrazolium salt) assay. Expression of TRPC genes in pulmonary arteries and PASMCs were detected and quantified by real-time polymerase chain reaction and Western blotting. Results LPS significantly induced neointimal growth and stenosis of pulmonary arteries and promoted proliferation of PASMCs. TRPC channel blockers 2-aminoethoxydiphenyl borate and SKF-96365 inhibited LPS-induced remodeling of pulmonary arteries and PASMC proliferation. Expression of TRPC1/3/4/6 was detected in pulmonary arteries and PASMCs. LPS treatment dramatically increased the expression of TRPC3 and TRPC4 at both messenger RNA and protein levels. Conclusions LPS stimulates stenosis of pulmonary arteries through enhancement of TRPC-mediated Ca2+ entry into PASMCs, which is caused by upregulation of TRPC3 and TRPC4 channels. PMID:27471122

  6. Zinc-induced neurotoxicity mediated by transient receptor potential melastatin 7 channels.

    PubMed

    Inoue, Koichi; Branigan, Deborah; Xiong, Zhi-Gang

    2010-03-01

    Transient receptor potential melastatin 7 (TRPM7) channels are novel Ca(2+)-permeable non-selective cation channels ubiquitously expressed. Activation of TRPM7 channels has been shown to be involved in cellular Mg(2+) homeostasis, diseases caused by abnormal magnesium absorption, and in Ca(2+)-mediated neuronal injury under ischemic conditions. Here we show strong evidence suggesting that TRPM7 channels also play an important role in cellular Zn(2+) homeostasis and in Zn(2+)-mediated neuronal injury. Using a combination of fluorescent Zn(2+) imaging, small interfering RNA, pharmacological analysis, and cell injury assays, we show that activation of TRPM7 channels augmented Zn(2+)-induced injury of cultured mouse cortical neurons. The Zn(2+)-mediated neurotoxicity was inhibited by nonspecific TRPM7 blockers Gd(3+) or 2-aminoethoxydiphenyl borate, and by knockdown of TRPM7 channels with small interfering RNA. In addition, Zn(2+)-mediated neuronal injury under oxygen-glucose deprivation conditions was also diminished by silencing TRPM7. Furthermore, we show that overexpression of TRPM7 channels in HEK293 cells increased intracellular Zn(2+) accumulation and Zn(2+)-induced cell injury, while silencing TRPM7 by small interfering RNA attenuated the Zn(2+)-mediated cell toxicity. Thus, TRPM7 channels may represent a novel target for neurological disorders where Zn(2+) toxicity plays an important role. PMID:20048154

  7. Transient Fluorescence Spectroscopy and laser induced fluorescence lifetimes of terbium doped dipicolinic acid

    NASA Astrophysics Data System (ADS)

    Makoui, Anali

    We have investigated the use of deep UV laser induced fluorescence for the sensitive detection and spectroscopic lifetime studies of terbium doped dipicolinic acid (DPA-Tb) and used this to study the optical characteristics of DPA which is a chemical surrounding most bacterial spores. Background absorption spectra, fluorescence spectra, and Excitation Emission Matrix (EEM) spectra were made of the DPA-Tb complex, using both fixed 266 nm wavelength and tunable (220 nm--280 nm) UV laser excitations. Of importance, the fluorescence lifetimes of the four main fluorescence peaks (488 nm, 543 nm, 581 nm, and 618 nm) of the DPA-Tb complex have been measured for the first time to our knowledge. The lifetimes of all the fluorescing lines have been measured as a function of DPA-Tb concentration, solvent pH, and solvent composition, including that for the weakest fluorescing line of DPA-Tb at 618 nm. In addition, a new spectroscopic lifetime measurement technique, which we call "Transient Fluorescence Spectroscopy", was developed. In this technique, a weak, quasi-CW, amplitude modulated UV laser (8.5 kHz) was used to measure the lifetimes of the fluorescence lines, and yields insight into energy transfer and excitation lifetimes within the system. This technique is especially useful when a high power laser is not either available or not suitable. In the latter case, this would be when a high power pulsed deep-UV laser could produce bleaching or destruction of the biological specimen. In addition, this technique simulated the excitation and fluorescence emission of the DPA-Tb using a 4-level energy model, and solved the dynamic transient rate equations to predict the temporal behavior of the DPA-Tb emitted fluorescence. Excellent agreement between the experiments and the simulation were found. This technique has the potential to provide a more accurate value for the fluorescence lifetime values. In addition, with the use of asymmetric excitation waveforms, the dynamic

  8. Inhaled Diesel Emissions Generated with Cerium Oxide Nanoparticle Fuel Additive Induce Adverse Pulmonary and Systemic Effects

    EPA Science Inventory

    Diesel exhaust (DE) exposure induces adverse cardiopulmonary effects. Cerium oxide nanoparticles added to diesel fuel (DECe) increases fuel burning efficiency but leads to altered emission characteristics and potentially altered health effects. Here, we evaluated whether DECe res...

  9. Ca2+ transients and Mn2+ entry in human neutrophils induced by thapsigargin.

    PubMed

    Foder, B; Scharff, O; Thastrup, O

    1989-10-01

    Human neutrophils, preloaded with the fluorescent probe, Fura-2, were exposed to Ca2+-releasing agents. The monitored traces of fluorescence were transformed by computer to cytosolic Ca2+ concentration ([ Ca2+]i). Due to quenching of Fura-2, the addition of Mn2+ enabled us to compute the cytosolic concentration of total manganese ([Mn]i). The agents used were the novel Ca2+-mobilizing agent, thapsigargin (Tg), the chemotactic peptide, formyl-methionyl-leucyl-phenylalanine (FMLP), and the divalent cation ionophore, A23187. The agents caused transient rises of [Ca2+]i and monotonous rises of [Mn]i, suggesting influx but no efflux of Mn2+. The rise time of [Ca2+]i and the time constants and magnitude of the apparent Mn2+ influx were strongly dependent on the sequence of addition of the agonist and Ca2+. Contrary to FMLP, Tg needed several minutes to exert its full effect on the rise of [Ca2+]i and on the influx of Mn2+, the latter being dependent on two phases, activation and partial inactivation. Pretreatment with phorbol 12-myristate 13-acetate (PMA) inhibited the responses of Tg, FMLP and A23187. For comparison, human red blood cells were tested. Contrary to A23187, Tg did not induce Ca2+ uptake in ATP-depleted red cells but increased the Ca2+ pump flux in intact red cells by 10%. The experimental data and computer simulations of the granulocyte data suggest that time-dependent changes of both passive Ca2+ flux into the cytosol and Ca2+ flux of the plasma membrane pump are involved in the transient [Ca2+]i response. PMID:2515000

  10. Transcranial magnetic stimulation-induced global propagation of transient phase resetting associated with directional information flow

    PubMed Central

    Kawasaki, Masahiro; Uno, Yutaka; Mori, Jumpei; Kobata, Kenji; Kitajo, Keiichi

    2014-01-01

    Electroencephalogram (EEG) phase synchronization analyses can reveal large-scale communication between distant brain areas. However, it is not possible to identify the directional information flow between distant areas using conventional phase synchronization analyses. In the present study, we applied transcranial magnetic stimulation (TMS) to the occipital area in subjects who were resting with their eyes closed, and analyzed the spatial propagation of transient TMS-induced phase resetting by using the transfer entropy (TE), to quantify the causal and directional flow of information. The time-frequency EEG analysis indicated that the theta (5 Hz) phase locking factor (PLF) reached its highest value at the distant area (the motor area in this study), with a time lag that followed the peak of the transient PLF enhancements of the TMS-targeted area at the TMS onset. Phase-preservation index (PPI) analyses demonstrated significant phase resetting at the TMS-targeted area and distant area. Moreover, the TE from the TMS-targeted area to the distant area increased clearly during the delay that followed TMS onset. Interestingly, the time lags were almost coincident between the PLF and TE results (152 vs. 165 ms), which provides strong evidence that the emergence of the delayed PLF reflects the causal information flow. Such tendencies were observed only in the higher-intensity TMS condition, and not in the lower-intensity or sham TMS conditions. Thus, TMS may manipulate large-scale causal relationships between brain areas in an intensity-dependent manner. We demonstrated that single-pulse TMS modulated global phase dynamics and directional information flow among synchronized brain networks. Therefore, our results suggest that single-pulse TMS can manipulate both incoming and outgoing information in the TMS-targeted area associated with functional changes. PMID:24723875

  11. RADIO TRANSIENTS FROM THE ACCRETION-INDUCED COLLAPSE OF WHITE DWARFS

    SciTech Connect

    Piro, Anthony L.; Kulkarni, S. R.

    2013-01-10

    It has long been expected that in some scenarios when a white dwarf (WD) grows to the Chandrasekhar limit, it can undergo an accretion-induced collapse (AIC) to form a rapidly rotating neutron star. Nevertheless, the detection of such events has so far evaded discovery, likely because the optical, supernova-like emission is expected to be dim and short-lived. Here we propose a novel signature of AIC: a transient radio source lasting for a few months. Rapid rotation along with flux freezing and dynamo action can grow the WD's magnetic field to magnetar strengths during collapse. The spin-down of this newly born magnetar generates a pulsar wind nebula (PWN) within the {approx}10{sup -3}-10{sup -1} M{sub Sun} of ejecta surrounding it. Our calculations show that synchrotron emission from the PWN may be detectable in the radio, even if the magnetar has a rather modest magnetic field of {approx}2 Multiplication-Sign 10{sup 14} G and an initial spin period of {approx}10 ms. An all-sky survey with a detection limit of 1 mJy at 1.4 GHz would see {approx}4(f/10{sup -2}) above threshold at any given time, where f is the ratio of the AIC rate to Type Ia supernova rate. A similar scenario may result from binary neutron stars if some mergers produce massive neutron stars rather than black holes. We conclude with a discussion of the detectability of these types of transient radio sources in an era of facilities with high mapping speeds.

  12. Principles of femtosecond X-ray/optical cross-correlation with X-ray induced transient optical reflectivity in solids

    SciTech Connect

    Eckert, S. E-mail: martin.beye@helmholtz-berlin.de; Beye, M. E-mail: martin.beye@helmholtz-berlin.de; Pietzsch, A.; Quevedo, W.; Hantschmann, M.; Ochmann, M.; Huse, N.; Ross, M.; Khalil, M.; Minitti, M. P.; Turner, J. J.; Moeller, S. P.; Schlotter, W. F.; Dakovski, G. L.; Föhlisch, A.

    2015-02-09

    The discovery of ultrafast X-ray induced optical reflectivity changes enabled the development of X-ray/optical cross correlation techniques at X-ray free electron lasers worldwide. We have now linked through experiment and theory the fundamental excitation and relaxation steps with the transient optical properties in finite solid samples. Therefore, we gain a thorough interpretation and an optimized detection scheme of X-ray induced changes to the refractive index and the X-ray/optical cross correlation response.

  13. Micelle depletion-induced vs. micelle-mediated aggregation in nanoparticles

    SciTech Connect

    Ray, D. Aswal, V. K.

    2015-06-24

    The phase behavior anionic silica nanoparticle (Ludox LS30) with non-ionic surfactants decaethylene glycol monododecylether (C12E10) and cationic dodecyltrimethyl ammonium bromide (DTAB) in aqueous electrolyte solution has been studied by small-angle neutron scattering (SANS). The measurements have been carried out for fixed concentrations of nanoparticle (1 wt%), surfactants (1 wt%) and electrolyte (0.1 M NaCl). Each of these nanoparticle–surfactant systems has been examined for different contrast conditions where individual components (nanoparticle or surfactant) are made visible. It is observed that the nanoparticle-micelle system in both the cases lead to the aggregation of nanoparticles. The aggregation is found to be micelle depletion-induced for C12E10 whereas micelle-mediated aggregation for DTAB. Interestingly, it is also found that phase behavior of mixed surfactant (C12E10 + DTAB) system is similar to that of C12E10 (unlike DTAB) micelles with nanoparticles.

  14. Radio frequency radiation-induced hyperthermia using Si nanoparticle-based sensitizers for mild cancer therapy

    NASA Astrophysics Data System (ADS)

    Tamarov, Konstantin P.; Osminkina, Liubov A.; Zinovyev, Sergey V.; Maximova, Ksenia A.; Kargina, Julia V.; Gongalsky, Maxim B.; Ryabchikov, Yury; Al-Kattan, Ahmed; Sviridov, Andrey P.; Sentis, Marc; Ivanov, Andrey V.; Nikiforov, Vladimir N.; Kabashin, Andrei V.; Timoshenko, Victor Yu

    2014-11-01

    Offering mild, non-invasive and deep cancer therapy modality, radio frequency (RF) radiation-induced hyperthermia lacks for efficient biodegradable RF sensitizers to selectively target cancer cells and thus avoid side effects. Here, we assess crystalline silicon (Si) based nanomaterials as sensitizers for the RF-induced therapy. Using nanoparticles produced by mechanical grinding of porous silicon and ultraclean laser-ablative synthesis, we report efficient RF-induced heating of aqueous suspensions of the nanoparticles to temperatures above 45-50°C under relatively low nanoparticle concentrations (<1 mg/mL) and RF radiation intensities (1-5 W/cm2). For both types of nanoparticles the heating rate was linearly dependent on nanoparticle concentration, while laser-ablated nanoparticles demonstrated a remarkably higher heating rate than porous silicon-based ones for the whole range of the used concentrations from 0.01 to 0.4 mg/mL. The observed effect is explained by the Joule heating due to the generation of electrical currents at the nanoparticle/water interface. Profiting from the nanoparticle-based hyperthermia, we demonstrate an efficient treatment of Lewis lung carcinoma in vivo. Combined with the possibility of involvement of parallel imaging and treatment channels based on unique optical properties of Si-based nanomaterials, the proposed method promises a new landmark in the development of new modalities for mild cancer therapy.

  15. Visualizing interfacial charge transfer in Ru-dye sensitized TiO{sub 2} nanoparticles using x-ray transient absorption spectroscopy.

    SciTech Connect

    Zhang, X.; Smolentsev, G.; Guo, J.; Attenkofer, K.; Kurtz, C.; Jennings, G.; Lockard, J. V.; Stickrath, A. B.; Chen, L. X.

    2011-03-01

    A molecular level understanding of the structural reorganization accompanying interfacial electron transfer is important for rational design of solar cells. Here we have applied XTA (X-ray transient absorption) spectroscopy to study transient structures in a heterogeneous interfacial system mimicking the charge separation process in dye-sensitized solar cell (DSSC) with Ru(dcbpy){sub 2}(NCS){sub 2} (RuN3) dye adsorbed to TiO{sub 2} nanoparticle surfaces. The results show that the average Ru-NCS bond length reduces by 0.06 {angstrom}, whereas the average Ru?N(dcbpy) bond length remains nearly unchanged after the electron injection. The differences in bond-order change and steric hindrance between two types of ligands are attributed to their structural response in the charge separation. This study extends the application of XTA into optically opaque hybrid interfacial systems relevant to the solar energy conversion.

  16. Transient infection of the zebrafish notochord with E. coli induces chronic inflammation

    PubMed Central

    Nguyen-Chi, Mai; Phan, Quang Tien; Gonzalez, Catherine; Dubremetz, Jean-François; Levraud, Jean-Pierre; Lutfalla, Georges

    2014-01-01

    Zebrafish embryos and larvae are now well-established models in which to study infectious diseases. Infections with non-pathogenic Gram-negative Escherichia coli induce a strong and reproducible inflammatory response. Here, we study the cellular response of zebrafish larvae when E. coli bacteria are injected into the notochord and describe the effects. First, we provide direct evidence that the notochord is a unique organ that is inaccessible to leukocytes (macrophages and neutrophils) during the early stages of inflammation. Second, we show that notochord infection induces a host response that is characterised by rapid clearance of the bacteria, strong leukocyte recruitment around the notochord and prolonged inflammation that lasts several days after bacteria clearance. During this inflammatory response, il1b is first expressed in macrophages and subsequently at high levels in neutrophils. Moreover, knock down of il1b alters the recruitment of neutrophils to the notochord, demonstrating the important role of this cytokine in the maintenance of inflammation in the notochord. Eventually, infection of the notochord induces severe defects of the notochord that correlate with neutrophil degranulation occurring around this tissue. This is the first in vivo evidence that neutrophils can degranulate in the absence of a direct encounter with a pathogen. Persistent inflammation, neutrophil infiltration and restructuring of the extracellular matrix are defects that resemble those seen in bone infection and in some chondropathies. As the notochord is a transient embryonic structure that is closely related to cartilage and bone and that contributes to vertebral column formation, we propose infection of the notochord in zebrafish larvae as a new model to study the cellular and molecular mechanisms underlying cartilage and bone inflammation. PMID:24973754

  17. Communication: Nanosize-induced restructuring of Sn nanoparticles

    SciTech Connect

    Sabet, Sareh; Kaghazchi, Payam

    2014-05-21

    Stabilities and structures of β- and α-Sn nanoparticles are studied using density functional theory. Results show that β-Sn nanoparticles are more stable. For both phases of Sn, nanoparticles smaller than 1 nm (∼48 atoms) are amorphous and have a band gap between 0.4 and 0.7 eV. The formation of band gap is found to be due to amorphization. By increasing the size of Sn nanoparticles (1–2.4 nm), the degree of crystallization increases and the band gap decreases. In these cases, structures of the core of nanoparticles are bulk-like, but structures of surfaces on the faces undergo reconstruction. This study suggests a strong size dependence of electronic and atomic structures for Sn nanoparticle anodes in Li-ion batteries.

  18. Direct extraction of intense-field-induced polarization in the continuum on the attosecond time scale from transient absorption

    NASA Astrophysics Data System (ADS)

    Li, X.; Haxton, D. J.; Gaarde, M. B.; Schafer, K. J.; McCurdy, C. W.

    2016-02-01

    A procedure is suggested for using transient absorption spectroscopy above the ionization threshold to measure the polarization of the continuum induced by an intense optical pulse. In this way transient absorption measurement can be used to probe subfemtosecond intense field dynamics in atoms and molecules. The method is based on an approximation to the dependence of these spectra on time delay between an attosecond XUV probe pulse and an intense pump pulse that is tested over a wide range of intensities and time delays by all-electrons-active calculations using the multiconfiguration time-dependent Hartree-Fock method in the case of neon.

  19. EVENT84 user's manual: a computer code for analyzing explosion-induced gas-dynamic transients in flow networks

    SciTech Connect

    Martin, R.A.; Wilson, T.L.

    1984-12-01

    This manual supports the computer code EVENT84, which can predict explosion-induced gas-dynamic transients in flow networks. The code can model transients in any arbitrarily designated network of building rooms and ventilation systems. A lumped-parameter formulation is used. EVENT84 was designed to provide a safety analysis tool for he nuclear, chemical, and mining industries. It is particularly suitable for calculating the detailed effects of explosions in the far field using a parametric representation of the explosive event. The code input and a sample problem that illustrates its capabilities are provided.

  20. Urate Crystal Induced Inflammation and Joint Pain Are Reduced in Transient Receptor Potential Ankyrin 1 Deficient Mice – Potential Role for Transient Receptor Potential Ankyrin 1 in Gout

    PubMed Central

    Moilanen, Lauri J.; Hämäläinen, Mari; Lehtimäki, Lauri; Nieminen, Riina M.; Moilanen, Eeva

    2015-01-01

    Introduction In gout, monosodium urate (MSU) crystals deposit intra-articularly and cause painful arthritis. In the present study we tested the hypothesis that Transient Receptor Poten-tial Ankyrin 1 (TRPA1), an ion channel mediating nociceptive signals and neurogenic in-flammation, is involved in MSU crystal-induced responses in gout by utilizing three experi-mental murine models. Methods The effects of selective pharmacological inhibition (by HC-030031) and genetic depletion of TRPA1 were studied in MSU crystal-induced inflammation and pain by using 1) spontaneous weight-bearing test to assess MSU crystal-induced joint pain, 2) subcutaneous air-pouch model resembling joint inflammation to measure MSU crystal-induced cytokine production and inflammatory cell accumulation, and 3) MSU crystal-induced paw edema to assess acute vascular inflammatory responses and swelling. Results Intra-articularly injected MSU crystals provoked spontaneous weight shift off from the affected limb in wild type but not in TRPA1 knock-out mice referring alleviated joint pain in TRPA1 deficient animals. MSU crystal-induced inflammatory cell infiltration and accumulation of cytokines MCP-1, IL-6, IL-1beta, MPO, MIP-1alpha and MIP-2 into subcu-taneous air-pouch (resembling joint cavity) was attenuated in TRPA1 deficient mice and in mice treated with the selective TRPA1 inhibitor HC-030031 as compared to control animals. Further, HC-030031 treated and TRPA1 deficient mice developed tempered inflammatory edema when MSU crystals were injected into the paw. Conclusions TRPA1 mediates MSU crystal-induced inflammation and pain in experimental models supporting the role of TRPA1 as a potential mediator and a drug target in gout flare. PMID:25658427

  1. Dynamic Response in Transient Stress-Field Behavior Induced by Hydraulic Fracturing

    NASA Astrophysics Data System (ADS)

    Jenkins, Andrew

    magnitude. These types of shifts are of great concern because they can impact subsequent fracture development causing non-uniform fracture propagation and the potential overlapping of fracture paths as they extend from the wellbore at the point of injection. The dynamics of stress variation that occur with respect to hydraulic fracturing is a somewhat new area of study. In order to accomplish the goals of this thesis and continue future research in this area a new transient model has been developed in order to asses these dynamic systems and determine their influence on fracture behavior. This applies the use of a fully coupled finite element method in 2-D using linear elastic fracture mechanics which is then expanded using displacement discontinuity to a cohesive zone model in 3-D. A static boundary element model was also used to determine stress fields surrounding static, predetermined fracture geometries. These models have been verified against analytical solutions for simple cases and are now being applied to more detailed case studies and analysis. These models have been briefly discussed throughout this thesis in order to give insight on their current capabilities and application as well as their future potential within this area of research. The majority of this work introduces transient stress field prediction to cases of single and multiple hydraulic fractures. The static assessment of these stresses is determined for verification of results to those found in publication which leads into these transient stress field variations. A new method has been developed and applied to the stress state prediction for the first time in a transient fracture model which is partly based upon a critical distance theory. These dynamic interactions can provide useful insight to pertinent issues within the petroleum and natural gas industry such as those to hydraulic fracturing fluid loss and induced seismic events, as well as to applications of efficiency and optimization of the

  2. Local Property Change of Graphene Induced by a Cu Nanoparticle

    NASA Astrophysics Data System (ADS)

    Huang, Li-Wei; Jeng, Horng-Tay; Chang, Chia-Seng

    2015-03-01

    Investigating the detailed impact from an individual nanoparticle on graphene membrane is a great challenge. We employed ultra-high vacuum electron microscopy and first-principles calculations to reveal the changes on the graphene's morphology and electronic structures upon adsorption of a Cu nanoparticle. Our findings show that the significant amount of charge transfer from the individual Cu nanoparticle to graphene causes local electronic redistributions at the interface and a consequent recess of the graphene with prominent tilt angles.

  3. Microbially induced synthesis of cubic and hexagonal selenium nanoparticles.

    PubMed

    Park, Bitna; Kang, Serku; Moon, Wonjin; Roh, Yul

    2013-03-01

    Nanobiotechnology represents an economic alternative for chemical and physical methods of nanoparticles formation. The objectives of this study were to synthesize selenium nanoparticles by microbial processes using anaerobic metal-reducing bacteria as well as to characterize mineralogical properties of the nanoparticles. The selenium nanoparticles were about 200 nm in size and ball shaped. Microbial processes for elemental selenium synthesis may be useful for recovery of natural selenate in the natural environments and immobilization of selenium isotope in the high level nuclear waste disposal sites. PMID:23755605

  4. Transient grating-induced phase inhomogeneity in FeRh studied by time-resolved hard x-ray nanodiffraction

    NASA Astrophysics Data System (ADS)

    Zhu, Yi; Zhang, Qingteng; Chen, Pice; Walko, D. A.; Dufresne, E. M.; Thiele, J. U.; Fullerton, E. E.; Cai, Zhonghou; Evans, P. G.; Wen, Haidan

    2014-03-01

    The photo-induced antiferromagnetic to ferromagnetic phase transition of FeRh at room temperature has important technological applications in the magnetic recording industry. This first-order phase transition is accompanied by a large, abrupt lattice expansion. In this study, spatially periodic phase modulation in a FeRh thin film was induced by an optical transient grating; the temporal and spatial evolution of the resulting lattice profile was probed by ultrafast hard x-ray nanodiffraction. We found that the transient grating induced lattice profile deviates from the initial sinusoidal spatial modulation during the recovery process, which allows us to quantitatively measure the in-plane propagation of the phase boundary. Work at Argonne was supported by the Argonne LDRD grant (2013-036-R1).

  5. Redox Nanoparticle Therapeutics for Acetaminophen-Induced Hepatotoxicity in Mice

    PubMed Central

    Boonruamkaew, Phetcharat; Chonpathompikunlert, Pennapa; Nagasaki, Yukio

    2016-01-01

    The purpose of this study was to evaluate the hepatoprotective effect of an antioxidative nanoparticle (RNPN) recently developed against APAP-induced hepatotoxicity in mice. The effects of oral administration of RNPN to APAP-treated mice were assessed for various biochemical liver function parameters: alanine transaminase (ALT) activity, aspartate transaminase (AST) activity, alkaline phosphatase (ALP) activity, prothrombin time, and serum albumin (ALB) level. The treatment effects were assessed in terms of free radical parameters: malondialdehyde (MDA) accumulation, glutathione peroxidase (GPx) activity, % inhibition of superoxide anion (O2−∙), and histopathological examination. The N-acetylcysteine (NAC)-treated group exhibited an enhanced prothrombin time relative to the control group, while RNPN did not prolong prothrombin time. The RNPN-treated animals exhibited lower levels of ALT, AST, and ALP, while increased ALB levels were measured in these animals compared to those in the other groups. The RNPN-treated animals furthermore exhibited improved MDA levels, GPx activity, and % inhibition of O2−∙, which relate to oxidative damage. Histological staining of liver tissues from RNPN-treated animals did not reveal any microscopic changes relative to the other groups. The findings of this study suggest that RNPN possesses effective hepatoprotective properties and does not exhibit the notable adverse effects associated with NAC treatment. PMID:27073589

  6. Dynamics of laser induced metal nanoparticle and pattern formation

    SciTech Connect

    Peláez, R. J. Kuhn, T.; Rodríguez, C. E.; Afonso, C. N.

    2015-02-09

    Discontinuous metal films are converted into either almost round, isolated, and randomly distributed nanoparticles (NPs) or fringed patterns of alternate non transformed film and NPs by exposure to single pulses (20 ns pulse duration and 193 nm wavelength) of homogeneous or modulated laser beam intensity. The dynamics of NPs and pattern formation is studied by measuring in real time the transmission and reflectivity of the sample upon homogeneous beam exposure and the intensity of the diffraction orders 0 and 1 in transmission configuration upon modulated beam exposure. The results show that laser irradiation induces melting of the metal either completely or at regions around intensity maxima sites for homogeneous and modulated beam exposure, respectively, within ≤10 ns. The aggregation and/or coalescence of the initially irregular metal nanostructures is triggered upon melting and continues after solidification (estimated to occur at ≤80 ns) for more than 1 μs. The present results demonstrate that real time transmission rather than reflectivity measurements is a valuable and easy-to-use tool for following the dynamics of NPs and pattern formation. They provide insights on the heat-driven processes occurring both in liquid and solid phases and allow controlling in-situ the process through the fluence. They also evidence that there is negligible lateral heat release in discontinuous films upon laser irradiation.

  7. Synergistic Effect of Bolus Exposure to Zinc Oxide Nanoparticles on Bleomycin-Induced Secretion of Pro-Fibrotic Cytokines without Lasting Fibrotic Changes in Murine Lungs

    PubMed Central

    Wu, Wenting; Ichihara, Gaku; Hashimoto, Naozumi; Hasegawa, Yoshinori; Hayashi, Yasuhiko; Tada-Oikawa, Saeko; Suzuki, Yuka; Chang, Jie; Kato, Masashi; D’Alessandro-Gabazza, Corina N.; Gabazza, Esteban C.; Ichihara, Sahoko

    2014-01-01

    Zinc oxide (ZnO) nanoparticles are widely used in various products, and the safety evaluation of this manufactured material is important. The present study investigated the inflammatory and fibrotic effects of pulmonary exposure to ZnO nanoparticles in a mouse model of pulmonary fibrosis. Pulmonary fibrosis was induced by constant subcutaneous infusion of bleomycin (BLM). Female C57BL/6Jcl mice were divided into BLM-treated and non-treated groups. In each treatment group, 0, 10, 20 or 30 µg of ZnO nanoparticles were delivered into the lungs through pharyngeal aspiration. Bronchoalveolar lavage fluid (BALF) and the lungs were sampled at Day 10 or 14 after administration. Pulmonary exposure by a single bolus of ZnO nanoparticles resulted in severe, but transient inflammatory infiltration and thickening of the alveolar septa in the lungs, along with the increase of total and differential cell counts in BLAF. The BALF level of interleukin (IL)-1β and transforming growth factor (TGF)-β was increased at Day 10 and 14, respectively. At Day 10, the synergistic effect of BLM and ZnO exposure was detected on IL-1β and monocyte chemotactic protein (MCP)-1 in BALF. The present study demonstrated the synergistic effect of pulmonary exposure to ZnO nanoparticles and subcutaneous infusion of BLM on the secretion of pro-fibrotic cytokines in the lungs. PMID:25561223

  8. Silver nanoparticles induce endoplasmatic reticulum stress response in zebrafish.

    PubMed

    Christen, Verena; Capelle, Martinus; Fent, Karl

    2013-10-15

    Silver nanoparticles (AgNPs) find increasing applications, and therefore humans and the environment are increasingly exposed to them. However, potential toxicological implications are not sufficiently known. Here we investigate effects of AgNPs (average size 120 nm) on zebrafish in vitro and in vivo, and compare them to human hepatoma cells (Huh7). AgNPs are incorporated in zebrafish liver cells (ZFL) and Huh7, and in zebrafish embryos. In ZFL cells AgNPs lead to induction of reactive oxygen species (ROS), endoplasmatic reticulum (ER) stress response, and TNF-α. Transcriptional alterations also occur in pro-apoptotic genes p53 and Bax. The transcriptional profile differed in ZFL and Huh7 cells. In ZFL cells, the ER stress marker BiP is induced, concomitant with the ER stress marker ATF-6 and spliced XBP-1 after 6h and 24h exposure to 0.5 g/L and 0.05 g/L AgNPs, respectively. This indicates the induction of different pathways of the ER stress response. Moreover, AgNPs induce TNF-α. In zebrafish embryos exposed to 0.01, 0.1, 1 and 5mg/L AgNPs hatching was affected and morphological defects occurred at high concentrations. ER stress related gene transcripts BiP and Synv are significantly up-regulated after 24h at 0.1 and 5mg/L AgNPs. Furthermore, transcriptional alterations occurred in the pro-apoptotic genes Noxa and p21. The ER stress response was strong in ZFL cells and occurred in zebrafish embryos as well. Our data demonstrate for the first time that AgNPs lead to induction of ER stress in zebrafish. The induction of ER stress can have several consequences including the activation of apoptotic and inflammatory pathways. PMID:23800688

  9. Data and results of a laboratory investigation of microprocessor upset caused by simulated lightning-induced analog transients

    NASA Technical Reports Server (NTRS)

    Belcastro, C. M.

    1984-01-01

    A methodology was developed a assess the upset susceptibility/reliability of a computer system onboard an aircraft flying through a lightning environment. Upset error modes in a general purpose microprocessor were studied. The upset tests involved the random input of analog transients which model lightning induced signals onto interface lines of an 8080 based microcomputer from which upset error data was recorded. The program code on the microprocessor during tests is designed to exercise all of the machine cycles and memory addressing techniques implemented in the 8080 central processing unit. A statistical analysis is presented in which possible correlations are established between the probability of upset occurrence and transient signal inputs during specific processing states and operations. A stochastic upset susceptibility model for the 8080 microprocessor is presented. The susceptibility of this microprocessor to upset, once analog transients have entered the system, is determined analytically by calculating the state probabilities of the stochastic model.

  10. Gold nanoparticle plasmonics enhanced ultrafast laser-induced optoporation and stimulation of targeted cells (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Meunier, Michel; Bergeron, Éric; Lavoie-Cardinal, Flavie; Boutopoulos, Christos; Salesse, Charleen; Winnik, Françoise M.; De Koninck, Paul

    2016-03-01

    Gold nanoparticles (AuNPs) have found numerous applications in nanomedicine in view of their robustness, ease of functionalization and low toxicity. Upon irradiation of AuNPs by a pulsed ultrafast laser, various highly localized phenomena can be obtained including a temperature rise, pressure wave, charge injection and production of nanobubbles close to the cellular membrane [1]. These phenomena can be used to manipulate, optoperforate, transfect and stimulate targeted cells [2-5]. Irradiating at 800 nm in the optically biological transparent window, we demonstrated local optoporation and transfection of cells as well as local stimulation of neurons. Two recent examples will be given: (i) Laser-induced selective optoporation of cells: The technique can be used on various types of cells and a proof of principle will be given on human cancer cells in a co-culture using functionalized AuNPs [6]. (ii) Laser-induced stimulation of neurons and monitoring of the localized Ca2+ signaling: This all optical method uses a standard confocal microscope to trigger a transient increase in free Ca2+ in neurons covered by functionalized AuNPs as well as to measure these local variations optically with the Ca2+ sensor GCaMP6s [7]. The proposed techniques provide a new complement to light-dependent methods in neuroscience. REFERENCES (by our group): (1) Boulais, J. Photochem. Photobiol. C Photochem. Rev. 17, 26 (2013); (2) Baumgart, Biomaterials 33, 2345 (2012); (3) Boulais, NanoLett. 12, 4763 (2012); (4) Boutopoulos, J. Biophotonics (2015); (5) Boutopoulos, Nanoscale 7, 11758 (2015); (6) Bergeron, Biomaterials, submitted (2015); (7) Lavoie-Cardinal, Nature Commun. submitted (2015).

  11. Live cell imaging using confocal microscopy induces intracellular calcium transients and cell death.

    PubMed

    Knight, Martin M; Roberts, Susan R; Lee, David A; Bader, Dan L

    2003-04-01

    Isolated chondrocytes stained with fluo 4-AM and visualized using standard confocal microscopy techniques exhibited Ca2- transients and oscillations. Decreasing the power of the laser light decreased the percent-age of cells exhibiting these Ca2+ signals. Treatment with the antioxidant ascorbate reduced the Ca2+ response, suggesting that it was mediated by light-induced release of reactive oxygen species (ROS). Cell viability 24 h after the 1-h confocal imaging period was approximately 90% for cells that were neither fluorescently stained nor subjected to laser excitation. By contrast, fluorescently stained cells imaged for 1 h exhibited greatly reduced viability. Treatment with ascorbate reduced the level of cell death, suggesting that the effect was mediated by release of exogenous ROS associated with the interaction of light and the fluorochrome. Ca2+ oscillations were not always associated with cell death, suggesting that separate light-sensitive pathways mediate the two processes. Light-activated Ca2+ signaling may trigger alterations in numerous cell processes and thereby represent an important and hitherto overlooked artifact in fluorescent microscopy of viable cells. PMID:12661552

  12. Line-edge roughness induced single event transient variation in SOI FinFETs

    NASA Astrophysics Data System (ADS)

    Weikang, Wu; Xia, An; Xiaobo, Jiang; Yehua, Chen; Jingjing, Liu; Xing, Zhang; Ru, Huang

    2015-11-01

    The impact of process induced variation on the response of SOI FinFET to heavy ion irradiation is studied through 3-D TCAD simulation for the first time. When FinFET biased at OFF state configuration (Vgs = 0, Vds = Vdd) is struck by a heavy ion, the drain collects ionizing charges under the electric field and a current pulse (single event transient, SET) is consequently formed. The results reveal that with the presence of line-edge roughness (LER), which is one of the major variation sources in nano-scale FinFETs, the device-to-device variation in terms of SET is observed. In this study, three types of LER are considered: type A has symmetric fin edges, type B has irrelevant fin edges and type C has parallel fin edges. The results show that type A devices have the largest SET variation while type C devices have the smallest variation. Further, the impact of the two main LER parameters, correlation length and root mean square amplitude, on SET variation is discussed as well. The results indicate that variation may be a concern in radiation effects with the down scaling of feature size.

  13. Diabetes Stimulates Osteoclastogenesis by Acidosis-Induced Activation of Transient Receptor Potential Cation Channels.

    PubMed

    Reni, Carlotta; Mangialardi, Giuseppe; Meloni, Marco; Madeddu, Paolo

    2016-01-01

    Patients with type 1 diabetes have lower bone mineral density and higher risk of fractures. The role of osteoblasts in diabetes-related osteoporosis is well acknowledged whereas the role of osteoclasts (OCLs) is still unclear. We hypothesize that OCLs participate in pathological bone remodeling. We conducted studies in animals (streptozotocin-induced type 1 diabetic mice) and cellular models to investigate canonical and non-canonical mechanisms underlying excessive OCL activation. Diabetic mice show an increased number of active OCLs. In vitro studies demonstrate the involvement of acidosis in OCL activation and the implication of transient receptor potential cation channel subfamily V member 1 (TRPV1). In vivo studies confirm the establishment of local acidosis in the diabetic bone marrow (BM) as well as the ineffectiveness of insulin in correcting the pH variation and osteoclast activation. Conversely, treatment with TRPV1 receptor antagonists re-establishes a physiological OCL availability. These data suggest that diabetes causes local acidosis in the BM that in turn increases osteoclast activation through the modulation of TRPV1. The use of clinically available TRPV1 antagonists may provide a new means to combat bone problems associated with diabetes. PMID:27468810

  14. Diabetes Stimulates Osteoclastogenesis by Acidosis-Induced Activation of Transient Receptor Potential Cation Channels

    PubMed Central

    Reni, Carlotta; Mangialardi, Giuseppe; Meloni, Marco; Madeddu, Paolo

    2016-01-01

    Patients with type 1 diabetes have lower bone mineral density and higher risk of fractures. The role of osteoblasts in diabetes-related osteoporosis is well acknowledged whereas the role of osteoclasts (OCLs) is still unclear. We hypothesize that OCLs participate in pathological bone remodeling. We conducted studies in animals (streptozotocin-induced type 1 diabetic mice) and cellular models to investigate canonical and non-canonical mechanisms underlying excessive OCL activation. Diabetic mice show an increased number of active OCLs. In vitro studies demonstrate the involvement of acidosis in OCL activation and the implication of transient receptor potential cation channel subfamily V member 1 (TRPV1). In vivo studies confirm the establishment of local acidosis in the diabetic bone marrow (BM) as well as the ineffectiveness of insulin in correcting the pH variation and osteoclast activation. Conversely, treatment with TRPV1 receptor antagonists re-establishes a physiological OCL availability. These data suggest that diabetes causes local acidosis in the BM that in turn increases osteoclast activation through the modulation of TRPV1. The use of clinically available TRPV1 antagonists may provide a new means to combat bone problems associated with diabetes. PMID:27468810

  15. Rapamycin transiently induces mitochondrial remodeling to reprogram energy metabolism in old hearts

    PubMed Central

    Chiao, Ying Ann; Kolwicz, Stephen C.; Basisty, Nathan; Gagnidze, Arni; Zhang, Julia; Gu, Haiwei; Djukovic, Danijel; Beyer, Richard P.; Raftery, Daniel; MacCoss, Michael; Tian, Rong; Rabinovitch, Peter S.

    2016-01-01

    Rapamycin, an inhibitor of mTOR signaling, has been shown to reverse diastolic dysfunction in old mice in 10 weeks, highlighting its therapeutic potential for a poorly treatable condition. However, the mechanisms and temporal regulation of its cardiac benefits remain unclear. We show that improved diastolic function in old mice begins at 2-4 weeks, progressing over the course of 10-week treatment. While TORC1-mediated S6 phosphorylation and TORC2 mediated AKT and PKCα phosphorylation are inhibited throughout the course of treatment, rapamycin inhibits ULK phosphorylation and induces autophagy during just the first week of treatment, returning to baseline at two weeks and after. Concordantly, markers of mitochondrial biogenesis increase over the first two weeks of treatment and return to control levels thereafter. This transient induction of autophagy and mitochondrial biogenesis suggests that damaged mitochondria are replaced by newly synthesized ones to rejuvenate mitochondrial homeostasis. This remodeling is shown to rapidly reverse the age-related reduction in fatty acid oxidation to restore a more youthful substrate utilization and energetic profile in old isolated perfused hearts, and modulates the myocardial metabolome in vivo. This study demonstrates the differential and dynamic mechanisms following rapamycin treatment and highlights the importance of understanding the temporal regulation of rapamycin effects. PMID:26872208

  16. Transient land breeze: Eclipse induced wind flow modifications—Observations over plant canopy

    NASA Astrophysics Data System (ADS)

    Murthy, B. S.; Latha, R.; Sreeja, P.; Dharmaraj, T.

    2012-11-01

    An experiment is conducted over Cassava plant canopy at a coastal station at CTCRI, Thiruvananthapuram (8°29'N, 76°59E) to study the response of meteorological parameters and land-sea breeze circulations to the annular solar eclipse on January 15, 2010. Observations reveal decrease of solar radiation to a minimum of 96 W m-2 during the peak eclipse period. Air temperature drops by 4 °C and relative humidity increases by 20%. Sensible heat flux reduces to zero. Transient land breeze occurs for a few minutes with a time lag of about 1 h possibly due to outflow from the umbra region or temperature gradient over land with the eclipse progressing in the eastward direction. Sea breeze is delayed by about 3 h on the next day of eclipse. Spectral energy density of wind (u, v, w) and temperature attains a minimum value during totality and increases later, attributable to reduction in turbulence due to eclipse-induced stability.

  17. Ultrastructural changes in methicillin-resistant Staphylococcus aureus induced by positively charged silver nanoparticles

    PubMed Central

    Romero-Urbina, Dulce G; Lara, Humberto H; Velázquez-Salazar, J Jesús; Arellano-Jiménez, M Josefina; Larios, Eduardo; Srinivasan, Anand; Lopez-Ribot, Jose L

    2015-01-01

    Summary Silver nanoparticles offer a possible means of fighting antibacterial resistance. Most of their antibacterial properties are attributed to their silver ions. In the present work, we study the actions of positively charged silver nanoparticles against both methicillin-sensitive Staphylococcus aureus and methicillin-resistant Staphylococcus aureus. We use aberration-corrected transmission electron microscopy to examine the bactericidal effects of silver nanoparticles and the ultrastructural changes in bacteria that are induced by silver nanoparticles. The study revealed that our 1 nm average size silver nanoparticles induced thinning and permeabilization of the cell wall, destabilization of the peptidoglycan layer, and subsequent leakage of intracellular content, causing bacterial cell lysis. We hypothesize that positively charged silver nanoparticles bind to the negatively charged polyanionic backbones of teichoic acids and the related cell wall glycopolymers of bacteria as a first target, consequently stressing the structure and permeability of the cell wall. This hypothesis provides a major mechanism to explain the antibacterial effects of silver nanoparticles on Staphylococcus aureus. Future research should focus on defining the related molecular mechanisms and their importance to the antimicrobial activity of silver nanoparticles. PMID:26734530

  18. Ultrastructural changes in methicillin-resistant Staphylococcus aureus induced by positively charged silver nanoparticles.

    PubMed

    Romero-Urbina, Dulce G; Lara, Humberto H; Velázquez-Salazar, J Jesús; Arellano-Jiménez, M Josefina; Larios, Eduardo; Srinivasan, Anand; Lopez-Ribot, Jose L; Yacamán, Miguel José

    2015-01-01

    Silver nanoparticles offer a possible means of fighting antibacterial resistance. Most of their antibacterial properties are attributed to their silver ions. In the present work, we study the actions of positively charged silver nanoparticles against both methicillin-sensitive Staphylococcus aureus and methicillin-resistant Staphylococcus aureus. We use aberration-corrected transmission electron microscopy to examine the bactericidal effects of silver nanoparticles and the ultrastructural changes in bacteria that are induced by silver nanoparticles. The study revealed that our 1 nm average size silver nanoparticles induced thinning and permeabilization of the cell wall, destabilization of the peptidoglycan layer, and subsequent leakage of intracellular content, causing bacterial cell lysis. We hypothesize that positively charged silver nanoparticles bind to the negatively charged polyanionic backbones of teichoic acids and the related cell wall glycopolymers of bacteria as a first target, consequently stressing the structure and permeability of the cell wall. This hypothesis provides a major mechanism to explain the antibacterial effects of silver nanoparticles on Staphylococcus aureus. Future research should focus on defining the related molecular mechanisms and their importance to the antimicrobial activity of silver nanoparticles. PMID:26734530

  19. Mitophagy induced by nanoparticle-peptide conjugates enabling an alternative intracellular trafficking route.

    PubMed

    Zhang, Zhaolei; Zhou, Lei; Zhou, Yanqing; Liu, Jinyin; Xing, Xiaoyun; Zhong, Jun; Xu, Guoqiang; Kang, Zhenhui; Liu, Jian

    2015-10-01

    The intracellular behaviors of nanoparticles are fundamentally important for the evaluation of their biosafety and the designs of nano carrier-assisted drug delivery with high therapeutic efficacy. It is still in a great need to discover how functionalized nanoparticles are transported inside the cells, for instance, in a complicated fashion of translocation between different types of cell organelles. Here we report a new understanding of the interactions between nanoparticles and cells by the development of polyoxometalates nanoparticle-peptide conjugates and investigation of their intracellular trafficking behaviors. The as-prepared nanoparticles are featured with a unique combination of fluorescence and high contrast for synchrotron X-ray-based imaging. Functional surface modification with peptides facilitates effective delivery of the nanoparticles onto the target organelle (mitochondria) and subsequent intracellular trafficking in a dynamic mode. Interestingly, our experimental results have revealed that autophagy of mitochondria (mitophagy) can be induced by NP-peptide as a cellular response for recycling the damaged organelles, through molecular mediation associated with the change of mitochondrial membrane potential. The biological effects induced by NP-peptide reciprocally affect the distribution patterns and fates of nanoparticles in the cell metabolism by providing an alternative route of intracellular trafficking. The new understanding of the mutual activities between nanoparticles and cells will enrich our approaches in the development of nanobiotechnology and nano-medicine for disease treatments. PMID:26142776

  20. Parathyroid Hormone (1-34) Transiently Protects Against Radiation-Induced Bone Fragility.

    PubMed

    Oest, Megan E; Mann, Kenneth A; Zimmerman, Nicholas D; Damron, Timothy A

    2016-06-01

    Radiation therapy for soft tissue sarcoma or tumor metastases is frequently associated with damage to the underlying bone. Using a mouse model of limited field hindlimb irradiation, we assessed the ability of parathyroid hormone (1-34) fragment (PTH) delivery to prevent radiation-associated bone damage, including loss of mechanical strength, trabecular architecture, cortical bone volume, and mineral density. Female BALB/cJ mice received four consecutive doses of 5 Gy to a single hindlimb, accompanied by daily injections of either PTH or saline (vehicle) for 8 weeks, and were followed for 26 weeks. Treatment with PTH maintained the mechanical strength of irradiated femurs in axial compression for the first eight weeks of the study, and the apparent strength of irradiated femurs in PTH-treated mice was greater than that of naïve bones during this time. PTH similarly protected against radiation-accelerated resorption of trabecular bone and transient decrease in mid-diaphyseal cortical bone volume, although this benefit was maintained only for the duration of PTH delivery. Overall, PTH conferred protection against radiation-induced fragility and morphologic changes by increasing the quantity of bone, but only during the period of administration. Following cessation of PTH delivery, bone strength and trabecular volume fraction rapidly decreased. These data suggest that PTH does not negate the longer-term potential for osteoclastic bone resorption, and therefore, finite-duration treatment with PTH alone may not be sufficient to prevent late onset radiotherapy-induced bone fragility. PMID:26847434

  1. Transient Receptor Potential Melastatin 7 Cation Channel Kinase: New Player in Angiotensin II-Induced Hypertension.

    PubMed

    Antunes, Tayze T; Callera, Glaucia E; He, Ying; Yogi, Alvaro; Ryazanov, Alexey G; Ryazanova, Lillia V; Zhai, Alexander; Stewart, Duncan J; Shrier, Alvin; Touyz, Rhian M

    2016-04-01

    Transient receptor potential melastatin 7 (TRPM7) is a bifunctional protein comprising a magnesium (Mg(2+))/cation channel and a kinase domain. We previously demonstrated that vasoactive agents regulate vascular TRPM7. Whether TRPM7 plays a role in the pathophysiology of hypertension and associated cardiovascular dysfunction is unknown. We studied TRPM7 kinase-deficient mice (TRPM7Δkinase; heterozygous for TRPM7 kinase) and wild-type (WT) mice infused with angiotensin II (Ang II; 400 ng/kg per minute, 4 weeks). TRPM7 kinase expression was lower in heart and aorta from TRPM7Δkinase versus WT mice, effects that were further reduced by Ang II infusion. Plasma Mg(2+) was lower in TRPM7Δkinase versus WT mice in basal and stimulated conditions. Ang II increased blood pressure in both strains with exaggerated responses in TRPM7Δkinase versus WT groups (P<0.05). Acetylcholine-induced vasorelaxation was reduced in Ang II-infused TRPM7Δkinase mice, an effect associated with Akt and endothelial nitric oxide synthase downregulation. Vascular cell adhesion molecule-1 expression was increased in Ang II-infused TRPM7 kinase-deficient mice. TRPM7 kinase targets, calpain, and annexin-1, were activated by Ang II in WT but not in TRPM7Δkinase mice. Echocardiographic and histopathologic analysis demonstrated cardiac hypertrophy and left ventricular dysfunction in Ang II-treated groups. In TRPM7 kinase-deficient mice, Ang II-induced cardiac functional and structural effects were amplified compared with WT counterparts. Our data demonstrate that in TRPM7Δkinase mice, Ang II-induced hypertension is exaggerated, cardiac remodeling and left ventricular dysfunction are amplified, and endothelial function is impaired. These processes are associated with hypomagnesemia, blunted TRPM7 kinase expression/signaling, endothelial nitric oxide synthase downregulation, and proinflammatory vascular responses. Our findings identify TRPM7 kinase as a novel player in Ang II-induced hypertension

  2. Evolution of light-induced vapor generation at a liquid-immersed metallic nanoparticle

    PubMed Central

    Zhen, Yu-Rong; Neumann, Oara; Polman, Albert; García de Abajo, F. Javier

    2013-01-01

    When an Au nanoparticle in a liquid medium is illuminated with resonant light of sufficient intensity, a nanometer scale envelope of vapor -a “nanobubble”- surrounding the particle, is formed. This is the nanoscale onset of the well-known process of liquid boiling, occurring at a single nanoparticle nucleation site, resulting from the photothermal response of the nanoparticle. Here we examine bubble formation at an individual metallic nanoparticle in detail. Incipient nanobubble formation is observed by monitoring the plasmon resonance shift of an individual, illuminated Au nanoparticle, when its local environment changes from liquid to vapor. The temperature on the nanoparticle surface is monitored during this process, where a dramatic temperature jump is observed as the nanoscale vapor layer thermally decouples the nanoparticle from the surrounding liquid. By increasing the intensity of the incident light or decreasing the interparticle separation, we observe the formation of micron sized bubbles resulting from the coalescence of nanoparticle-“bound” vapor envelopes. These studies provide the first direct and quantitative analysis of the evolution of light-induced steam generation by nanoparticles from the nanoscale to the macroscale, a process that is of fundamental interest for a growing number of applications. PMID:23517407

  3. Evolution of light-induced vapor generation at a liquid-immersed metallic nanoparticle.

    PubMed

    Fang, Zheyu; Zhen, Yu-Rong; Neumann, Oara; Polman, Albert; García de Abajo, F Javier; Nordlander, Peter; Halas, Naomi J

    2013-04-10

    When an Au nanoparticle in a liquid medium is illuminated with resonant light of sufficient intensity, a nanometer scale envelope of vapor-a "nanobubble"-surrounding the particle, is formed. This is the nanoscale onset of the well-known process of liquid boiling, occurring at a single nanoparticle nucleation site, resulting from the photothermal response of the nanoparticle. Here we examine bubble formation at an individual metallic nanoparticle in detail. Incipient nanobubble formation is observed by monitoring the plasmon resonance shift of an individual, illuminated Au nanoparticle, when its local environment changes from liquid to vapor. The temperature on the nanoparticle surface is monitored during this process, where a dramatic temperature jump is observed as the nanoscale vapor layer thermally decouples the nanoparticle from the surrounding liquid. By increasing the intensity of the incident light or decreasing the interparticle separation, we observe the formation of micrometer-sized bubbles resulting from the coalescence of nanoparticle-"bound" vapor envelopes. These studies provide the first direct and quantitative analysis of the evolution of light-induced steam generation by nanoparticles from the nanoscale to the macroscale, a process that is of fundamental interest for a growing number of applications. PMID:23517407

  4. Stress-induced phase transformation and optical coupling of silver nanoparticle superlattices into mechanically stable nanowires.

    PubMed

    Li, Binsong; Wen, Xiaodong; Li, Ruipeng; Wang, Zhongwu; Clem, Paul G; Fan, Hongyou

    2014-01-01

    One-dimensional silver materials display unique optical and electrical properties with promise as functional blocks for a new generation of nanoelectronics. To date, synthetic approaches and property engineering of silver nanowires have primarily focused on chemical methods. Here we report a simple physical method of metal nanowire synthesis, based on stress-induced phase transformation and sintering of spherical Ag nanoparticle superlattices. Two phase transformations of nanoparticles under stress have been observed at distinct length scales. First, the lattice dimensions of silver nanoparticle superlattices may be reversibly manipulated between 0-8 GPa compressive stresses to enable systematic and reversible changes in mesoscale optical coupling between silver nanoparticles. Second, stresses greater than 8 GPa induced an atomic lattice phase transformation, which induced sintering of silver nanoparticles into micron-length scale nanowires. The nanowire synthesis mechanism displays a dependence on both nanoparticle crystal surface orientation and presence of particular grain boundaries to enable nanoparticle consolidation into nanowires. PMID:24957078

  5. Semihydrophobic nanoparticle-induced disruption of supported lipid bilayers: specific ion effect.

    PubMed

    Jing, Benxin; Abot, Rosary C T; Zhu, Yingxi

    2014-11-20

    The interaction of nanoparticles with cell membranes is critical to understand and control the structural change and molecular transport of cell membranes for medicines and medical diagnostics, in which hydrophobic interaction is often involved. We examine the specific ion effect on the interaction of semihydrophobic nanoparticle with zwitterionic phospholipid bilayer in aqueous media added with different types of salts. Specifically, we compare the effect of different anions or cations on the adsorption of carboxyl-functionalized polystyrene nanoparticle on supported lipid bilayer and its induced bilayer disruption. By adding different anions at the same ionic concentration to the nanoparticle-lipid bilayer interface, we observe that the growth rate of nanoparticle-induced lipid-poor regions follows the exact Hofmeister anion order of CH3COO(-) > Cl(-) > NO3(-) ≫ SCN(-), suggesting the regulated hydrophobic interaction by anions. In contrast, the specific cation effect on nanoparticle-induced disruption rate of lipid bilayer does not follow the Hofmeister cation order and instead exhibits a trend of Cs(+) ∼ Rb(+) > Na(+) ≫ N(CH3)4(+). It is suggested that the effect of specific ions can be exploited as a simple and efficient approach to modify the nanoparticles-biomembrane interactions with the implication from drug delivery to nontoxic nanomaterial design. PMID:25337793

  6. Coalescence-induced crystallisation wave in Pd nanoparticles

    PubMed Central

    Grammatikopoulos, Panagiotis; Cassidy, Cathal; Singh, Vidyadhar; Sowwan, Mukhles

    2014-01-01

    Palladium nanoparticles offer an attractive alternative to bulk palladium for catalysis, hydrogen storage and gas sensing applications. Their performance depends strongly on surface structure; therefore, nanoparticle coalescence can play an important role, as it determines the resultant structure of the active sites where reactions (e.g. catalysis) actually take place, i.e. facets, edges, vertices or protrusions. With this in mind, we performed classical molecular dynamics (MD) simulations and magnetron-sputtering inert gas condensation depositions of palladium nanoparticles, supported by high-resolution transmission electron microscopy (HRTEM), to study the mechanisms that govern their coalescence. Surface energy minimisation drove the interactions initially, leading to the formation of an interface/neck, as expected. Intriguingly, at a later stage, atomic rearrangements triggered a crystallisation wave propagating through the amorphous nanoparticles, leading to mono- or polycrystalline fcc structures. In the case of crystalline nanoparticles, almost-epitaxial alignment occurred and the formation of twins and surface protrusions were observed. PMID:25047807

  7. Enzyme Induced Formation of Monodisperse Hydrogel Nanoparticles Tunable in Size

    SciTech Connect

    Bocharova, Vera; Sharp, Danna; Jones, Aaron; Cheng, Shiwang; Griffin, Philip J.; Agapov, Alexander L.; Voylov, Dmitry; Wang, Yangyang; Kisliuk, Alexander; Melman, Artem; Sokolov, Alexei P.

    2015-03-09

    Here, we report a novel approach to synthesize monodisperse hydrogel nanoparticles that are tunable in size. The distinctive feature of our approach is the use of a multicopper oxidase enzyme, laccase, as both a biocatalyst and template for nanoparticle growth. We utilize the ferroxidase activity of laccase to initiate localized production of iron(III) cations from the oxidation of iron(II) cations. We demonstrate that nanoparticles are formed in a dilute polymer solution of alginate as a result of cross-linking between alginate and enzymatically produced iron(III) cations. Exerting control over the enzymatic reaction allows for nanometer-scale tuning of the hydrogel nanoparticle radii in the range of 30–100 nm. Moreover, the nanoparticles and their growth kinetics were characterized via dynamic light scattering, atomic force microscopy, and UV–vis spectroscopy. Our finding opens up a new avenue for the synthesis of tunable nanoscale hydrogel particles for biomedical applications.

  8. Radiation-Induced Transient Effects in Near Infrared Focal Plane Arrays

    NASA Technical Reports Server (NTRS)

    Reed, Robert A.; Pickel, J.; Marshall, P.; Waczynski, A.; McMurray, R.; Gee, G.; Polidan, E.; Johnson, S.; McKeivey, M.; Ennico, K.; Johnson, R.

    2004-01-01

    This viewgraph presentation describes a test simulate the transient effects of cosmic ray impacts on near infrared focal plane arrays. The objectives of the test are to: 1) Characterize proton single events as function of energy and angle of incidence; 2) Measure charge spread (crosstalk) to adjacent pixels; 3) Assess transient recovery time.

  9. Spectrum of laser light scattered by nanoparticles in an ablation-induced cavitation bubble

    NASA Astrophysics Data System (ADS)

    Takeuchi, Masato; Sasaki, Koichi

    2016-04-01

    The spectrum of the laser light scattered by nanoparticles in a cavitation bubble, which was induced by laser ablation of a titanium target in water, was measured using a triple-grating spectrograph. The scattered laser light observed at 100 \\upmu s after laser ablation had no wavelength-shifted component, suggesting that nanoparticles at this delay time were metallic. The wavelength-shifted component was observed in the spectrum at a delay time of 200 \\upmu s, suggesting the formation of oxidized nanoparticles. However, we observed no peaks in the spectrum of the scattered laser light in the present in situ laser-light scattering experiment. On the other hand, we observed clear peaks in the Raman spectrum of synthesized nanoparticles. The experimental results suggest slow crystallization of nanoparticles in liquid in liquid-phase laser ablation.

  10. A review on radiation-induced nucleation and growth of colloidal metallic nanoparticles

    PubMed Central

    2013-01-01

    This review presents an introduction to the synthesis of metallic nanoparticles by radiation-induced method, especially gamma irradiation. This method offers some benefits over the conventional methods because it provides fully reduced and highly pure nanoparticles free from by-products or chemical reducing agents, and is capable of controlling the particle size and structure. The nucleation and growth mechanism of metallic nanoparticles are also discussed. The competition between nucleation and growth process in the formation of nanoparticles can determine the size of nanoparticles which is influenced by certain parameters such as the choice of solvents and stabilizer, the precursor to stabilizer ratio, pH during synthesis, and absorbed dose. PMID:24225302

  11. Different cell responses induced by exposure to maghemite nanoparticles

    NASA Astrophysics Data System (ADS)

    Luengo, Yurena; Nardecchia, Stefania; Morales, María Puerto; Serrano, M. Concepción

    2013-11-01

    Recent advances in nanotechnology have permitted the development of a wide repertoire of inorganic magnetic nanoparticles (NPs) with extensive promise for biomedical applications. Despite this remarkable potential, many questions still arise concerning the biocompatible nature of NPs when in contact with biological systems. Herein, we have investigated how controlled changes in the physicochemical properties of iron oxide NPs at their surface (i.e., surface charge and hydrodynamic size) affect, first, their interaction with cell media components and, subsequently, cell responses to NP exposure. For that purpose, we have prepared iron oxide NPs with three different coatings (i.e., dimercaptosuccinic acid - DMSA, (3-aminopropyl)triethoxysilane - APS and dextran) and explored the response of two different cell types, murine L929 fibroblasts and human Saos-2 osteoblasts, to their exposure. Interestingly, different cell responses were found depending on the NP concentration, surface charge and cell type. In this sense, neutral NPs, as those coated with dextran, induced negligible cell damage, as their cellular internalization was significantly reduced. In contrast, surface-charged NPs (i.e., those coated with DMSA and APS) caused significant cellular changes in viability, morphology and cell cycle under certain culture conditions, as a result of a more active cellular internalization. These results also revealed a particular cellular ability to detect and remember the original physicochemical properties of the NPs, despite the formation of a protein corona when incubated in culture media. Overall, conclusions from these studies are of crucial interest for future biomedical applications of iron oxide NPs.Recent advances in nanotechnology have permitted the development of a wide repertoire of inorganic magnetic nanoparticles (NPs) with extensive promise for biomedical applications. Despite this remarkable potential, many questions still arise concerning the biocompatible

  12. Role of Induced Magnetic Field on Transient Natural Convection Flow in a Vertical Channel: The Riemann Sum Approximation Approach

    NASA Astrophysics Data System (ADS)

    Jha, B. K.; Sani, I.

    2015-02-01

    This paper investigates the role of induced magnetic field on a transient natural convection flow of an electrically conducting, incompressible and viscous fluid in a vertical channel formed by two infinite vertical parallel plates. The transient flow formation inside the channel is due to sudden asymmetric heating of channel walls. The time dependent momentum, energy and magnetic induction equations are solved semi-analytically using the Laplace transform technique along with the Riemann-sum approximation method. The solutions obtained are validated by comparisons with the closed form solutions obtained for the steady states which have been derived separately and also by the implicit finite difference method. Graphical results for the temperature, velocity, induced magnetic field, current density, and skin-friction based on the semi-analytical solutions are presented and discussed.

  13. Heavy Ion Microbeam- and Broadbeam-Induced Current Transients in SiGe HBTs

    NASA Technical Reports Server (NTRS)

    Pellish, Jonathan A.; Reed, R. A.; McMorrow, D.; Vizkelethy, G.; Ferlet-Cavrois, V.; Baggio, J.; Duhamel, O.; Moen, K. A.; Phillips, S. D.; Diestelhorst, R. M.; Cressler, J. D.; Sutton, A. K.; Raman, A.; Turowski, M.; Dodd, P. E.; Alles, M. L.; Schrimpf, R. D.; Marshall, P. W.; Labeal, K. A.

    2009-01-01

    IBM 5AM SiGe HBT is device-under-test. High-speed measurement setup. Low-impedance current transient measurements. SNL, JYFL, GANIL. Microbeam to broadbeam position inference. Improvement to state-of-the-art. Microbeam (SNL) transients reveal position dependent heavy ion response, Unique response for different device regions Unique response for different bias schemes. Similarities to TPA pulsed-laser data. Broadbeam transients (JYFL and GANIL) provide realistic heavy ion response. Feedback using microbeam data. Overcome issues of LET and ion range with microbeam. **Angled Ar-40 data in full paper. Data sets yield first-order results, suitable for TCAD calibration feedback.

  14. Hepcidin-Induced Iron Deficiency Is Related to Transient Anemia and Hypoferremia in Kawasaki Disease Patients.

    PubMed

    Huang, Ying-Hsien; Kuo, Ho-Chang; Huang, Fu-Chen; Yu, Hong-Ren; Hsieh, Kai-Sheng; Yang, Ya-Ling; Sheen, Jiunn-Ming; Li, Sung-Chou; Kuo, Hsing-Chun

    2016-01-01

    Kawasaki disease (KD) is a type of systemic vasculitis that primarily affects children under the age of five years old. For sufferers of KD, intravenous immunoglobulin (IVIG) has been found to successfully diminish the occurrence of coronary artery lesions. Anemia is commonly found in KD patients, and we have shown that in appropriately elevated hepcidin levels are related to decreased hemoglobin levels in these patients. In this study, we investigated the time period of anemia and iron metabolism during different stages of KD. A total of 100 patients with KD and 20 control subjects were enrolled in this study for red blood cell and hemoglobin analysis. Furthermore, plasma, urine hepcidin, and plasma IL-6 levels were evaluated using enzyme-linked immunosorbent assay in 20 KD patients and controls. Changes in hemoglobin, plasma iron levels, and total iron binding capacity (TIBC) were also measured in patients with KD. Hemoglobin, iron levels, and TIBC were lower (p < 0.001, p = 0.009, and p < 0.001, respectively) while plasma IL-6 and hepcidin levels (both p < 0.001) were higher in patients with KD than in the controls prior to IVIG administration. Moreover, plasma hepcidin levels were positively and significantly correlated with urine hepcidin levels (p < 0.001) prior to IVIG administration. After IVIG treatment, plasma hepcidin and hemoglobin levels significantly decreased (both p < 0.001). Of particular note was a subsequent gradual increase in hemoglobin levels during the three weeks after IVIG treatment; nevertheless, the hemoglobin levels stayed lower in KD patients than in the controls (p = 0.045). These findings provide a longitudinal study of hemoglobin changes and among the first evidence that hepcidin induces transient anemia and hypoferremia during KD's acute inflammatory phase. PMID:27187366

  15. Hepcidin-Induced Iron Deficiency Is Related to Transient Anemia and Hypoferremia in Kawasaki Disease Patients

    PubMed Central

    Huang, Ying-Hsien; Kuo, Ho-Chang; Huang, Fu-Chen; Yu, Hong-Ren; Hsieh, Kai-Sheng; Yang, Ya-Ling; Sheen, Jiunn-Ming; Li, Sung-Chou; Kuo, Hsing-Chun

    2016-01-01

    Kawasaki disease (KD) is a type of systemic vasculitis that primarily affects children under the age of five years old. For sufferers of KD, intravenous immunoglobulin (IVIG) has been found to successfully diminish the occurrence of coronary artery lesions. Anemia is commonly found in KD patients, and we have shown that in appropriately elevated hepcidin levels are related to decreased hemoglobin levels in these patients. In this study, we investigated the time period of anemia and iron metabolism during different stages of KD. A total of 100 patients with KD and 20 control subjects were enrolled in this study for red blood cell and hemoglobin analysis. Furthermore, plasma, urine hepcidin, and plasma IL-6 levels were evaluated using enzyme-linked immunosorbent assay in 20 KD patients and controls. Changes in hemoglobin, plasma iron levels, and total iron binding capacity (TIBC) were also measured in patients with KD. Hemoglobin, iron levels, and TIBC were lower (p < 0.001, p = 0.009, and p < 0.001, respectively) while plasma IL-6 and hepcidin levels (both p < 0.001) were higher in patients with KD than in the controls prior to IVIG administration. Moreover, plasma hepcidin levels were positively and significantly correlated with urine hepcidin levels (p < 0.001) prior to IVIG administration. After IVIG treatment, plasma hepcidin and hemoglobin levels significantly decreased (both p < 0.001). Of particular note was a subsequent gradual increase in hemoglobin levels during the three weeks after IVIG treatment; nevertheless, the hemoglobin levels stayed lower in KD patients than in the controls (p = 0.045). These findings provide a longitudinal study of hemoglobin changes and among the first evidence that hepcidin induces transient anemia and hypoferremia during KD’s acute inflammatory phase. PMID:27187366

  16. Remote measurement of photosynthetic efficiency using laser induced fluorescence transient (LIFT) technique.

    NASA Astrophysics Data System (ADS)

    Pieruschka, R.; Rascher, U.; Klimov, D.; Kolber, Z. S.; Berry, J. A.

    2007-12-01

    An understanding of spatial and temporal diversity of photosynthetic processes, water and energy exchange of complex plant canopies is essential for carbon and climate models. Remote sensing from space or aircraft platforms provides the only practical way to characterize the vast extent of plant canopies around the globe, but the basis for relating physiological processes to remote sensing is still largely theoretical. Experiments that bridge this gap are needed. Chlorophyll fluorescence measurements have been widely applied to quantify photosynthetic efficiency and non- photochemical energy dissipation non-destructively in photosynthetically active organisms. The most commonly used Pulse Amplitude Modulated (PAM) technique provides a saturating light pulse and is not practical at the canopy scale. We report here on a recently developed technique, Laser Induced Fluorescence Transient (LIFT), capable of remote measurement of photosynthetic efficiency of selected leaves at a distance of up to 50 m and we present here continuous studies on plans growing under natural conditions during the beginning of the winter season and the onset of summer drought in this Mediterranean climate. i) Lichens showed a strong diurnal variation in photosynthetic efficiency which correlated with relative humidity; ii) Photosynthetic efficiency of annual grass decreased with progressing drought stress; iii) An oak canopy showed very little variation of quantum yield from leaf out in spring to summer; iv) The combined effect of low temperature and high light intensity during an early winter strongly reduced the photosynthetic efficiency of four different species in response to chilling stress. These measures with the LIFT correlated well with (more limited) sampling by PAM fluoromentry and gas exchange. The ability to make continuous, automatic and remote measurements of photosynthetic efficiency of leaves with the LIFT provides a new approach for studying the heterogeneity of

  17. Epimural Indicator Phylotypes of Transiently-Induced Subacute Ruminal Acidosis in Dairy Cattle

    PubMed Central

    Wetzels, Stefanie U.; Mann, Evelyne; Metzler-Zebeli, Barbara U.; Pourazad, Poulad; Qumar, Muhammad; Klevenhusen, Fenja; Pinior, Beate; Wagner, Martin; Zebeli, Qendrim; Schmitz-Esser, Stephan

    2016-01-01

    The impact of a long-term subacute rumen acidosis (SARA) on the bovine epimural bacterial microbiome (BEBM) and its consequences for rumen health is poorly understood. This study aimed to investigate shifts in the BEBM during a long-term transient SARA model consisting of two concentrate-diet-induced SARA challenges separated by a 1-week challenge break. Eight cows were fed forage and varying concentrate amounts throughout the experiment. In total, 32 rumen papilla biopsies were taken for DNA isolation (4 sampling time points per cow: at the baseline before concentrate was fed, after the first SARA challenge, after the challenge break, and after the second SARA challenge). Ruminal pH was continuously monitored. The microbiome was determined using Illumina MiSeq sequencing of the 16S rRNA gene (V345 region). In total 1,215,618 sequences were obtained and clustered into 6833 operational taxonomic units (OTUs). Campylobacter and Kingella were the most abundant OTUs (16.5 and 7.1%). According to ruminal pH dynamics, the second challenge was more severe than the first challenge. Species diversity estimates and evenness increased during the challenge break compared to all other sampling time points (P < 0.05). During both SARA challenges, Kingella- and Azoarcus-OTUs decreased (0.5 and 0.4 fold-change) and a dominant Ruminobacter-OTU increased during the challenge break (18.9 fold-change; P < 0.05). qPCR confirmed SARA-related shifts. During the challenge break noticeably more OTUs increased compared to other sampling time points. Our results show that the BEBM re-establishes the baseline conditions slower after a SARA challenge than ruminal pH. Key phylotypes that were reduced during both challenges may help to establish a bacterial fingerprint to facilitate understanding effects of SARA conditions on the BEBM and their consequences for the ruminant host. PMID:26973642

  18. Measuring Near Induced Transient Myopia in College Students with Visual Discomfort

    PubMed Central

    Borsting, Eric; Tosha, Chinatsu; Chase, Chris; Ridder, William H.

    2010-01-01

    Purpose Visual discomfort is a common problem and our previous research indicated that 17% of college students experience moderate to high levels of discomfort when reading or studying. There have been several visual factors associated with visual discomfort and in this study we focused on measuring the near induced transient myopia (NITM) response in a group of college students with significant visual discomfort. Methods Visual discomfort was evaluated with a survey developed by Conlon et al (1999). Twelve college students with high visual discomfort (scoring one standard deviation higher than the mean value) and 12 college students with low visual discomfort (scoring within one-half standard deviation of the mean value) participated in the study. All students had 20/25 or better visual acuity, no strabismus, and no significant uncorrected refractive error. All refractive error and accommodative measurements were made with the WAM-5500 auto-refractor. A pre-task distance refraction at 6 m was taken for 60 sec and then the students read a story for 10 min at 20 cm. After reading the passage the post-task distance refraction was measured for 2 min at 6 m. Values for the pre- and post-task measures were averaged in 10 sec blocks of time. Results A mixed ANOVA comparing discomfort group by pre- and post-near work distance refraction showed a significant interaction (p=0.05). Comparing the means of the pre and post task distance refraction indicated that the high discomfort group showed no change in refractive error but the low discomfort group showed a myopic shift of 0.13 D. Conclusions An NITM response is not associated with high visual discomfort experienced by college students when reading or doing near work. PMID:20802366

  19. Changes in metal nanoparticle shape and size induced by swift heavy-ion irradiation

    NASA Astrophysics Data System (ADS)

    Ridgway, M. C.; Kluth, P.; Giulian, R.; Sprouster, D. J.; Araujo, L. L.; Schnohr, C. S.; Llewellyn, D. J.; Byrne, A. P.; Foran, G. J.; Cookson, D. J.

    2009-03-01

    Changes in the shape and size of Co, Pt and Au nanoparticles induced by swift heavy-ion irradiation (SHII) have been characterized using a combination of transmission electron microscopy, small-angle X-ray scattering and X-ray absorption near-edge structure. Elemental nanoparticles of diameters 2-15 nm were first formed in amorphous SiO 2 by ion implantation and thermal annealing and then irradiated at room temperature with 27-185 MeV Au ions as a function of fluence. Spherical nanoparticles below a minimum diameter (4-7 nm) remained spherical under SHII but progressively decreased in size as a result of dissolution into the SiO 2 matrix. Spherical nanoparticles above the minimum diameter threshold were transformed to elongated rods aligned with the ion beamdirection. The nanorod width saturated at an electronic energy deposition dependent value, progressively increasing from 4-6 to 7-10 nm (at 5-18 keV/nm, respectively) while the nanorod length exhibited a broad distribution consistent with that of the unirradiated spherical nanoparticles. The threshold diameter for spherical nanoparticle elongation was comparable to the saturation value of nanorod width. We correlate this saturation value with the diameter of the molten track induced in amorphous SiO 2 by SHII. In summary, changes in nanoparticle shape and size are governed to a large extent by the ion irradiation parameters.

  20. Metal Oxide Nanoparticles Induce Unique Inflammatory Footprints in the Lung: Important Implications for Nanoparticle Testing

    PubMed Central

    Cho, Wan-Seob; Duffin, Rodger; Poland, Craig A.; Howie, Sarah E.M.; MacNee, William; Bradley, Mark; Megson, Ian L.; Donaldson, Ken

    2010-01-01

    Background Metal oxide nanoparticles (NPs) have been widely used in industry, cosmetics, and biomedicine. Objectives We examined hazards of several well-characterized high production volume NPs because of increasing concern about occupational exposure via inhalation. Methods A panel of well-characterized NPs [cerium oxide (CeO2NP), titanium dioxide (TiO2NP), carbon black (CBNP), silicon dioxide (SiO2NP), nickel oxide (NiONP), zinc oxide (ZnONP), copper oxide (CuONP), and amine-modified polystyrene beads] was instilled into lungs of rats. We evaluated the inflammation potencies of these NPs 24 hr and 4 weeks postinstillation. For NPs that caused significant inflammation at 24 hr, we then investigated the characteristics of the inflammation. All exposures were carried out at equal-surface-area doses. Results Only CeO2NP, NiONP, ZnONP, and CuONP were inflammogenic to the lungs of rats at the high doses used. Strikingly, each of these induced a unique inflammatory footprint both acutely (24 hr) and chronically (4 weeks). Acutely, patterns of neutrophil and eosinophil infiltrates differed after CeO2NP, NiONP, ZnONP, and CuONP treatment. Chronic inflammatory responses also differed after 4 weeks, with neutrophilic, neutrophilic/lymphocytic, eosinophilic/fibrotic/granulomatous, and fibrotic/granulomatous inflammation being caused respectively by CeO2NP, NiONP, ZnONP, and CuONP. Conclusion Different types of inflammation imply different hazards in terms of pathology, risks, and risk severity. In vitro testing could not have differentiated these complex hazard outcomes, and this has important implications for the global strategy for NP hazard assessment. Our results demonstrate that NPs cannot be viewed as a single hazard entity and that risk assessment should be performed separately and with caution for different NPs. PMID:20729176

  1. Electric-Field-Induced Alignment of Block Copolymer/Nanoparticle Blends

    SciTech Connect

    Liedel, Clemens; Schindler, Kerstin; Pavan, Mariela J.; Lewin, Christian; Pester, Christian W; Ruppel, Markus A; Urban, Volker S; Shenhar, Roy; Boker, Alexander

    2013-01-01

    External electric fi elds readily align birefringent block-copolymer mesophases. In this study the effect of gold nanoparticles on the electric-fi eld-induced alignment of a lamellae-forming polystyrene- block -poly(2-vinylpyridine) copolymer is assessed. Nanoparticles are homogeneously dispersed in the styrenic phase and promote the quantitative alignment of lamellar domains by substantially lowering the critical field strength above which alignment proceeds. The results suggest that the electric-fi eldassisted alignment of nanostructured block copolymer/nanoparticle composites may offer a simple way to greatly mitigate structural and orientational defects of such fi lms under benign experimental conditions.

  2. Nanoparticle-induced negative differential resistance and memory effect in polymer bistable light-emitting device

    NASA Astrophysics Data System (ADS)

    Tseng, Ricky J.; Ouyang, Jianyong; Chu, Chih-Wei; Huang, Jinsong; Yang, Yang

    2006-03-01

    Recently, electrical bistability was demonstrated in polymer thin films incorporated with metal nanoparticles [J. Ouyang, C. W. Chu, C. R. Szmanda, L. P. Ma, and Y. Yang, Nat. Mater. 3, 918 (2004)]. In this letter, we show the evidence that electrons are the dominant charge carriers in these bistable devices. Direct integration of bistable polymer layer with a light-emitting polymer layer shows a unique light-emitting property modulated by the electrical bistability. A unique negative differential resistance induced by the charged gold nanoparticles is observed due to the charge trapping effect from the nanoparticles when interfaced with the light-emitting layer.

  3. Aqueous medium induced optical transitions in cerium oxide nanoparticles

    SciTech Connect

    Inerbaev, Talgat M.; Karakoti, Ajay S.; Kuchibhatla, S. V. N. T.; Kumar, Amit; Masunov, Artem E.; Seal, Sudipta

    2015-03-07

    Experimental and theoretical investigations were performed to investigate the effect of water on optical properties of nanoceria as a function of Ce3+ concentration. Theoretical studies based on density functional plane-wave calculations reveal that the indirect optical transitions in bare ceria nanoparticles are red-shifted with an increase in the concentration of Ce3+. However, ceria nanoparticles model with adsorbed water molecules show a blue shift in the indirect optical spectra under identical conditions. Direct optical transitions are almost independent of Ce3+ concentration but show a pronounced blue shift in the aqueous environment relative to the bare nanoparticles. The theoretical study is consistent with our experimental observation in difference of shift behaviour in bare and aqueous suspended ceria nanoparticles. This change from red- to blue-shift in indirect optical transitions is associated with the polarization effect of water molecules on f-electron states.

  4. Spectral Induced Polarization Measurements of Nanoparticles in Laboratory Column Experiments

    EPA Science Inventory

    Nano sized materials are prevalent in consumer goods, manufacturing, industrial processes, and remediation technologies. The intentional and accidental introduction of nanoparticles (NP) into the subsurface pose a potential risk to the environment and public health. This resea...

  5. Ionic liquid-induced synthesis of selenium nanoparticles

    SciTech Connect

    Langi, Bhushan; Shah, Chetan; Singh, Krishankant; Chaskar, Atul; Kumar, Manmohan; Bajaj, Parma N.

    2010-06-15

    A simple wet chemical method has been used to synthesize selenium nanoparticles by the reaction of ionic liquid with sodium selenosulphate, a selenium precursor, in the presence of polyvinyl alcohol stabilizer, in aqueous medium. The method is capable of producing spherical selenium nanoparticles in the size range of 76-150 nm under ambient conditions. This is a first report on the production of nano-selenium assisted by an ionic liquid. The synthesized nanoparticles can be separated easily from the aqueous sol by a high-speed centrifuge machine, and can be re-dispersed in an aqueous medium. The synthesized selenium nanoparticles have been characterized by X-ray diffraction, energy dispersive X-ray analysis, differential scanning calorimetry and transmission electron microscopy techniques.

  6. Size and alloying induced shift in core and valence bands of Pd-Ag and Pd-Cu nanoparticles

    SciTech Connect

    Sengar, Saurabh K.; Mehta, B. R.; Govind

    2014-03-28

    In this report, X-ray photoelectron spectroscopy studies have been carried out on Pd, Ag, Cu, Pd-Ag, and Pd-Cu nanoparticles having identical sizes corresponding to mobility equivalent diameters of 60, 40, and 20 nm. The nanoparticles were prepared by the gas phase synthesis method. The effect of size on valence and core levels in metal and alloy nanoparticles has been studied by comparing the values to those with the 60 nm nanoparticles. The effect of alloying has been investigated by comparing the valence and core level binding energies of Pd-Cu and Pd-Ag alloy nanoparticles with the corresponding values for Pd, Ag, and Cu nanoparticles of identical sizes. These effects have been explained in terms of size induced lattice contractions, alloying induced charge transfer, and hybridization effects. The observation of alloying and size induced binding energy shifts in bimetallic nanoparticles is important from the point of view of hydrogen reactivity.

  7. Swift heavy-ion irradiation-induced shape and structural transformation in cobalt nanoparticles

    NASA Astrophysics Data System (ADS)

    Sprouster, D. J.; Giulian, R.; Araujo, L. L.; Kluth, P.; Johannessen, B.; Cookson, D. J.; Ridgway, M. C.

    2011-06-01

    The shape and structural evolution of Co nanoparticles embedded in SiO2 and subjected to swift heavy-ion irradiation have been investigated over a wide energy and fluence range. Modifications of the nanoparticle size and shape were characterized with transmission electron microscopy and small-angle x-ray scattering. Nanoparticles below a threshold diameter remained spherical in shape and progressively decreased in size under irradiation due to dissolution. Nanoparticles above the threshold diameter transformed into nanorods with their major dimension parallel to the incident ion direction. Modifications of the atomic-scale structure of the Co nanoparticles were identified with x-ray absorption spectroscopy. Analysis of the x-ray absorption near-edge spectra showed that prior to irradiation all Co atoms were in a metallic state, while after irradiation Co atoms were in both oxidized and metallic environments, the former consistent with dissolution. The evolution of the nanoparticle short-range order was determined from extended x-ray absorption fine structure spectroscopy. Structural changes in the Co nanoparticles as a function of ion fluence included an increase in disorder and asymmetric deviation from a Gaussian interatomic distance distribution coupled with a decrease in bondlength. Such changes resulted from the irradiation-induced decrease in nanoparticle size and subsequent dissolution.

  8. Ion-induced fabrication of silk fibroin nanoparticles from Chinese oak tasar Antheraea pernyi.

    PubMed

    Wang, Juan; Zhang, Shanshan; Xing, Tieling; Kundu, Banani; Li, Mingzhong; Kundu, Subhas C; Lu, Shenzhou

    2015-08-01

    Silk protein fibroin in nanoparticles form is a promising material for drug delivery due to its pleiotropic properties, including biocompatibility, biodegradability, ease in fabrication into smaller diameters, high bioavailability, and therapeutic retention at target sites. In the present study, silk nanoparticles are fabricated from regenerated fibroin solution of the Chinese temperate oak tasar Antheraea pernyi by novel ion-induced self-assembly in a very short time under mild conditions. The resultant fibroin nanoparticles range in size from 100 to 500 nm. The molecular conformation of regenerated fibroin changes from α-helical to a β-sheet structure as a rapid function of the ionic strength and the hydrophobic and electrostatic interactions. The mild conditions are potentially advantageous for the encapsulation of sensitive drugs and therapeutic molecules such as doxorubicin hydrochloride, an amphiphilic anticancer therapeutic. In vitro release of doxorubicin from nanoparticles is pH sensitive, with approx. 65% doxorubicin remaining in the fibroin nanoparticles after 11 days. The activity of fibroin nanoparticles on hepatomas indicates the efficacy of the fibroin nanoparticles to maintain the bioactivity of the loaded doxorubicin and impart a dose-dependent cell growth inhibition. The results suggest that Chinese temperate oak tasar silk fibroin nanoparticles can be used as a sustained drug delivery vehicle. PMID:25936281

  9. Dynamical cancellation of pulse-induced transients in a metallic shielded room for ultra-low-field magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Zevenhoven, Koos C. J.; Dong, Hui; Ilmoniemi, Risto J.; Clarke, John

    2015-01-01

    Pulse-induced transients such as eddy currents can cause problems in measurement techniques where a signal is acquired after an applied preparatory pulse. In ultra-low-field magnetic resonance imaging, performed in magnetic fields typically of the order of 100 μT, the signal-to-noise ratio is enhanced in part by prepolarizing the proton spins with a pulse of much larger magnetic field and in part by detecting the signal with a Superconducting QUantum Interference Device (SQUID). The pulse turn-off, however, can induce large eddy currents in the shielded room, producing an inhomogeneous magnetic-field transient that both seriously distorts the spin dynamics and exceeds the range of the SQUID readout. It is essential to reduce this transient substantially before image acquisition. We introduce dynamical cancellation (DynaCan), a technique in which a precisely designed current waveform is applied to a separate coil during the later part and turn off of the polarizing pulse. This waveform, which bears no resemblance to the polarizing pulse, is designed to drive the eddy currents to zero at the precise moment that the polarizing field becomes zero. We present the theory used to optimize the waveform using a detailed computational model with corrections from measured magnetic-field transients. SQUID-based measurements with DynaCan demonstrate a cancellation of 99%. Dynamical cancellation has the great advantage that, for a given system, the cancellation accuracy can be optimized in software. This technique can be applied to both metal and high-permeability alloy shielded rooms, and even to transients other than eddy currents.

  10. Dynamical cancellation of pulse-induced transients in a metallic shielded room for ultra-low-field magnetic resonance imaging

    SciTech Connect

    Zevenhoven, Koos C. J. Ilmoniemi, Risto J.; Dong, Hui; Clarke, John

    2015-01-19

    Pulse-induced transients such as eddy currents can cause problems in measurement techniques where a signal is acquired after an applied preparatory pulse. In ultra-low-field magnetic resonance imaging, performed in magnetic fields typically of the order of 100 μT, the signal-to-noise ratio is enhanced in part by prepolarizing the proton spins with a pulse of much larger magnetic field and in part by detecting the signal with a Superconducting QUantum Interference Device (SQUID). The pulse turn-off, however, can induce large eddy currents in the shielded room, producing an inhomogeneous magnetic-field transient that both seriously distorts the spin dynamics and exceeds the range of the SQUID readout. It is essential to reduce this transient substantially before image acquisition. We introduce dynamical cancellation (DynaCan), a technique in which a precisely designed current waveform is applied to a separate coil during the later part and turn off of the polarizing pulse. This waveform, which bears no resemblance to the polarizing pulse, is designed to drive the eddy currents to zero at the precise moment that the polarizing field becomes zero. We present the theory used to optimize the waveform using a detailed computational model with corrections from measured magnetic-field transients. SQUID-based measurements with DynaCan demonstrate a cancellation of 99%. Dynamical cancellation has the great advantage that, for a given system, the cancellation accuracy can be optimized in software. This technique can be applied to both metal and high-permeability alloy shielded rooms, and even to transients other than eddy currents.

  11. Laser-induced incandescence diagnostic for in situ monitoring of nanoparticle synthesis in an atmospheric plasma

    NASA Astrophysics Data System (ADS)

    Mitrani, James; Patel, Shane; Shneider, Mikhail; Stratton, Brent; Raitses, Yevgeny

    2014-10-01

    A DC arc discharge with a consumed graphite electrode is commonly used for synthesis of carbon nanoaparticles in a low temperature (0.1-1 eV), atmospheric pressure plasma. The formation of nanoparticles in this plasma is poorly understood; it is not clear where nanoparticles nucleate and grow in the arc discharge. Therefore, a laser-induced incandescence (LII) diagnostic for in situ monitoring of the nanoparticles' spatial distribution in the plasma is currently being constructed. The LII diagnostic involves heating the particles with a short-pulsed laser, and measuring the induced spatiotemporal incandescence profiles on longer timescales. By appropriately modeling the induced spatiotemporal incandescence profiles, one can measure particle diameters and volume fraction. LII diagnostics have been extensively used to study soot particles in flames. However, they have never been applied in a strongly coupled plasma background. Even though the spatial dimensions for soot and nanoparticles are similar, great care is needed in developing an LII diagnostic for monitoring nanoparticles in a plasma background. Therefore, we will calibrate our LII diagnostic by measuring spatiotemporal incandescence profiles of known, research grade soot and nanoparticles. This work was supported by DOE Contract DE-AC02-09CH11466.

  12. Nanosecond light induced, thermally tunable transient dual absorption bands in a-Ge₅As₃₀Se₆₅ thin film.

    PubMed

    Khan, Pritam; Saxena, Tarun; Jain, H; Adarsh, K V

    2014-01-01

    In this article, we report the first observation of nanosecond laser induced transient dual absorption bands, one in the bandgap (TA₁) and another in the sub-bandgap (TA₂) regions of a-Ge₅As₃₀Se₆₅ thin films. Strikingly, these bands are thermally tunable and exhibit a unique contrasting characteristic: the magnitude of TA₁ decreases while that of TA₂ increases with increasing temperature. Further, the decay kinetics of these bands is strongly influenced by the temperature, which signifies a strong temperature dependent exciton recombination mechanism. The induced absorption shows quadratic and the decay time constant shows linear dependence on the laser beam fluence. PMID:25300520

  13. Investigation of electrically-active deep levels in single-crystalline diamond by particle-induced charge transient spectroscopy

    NASA Astrophysics Data System (ADS)

    Kada, W.; Kambayashi, Y.; Ando, Y.; Onoda, S.; Umezawa, H.; Mokuno, Y.; Shikata, S.; Makino, T.; Koka, M.; Hanaizumi, O.; Kamiya, T.; Ohshima, T.

    2016-04-01

    To investigate electrically-active deep levels in high-resistivity single-crystalline diamond, particle-induced charge transient spectroscopy (QTS) techniques were performed using 5.5 MeV alpha particles and 9 MeV carbon focused microprobes. For unintentionally-doped (UID) chemical vapor deposition (CVD) diamond, deep levels with activation energies of 0.35 eV and 0.43 eV were detected which correspond to the activation energy of boron acceptors in diamond. The results suggested that alpha particle and heavy ion induced QTS techniques are the promising candidate for in-situ investigation of deep levels in high-resistivity semiconductors.

  14. Factors affecting T cell responses induced by fully synthetic glyco-gold-nanoparticles

    NASA Astrophysics Data System (ADS)

    Fallarini, Silvia; Paoletti, Tiziana; Battaglini, Carolina Orsi; Ronchi, Paolo; Lay, Luigi; Bonomi, Renato; Jha, Satadru; Mancin, Fabrizio; Scrimin, Paolo; Lombardi, Grazia

    2012-12-01

    We have synthesized and characterized nearly monodisperse and highly pure gold nanoparticles (2 and 5 nm) coated with non-immunoactive mono- and disaccharides, modelled after the capsular polysaccharide of serogroup A of the Neisseria meningitidis bacterium. We have used them to test their ability to induce immune cell responses as a consequence of their multivalency. The results indicate that they are indeed immunoactive and that immunoactivity is strongly dependent on size, and larger, 5 nm nanoparticles perform far better than smaller, 2 nm ones. Immune response (activation of macrophages) initiates with the whole nanoparticle recognition by the surface of antigen-presenting cells, independent of the saccharide oligomerization (or charge) on the nanoparticle surface. The induction of T cell proliferation and the increase of IL-2 levels, a consequence of the expression of MHC II involved in antigen presentation, require the presence of a disaccharide on the nanoparticle, not just a monosaccharide. A possible explanation is that, at this stage, the saccharides are detached from the gold surface. These results may provide leads for designing new saccharide-based, nanoparticle-conjugate vaccines.We have synthesized and characterized nearly monodisperse and highly pure gold nanoparticles (2 and 5 nm) coated with non-immunoactive mono- and disaccharides, modelled after the capsular polysaccharide of serogroup A of the Neisseria meningitidis bacterium. We have used them to test their ability to induce immune cell responses as a consequence of their multivalency. The results indicate that they are indeed immunoactive and that immunoactivity is strongly dependent on size, and larger, 5 nm nanoparticles perform far better than smaller, 2 nm ones. Immune response (activation of macrophages) initiates with the whole nanoparticle recognition by the surface of antigen-presenting cells, independent of the saccharide oligomerization (or charge) on the nanoparticle surface. The

  15. Plasmon-Induced Water Splitting Using Metallic-Nanoparticle-Loaded Photocatalysts and Photoelectrodes.

    PubMed

    Ueno, Kosei; Oshikiri, Tomoya; Misawa, Hiroaki

    2016-01-18

    Visible- and near-infrared-light-driven water splitting, which splits water molecules to generate hydrogen and oxygen gases, is a significant subject in artificial photosynthesis with the goal of achieving a low-carbon society. In recent years, considerable attention has been paid to studies on the development of a plasmon-induced water-splitting system responding to visible light. In this review, we categorized water-splitting systems as gold-nanoparticle-loaded semiconductor photocatalytic particles system and metallic-nanoparticles-loaded semiconductor photoelectrode systems, and introduce the latest studies according to these categories. Especially, we describe the studies that optimize a material or a structural design of metallic-nanoparticle-loaded semiconductor photoelectrodes and consider a whole water-splitting system, including a cathode design. Furthermore, we discuss important points when studying plasmon-induced water splitting, and we describe a methodology that enhances plasmon-induced water-splitting efficiency. PMID:26593450

  16. Drug-loaded nanoparticles induce gene expression in human pluripotent stem cell derivatives

    PubMed Central

    Gajbhiye, Virendra; Escalante, Leah; Chen, Guojun; Laperle, Alex; Zheng, Qifeng; Steyer, Benjamin; Gong, Shaoqin; Saha, Krishanu

    2014-01-01

    Tissue engineering and advanced manufacturing of human stem cells requires a suite of tools to control gene expression spatiotemporally in culture. Inducible gene expression systems offer cell-extrinsic control, typically through addition of small molecules, but small molecule inducers typically contain few functional groups for further chemical modification. Doxycycline (DXC), a potent small molecule inducer of tetracycline (Tet) transgene systems, was conjugated to a hyperbranched dendritic polymer (Boltorn H40) and subsequently reacted with polyethylene glycol (PEG). The resulting PEG-H40-DXC nanoparticle exhibited pH-sensitive drug release behavior and successfully controlled gene expression in stem-cell-derived fibroblasts with a Tet-On system. While free DXC inhibited fibroblast proliferation and matrix metalloproteinase (MMP) activity, PEG-H40-DXC nanoparticles maintained higher fibroblast proliferation levels and MMP activity. The results demonstrate that the PEG-H40-DXC nanoparticle system provides an effective tool to controlling gene expression in human stem cell derivatives. PMID:24232694

  17. Effect of recondensation of sublimed species on nanoparticle temperature evolution in time-resolved laser-induced incandescence

    NASA Astrophysics Data System (ADS)

    Memarian, F.; Liu, F.; Thomson, K. A.; Daun, K. J.; Snelling, D. R.; Smallwood, G. J.

    2015-03-01

    In high-fluence laser-induced incandescence (LII), current LII models significantly overpredict the soot nanoparticle temperature decay rate compared to that inferred from two-color pyrometry at the first 100 ns after the peak laser pulse in atmospheric pressure flames. One possible cause is the back flow of sublimed species, which to date has been neglected in LII modeling. In this study, the transient direct simulation Monte Carlo (DSMC) method has been used, for the first time, to calculate the temperature evolution of soot particles, taking into account recondensation of sublimed species. In this algorithm, the physical time is discretized into a number of time steps called ensemble time steps, and the heat flux is calculated by performing several DSMC runs in each ensemble time step before proceeding to the next ensemble time step until the variance reaches an acceptable value. This heat flux is then used to update the nanoparticle temperature over the ensemble time step. Using the new algorithm, the temperature evolution of the particle can be predicted by the DSMC code, which is an improvement to previous DSMC simulations in which predetermined temperature decay curves must be prescribed. The results show that recondensation of sublimed species on the originating nanoparticle is not significant. Although accounting for condensation of sublimed species originating from neighboring soot particles enhances the role of recondensation of sublimed species in slowing down the soot particle temperature decay, it is still not sufficient to be considered as a plausible cause for the discrepancy between modeled soot temperature and the two-color pyrometry measured one in high-fluence LII.

  18. Lanthanide Hydroxide Nanoparticles Induce Angiogenesis via ROS-Sensitive Signaling.

    PubMed

    Zhao, Haishan; Osborne, Olivia J; Lin, Sijie; Ji, Zhaoxia; Damoiseux, Robert; Wang, Yuqiang; Nel, André E; Lin, Shuo

    2016-08-01

    Recent studies suggest that the nanorods consisting of europium hydroxide could promote angiogenesis. In this study, it is sought to determine if additional types of nanoparticles are capable of enhancing angiogenesis and in addition, understand the underlying mechanisms. For this reason, a method is employed that combines a high throughput in vitro cell based screen coupled with an in vivo validation using vascular specific green fluorescent protein reporter transgenic zebrafish for examining proangiogenesis activity. After screening multiple types of nanoparticles, it is discovered that four of them, Eu(III) (OH)3 rods (Eu rods), Eu(III) (OH)3 spheres (Eu spheres), Tb(III) (OH)3 rods (Tb rods), and Tb(III) (OH)3 spheres (Tb spheres), are the most effective in promoting angiogenesis. It is also showed that ionic forms of europium nitrate [Eu(NO3 )3 ] (Eu) and terbium nitrate [Tb(NO3 )3 ] (Tb), the two lanthanide elements for these four nanoparticles, are also capable of enhancing angiogenesis. However, this effect is further enhanced by nanoparticle synthesis. Finally, it is demonstrated that reactive oxygen species H2 O2 is a key factor in the process of proangiogenesis by lanthanide elemental nanoparticles. PMID:27383397

  19. Enzyme Induced Formation of Monodisperse Hydrogel Nanoparticles Tunable in Size

    DOE PAGESBeta

    Bocharova, Vera; Sharp, Danna; Jones, Aaron; Cheng, Shiwang; Griffin, Philip J.; Agapov, Alexander L.; Voylov, Dmitry; Wang, Yangyang; Kisliuk, Alexander; Melman, Artem; et al

    2015-03-09

    Here, we report a novel approach to synthesize monodisperse hydrogel nanoparticles that are tunable in size. The distinctive feature of our approach is the use of a multicopper oxidase enzyme, laccase, as both a biocatalyst and template for nanoparticle growth. We utilize the ferroxidase activity of laccase to initiate localized production of iron(III) cations from the oxidation of iron(II) cations. We demonstrate that nanoparticles are formed in a dilute polymer solution of alginate as a result of cross-linking between alginate and enzymatically produced iron(III) cations. Exerting control over the enzymatic reaction allows for nanometer-scale tuning of the hydrogel nanoparticle radiimore » in the range of 30–100 nm. Moreover, the nanoparticles and their growth kinetics were characterized via dynamic light scattering, atomic force microscopy, and UV–vis spectroscopy. Our finding opens up a new avenue for the synthesis of tunable nanoscale hydrogel particles for biomedical applications.« less

  20. Si nanoparticles as sensitizers for radio frequency-induced cancer hyperthermia

    NASA Astrophysics Data System (ADS)

    Kabashin, A. V.; Tamarov, K. P.; Ryabchikov, Yu. V.; Osminkina, L. A.; Zinovyev, S. V.; Kargina, J. V.; Gongalsky, M. B.; Al-Kattan, A.; Yakunin, V. G.; Sentis, M. L.; Ivanov, A. V.; Nikiforov, V. N.; Kanavin, A. P.; Zavestovskaya, I. N.; Timoshenko, V. Y.

    2016-03-01

    We review our recently obtained data on the employment of Si nanoparticles as sensitizers of radiofrequency (RF) - induced hyperthermia for mild cancer therapy tasks. Such an approach makes possible the heating of aqueous suspensions of Si nanoparticles by tens of degrees Celsius under relatively low intensities (1-5 W/cm2) of 27 MHz RF radiation. The heating effect is demonstrated for nanoparticles synthesized by laser ablation in water and mechanical grinding of porous silicon, while laser-ablated nanoparticles demonstrate a remarkably higher heating rate than porous silicon-based ones for the whole range of the used concentrations. The observed RF heating effect can be explained in the frame of a model considering the polarization of Si NPs and electrolyte in the external oscillating electromagnetic field and the corresponding release of heat by electric currents around the nanoparticles. Our tests evidence relative safety of Si nanostructures and their efficient dissolution in physiological solutions, suggesting potential clearance of nanoparticles from a living organism without any side effects. Profiting from Si nanoparticle-based heating, we finally demonstrate an efficient treatment of Lewis Lung carcinoma in vivo. The obtained data promise a breakthrough in the development of mild, non-invasive methods for cancer therapy.

  1. Voltage induced electrochemical reactions in the single lithium-rich layer-oxide nanoparticles.

    PubMed

    Li, Tao; Song, Bohang; Lu, Li; Zeng, Kaiyang

    2015-04-21

    As a crucial building block of the electrode in the lithium-ion battery (LIB), single nanoparticles that respond to an electric field have rarely been characterized experimentally. It is important to study the intrinsic properties of nanoparticles independently, excluding the effects from binders and additives. In this paper, isolated Li-rich layer-oxide (Li1.2Mn0.54Ni0.13Co0.13O2) nanoparticles are studied in comparison with individual Li2MnO3 and LiNi1/3Co1/3Mn1/3O2 nanoparticles. The bias triggered changes in morphology and material properties are characterized using dual-frequency scanning probe microscopy (SPM) techniques in ambient air, synthetic air, and an argon atmosphere. Inhomogeneous stiffness/composition is observed on single nanoparticles. The change in local Li(+)-ion concentration may contribute to the stiffness variation. Bias induced Li(+)-ion redistributions and electrochemical reactions are observed. Nanoparticles are fragmented at high voltage (>5 V) when an excessive amount of Li-ions are removed. This work further demonstrates the application of multi-frequency SPM techniques for the characterization of nanoparticles for energy storage applications. PMID:25798700

  2. Antidiabetic activity of zinc oxide and silver nanoparticles on streptozotocin-induced diabetic rats.

    PubMed

    Alkaladi, Ali; Abdelazim, Aaser Mohamed; Afifi, Mohamed

    2014-01-01

    The use of nanoparticles in medicine is an attractive proposition. In the present study, zinc oxide and silver nanoparticles were evaluated for their antidiabetic activity. Fifty male albino rats with weight 120 ± 20 and age 6 months were used. Animals were grouped as follows: control; did not receive any type of treatment, diabetic; received a single intraperitoneal dose of streptozotocin (100 mg/kg), diabetic + zinc oxide nanoparticles (ZnONPs), received single daily oral dose of 10 mg/kg ZnONPs in suspension, diabetic + silver nanoparticles (SNPs); received a single daily oral dose of SNP of 10 mg/kg in suspension and diabetic + insulin; received a single subcutaneous dose of 0.6 units/50 g body weight. Zinc oxide and silver nanoparticles induce a significant reduced blood glucose, higher serum insulin, higher glucokinase activity higher expression level of insulin, insulin receptor, GLUT-2 and glucokinase genes in diabetic rats treated with zinc oxide, silver nanoparticles and insulin. In conclusion, zinc oxide and sliver nanoparticles act as potent antidiabetic agents. PMID:24477262

  3. Ultrasound-induced inertial cavitation from gas-stabilizing nanoparticles

    NASA Astrophysics Data System (ADS)

    Kwan, J. J.; Graham, S.; Myers, R.; Carlisle, R.; Stride, E.; Coussios, C. C.

    2015-08-01

    The understanding of cavitation from nanoparticles has been hindered by the inability to control nanobubble size. We present a method to manufacture nanoparticles with a tunable single hemispherical depression (nanocups) of mean diameter 90, 260, or 650 nm entrapping a nanobubble. A modified Rayleigh-Plesset crevice model predicts the inertial cavitation threshold as a function of cavity size and frequency, and is verified experimentally. The ability to tune cavitation nanonuclei and predict their behavior will be useful for applications ranging from cancer therapy to ultrasonic cleaning.

  4. Ultrasound-induced inertial cavitation from gas-stabilizing nanoparticles.

    PubMed

    Kwan, J J; Graham, S; Myers, R; Carlisle, R; Stride, E; Coussios, C C

    2015-08-01

    The understanding of cavitation from nanoparticles has been hindered by the inability to control nanobubble size. We present a method to manufacture nanoparticles with a tunable single hemispherical depression (nanocups) of mean diameter 90, 260, or 650 nm entrapping a nanobubble. A modified Rayleigh-Plesset crevice model predicts the inertial cavitation threshold as a function of cavity size and frequency, and is verified experimentally. The ability to tune cavitation nanonuclei and predict their behavior will be useful for applications ranging from cancer therapy to ultrasonic cleaning. PMID:26382515

  5. Transient and persistent current induced conductivity changes in GaAs/AlGaAs high-electron-mobility transistors

    SciTech Connect

    Schulte-Braucks, Christian Valentin, Sascha R.; Ludwig, Arne; Wieck, Andreas D.

    2014-03-31

    We report the observation of a current induced change of the low temperature conductivity of two-dimensional electron gases in GaAs/AlGaAs-high-electron-mobility transistors. By applying voltage pulses on the ohmic contacts of a Hall bar-mesa-structure, both sheet-carrier-density n{sub 2D} and electron mobility μ are decreased. At temperatures below 50 K, a persistent change combined with a partial transient recovery of n{sub 2D} has been observed. The transient behaviour and the lateral spreading of the effect are studied. Moreover, a temperature dependent investigation has been done in order to get insight into the addressed defect energy levels. A model based on the phenomenology of the effect is proposed. The observed effect is not a permanent degradation as the original carrier concentration can be restored by warming up the sample to room temperature and recooling it.

  6. Alpha-alumina nanoparticles induce efficient autophagy-dependent cross-presentation and potent antitumour response

    NASA Astrophysics Data System (ADS)

    Li, Haiyan; Li, Yuhuan; Jiao, Jun; Hu, Hong-Ming

    2011-10-01

    Therapeutic cancer vaccination is an attractive strategy because it induces T cells of the immune system to recognize and kill tumour cells in cancer patients. However, it remains difficult to generate large numbers of T cells that can recognize the antigens on cancer cells using conventional vaccine carrier systems. Here we show that α-Al2O3 nanoparticles can act as an antigen carrier to reduce the amount of antigen required to activate T cells in vitro and in vivo. We found that α-Al2O3 nanoparticles delivered antigens to autophagosomes in dendritic cells, which then presented the antigens to T cells through autophagy. Immunization of mice with α-Al2O3 nanoparticles that are conjugated to either a model tumour antigen or autophagosomes derived from tumour cells resulted in tumour regression. These results suggest that α-Al2O3 nanoparticles may be a promising adjuvant in the development of therapeutic cancer vaccines.

  7. Direct patterning of Cu microstructures using femtosecond laser-induced CuO nanoparticle reduction

    NASA Astrophysics Data System (ADS)

    Arakane, Shun; Mizoshiri, Mizue; Hata, Seiichi

    2015-06-01

    Cu-based microstructures were directly patterned using femtosecond laser-induced CuO nanoparticle reduction. CuO nanoparticle-based solution, consisting CuO nanoparticles, ethylene glycol, and polyvinylpyrrolidone, was spin-coated on glass substrates. Microstructures were formed by irradiating focused femtosecond laser pulses. Cu and Cu2O peak intensities were observed in the X-ray diffraction (XRD) spectra of the microstructures. Compared to single scan, the Cu peak intensities increased by double scan. This result suggests that double scan is effective for increasing the amount of Cu from CuO nanoparticle solution. Cu- and Cu2O-rich microstructures were formed selectively by controlling laser irradiation conditions. The resistivity of the Cu-rich microstructures was estimated by 528 µΩ m which was 104 times and 10 times larger than the values of Cu and Cu2O, respectively. This large resistivity could be applied for microheaters.

  8. High ordered biomineralization induced by carbon nanoparticles in the sea urchin Paracentrotus lividus

    NASA Astrophysics Data System (ADS)

    Manno, Daniela; Carata, Elisabetta; Tenuzzo, Bernadetta A.; Panzarini, Elisa; Buccolieri, Alessandro; Filippo, Emanuela; Rossi, Marco; Serra, Antonio; Dini, Luciana

    2012-12-01

    A surprising and unexpected biomineralization process was observed during toxicological assessment of carbon nanoparticles on Paracentrotus lividus (sea urchin) pluteus larvae. The larvae activate a process of defense against external material, by incorporating the nanoparticles into microstructures of aragonite similarly to pearl oysters. Aiming at a better understanding of this phenomenon, the larvae were exposed to increasing concentrations of carbon nanoparticles and the biomineralization products were analyzed by electron microscopy, x-ray diffraction and Raman spectroscopy. In order to evaluate the possible influence of Sp-CyP-1 expression on this biomineralization process by larvae, analyses of gene expression (Sp-CyP-1) and calcein labeling were performed. Overall, we report experimental evidence about the capability of carbon nanoparticles to induce an increment of Sp-CyP-1 expression with the consequent activation of a biomineralization process leading to the production of a new pearl-like biomaterial never previously observed in sea urchins.

  9. Transient cracks and triple junctions induced by Cocos-Nazca propagating rift

    NASA Astrophysics Data System (ADS)

    Schouten, H.; Smith, D. K.; Zhu, W.; Montesi, L. G.; Mitchell, G. A.; Cann, J. R.

    2009-12-01

    The Galapagos triple junction is a ridge-ridge-ridge triple junction where the Cocos, Nazca, and Pacific plates meet around the Galapagos microplate (GMP). On the Cocos plate, north of the large gore that marks the propagating Cocos-Nazca (C-N) Rift, a 250-km-long and 50-km-wide band of NW-SE-trending cracks crosscuts the N-S-trending abyssal hills of the East Pacific Rise (EPR). These appear as a succession of minor rifts, accommodating some NE-SW extension of EPR-generated seafloor. The rifts successively intersected the EPR in triple junctions at distances of 50-100 km north of the tip of the C-N Rift. We proposed a simple crack interaction model to explain the location of the transient rifts and their junction with the EPR. The model predicts that crack locations are controlled by the stress perturbation along the EPR, induced by the dominant C-N Rift, and scaled by the distance of its tip to the EPR (Schouten et al., 2008). The model also predicts that tensile stresses are symmetric about the C-N Rift and thus, similar cracks should have occurred south of the C-N Rift prior to formation of the GMP about 1 Ma. There were no data at the time to test this prediction. In early 2009 (AT 15-41), we mapped an area on the Nazca plate south of the C-N rift out to 4 Ma. The new bathymetric data confirm the existence of a distinctive pattern of cracks south of the southern C-N gore that mirrors the pattern on the Cocos plate until about 1 Ma, and lends support to the crack interaction model. The envelope of the symmetric cracking pattern indicates that the distance between the C-N Rift tip and the EPR varied between 40 and 65 km during this time (1-4 Ma). The breakdown of the symmetry at 1 Ma accurately dates the onset of a southern plate boundary of the GMP, now Dietz Deep Rift. At present, the southern rift boundary of the GMP joins the EPR with a steep-sided, 80 km long ridge. This ridge releases the stress perturbation otherwise induced along the EPR by elastic

  10. Chloride-inducible transient apoplastic alkalinizations induce stomata closure by controlling abscisic acid distribution between leaf apoplast and guard cells in salt-stressed Vicia faba.

    PubMed

    Geilfus, Christoph-Martin; Mithöfer, Axel; Ludwig-Müller, Jutta; Zörb, Christian; Muehling, Karl H

    2015-11-01

    Chloride stress causes the leaf apoplast transiently to alkalize, an event that is presumed to contribute to the ability of plants to adapt to saline conditions. However, the initiation of coordinated processes downstream of the alkalinization is unknown. We hypothesize that chloride-inducible pH dynamics are a key chemical feature modulating the compartmental distribution of abscisic acid (ABA) and, as a consequence, affecting stomata aperture. Apoplastic pH and stomata aperture dynamics in intact Vicia faba leaves were monitored by microscopy-based ratio imaging and porometric measurements of stomatal conductance. ABA concentrations in leaf apoplast and guard cells were compared with pH dynamics by gas-chromatography-mass-spectrometry (GC-MS) and liquid-chromatography-tandem-mass spectrometry (LC-MS/MS). Results demonstrate that, upon chloride addition to roots, an alkalizing factor that initiates the pH dynamic propagates from root to leaf in a way similar to xylem-distributed water. In leaves, it induces a systemic transient apoplastic alkalinization that causes apoplastic ABA concentration to increase, followed by an elevation of endogenous guard cell ABA. We conclude that the transient alkalinization, which is a remote effect of chloride stress, modulates the compartmental distribution of ABA between the leaf apoplast and the guard cells and, in this way, is instrumental in inducing stomata closure during the beginning of salinity. PMID:26096890