WorldWideScience

Sample records for membrane interphase probe

  1. Multicolour interphase cytogenetics: 24 chromosome probes, 6 colours, 4 layers

    OpenAIRE

    2011-01-01

    From the late 1980s onwards, the use of DNA probes to visualise sequences on individual chromosomes (fluorescent in-situ hybridisation - FISH) revolutionised the study of cytogenetics. Following single colour experiments, more fluorochromes were added, culminating in a 24 colour assay that could distinguish all human chromosomes. Interphase cytogenetics (the detection of chromosome copy number in interphase nuclei) soon followed, however 24 colour experiments are hampered for this application...

  2. Multicolour interphase cytogenetics: 24 chromosome probes, 6 colours, 4 layers.

    Science.gov (United States)

    Ioannou, D; Meershoek, E J; Thornhill, A R; Ellis, M; Griffin, D K

    2011-01-01

    From the late 1980s onwards, the use of DNA probes to visualise sequences on individual chromosomes (fluorescent in-situ hybridisation - FISH) revolutionised the study of cytogenetics. Following single colour experiments, more fluorochromes were added, culminating in a 24 colour assay that could distinguish all human chromosomes. Interphase cytogenetics (the detection of chromosome copy number in interphase nuclei) soon followed, however 24 colour experiments are hampered for this application as mixing fluorochromes to produce secondary colours produces images that are not easily distinguishable from overlapping signals. This study reports the development and use of a novel protocol, new fast hybridising FISH probes, and a bespoke image capture system for the assessment of chromosome copy number in interphase nuclei. The multicolour probe sets can be used individually or in sequential hybridisation layers to assess ploidy of all 24 human chromosomes in the same nucleus. Applications of this technique are in the investigation of chromosome copy number and the assessment of nuclear organisation for a range of different cell types including human sperm, cancer cells and preimplantation embryos.

  3. Mechanical properties of interphase nuclei probed by cellular strain application.

    Science.gov (United States)

    Lammerding, Jan; Lee, Richard T

    2009-01-01

    The mechanical properties of the interphase nucleus have important implications for cellular function and can reflect changes in nuclear envelope structure and/or chromatin organization. Mutations in the nuclear envelope proteins lamin A and C cause several human diseases, such as Emery-Dreifuss muscular dystrophy, and dramatic changes in nuclear stiffness have been reported in cells from lamin A/C-deficient mice. We have developed a cellular strain technique to measure nuclear stiffness in intact, adherent cells and have applied this experimental method to fibroblasts from mouse models of Emery-Dreifuss muscular dystrophy and to skin fibroblasts from laminopathy patients and healthy control subjects. The experimental protocol is based on measuring induced nuclear deformations in cells plated on a flexible silicone substrate; the nuclear stiffness can subsequently be inferred from the ratio of induced nuclear strain to the applied membrane strain. These experiments reveal that lamins A and C are important determinants of nuclear stiffness and that lamin mutations associated with muscular dystrophies and other laminopathies often result in disturbed nuclear stiffness that could contribute to the tissue-specific disease phenotypes.

  4. APPLICATION OF TWO-COLOR INTERPHASE FISH USING SEX PROBE IN ALLOGENEIC STEM CELL TRANSPLANTATION

    Institute of Scientific and Technical Information of China (English)

    曾慧兰; 李建勇; 朱康儿; 薛永权; 李杨秋; 刘晓力; 过宇

    2002-01-01

    Objective: To evaluate the significance of two-color interphase fluorescence in situ hybridization (FISH) using X and Y centromere probe in the engraftment estimation and minimal residual disease (MRD) monitoring after allogeneic stem cell transplantation (alloSCT). Methods: Samples from 12 cases patients in different periods after alloSCT were detected by interphase FISH. Results: All of the 12 patients were proved to obtain engraftment 22(35 days after alloSCT. While traditional karyotype showed as 100%XX or 100%XY invariably, FISH showed different percentages of donor original sex chromosome. Conclusion: Two-color interphase FISH is a more sensitive and simple test for engraftment evaluation and MRD monitoring post SCT, though, it can not entirely replace traditional karyotype analysis and gene detection by RT-PCR.

  5. [Optimized protocols for interphase FISH analysis of imprints and sections using split signal probes].

    Science.gov (United States)

    Pelluard-Nehme, F; Dupont, T; Turmo, M; Merlio, J-P; Belaud-Rotureau, M-A

    2007-03-01

    Fluorescent in situ hybridization (FISH) analysis is a molecular technique allowing the detection of recurrent translocations in cancer. Several hybridization protocols were assayed in order to evaluate their performances for interphase FISH analysis of histological sections and imprints using split probes. Adult and foetal lymphoid tissues were selected. Touch imprints of fresh (EF) or frozen (EC) tissues, sections (CF) and isolated nuclei (NI) of formol-fixed paraffin-embedded tissues were performed. The cut-off values of the IGH, IGlambda, BCL-2, BCL-6, CCND1 and MYC DNA FISH split signal probes were calculated for adult reactive lymph nodes on the different histological preparations (EC, CF, CC, NI) and on several tissues for the IGH and BCL-6 probes. In reactive lymph nodes, the cut-off values of the probes were between 3 and 13% and found independent of the preparation type. Conversely, slight but significant variations of the cut-off level were observed when different foetal control tissues were assayed with the same probe set. Finally, this study provided optimized-protocols for FISH analysis of either fresh/frozen imprints or formalin-fixed paraffin-embedded sections using split signal DNA probes.

  6. An extended micromechanics method for probing interphase properties in polymer nanocomposites

    Science.gov (United States)

    Liu, Zeliang; Moore, John A.; Liu, Wing Kam

    2016-10-01

    Inclusions comprised on filler particles and interphase regions commonly form complex morphologies in polymer nanocomposites. Addressing these morphologies as systems of overlapping simple shapes allows for the study of dilute particles, clustered particles, and interacting interphases all in one general modeling framework. To account for the material properties in these overlapping geometries, weighted-mean and additive overlapping conditions are introduced and the corresponding inclusion-wise integral equations are formulated. An extended micromechanics method based on these overlapping conditions for linear elastic and viscoelastic heterogeneous material is then developed. An important feature of the proposed approach is that the effect of both the geometric overlapping (clustered particles) and physical overlapping (interacting interphases) on the effective properties can be distinguished. We apply the extended micromechanics method to a viscoelastic polymer nanocomposite with interphase regions, and estimate the properties and thickness of the interphase region based on experimental data for carbon-black filled styrene butadiene rubbers.

  7. Generation of micronuclei during interphase by coupling between cytoplasmic membrane blebbing and nuclear budding.

    Directory of Open Access Journals (Sweden)

    Koh-ichi Utani

    Full Text Available Micronucleation, mediated by interphase nuclear budding, has been repeatedly suggested, but the process is still enigmatic. In the present study, we confirmed the previous observation that there are lamin B1-negative micronuclei in addition to the positive ones. A large cytoplasmic bleb was found to frequently entrap lamin B1-negative micronuclei, which were connected to the nucleus by a thin chromatin stalk. At the bottom of the stalk, the nuclear lamin B1 structure appeared broken. Chromatin extrusion through lamina breaks has been referred to as herniation or a blister of the nucleus, and has been observed after the expression of viral proteins. A cell line in which extrachromosomal double minutes and lamin B1 protein were simultaneously visualized in different colors in live cells was established. By using these cells, time-lapse microscopy revealed that cytoplasmic membrane blebbing occurred simultaneously with the extrusion of nuclear content, which generated lamin B1-negative micronuclei during interphase. Furthermore, activation of cytoplasmic membrane blebbing by the addition of fresh serum or camptothecin induced nuclear budding within 1 to 10 minutes, which suggested that blebbing might be the cause of the budding. After the induction of blebbing, the frequency of lamin-negative micronuclei increased. The budding was most frequent during S phase and more efficiently entrapped small extrachromosomal chromatin than the large chromosome arm. Based on these results, we suggest a novel mechanism in which cytoplasmic membrane dynamics pulls the chromatin out of the nucleus through the lamina break. Evidence for such a mechanism was obtained in certain cancer cell lines including human COLO 320 and HeLa. The mechanism could significantly perturb the genome and influence cancer cell phenotypes.

  8. Interphase FISH detection of BCL2 rearrangement in follicular lymphoma using breakpoint-flanking probes

    NARCIS (Netherlands)

    Vaandrager, J W; Schuuring, E; Raap, T; Philippo, K; Kleiverda, K; Kluin, P

    2000-01-01

    Rearrangement of the BCL2 gene is an important parameter for the differential diagnosis of non-Hodgkin lymphomas. Although a relatively large proportion of breakpoints is clustered, many are missed by standard PCR. A FISH assay is therefore desired. Up to now, a lack of probes flanking the BCL2 gene

  9. Introduction to fluorescence probing of biological membranes.

    Science.gov (United States)

    Demchenko, Alexander P; Duportail, Guy; Oncul, Sule; Klymchenko, Andrey S; Mély, Yves

    2015-01-01

    Fluorescence is one of the most powerful and commonly used tools in biophysical studies of biomembrane structure and dynamics that can be applied on different levels, from lipid monolayers and bilayers to living cells, tissues, and whole animals. Successful application of this method relies on proper design of fluorescence probes with optimized photophysical properties. These probes are efficient for studying the microscopic analogs of viscosity, polarity, and hydration, as well as the molecular order, environment relaxation, and electrostatic potentials at the sites of their location. Being smaller than the membrane width they can sense the gradients of these parameters across the membrane. We present examples of novel dyes that achieve increased spatial resolution and information content of the probe responses. In this respect, multiparametric environment-sensitive probes feature considerable promise.

  10. Probing cellular behaviors through nanopatterned chitosan membranes

    Directory of Open Access Journals (Sweden)

    Chung-Yao Yang, Chun-Yen Sung, Hung-Hsun Shuai, Chao-Min Cheng and J Andrew Yeh

    2013-01-01

    Full Text Available This paper describes a high-throughput method for developing physically modified chitosan membranes to probe the cellular behavior of MDCK epithelial cells and HIG-82 fibroblasts adhered onto these modified membranes. To prepare chitosan membranes with micro/nanoscaled features, we have demonstrated an easy-to-handle, facile approach that could be easily integrated with IC-based manufacturing processes with mass production potential. These physically modified chitosan membranes were observed by scanning electron microscopy to gain a better understanding of chitosan membrane surface morphology. After MDCK cells and HIG-82 fibroblasts were cultured on these modified chitosan membranes for various culture durations (i.e. 1, 2, 4, 12 and 24 h, they were investigated to decipher cellular behavior. We found that both cells preferred to adhere onto a flat surface rather than on a nanopatterned surface. However, most (> 80% of the MDCK cells showed rounded morphology and would suspend in the cultured medium instead of adhering onto the planar surface of negatively nanopatterned chitosan membranes. This means different cell types (e.g. fibroblasts versus epithelia showed distinct capabilities/preferences of adherence for materials of varying surface roughness. We also showed that chitosan membranes could be re-used at least nine times without significant contamination and would provide us consistency for probing cell–material interactions by permitting reuse of the same substrate. We believe these results would provide us better insight into cellular behavior, specifically, microscopic properties and characteristics of cells grown under unique, nanopatterned cell-interface conditions.

  11. Monitoring membrane hydration with 2-(dimethylamino)-6-acylnaphtalenes fluorescent probes

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2015-01-01

    , were used to study membrane lateral structure and associated dynamics. Once incorporated into membranes, the (nanosecond) fluorescent decay of these probes is strongly affected by changes in the local polarity and relaxation dynamics of restricted water molecules existing at the membrane....../water interface. For instance, when glycerophospholipid containing membranes undertake a solid ordered (gel) to liquid disordered phase transition the fluorescence emission maximum of these probes shift ~ 50 nm with a significant change in their fluorescence lifetime. Furthermore, the fluorescence parameters...... of LAURDAN and PRODAN are exquisitely sensitive to cholesterol effects, allowing interpretations that correlate changes in membrane packing with membrane hydration. Different membrane model systems as well as innate biological membranes have been studied with this family of probes allowing interesting...

  12. Monitoring membrane hydration with 2-(dimethylamino)-6-acylnaphtalenes fluorescent probes

    DEFF Research Database (Denmark)

    Bagatolli, Luis

    2015-01-01

    A family of polarity sensitive fluorescent probes (2-(dimethylamino)-6-acylnaphtalenes, i.e. LAURDAN, PRODAN, ACDAN) was introduced by Gregorio Weber in 1979, with the aim to monitor solvent relaxation phenomena on protein matrices. In the following years, however, PRODAN and particularly LAURDAN......, were used to study membrane lateral structure and associated dynamics. Once incorporated into membranes, the (nanosecond) fluorescent decay of these probes is strongly affected by changes in the local polarity and relaxation dynamics of restricted water molecules existing at the membrane/water...

  13. Optical tweezer for probing erythrocyte membrane deformability

    CERN Document Server

    Khan, Manas; Sood, A K; 10.1063/1.3272269

    2010-01-01

    We report that the average rotation speed of optically trapped crenated erythrocytes is direct signature of their membrane deformability. When placed in hypertonic buffer, discocytic erythrocytes are subjected to crenation. The deformation of cells brings in chirality and asymmetry in shape that make them rotate under the scattering force of a linearly polarized optical trap. A change in the deformability of the erythrocytes, due to any internal or environmental factor, affects the rotation speed of the trapped crenated cells. Here we show how the increment in erythrocyte membrane rigidity with adsorption of $Ca^{++}$ ions can be exhibited through this approach.

  14. Synthesis of platinum-polyaniline composite, its evaluation as a performance boosting interphase in the electrode assembly of proton exchange membrane fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Jayasree, R.; Mohanraju, K. [Fuel Cell Laboratory, Department of Chemistry, National Institute of Technology, Tiruchirappalli 620015 (India); Cindrella, L., E-mail: cind@nitt.edu [Fuel Cell Laboratory, Department of Chemistry, National Institute of Technology, Tiruchirappalli 620015 (India)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Pt-polyaniline composite has been prepared and characterized. Black-Right-Pointing-Pointer It has been used as an interlayer in membrane electrode assembly and has been evaluated to boost the performance of the proton exchange membrane fuel cell. - Abstract: Platinum formed on polyaniline (PANi) is used as the interlayer between porous gas diffusion layer and the catalyst layer with the aim to reduce the thickness of the ordinary gas diffusion layer and provide a performance boosting electrostatic layer. The doping tendency of PANi is utilized to incorporate platinum(IV) ion in its matrix by chemisorption followed by its reduction to metallic platinum. Platinum is deposited on polyaniline by a simple wet chemistry method. PANi is prepared by the chemical oxidative polymerization of aniline by ammonium persulphate while Pt deposition on PANi is achieved by a phase transfer method (water-toluene) to yield Pt nanoparticles on PANi. The composite is characterized by XRD, Scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), IR spectroscopy, cyclic voltammetry (CV), AC impedance studies, density and conductivity measurements. The Pt/PANi composite is assessed in the proton exchange membrane fuel cell (PEMFC) using H{sub 2}/O{sub 2} gases at ambient pressure. The performance of the PEMFC with Pt/PANi composite interphase on cathode side of the gas diffusion layer (GDL) shows improvement at high current densities which is attributed to the increased capacitative current of Pt/PANi layer in the presence of O{sub 2} thereby improving the kinetics of subsequent reduction of O{sub 2}.

  15. Synthesis of platinum-polyaniline composite, its evaluation as a performance boosting interphase in the electrode assembly of proton exchange membrane fuel cell

    Science.gov (United States)

    Jayasree, R.; Mohanraju, K.; Cindrella, L.

    2013-01-01

    Platinum formed on polyaniline (PANi) is used as the interlayer between porous gas diffusion layer and the catalyst layer with the aim to reduce the thickness of the ordinary gas diffusion layer and provide a performance boosting electrostatic layer. The doping tendency of PANi is utilized to incorporate platinum(IV) ion in its matrix by chemisorption followed by its reduction to metallic platinum. Platinum is deposited on polyaniline by a simple wet chemistry method. PANi is prepared by the chemical oxidative polymerization of aniline by ammonium persulphate while Pt deposition on PANi is achieved by a phase transfer method (water-toluene) to yield Pt nanoparticles on PANi. The composite is characterized by XRD, Scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDX), IR spectroscopy, cyclic voltammetry (CV), AC impedance studies, density and conductivity measurements. The Pt/PANi composite is assessed in the proton exchange membrane fuel cell (PEMFC) using H2/O2 gases at ambient pressure. The performance of the PEMFC with Pt/PANi composite interphase on cathode side of the gas diffusion layer (GDL) shows improvement at high current densities which is attributed to the increased capacitative current of Pt/PANi layer in the presence of O2 thereby improving the kinetics of subsequent reduction of O2.

  16. Patterning and lifetime of plasma membrane-localized cellulose synthase is dependent on actin organization in Arabidopsis interphase cells.

    Science.gov (United States)

    Sampathkumar, Arun; Gutierrez, Ryan; McFarlane, Heather E; Bringmann, Martin; Lindeboom, Jelmer; Emons, Anne-Mie; Samuels, Lacey; Ketelaar, Tijs; Ehrhardt, David W; Persson, Staffan

    2013-06-01

    The actin and microtubule cytoskeletons regulate cell shape across phyla, from bacteria to metazoans. In organisms with cell walls, the wall acts as a primary constraint of shape, and generation of specific cell shape depends on cytoskeletal organization for wall deposition and/or cell expansion. In higher plants, cortical microtubules help to organize cell wall construction by positioning the delivery of cellulose synthase (CesA) complexes and guiding their trajectories to orient newly synthesized cellulose microfibrils. The actin cytoskeleton is required for normal distribution of CesAs to the plasma membrane, but more specific roles for actin in cell wall assembly and organization remain largely elusive. We show that the actin cytoskeleton functions to regulate the CesA delivery rate to, and lifetime of CesAs at, the plasma membrane, which affects cellulose production. Furthermore, quantitative image analyses revealed that actin organization affects CesA tracking behavior at the plasma membrane and that small CesA compartments were associated with the actin cytoskeleton. By contrast, localized insertion of CesAs adjacent to cortical microtubules was not affected by the actin organization. Hence, both actin and microtubule cytoskeletons play important roles in regulating CesA trafficking, cellulose deposition, and organization of cell wall biogenesis.

  17. Molecular probes for nonlinear optical imaging of biological membranes

    Science.gov (United States)

    Blanchard-Desce, Mireille H.; Ventelon, Lionel; Charier, Sandrine; Moreaux, Laurent; Mertz, Jerome

    2001-12-01

    Second-harmonic generation (SHG) and two-photon excited fluorescence (TPEF) are nonlinear optical (NLO) phenomena that scale with excitation intensity squared, and hence give rise to an intrinsic 3-dimensional resolution when used in microscopic imaging. TPEF microscopy has gained widespread popularity in the biology community whereas SHG microscopy promises to be a powerful tool because of its sensitivity to local asymmetry. We have implemented an approach toward the design of NLO-probes specifically adapted for SHG and/or TPEF imaging of biological membranes. Our strategy is based on the design of nanoscale amphiphilic NLO-phores. We have prepared symmetrical bolaamphiphilic fluorophores combining very high two-photon absorption (TPA) cross-sections in the visible red region and affinity for cellular membranes. Their incorporation and orientation in lipid membranes can be monitored via TPEF anisotropy. We have also prepared amphiphilic push-pull chromophores exhibiting both large TPA cross-sections and very large first hyperpolarizabilities in the near-IR region. These NLO-probes have proved to be particularly useful for imaging of biological membranes by simultaneous SHG and TPEF microscopy and offer attractive prospects for real-time imaging of fundamental biological processes such as adhesion, fusion or reporting of membrane potentials.

  18. Probing Lipid Membrane Rafts (Microdomains) with Fluorescent Phospholipids

    Science.gov (United States)

    Gu, Yongwen; Mitchel, Drake

    2011-10-01

    Membrane rafts are enriched in sphingolipids and cholesterol, they exist in a more ordered state (the liquid-ordered phase; lo) than the bulk membrane (the liquid-disordered phase; ld). Ternary mixtures of palmitoyl-oleoyl-phosphocholine (POPC; 16:0,18:1 PC), sphingomyelin (SPM), and cholesterol (Chol) form membrane rafts over a wide range of molar ratios. We are examining the ability of two fluorescent probes, NBD linked to di-16:0 PE which partitions into the lo phase, and NBD linked to di-18:1 PE which partitions into the ld phase, to detect these two phases. We are also examining the effect of the highly polyunsaturated phospholipid stearoyl-docosahexanoyl-phosphocholine (SDPC; 18:0, 22:6 PC) on the size and stability of POPC/SPM/Chol membrane rafts. We report on the fluorescence lifetime and anisotropy decay dynamics of two fluorescent probes. Data were acquired via frequency-domain measurements from 5 to 250 MHz.

  19. Multiple membrane tethers probed by atomic force microscopy.

    Science.gov (United States)

    Sun, Mingzhai; Graham, John S; Hegedüs, Balazs; Marga, Françoise; Zhang, Ying; Forgacs, Gabor; Grandbois, Michel

    2005-12-01

    Using the atomic force microscope to locally probe the cell membrane, we observed the formation of multiple tethers (thin nanotubes, each requiring a similar pulling force) as reproducible features within force profiles recorded on individual cells. Forces obtained with Chinese hamster ovary cells, a malignant human brain tumor cell line, and human endothelial cells (EA hy926) were found to be 28 +/- 10 pN, 29 +/- 9 pN, and 29 +/- 10 pN, respectively, independent of the nature of attachment to the cantilever. The rather large variation of the tether pulling forces measured at several locations on individual cells points to the existence of heterogeneity in the membrane properties of a morphologically homogeneous cell. Measurement of the summary lengths of the simultaneously extracted tethers provides a measure of the size of the available membrane reservoir through which co-existing tethers are associated. As expected, partial disruption of the actin cytoskeleton and removal of the hyaluronan backbone of the glycocalyx were observed to result in a marked decrease (30-50%) in the magnitude and a significant sharpening of the force distribution indicating reduced heterogeneity of membrane properties. Taken together, our results demonstrate the ability of the plasma membrane to locally produce multiple interdependent tethers-a process that could play an important role in the mechanical association of cells with their environment.

  20. Time resolved multiphoton excited fluorescence probes in model membranes

    CERN Document Server

    Bai, Y

    2000-01-01

    Using the time-correlated single-photon counting technique, this thesis reports on a time-resolved fluorescence study of several fluorescent probes successfully employed in membrane research. Concentration and temperature effects on fluorescence anisotropy parameters are demonstrated by DPH, p-terphenyl, alpha-NPO and PPO in DPPC lipid bilayers. Fluorescence anisotropy has shown that trans-stilbene and Rhd 800 have a two-site location in membranes. Multiphoton induced fluorescence of DPH, p-terphenyl, alpha-NPO and v-biphenyl in liposomes was measured using 800nm excitation with a femtosecond Ti:Sapphire laser. P-terphenyl, alpha-NPO and v-biphenyl are new probes for membranes. Comparison of one and multiphoton excitation results has demonstrated higher initial anisotropy with multiphoton excitation than with one-photon excitation. The rotational times were identical for one and multiphoton excitation, indicating the absence of significant local heating or sample perturbation. Excimer formation of alpha-NPO w...

  1. QM/MM Studies of Contemporary and Novel Membrane Raft Fluorescent Probes

    Directory of Open Access Journals (Sweden)

    Hannah L. Blake

    2014-07-01

    Full Text Available We have studied a number of contemporary and novel membrane probes, selected for their structural similarity to membrane raft components, in order to properly anchor themselves within a sphingolipid/cholesterol rich region. A QM/MM approach was adopted in order to understand the structural and electrostatic influences of fluorescence emission shifts of the probes in different lipid and solvation environments. The proposed modifications to the membrane probes have shown encouraging data relating not only to emission shifts within the membrane, but also their ability to anchor within a membrane raft domain and the stability to internalization within a membrane system.

  2. Spectroscopic probing of location and dynamics of an environment-sensitive intramolecular charge transfer probe within liposome membranes.

    Science.gov (United States)

    Paul, Bijan Kumar; Guchhait, Nikhil

    2011-11-15

    The present work demonstrates the interaction of an intramolecular charge transfer (ICT) probe 5-(4-dimethylamino-phenyl)-penta-2,4-dienoic acid methyl ester (DPDAME) with liposome membranes of dimyristoyl-L-α-phosphatidylcholine (DMPC) and dimyristoyl-L-α-phosphatidylglycerol (DMPG) studied by steady-state absorption, emission and time-resolved emission techniques. A huge hypsochromic shift together with remarkable enhancement of fluorescence quantum yield of the polarity sensitive ICT emission of DPDAME upon interaction with the lipids has been rationalized in terms of incorporation of the probe into hydrophobic interior of the lipids. Compelling evidences for penetration of the probe into the hydrocarbon interior of the lipids have been deduced from intertwining different experimental results e.g., micropolarity in the immediate vicinity of the probe in lipid environments, steady-state anisotropy, red-edge excitation shift (REES), fluorescence quenching experiments and time-resolved measurements. The rotational relaxation dynamics study of the membrane-bound probe unveils the impartation of high degree of motional rigidity. Wavelength-selective emission behaviour paves way for monitoring of solvent-relaxation in the membranes. Overall, the ICT probe DPDAME displays its commendable sensitivity in deciphering the microheterogeneous environments of liposomal membranes of DMPC and DMPG and promises a new membrane-polarity sensitizing probe.

  3. Detection of chromosome aberrations in interphase nuclei using fluorescence in situ hybridization technique.

    OpenAIRE

    1993-01-01

    We report here several experiences of interphase cytogenetics, using fluorescence in situ hybridization (FISH) technique, for the detection of chromosome aberrations. FISH, using alpha satellite specific probes of 18, X, Y chromosomes, was done in interphase nuclei from peripheral blood of patients with Edwards' syndrome, Klinefelter's syndrome and Turner's syndrome with healthy male and female controls, respectively. The distributions of fluorescent signals in 100 interphase nuclei were well...

  4. Molecular modeling of lipid probes and their influence on the membrane.

    Science.gov (United States)

    Faller, Roland

    2016-10-01

    In this review a number of Molecular Dynamics simulation studies are discussed which focus on the understanding of the behavior of lipid probes in biomembranes. Experiments often use specialized probe moieties or molecules to report on the behavior of a membrane and try to gain information on the membrane as a whole from the probe lipids as these probes are the only things an experiment sees. Probes can be used to make NMR, EPR and fluorescence accessible to the membrane and use fluorescent or spin-active moieties for this purpose. Clearly membranes with and without probes are not identical which makes it worthwhile to elucidate the differences between them with detailed atomistic simulations. In almost all cases these differences are confined to the local neighborhood of the probe molecules which are sparsely used and generally present as single molecules. In general, the behavior of the bulk membrane lipids can be qualitatively understood from the probes but in most cases their properties cannot be directly quantitatively deduced from the probe behavior. This article is part of a Special Issue entitled: Biosimulations edited by Ilpo Vattulainen and Tomasz Róg.

  5. Laurdan and Di-4-ANEPPDHQ probe different properties of the membrane

    Science.gov (United States)

    Amaro, Mariana; Reina, Francesco; Hof, Martin; Eggeling, Christian; Sezgin, Erdinc

    2017-04-01

    Lipid packing is a crucial feature of cellular membranes. Quantitative analysis of membrane lipid packing can be achieved using polarity sensitive probes whose emission spectrum depends on the lipid packing. However, detailed insights into the exact mechanisms that cause the changes in the spectra are necessary to interpret experimental fluorescence emission data correctly. Here, we analysed frequently used polarity sensitive probes, Laurdan and di-4-ANEPPDHQ, to test whether the underlying physical mechanisms of their spectral changes are the same and, thus, whether they report on the same physico-chemical properties of the cell membrane. Steady-state spectra as well as time-resolved emission spectra of the probes in solvents and model membranes revealed that they probe different properties of the lipid membrane. Our findings are important for the application of these dyes in cell biology.

  6. Rational design of fluorescent membrane probes for apoptosis based on 3-hydroxyflavone

    Science.gov (United States)

    Darwich, Zeinab; Kucherak, Oleksandr A.; Kreder, Rémy; Richert, Ludovic; Vauchelles, Romain; Mély, Yves; Klymchenko, Andrey S.

    2013-06-01

    Environment-sensitive probes constitute powerful tools for monitoring changes in the physico-chemical properties of cell plasma membranes. Among these probes, 3-hydroxyflavone probes are of great interest due to their dual emission and ratiometric response. Here, three probes derived from the parent F2N12S were designed, characterized and applied to monitor the membrane changes occurring during apoptosis. These three probes were designed to orient the dye vertically in the membrane. They differ by the length of their alkyl chains (from 4 to 8 carbons), which were included to optimize their affinity to the lipid membranes. Among these three probes, the one with medium chain length (hexyl) showed the best affinity to model and cell membranes, while the one with the longest alkyl chains (octyl) did not efficiently stain the membranes, probably due to aggregation. The new probes were found to be more sensitive than F2N12S to both the lipid phase and surface charge in lipid vesicles and to loss of lipid order in cell plasma membranes after cholesterol extraction. The one with the shortest (butyl) chains was found to be the most sensitive to apoptosis, while the one with medium-length (hexyl) chains was the brightest. Interestingly, apoptosis induced by different agents led to similar spectroscopic effects to those produced by the loss of lipid order and change in the surface charge, confirming that apoptosis decreases the lipid order and increases the negative surface charge in the outer leaflet of cell membranes. In conclusion, these studies report the relationship between the probe structures and their sensitivity to lipid order, surface charge and apoptosis and propose new probes for membrane research.

  7. A chromosome 21-specific cosmid cocktail for the detection of chromosome 21 aberrations in interphase nuclei

    NARCIS (Netherlands)

    A.R.M. van Opstal (Diane); J.O. van Hmel (J.); H.J.F.M.M. Eussen (Bert); A. van der Heide (Annette); C.D.F. van den Berg (Cardi); P.A. In't Veld (Peter); F.J. Los

    1995-01-01

    textabstractFluorescent in situ hybridization (FISH) with a 21q11-specific probe (CB21c1) consisting of three non-overlapping cosmids has been applied to interphase amniocytes of pregnancies at increased risk for fetal aneuploidy (N = 78) and to interphase lymphocytes, cultured and uncultured, of pa

  8. A chromosome 21-specific cosmid cocktail for the detection of chromosome 21 aberrations in interphase nuclei

    NARCIS (Netherlands)

    A.R.M. van Opstal (Diane); J.O. van Hmel (J.); H.J.F.M.M. Eussen (Bert); A. van der Heide (Annette); C.D.F. van den Berg (Cardi); P.A. In't Veld (Peter); F.J. Los

    1995-01-01

    textabstractFluorescent in situ hybridization (FISH) with a 21q11-specific probe (CB21c1) consisting of three non-overlapping cosmids has been applied to interphase amniocytes of pregnancies at increased risk for fetal aneuploidy (N = 78) and to interphase lymphocytes, cultured and uncultured, of pa

  9. Chromatin associations in Arabidopsis interphase nuclei

    Directory of Open Access Journals (Sweden)

    Veit eSchubert

    2014-11-01

    Full Text Available The arrangement of chromatin within interphase nuclei seems to be caused by topological constraints and related to gene expression depending on tissue and developmental stage. In yeast and animals it was found that homologous and heterologous chromatin association are required to realize faithful expression and DNA repair. To test whether such associations are present in plants we analysed Arabidopsis thaliana interphase nuclei by FISH using probes from different chromosomes. We found that chromatin fibre movement and variable associations, although in general relatively seldom, may occur between euchromatin segments along chromosomes, sometimes even over large distances. The combination of euchromatin segments bearing high or low co-expressing genes did not reveal different association frequencies probably due to adjacent genes of deviating expression patterns.Based on previous data and on FISH analyses presented here, we conclude that the global interphase chromatin organization in A. thaliana is relatively stable, due to the location of its ten centromeres at the nuclear periphery and of the telomeres mainly at the centrally localized nucleolus. Nevertheless, chromatin movement enables a flexible spatial genome arrangement in plant nuclei.

  10. Quantitative analysis of cell surface membrane proteins using membrane-impermeable chemical probe coupled with 18O labeling.

    Science.gov (United States)

    Zhang, Haizhen; Brown, Roslyn N; Qian, Wei-Jun; Monroe, Matthew E; Purvine, Samuel O; Moore, Ronald J; Gritsenko, Marina A; Shi, Liang; Romine, Margaret F; Fredrickson, James K; Pasa-Tolić, Ljiljana; Smith, Richard D; Lipton, Mary S

    2010-05-07

    We report a mass spectrometry-based strategy for quantitative analysis of cell surface membrane proteome changes. The strategy includes enrichment of surface membrane proteins using a membrane-impermeable chemical probe followed by stable isotope (18)O labeling and LC-MS analysis. We applied this strategy for enriching membrane proteins expressed by Shewanella oneidensis MR-1, a Gram-negative bacterium with known metal-reduction capability via extracellular electron transfer between outer membrane proteins and extracellular electron receptors. LC/MS/MS analysis resulted in the identification of about 400 proteins with 79% of them being predicted to be membrane localized. Quantitative aspects of the membrane enrichment were shown by peptide level (16)O and (18)O labeling of proteins from wild-type and mutant cells (generated from deletion of a type II secretion protein, GspD) prior to LC-MS analysis. Using a chemical probe labeled pure protein as an internal standard for normalization, the quantitative data revealed reduced abundances in Delta gspD mutant cells of many outer membrane proteins including the outer membrane c-type cytochromes OmcA and MtrC, in agreement with a previous report that these proteins are substrates of the type II secretion system.

  11. Quantitative analysis of cell surface membrane proteins using membrane-impermeable chemical probe coupled with 18O labeling

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Haizhen; Brown, Roslyn N.; Qian, Weijun; Monroe, Matthew E.; Purvine, Samuel O.; Moore, Ronald J.; Gritsenko, Marina A.; Shi, Liang; Romine, Margaret F.; Fredrickson, Jim K.; Pasa-Tolic, Ljiljana; Smith, Richard D.; Lipton, Mary S.

    2010-05-03

    We report a mass spectrometry-based strategy for quantitative analysis of cell surface membrane proteome changes. The strategy includes enrichment of surface membrane proteins using a membrane-impermeable chemical probe followed by stable isotope 18O labeling and LC-MS analysis. We applied this strategy for enriching membrane proteins expressed by Shewanella oneidensis MR-1, a gram-negative bacterium with known metal-reduction capability via extracellular electron transfer between outer membrane proteins and environmental electron receptors. LC/MS/MS analysis resulted in the identification of about 79% membrane proteins among all proteins identified from the enriched sample. To illustrate the quantification of membrane proteome changes, enriched membrane protein samples from wild-type and mutant cells (generated from deletion of a type II secretion protein, GspD) were further labeled with 16O and 18O at the peptide level prior to LC-MS analysis. A chemical-probe-labeled pure protein has also been used as an internal standard for normalization purpose. The quantitative data revealed reduced abundances of many outer membrane proteins such as OmcA and MtrC in ΔgspD mutant cells, which agreed well with previously published studies.

  12. Quantitative analysis of cell surface membrane proteins using membrane-impermeable chemical probe coupled with 18O labeling

    Science.gov (United States)

    Zhang, Haizhen; Brown, Roslyn N.; Qian, Wei-Jun; Monroe, Matthew E.; Purvine, Samuel O.; Moore, Ronald J.; Gritsenko, Marina A.; Shi, Liang; Romine, Margaret F; Fredrickson, James K.; Paša-Tolić, Ljiljana; Smith, Richard D.; Lipton, Mary S.

    2010-01-01

    We report a mass spectrometry-based strategy for quantitative analysis of cell surface membrane proteome changes. The strategy includes enrichment of surface membrane proteins using a membrane-impermeable chemical probe followed by stable isotope 18O labeling and LC-MS analysis. We applied this strategy for enriching membrane proteins expressed by Shewanella oneidensis MR-1, a gram-negative bacterium with known metal-reduction capability via extracellular electron transfer between outer membrane proteins and extracellular electron receptors. LC/MS/MS analysis resulted in the identification of about 400 proteins with 79% of them being predicted to be membrane localized. Quantitative aspects of the membrane enrichment were shown by peptide level 16O and 18O labeling of proteins from wild-type and mutant cells (generated from deletion of a type II secretion protein, GspD) prior to LC-MS analysis. Using a chemical probe labeled pure protein as an internal standard for normalization, the quantitative data revealed reduced abundances in ΔgspD mutant cells of many outer membrane proteins including the outer membrane c-cype cytochromes OmcA and MtrC, in agreement with previously investigation demonstrating that these proteins are substrates of the type II secretion system. PMID:20380418

  13. [Interphase cytogenetics in oncologic diagnosis].

    Science.gov (United States)

    Pajor, L

    1998-12-06

    Nowadays, the detection of specific DNA sequences on interphase nuclei of cytological and paraffin slide preparations by in situ hybridization, the interphase cytogenetics became an established technology in the pathological diagnostics. A historical overview on the development of the technique is presented, the theoretical basis of the detection of numerical and structural chromosomal aberrations is demonstrated and the applications are exemplified on different types of malignant lymphomas, leukaemias as well as epithelial tumors. Combined use of the interphase cytogenetics, light microscopy and immunohistochemistry with the digital imaging techniques can provide us with morphological, immunophenotypic and genotypic informations of the same cellular object which might be a milestone in the pathomorphological diagnostics.

  14. Probing glycolytic and membrane potential oscillations in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Poulsen, Allan K.; Andersen, Ann Zahle; Brasen, Jens Christian

    2008-01-01

    , while mitochondrial membrane potential was measured using the fluorescent dye DiOC(2)(3). The results show that, as opposed to NADH and other intermediates in glycolysis, intracellular glucose is not oscillating. Furthermore, oscillations in NADH and membrane potential are inhibited by the ATP...

  15. Chemically-activatable alkyne-tagged probe for imaging microdomains in lipid bilayer membranes

    Science.gov (United States)

    Yamaguchi, Satoshi; Matsushita, Taku; Izuta, Shin; Katada, Sumika; Ura, Manami; Ikeda, Taro; Hayashi, Gosuke; Suzuki, Yuta; Kobayashi, Koya; Tokunaga, Kyoya; Ozeki, Yasuyuki; Okamoto, Akimitsu

    2017-01-01

    A chemically-activatable alkynyl steroid analogue probe has been synthesized for visualizing the lipid raft membrane domains by Raman microscopy. The Raman probe, in which ring A of its steroid backbone is replaced with an alkynyl group, was designed to enable activation of the alkyne signal through the Eschenmoser-Tanabe fragmentation reaction of the oxidized cholesterol precursor in lipid bilayer membranes. The alkynyl steroid analogue was observed to form liquid-ordered raft-like domains on a model giant-liposome system in a similar manner as cholesterol, and the large alkyne signal of the accumulated probe at 2120 cm−1 was mapped on the microdomains with a Raman microscope. The alkyne moiety of the probe was confirmed to be converted from the α,β-epoxy ketone group of its precursor by reaction with p-toluensulfonyl hydrazine under a mild condition. Through the reaction, the alkyne signal of the probe was activated on the lipid bilayer membrane of liposomes. Furthermore, the signal activation of the probe was also detected on living cells by stimulated Raman scattering microscopy. The ring-A-opened alkyne steroid analogue, thus, provides a first chemically-activatable Raman probe as a promising tool for potentially unravelling the intracellular formation and trafficking of cholesterol-rich microdomains. PMID:28117375

  16. Two photon fluorescence imaging of lipid membrane domains and potentials using advanced fluorescent probes

    Science.gov (United States)

    Kilin, Vasyl; Darwich, Zeinab; Richert, Ludovic; Didier, Pascal; Klymchenko, Andrey; Mély, Yves

    2013-02-01

    Biomembranes are ordered and dynamic nanoscale structures critical for cell functions. The biological functions of the membranes strongly depend on their physicochemical properties, such as electrostatics, phase state, viscosity, polarity and hydration. These properties are essential for the membrane structure and the proper folding and function of membrane proteins. To monitor these properties, fluorescence techniques and notably, two-photon microscopy appear highly suited due to their exquisite sensitivity and their capability to operate in complex biological systems, such as living cells and tissues. In this context, we have developed multiparametric environment-sensitive fluorescent probes tailored for precise location in the membrane bilayer. We notably developed probes of the 3-hydroxychromone family, characterized by an excited state intramolecular proton transfer reaction, which generates two tautomeric emissive species with well-separated emission bands. As a consequence, the response of these probes to changes in their environment could be monitored through changes in the ratios of the two bands, as well as through changes in the fluorescence lifetimes. Using two-photon ratiometric imaging and FLIM, these probes were used to monitor the surface membrane potential, and were applied to detect apoptotic cells and image membrane domains.

  17. Patterning and Lifetime of Plasma Membrane-Localized Cellulose Synthase Is Dependent on Actin Organization in Arabidopsis Interphase Cells1[W

    Science.gov (United States)

    Sampathkumar, Arun; Gutierrez, Ryan; McFarlane, Heather E.; Bringmann, Martin; Lindeboom, Jelmer; Emons, Anne-Mie; Samuels, Lacey; Ketelaar, Tijs; Ehrhardt, David W.; Persson, Staffan

    2013-01-01

    The actin and microtubule cytoskeletons regulate cell shape across phyla, from bacteria to metazoans. In organisms with cell walls, the wall acts as a primary constraint of shape, and generation of specific cell shape depends on cytoskeletal organization for wall deposition and/or cell expansion. In higher plants, cortical microtubules help to organize cell wall construction by positioning the delivery of cellulose synthase (CesA) complexes and guiding their trajectories to orient newly synthesized cellulose microfibrils. The actin cytoskeleton is required for normal distribution of CesAs to the plasma membrane, but more specific roles for actin in cell wall assembly and organization remain largely elusive. We show that the actin cytoskeleton functions to regulate the CesA delivery rate to, and lifetime of CesAs at, the plasma membrane, which affects cellulose production. Furthermore, quantitative image analyses revealed that actin organization affects CesA tracking behavior at the plasma membrane and that small CesA compartments were associated with the actin cytoskeleton. By contrast, localized insertion of CesAs adjacent to cortical microtubules was not affected by the actin organization. Hence, both actin and microtubule cytoskeletons play important roles in regulating CesA trafficking, cellulose deposition, and organization of cell wall biogenesis. PMID:23606596

  18. Mitochondrial membrane potential probes and the proton gradient: a practical usage guide.

    Science.gov (United States)

    Perry, Seth W; Norman, John P; Barbieri, Justin; Brown, Edward B; Gelbard, Harris A

    2011-02-01

    Fluorescent probes for monitoring mitochondrial membrane potential are frequently used for assessing mitochondrial function, particularly in the context of cell fate determination in biological and biomedical research. However, valid interpretation of results obtained with such probes requires careful consideration of numerous controls, as well as possible effects of non-protonic charges on dye behavior. In this context, we provide an overview of some of the important technical considerations, controls, and parallel complementary assays that can be employed to help ensure appropriate interpretation of results, thus providing a practical usage guide for monitoring mitochondrial membrane potentials with cationic probes. In total, this review will help illustrate both the strengths and potential pitfalls of common mitochondrial membrane potential dyes, and highlight best-usage approaches for their efficacious application in life sciences research.

  19. Mitochondrial membrane potential probes and the proton gradient: a practical usage guide

    OpenAIRE

    Seth W Perry; Norman, John P.; Barbieri, Justin; Brown, Edward B.; Gelbard, Harris A.

    2011-01-01

    Fluorescent probes for monitoring mitochondrial membrane potential are frequently used for assessing mitochondrial function, particularly in the context of cell fate determination in biological and biomedical research. However, valid interpretation of results obtained with such probes requires careful consideration of numerous controls, as well as possible effects of non-protonic charges on dye behavior. In this context, we provide an overview of some of the important technical considerations...

  20. Plasma membrane organization and dynamics is probe and cell line dependent.

    Science.gov (United States)

    Huang, Shuangru; Lim, Shi Ying; Gupta, Anjali; Bag, Nirmalya; Wohland, Thorsten

    2017-09-01

    The action and interaction of membrane receptor proteins take place within the plasma membrane. The plasma membrane, however, is not a passive matrix. It rather takes an active role and regulates receptor distribution and function by its composition and the interaction of its lipid components with embedded and surrounding proteins. Furthermore, it is not a homogenous fluid but contains lipid and protein domains of various sizes and characteristic lifetimes which are important in regulating receptor function and signaling. The precise lateral organization of the plasma membrane, the differences between the inner and outer leaflet, and the influence of the cytoskeleton are still debated. Furthermore, there is a lack of comparisons of the organization and dynamics of the plasma membrane of different cell types. Therefore, we used four different specific membrane markers to test the lateral organization, the differences between the inner and outer membrane leaflet, and the influence of the cytoskeleton of up to five different cell lines, including Chinese hamster ovary (CHO-K1), Human cervical carcinoma (HeLa), neuroblastoma (SH-SY5Y), fibroblast (WI-38) and rat basophilic leukemia (RBL-2H3) cells by Imaging Total Internal Reflection (ITIR)-Fluorescence Correlation Spectroscopy (FCS). We measure diffusion in the temperature range of 298-310K to measure the Arrhenius activation energy (EArr) of diffusion and apply the FCS diffusion law to obtain information on the spatial organization of the probe molecules on the various cell membranes. Our results show clear differences of the FCS diffusion law and EArr for the different probes in dependence of their localization. These differences are similar in the outer and inner leaflet of the membrane. However, these values can differ significantly between different cell lines raising the question how molecular plasma membrane events measured in different cell lines can be compared. This article is part of a Special Issue

  1. Nylon membrane as a fluorimetric probe for the herbicide bentazone.

    Science.gov (United States)

    Chiarandini, Jessica P; Escandar, Graciela M

    2012-02-01

    The fluorimetric signal produced by bentazone retained in selected solid surfaces was investigated. Among the different tested supports, only a microporous nylon membrane produced the desired signal. The quantitative study was carried out by second-order calibration using parallel factor analysis, allowing the determination in a highly interfering medium. A detection limit of 0.4 ng mL(-1), a prediction relative error of 8%, and a sample frequency of ten samples per hour were obtained in spiked natural waters using green analytical chemistry principles.

  2. Tryptophan probes at the α-synuclein and membrane interface

    Science.gov (United States)

    Pfefferkorn, Candace M.; Lee, Jennifer C.

    2010-01-01

    Understanding how environmental factors affect the conformational dynamics of α-synuclein (α-syn) is of great importance because the accumulation and deposit of aggregated α-syn in the brain are intimately connected to Parkinson’s disease etiology. Measurements of steady-state and time-resolved fluorescence of single tryptophan-containing α-syn variants have revealed distinct phospholipid vesicle and micelle interactions at residues 4, 39, 94, and 125. Our circular dichroism (CD) data confirm that Trp mutations do not affect α-syn membrane binding properties (apparent association constant Kaapp∼1×107M−1 for all synucleins) saturating at an estimated lipid-to-protein molar ratio of 380 or approximately 120 proteins covering ~7% of the surface area of an 80 nm diameter vesicle. Fluorophores at positions 4 and 94 are the most sensitive to the lipid bilayer with pronounced spectral blue-shifts (W4: Δλmax ~23 nm; W94: Δλmax ~10 nm) and quantum yield increases (W4, W94: ~3 fold) while W39 and W125 remain primarily water-exposed. Time-resolved fluorescence data show that all sites (except W125) have subpopulations that interact with the membrane. PMID:20229987

  3. Probing Site-Specific Structural Information of Peptides at Model Membrane Interface In Situ.

    Science.gov (United States)

    Ding, Bei; Panahi, Afra; Ho, Jia-Jung; Laaser, Jennifer E; Brooks, Charles L; Zanni, Martin T; Chen, Zhan

    2015-08-19

    Isotope labeling is a powerful technique to probe detailed structures of biological molecules with a variety of analytical methods such as NMR and vibrational spectroscopies. It is important to obtain molecular structural information on biological molecules at interfaces such as cell membranes, but it is challenging to use the isotope labeling method to study interfacial biomolecules. Here, by individually (13)C═(16)O labeling ten residues of a peptide, Ovispirin-1, we have demonstrated for the first time that a site-specific environment of membrane associated peptide can be probed by the submonolayer surface sensitive sum frequency generation (SFG) vibrational spectroscopy in situ. With the peptide associated with a single lipid bilayer, the sinusoidal trend of the SFG line width and peak-center frequency suggests that the peptide is located at the interface beneath the lipid headgroup region. The constructive interferences between the isotope labeled peaks and the main peptide amide I peak contributed by the unlabeled components were used to determine the membrane orientation of the peptide. From the SFG spectral peak-center frequency, line width, and polarization dependence of the isotope labeled units, we deduced structural information on individual units of the peptide associated with a model cell membrane. We also performed molecular dynamics (MD) simulations to understand peptide-membrane interactions. The physical pictures described by simulation agree well with the SFG experimental result. This research demonstrates the feasibility and power of using isotope labeling SFG to probe molecular structures of interfacial biological molecules in situ in real time.

  4. Surface-enhanced infrared absorption spectroscopy (SEIRAS) to probe monolayers of membrane proteins.

    Science.gov (United States)

    Ataka, Kenichi; Stripp, Sven Timo; Heberle, Joachim

    2013-10-01

    Surface-enhanced infrared absorption spectroscopy (SEIRAS) represents a variation of conventional infrared spectroscopy and exploits the signal enhancement exerted by the plasmon resonance of nano-structured metal thin films. The surface enhancement decays in about 10nm with the distance from the surface and is, thus, perfectly suited to selectively probe monolayers of biomembranes. Peculiar to membrane proteins is their vectorial functionality, the probing of which requires proper orientation within the membrane. To this end, the metal surface used in SEIRAS is chemically modified to generate an oriented membrane protein film. Monolayers of uniformly oriented membrane proteins are formed by tethering His-tagged proteins to a nickel nitrilo-triacetic acid (Ni-NTA) modified gold surface and SEIRAS commands molecular sensitivity to probe each step of surface modification. The solid surface used as plasmonic substrate for SEIRAS, can also be employed as an electrode to investigate systems where electron transfer reactions are relevant, like e.g. cytochrome c oxidase or plant-type photosystems. Furthermore, the interaction of these membrane proteins with water-soluble proteins, like cytochrome c or hydrogenase, is studied on the molecular level by SEIRAS. The impact of the membrane potential on protein functionality is verified by monitoring light-dark difference spectra of a monolayer of sensory rhodopsin (SRII) at different applied potentials. It is demonstrated that the interpretations of all of these experiments critically depend on the orientation of the solid-supported membrane protein. Finally, future directions of SEIRAS including cellular systems are discussed. This article is part of a Special Issue entitled: FTIR in membrane proteins and peptide studies.

  5. Probing the function of ionotropic and G protein-coupled receptors in surface-confined membranes.

    Science.gov (United States)

    Danelon, Christophe; Terrettaz, Samuel; Guenat, Olivier; Koudelka, Milena; Vogel, Horst

    2008-10-01

    This article reports on recent electrical and optical techniques for investigating cellular signaling reactions in artificial and native membranes immobilized on solid supports. The first part describes the formation of planar artificial lipid bilayers on gold electrodes, which reveal giga-ohm electrical resistance and the insertion and characterization of ionotropic receptors therein. These membranes are suited to record a few or even single ion channels by impedance spectroscopy. Such tethered membranes on planar arrays of microelectrodes offer mechanically robust, long-lasting measuring devices to probe the influence of different chemistries on biologically important ionotropic receptors and therefore will have a future impact to probe the function of channel proteins in basic science and in biosensor applications. In a second part, we present complementary approaches to form inside-out native membrane sheets that are immobilized on micrometer-sized beads or across submicrometer-sized holes machined in a planar support. Because the native membrane sheets are plasma membranes detached from live cells, these approaches offer a unique possibility to investigate cellular signaling processes, such as those mediated by ionotropic or G protein-coupled receptors, with original composition of lipids and proteins.

  6. Probing Induced Structural Changes in Biomimetic Bacterial Cell Membrane Interactions with Divalent Cations

    Energy Technology Data Exchange (ETDEWEB)

    Holt, Allison M [ORNL; Standaert, Robert F [ORNL; Jubb, Aaron M [ORNL; Katsaras, John [ORNL; Johs, Alexander [ORNL

    2017-01-01

    Biological membranes, formed primarily by the self-assembly of complex mixtures of phospholipids, provide a structured scaffold for compartmentalization and structural processes in living cells. The specific physical properties of phospholipid species present in a given membrane play a key role in mediating these processes. Phosphatidylethanolamine (PE), a zwitterionic lipid present in bacterial, yeast, and mammalian cell membranes, is exceptional. In addition to undergoing the standard lipid polymorphic transition between the gel and liquid-crystalline phase, it can also assume an unusual polymorphic state, the inverse hexagonal phase (HII). Divalent cations are among the factors that drive the formation of the HII phase, wherein the lipid molecules form stacked tubular structures by burying the hydrophilic head groups and exposing the hydrophobic tails to the bulk solvent. Most biological membranes contain a lipid species capable of forming the HII state suggesting that such lipid polymorphic structural states play an important role in structural biological processes such as membrane fusion. In this study, the interactions between Mg2+ and biomimetic bacterial cell membranes composed of PE and phosphatidylglycerol (PG) were probed using differential scanning calorimetry (DSC), small-angle x-ray scattering (SAXS), and fluorescence spectroscopy. The lipid phase transitions were examined at varying ratios of PE to PG and upon exposure to physiologically relevant concentrations of Mg2+. An understanding of these basic interactions enhances our understanding of membrane dynamics and how membrane-mediated structural changes may occur in vivo.

  7. {sup 57}Fe Moessbauer probe of spin crossover thin films on a bio-membrane

    Energy Technology Data Exchange (ETDEWEB)

    Naik, Anil D.; Garcia, Yann, E-mail: yann.garcia@uclouvain.be [Universite Catholique de Louvain, Institute of Condensed Matter and Nanosciences (Belgium)

    2012-03-15

    An illustrious complex [Fe(ptz){sub 6}](BF{sub 4}){sub 2} (ptz = 1-propyl-tetrazole) (1) which was produced in the form of submicron crystals and thin film on Allium cepa membrane was probed by {sup 57}Fe Mossbauer spectroscopy in order to follow its intrinsic spin crossover. In addition to a weak signal that corresponds to neat SCO compound significant amount of other iron compounds are found that could have morphed from 1 due to specific host-guest interaction on the lipid-bilayer of bio-membrane. Further complimentary information about biogenic role of membrane, was obtained from variable temperature Mossbauer spectroscopy on a {approx}5% enriched [{sup 57}Fe(H{sub 2}O){sub 6}](BF{sub 4}){sub 2} salt on this membrane.

  8. 57 Fe Mössbauer probe of spin crossover thin films on a bio-membrane

    Science.gov (United States)

    Naik, Anil D.; Garcia, Yann

    2012-03-01

    An illustrious complex [Fe(ptz)6](BF4)2 (ptz = 1-propyl-tetrazole) ( 1) which was produced in the form of submicron crystals and thin film on Allium cepa membrane was probed by 57Fe Mossbauer spectroscopy in order to follow its intrinsic spin crossover. In addition to a weak signal that corresponds to neat SCO compound significant amount of other iron compounds are found that could have morphed from 1 due to specific host-guest interaction on the lipid-bilayer of bio-membrane. Further complimentary information about biogenic role of membrane, was obtained from variable temperature Mossbauer spectroscopy on a ~5% enriched [57Fe(H2O)6](BF4)2 salt on this membrane.

  9. Investigation of pig sperm plasma membrane reorganization using progesterone-albumin-fluorescein probes

    Institute of Scientific and Technical Information of China (English)

    Alfredo Medrano; Paul F Watson; William V Holt

    2012-01-01

    Objective:To relate semen susceptibility in cooling protocols to sperm plasma membrane properties.Methods:A series of experiments was performed using the fluorescent markers, progesterone-BSA-FITC andBSA-FITC.Results:These experiments indicated that both progesterone-BSA-FITC andBSA-FITC bound to specific sperm plasma membrane domains, thus producing four different binding patterns, revealing probable changes in membrane organization during capacitation and during cooling.Those patterns seem to make a sequence progressing from non-capacitated status to capacitated status.The proportion of each pattern was different during incubation than during cooling, showing the latter had a higher proportion of dead sperm than the former.Conclusions:At this stage, the association of sperm plasma membrane alterations was revealed byBSA-FITC probes and cryosensitivity remains unclear.

  10. The distribution of lipid attached spin probes in bilayers: application to membrane protein topology.

    Science.gov (United States)

    Vogel, Alexander; Scheidt, Holger A; Huster, Daniel

    2003-09-01

    The distribution of the lipid-attached doxyl electron paramagnetic resonance (EPR) spin label in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine membranes has been studied by (1)H and (13)C magic angle spinning nuclear magnetic resonance relaxation measurements. The doxyl spin label was covalently attached to the 5th, 10th, and 16th carbons of the sn-2 stearic acid chain of a 1-palmitoyl-2-stearoyl-(5/10/16-doxyl)-sn-glycero-3-phosphocholine analog. Due to the unpaired electron of the spin label, (1)H and (13)C lipid relaxation rates are enhanced by paramagnetic relaxation. For all lipid segments the influence of paramagnetic relaxation is observed even at low probe concentrations. Paramagnetic relaxation rates provide a measure for the interaction strength between lipid segments and the doxyl group. Plotted along the membrane director a transverse distribution profile of the EPR probe is obtained. The chain-attached spin labels are broadly distributed in the membrane with a maximum at the approximate chain position of the probe. Both (1)H and (13)C relaxation measurements show these broad distributions of the doxyl group in the membrane indicating that (1)H spin diffusion does not influence the relaxation measurements. The broad distributions of the EPR label result from the high degree of mobility and structural heterogeneity in liquid-crystalline membranes. Knowing the distribution profiles of the EPR probes, their influence on relaxation behavior of membrane inserted peptide and protein segments can be studied by (13)C magic angle spinning nuclear magnetic resonance. As an example, the location of Ala residues positioned at three sites of the transmembrane WALP-16 peptide was investigated. All three doxyl-labeled phospholipid analogs induce paramagnetic relaxation of the respective Ala site. However, for well ordered secondary structures the strongest relaxation enhancement is observed for that doxyl group in the closest proximity to the respective Ala. Thus

  11. Probing a self-assembled fd virus membrane with a microtubule

    Science.gov (United States)

    Xie, Sheng; Pelcovits, Robert A.; Hagan, Michael F.

    2016-06-01

    The self-assembly of highly anisotropic colloidal particles leads to a rich variety of morphologies whose properties are just beginning to be understood. This article uses computer simulations to probe a particle-scale perturbation of a commonly studied colloidal assembly, a monolayer membrane composed of rodlike fd viruses in the presence of a polymer depletant. Motivated by experiments currently in progress, we simulate the interaction between a microtubule and a monolayer membrane as the microtubule "pokes" and penetrates the membrane face-on. Both the viruses and the microtubule are modeled as hard spherocylinders of the same diameter, while the depletant is modeled using ghost spheres. We find that the force exerted on the microtubule by the membrane is zero either when the microtubule is completely outside the membrane or when it has fully penetrated the membrane. The microtubule is initially repelled by the membrane as it begins to penetrate but experiences an attractive force as it penetrates further. We assess the roles played by translational and rotational fluctuations of the viruses and the osmotic pressure of the polymer depletant. We find that rotational fluctuations play a more important role than the translational ones. The dependence on the osmotic pressure of the depletant of the width and height of the repulsive barrier and the depth of the attractive potential well is consistent with the assumed depletion-induced attractive interaction between the microtubule and viruses. We discuss the relevance of these studies to the experimental investigations.

  12. Lipid bilayer regulation of membrane protein function: gramicidin channels as molecular force probes

    DEFF Research Database (Denmark)

    Lundbæk, Jens August; Collingwood, S.A.; Ingolfsson, H.I.

    2010-01-01

    physical properties. This advance is because of the introduction of new tools for studying lipid bilayer regulation of protein function. The present review provides an introduction to the regulation of membrane protein function by the bilayer physical properties. We further describe the use of gramicidin...... channels as molecular force probes for studying this mechanism, with a unique ability to discriminate between consequences of changes in monolayer curvature and bilayer elastic moduli....

  13. Membrane orientation and lateral diffusion of BODIPY-cholesterol as a function of probe structure.

    Science.gov (United States)

    Solanko, Lukasz M; Honigmann, Alf; Midtiby, Henrik Skov; Lund, Frederik W; Brewer, Jonathan R; Dekaris, Vjekoslav; Bittman, Robert; Eggeling, Christian; Wüstner, Daniel

    2013-11-05

    Cholesterol tagged with the BODIPY fluorophore via the central difluoroboron moiety of the dye (B-Chol) is a promising probe for studying intracellular cholesterol dynamics. We synthesized a new BODIPY-cholesterol probe (B-P-Chol) with the fluorophore attached via one of its pyrrole rings to carbon-24 of cholesterol (B-P-Chol). Using two-photon fluorescence polarimetry in giant unilamellar vesicles and in the plasma membrane (PM) of living intact and actin-disrupted cells, we show that the BODIPY-groups in B-Chol and B-P-Chol are oriented perpendicular and almost parallel to the bilayer normal, respectively. B-Chol is in all three membrane systems much stronger oriented than B-P-Chol. Interestingly, we found that the lateral diffusion in the PM was two times slower for B-Chol than for B-P-Chol, although we found no difference in lateral diffusion in model membranes. Stimulated emission depletion microscopy, performed for the first time, to our knowledge, with fluorescent sterols, revealed that the difference in lateral diffusion of the BODIPY-cholesterol probes was not caused by anomalous subdiffusion, because diffusion of both analogs in the PM was free but not hindered. Our combined measurements show that the position and orientation of the BODIPY moiety in cholesterol analogs have a severe influence on lateral diffusion specifically in the PM of living cells.

  14. Diffusion studies on permeable nitroxyl spin probes through bilayer lipid membranes: A low frequency ESR study

    Energy Technology Data Exchange (ETDEWEB)

    Meenakumari, V.; Benial, A. Milton Franklin, E-mail: miltonfranklin@yahoo.com [Department of Physics, NMSSVN College, Nagamalai, Madurai-625019, Tamilnadu (India); Utsumi, Hideo; Ichikawa, Kazuhiro; Yamada, Ken-ichi [Department of Bio-functional Science, Kyushu University, Fukuoka (Japan); Hyodo, Fuminori [Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka (Japan); Jawahar, A. [Department of Chemistry, NMSSVN College, Nagamalai, Madurai-625019, Tamilnadu (India)

    2015-06-24

    Electron spin resonance (ESR) studies were carried out for permeable 2mM {sup 14}N-labeled deutrated 3 Methoxy carbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl (MC-PROXYL) in pure water and 1mM, 2mM, 3mM, 4mM concentration of 14N-labeled deutrated MC-PROXYL in 400mM concentration of liposomal solution by using a 300 MHz ESR spectrometer. The ESR parameters such as linewidth, hyperfine coupling constant, g-factor, partition parameter and permeability were reported for these samples. The line broadening was observed for the nitroxyl spin probe in the liposomal solution. The line broadening indicates that the high viscous nature of the liposomal solution. The partition parameter and permeability values indicate the maximum diffusion of nitroxyl spin probes in the bilayer lipid membranes at 2 mM concentration of nitroxyl radical. This study illustrates that ESR can be used to differentiate between the intra and extra- membrane water by loading the liposome vesicles with a lipid-permeable nitroxyl spin probe. From the ESR results, the spin probe concentration was optimized as 2mM in liposomal solution for ESR phantom studies/imaging, invivo and invitro experiments.

  15. Interactions of egg yolk lipoprotein fraction with boar spermatozoa assessed with a fluorescent membrane probe.

    Directory of Open Access Journals (Sweden)

    Łukasz Zasiadczyk

    2010-08-01

    Full Text Available The interactions of a fluorescent membrane probe, 1-anilinonaphthalene-8-sulfonic acid (1,8-ANS, with boar spermatozoa were followed through the use of lipoprotein fraction of ostrich egg yolk (LPFo. Semen samples, extended in Kortowo 3 (K3 extender, were supplemented with 2% or 5% LPFo and stored for 3h at 16 degrees C. Additionally, cold shock-treated spermatozoa (1h at 4 degrees C were stored in K3 extender supplemented with LPFo for 3h at 16 degrees C. In each boar, the fluorescent enhancement of ANS was observed in K3-extended semen supplemented with LPFo, prior to storage. Following storage, there was a significant increase in LPFo-ANS fluorescence, particularly in the sperm membrane overlying the head and midpiece regions. There were significant differences among the boars with respect to the sperm populations defined by the LPFo-ANS fluorescence. Sperm viability was not significantly affected during the storage period. Furthermore, the proportions of spermatozoa defined by the different patterns of LPFo-ANS fluorescence were low and remained unchanged after storage of cold shock-treated spermatozoa with 2% or 5% LPFo, suggesting irreversible damage to the sperm membrane architecture. These findings indicate that the ANS fluorescent probe could be used to shed more light on the nature of the interactions between LPFo and sperm membrane following semen preservation. Such valuable information could contribute to the development of an optimal protocol for cryopreservation of boar semen.

  16. Diphenylhexatriene membrane probes DPH and TMA-DPH: A comparative molecular dynamics simulation study.

    Science.gov (United States)

    do Canto, António M T M; Robalo, João R; Santos, Patrícia D; Carvalho, Alfredo J Palace; Ramalho, J P Prates; Loura, Luís M S

    2016-11-01

    Fluorescence spectroscopy and microscopy have been utilized as tools in membrane biophysics for decades now. Because phospholipids are non-fluorescent, the use of extrinsic membrane probes in this context is commonplace. Among the latter, 1,6-diphenylhexatriene (DPH) and its trimethylammonium derivative (TMA-DPH) have been extensively used. It is widely believed that, owing to its additional charged group, TMA-DPH is anchored at the lipid/water interface and reports on a bilayer region that is distinct from that of the hydrophobic DPH. In this study, we employ atomistic MD simulations to characterize the behavior of DPH and TMA-DPH in 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and POPC/cholesterol (4:1) bilayers. We show that although the dynamics of TMA-DPH in these membranes is noticeably more hindered than that of DPH, the location of the average fluorophore of TMA-DPH is only ~3-4Å more shallow than that of DPH. The hindrance observed in the translational and rotational motions of TMA-DPH compared to DPH is mainly not due to significant differences in depth, but to the favorable electrostatic interactions of the former with electronegative lipid atoms instead. By revealing detailed insights on the behavior of these two probes, our results are useful both in the interpretation of past work and in the planning of future experiments using them as membrane reporters. Copyright © 2016 Elsevier B.V. All rights reserved.

  17. Strategies for Probing Nanometer-Scale Electrocatalysts: From Single Particles to Catalyst-Membrane Architectures

    Energy Technology Data Exchange (ETDEWEB)

    Korzeniewski, Carol

    2014-01-20

    The project primary objectives are to prepare and elucidate the promoting properties of materials that possess high activity for the conversion of hydrogen and related small molecules (water, oxygen, carbon monoxide and methanol) in polymer electrolyte fuel cells. One area of research has focused on the study of catalyst materials. Protocols were developed for probing the structure and benchmarking the activity of Pt and Pt bimetallic nanometer-scale catalyst against Pt single crystal electrode standards. A second area has targeted fuel cell membrane and the advancement of simple methods mainly based on vibrational spectroscopy that can be applied broadly in the study of membrane structure and transport properties. Infrared and Raman methods combined with least-squares data modeling were applied to investigate and assist the design of robust, proton conductive membranes, which resist reactant crossover.

  18. FITC-labeled lipopolysaccharide: use as a probe for liposomal membrane incorporation studies.

    Science.gov (United States)

    Trubetskoy, V S; Koshkina, N V; Omel'yanenko, V G; L'vov, V L; Dmitriev, B A; Petrov, A B; Torchilin, V P

    1990-08-20

    FITC-labeled LPS from Neisseria meningitidis can be used as a probe to follow the process of LPS incorporation into liposomal membrane and to study its interaction with a bilayer. The incorporation of FITC-LPS into the bilayer was proved by physicochemical methods as well as by liposomal LPS toxicity decrease in actinomycin D-sensitized mice. Fluorescence intensity increase was observed upon the insertion of FITC-LPS into the membrane of dehydration/rehydration vesicles and vesicles obtained by co-sonication of lipid suspension and FITC-LPS. Following FITC-LPS fluorescence polarization it was shown that the substance seems to be clusterized in the liposomal membrane starting from FITC-LPS/lipid molar ratio 1:800.

  19. Nonlinear Dielectric Spectroscopy as an Indirect Probe of Metabolic Activity in Thylakoid Membrane

    Directory of Open Access Journals (Sweden)

    John H. Miller

    2011-01-01

    Full Text Available Nonlinear dielectric spectroscopy (NDS is a non-invasive probe of cellular metabolic activity with potential application in the development of whole-cell biosensors. However, the mechanism of NDS interaction with metabolic membrane proteins is poorly understood, partly due to the inherent complexity of single cell organisms. Here we use the light-activated electron transport chain of spinach thylakoid membrane as a model system to study how NDS interacts with metabolic activity. We find protein modification, as opposed to membrane pump activity, to be the dominant source of NDS signal change in this system. Potential mechanisms for such protein modifications include reactive oxygen species generation and light-activated phosphorylation.

  20. Fluorescent probes sensitive to changes in the cholesterol-to-phospholipids molar ratio in human platelet membranes during atherosclerosis

    Science.gov (United States)

    Posokhov, Yevgen

    2016-09-01

    Environment-sensitive fluorescent probes were used for the spectroscopic visualization of pathological changes in human platelet membranes during cerebral atherosclerosis. It has been estimated that the ratiometric probes 2-(2‧-hydroxyphenyl)-5-phenyl-1,3,4-oxadiazole and 2-phenyl-phenanthr[9,10]oxazole can detect changes in the cholesterol-to-phospholipids molar ratio in human platelet membranes during the disease.

  1. A new probe for super-resolution imaging of membranes elucidates trafficking pathways.

    Science.gov (United States)

    Revelo, Natalia H; Kamin, Dirk; Truckenbrodt, Sven; Wong, Aaron B; Reuter-Jessen, Kirsten; Reisinger, Ellen; Moser, Tobias; Rizzoli, Silvio O

    2014-05-26

    The molecular composition of the organelles involved in membrane recycling is difficult to establish as a result of the absence of suitable labeling tools. We introduce in this paper a novel probe, named membrane-binding fluorophore-cysteine-lysine-palmitoyl group (mCLING), which labels the plasma membrane and is taken up during endocytosis. It remains attached to membranes after fixation and permeabilization and can therefore be used in combination with immunostaining and super-resolution microscopy. We applied mCLING to mammalian-cultured cells, yeast, bacteria, primary cultured neurons, Drosophila melanogaster larval neuromuscular junctions, and mammalian tissue. mCLING enabled us to study the molecular composition of different trafficking organelles. We used it to address several questions related to synaptic vesicle recycling in the auditory inner hair cells from the organ of Corti and to investigate molecular differences between synaptic vesicles that recycle actively or spontaneously in cultured neurons. We conclude that mCLING enables the investigation of trafficking membranes in a broad range of preparations.

  2. Fluorescent molecular probes based on excited state prototropism in lipid bilayer membrane

    Science.gov (United States)

    Mohapatra, Monalisa; Mishra, Ashok K.

    2012-03-01

    Excited state prototropism (ESPT) is observed in molecules having one or more ionizable protons, whose proton transfer efficiency is different in ground and excited states. The interaction of various ESPT molecules like naphthols and intramolecular ESPT (ESIPT) molecules like hydroxyflavones etc. with different microheterogeneous media have been studied in detail and excited state prototropism as a probe concept has been gaining ground. The fluorescence of different prototropic forms of such molecules, on partitioning to an organized medium like lipid bilayer membrane, often show sensitive response to the local environment with respect to the local structure, physical properties and dynamics. Our recent work using 1-naphthol as an ESPT fluorescent molecular probe has shown that the incorporation of monomeric bile salt molecules into lipid bilayer membranes composed from dipalmitoylphosphatidylcholine (DPPC, a lung surfactant) and dimyristoylphosphatidylcholine (DMPC), in solid gel and liquid crystalline phases, induce appreciable wetting of the bilayer up to the hydrocarbon core region, even at very low (fisetin, an ESIPT molecule having antioxidant properties, in lipid bilayer membrane has been sensitively monitored from its intrinsic fluorescence behaviour.

  3. Imaging individual proteins and nanodomains on intact cell membranes with a probe-based optical antenna.

    Science.gov (United States)

    van Zanten, Thomas S; Lopez-Bosque, Maria J; Garcia-Parajo, Maria F

    2010-01-01

    Optical antennas that confine and enhance electromagnetic fields in a nanometric region hold great potential for nanobioimaging and biosensing. Probe-based monopole optical antennas are fabricated to enhance fields localized to <30 nm near the antenna apex in aqueous conditions. These probes are used under appropriate excitation antenna conditions to image individual antibodies with an unprecedented resolution of 26 +/- 4 nm and virtually no surrounding background. On intact cell membranes in physiological conditions, the obtained resolution is 30 +/- 6 nm. Importantly, the method allows individual proteins to be distinguished from nanodomains and the degree of clustering to be quantified by directly measuring physical size and intensity of individual fluorescent spots. Improved antenna geometries should lead to true live cell imaging below 10-nm resolution with position accuracy in the subnanometric range.

  4. Electronic nose system combined with membrane interface probe for detection of VOCs in water

    Science.gov (United States)

    Cho, Junghwan; Howard, Zachary; Kurup, Pradeep

    2011-09-01

    This paper describes a novel electronic nose system combined with a membrane interface probe (MIP) for detecting volatile organic compounds (VOCs) in water. The MIP is an in situ tool that allows the detection of certain VOCs in the soil via a pushed or driven probe. The MIP was combined with a sensor array consisting of four different tin-oxide gas sensors known as an electronic nose (e-nose). The designed e-nose system was calibrated in aqueous media spiked with benzene, toluene, ethylbenzene, and p-xylene (BTEX) at concentrations of 100, 250, and 500 ppm. Since the experiment was conducted utilizing five repetitions for each analyte, a data set of 60 measurements was prepared for principal components analysis (PCA). The results of the PCA showed that two principal components contain more than 99% variance information and each VOC is separable and detectable by the e-nose.

  5. Visualization of lipid domains in giant unilamellar vesicles using an environment-sensitive membrane probe based on 3-hydroxyflavone.

    Science.gov (United States)

    Klymchenko, Andrey S; Oncul, Sule; Didier, Pascal; Schaub, Emmanuel; Bagatolli, Luis; Duportail, Guy; Mély, Yves

    2009-02-01

    We characterized the recently introduced environment-sensitive fluorescent membrane probe based on 3-hydroxyflavone, F2N12S, in model lipid membranes displaying liquid disordered (Ld) phase, liquid ordered (Lo) phase, or their coexistence. Steady-state fluorescence studies in large unilamellar vesicles show that the probe dual emission drastically changes with the lipid bilayer phase, which can be correlated with the difference in their hydration. Using two-photon excitation microscopy on giant unilamellar vesicles, the F2N12S probe was found to bind both Ld and Lo phases, allowing visualization of the individual phases from the fluorescence intensity ratio of its two emission bands. By using a linearly polarized excitation light, a strong photoselection was observed for F2N12S in the Lo phase, indicating that its fluorophore is nearly parallel to the lipid chains of the bilayer. In contrast, the absence of the photoselection with the Ld phase indicated no predominant orientation of the probe in the Ld phase. Comparison of the present results with those reported previously for F2N12S in living cells suggests a high content of the Lo phase in the outer leaflet of the cell plasma membranes. Taking into account the high selectivity of F2N12S for the cell plasma membranes and its suitability for both single- and two-photon excitation, applications of this probe to study membrane lateral heterogeneity in biological membranes are foreseen.

  6. Improved signal recognition for interphase fluorescent in-situ hybridization using a non-ionic detergent (NP-40) pretreatment

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, H.M.; Day-Salvatore, D.L.; Sciorra, L.J. [Univ. of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, New Brunswick, NJ (United States)] [and others

    1994-09-01

    We have reported that the non-ionic detergent ethylphenolpoly (ethyleneglycolether)x known as Noniet-P40 (Shell International Petroleum) can gently disrupt cell membranes, resulting in cells with varying degrees of free chromatin release. The extent of this phenomena is dependent upon the concentration of NP-40 and the detergent`s exposure time to the cells. Treated cells can range from halos of DNA around the cells to fully extended free chromatin configurations. We have demonstrated that these treated cells are excellent targets for many different fluorescently labelled probes used for in situ hybridization studies. Recently, we have compared NP-40 harvested lymphocytes with normally harvested cells to see if we could improve upon the number of cells showing discreet signals in interphase fluorescent in situ hybridization. Preliminary work has shown that using a trisomy 21 cell line, one can get a statistically significant improvement with NP-40 pretreatment cells over control levels, in the number of cells having three discreet signals in interphase {open_quotes}FISH{close_quotes}. Such a pretreatment is simple to perform and may be of value when the number of cells available for analysis is low, as in the search for fetal cells from maternal circulation.

  7. Behavior of plant plasma membranes under hydrostatic pressure as monitored by fluorescent environment-sensitive probes.

    Science.gov (United States)

    Roche, Yann; Klymchenko, Andrey S; Gerbeau-Pissot, Patricia; Gervais, Patrick; Mély, Yves; Simon-Plas, Françoise; Perrier-Cornet, Jean-Marie

    2010-08-01

    We monitored the behavior of plasma membrane (PM) isolated from tobacco cells (BY-2) under hydrostatic pressures up to 3.5kbar at 30 degrees C, by steady-state fluorescence spectroscopy using the newly introduced environment-sensitive probe F2N12S and also Laurdan and di-4-ANEPPDHQ. The consequences of sterol depletion by methyl-beta-cyclodextrin were also studied. We found that application of hydrostatic pressure led to a marked decrease of hydration as probed by F2N12S and to an increase of the generalized polarization excitation (GPex) of Laurdan. We observed that the hydration effect of sterol depletion was maximal between 1 and 1.5 kbar but was much less important at higher pressures (above 2 kbar) where both parameters reached a plateau value. The presence of a highly dehydrated gel state, insensitive to the sterol content, was thus proposed above 2.5 kbar. However, the F2N12S polarity parameter and the di-4-ANEPPDHQ intensity ratio showed strong effect on sterol depletion, even at very high pressures (2.5-3.5 kbar), and supported the ability of sterols to modify the electrostatic properties of membrane, notably its dipole potential, in a highly dehydrated gel phase. We thus suggested that BY-2 PM undergoes a complex phase behavior in response to the hydrostatic pressure and we also emphasized the role of phytosterols to regulate the effects of high hydrostatic pressure on plant PM.

  8. Probing phosphoethanolamine-containing lipids in membranes with duramycin/cinnamycin and aegerolysin proteins.

    Science.gov (United States)

    Hullin-Matsuda, Françoise; Makino, Asami; Murate, Motohide; Kobayashi, Toshihide

    2016-11-01

    In this mini-review, we summarize current knowledge about the lipid-binding characteristics of two types of toxins used to visualize the membrane distribution of phosphoethanolamine-containing lipid species: the glycerophospholipid, phosphatidylethanolamine (PE) and the sphingolipid, ceramide phosphoethanolamine (CPE). The lantibiotic cinnamycin and the structurally-related peptide duramycin produced by some Gram-positive bacteria were among the first toxins characterized by their specificity for PE which is widely present in animal kingdoms from bacteria to mammals. These toxins promoted their binding to PE-containing membranes by changing membrane curvature and by inducing transbilayer lipid movement. The recognition of the conical shape and negative curvature adopted by the PE species within the membrane, is important to understand how lipid-peptide interaction can occur. Three mushroom-derived proteins belonging to the aegerolysin family, pleurotolysin A2, ostreolysin and erylysin A were recently described as efficient tools to visualize the membrane distribution of CPE which is found in trace amounts in mammalian cells but in higher amounts in some developmental stages of lower eukaryotes like Trypanosoma and in invertebrates such as Drosophila. The recent development of lantibiotic-based PE-specific and aegerolysin-based CPE-specific probes is useful to visualize and specify the role of these lipids in various pathophysiological events such as cell division, apoptosis, tumor vasculature and parasite developmental stages. Copyright © 2016 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

  9. A new fluorescent squaraine probe for the measurement of membrane polarity.

    Science.gov (United States)

    Ioffe, Valeriya M; Gorbenko, Galyna P; Domanov, Yegor A; Tatarets, Anatoliy L; Patsenker, Leonid D; Terpetsching, Ewald A; Dyubko, Tatyana S

    2006-01-01

    The present study was undertaken to evaluate the sensitivity of newly synthesized squaraine dye 1 to the changes in lipid bilayer physical properties and compared it with the well-known dye 2. Partitioning of the dye 1 into lipid bilayer was found to be followed by significant increase of its fluorescence intensity and red-shift of emission maximum, while intensity of the dye 2 fluorescence increased only slightly on going from aqueous to lipidic environment. This suggests that dye 1 is more sensitive to the changes in membrane properties as compared to dye 2. Partition coefficients of the dye 1 have been determined for the model membranes composed of zwitterionic phospholipid phosphatidylcholine (PC) and its mixtures with positively charged detergent cetyltrimethylammonium bromide (CTAB), anionic phospholipid cardiolipin (CL), and sterol (Chol). The spectral responses of the dye 1 in different liposome media proved to correlate with the increase of bilayer polarity induced by Chol and CL or its decrease caused by CTAB. It was concluded that dye 1 can be used as fluorescent probe for examining membrane-related processes.

  10. Computational analysis of the tether-pulling experiment to probe plasma membrane-cytoskeleton interaction in cells

    Science.gov (United States)

    Schumacher, Kristopher R.; Popel, Aleksander S.; Anvari, Bahman; Brownell, William E.; Spector, Alexander A.

    2009-10-01

    Tethers are thin membrane tubes that can be formed when relatively small and localized forces are applied to cellular membranes and lipid bilayers. Tether pulling experiments have been used to better understand the fine membrane properties. These include the interaction between the plasma membrane and the underlying cytoskeleton, which is an important factor affecting membrane mechanics. We use a computational method aimed at the interpretation and design of tether pulling experiments in cells with a strong membrane-cytoskeleton attachment. In our model, we take into account the detailed information in the topology of bonds connecting the plasma membrane and the cytoskeleton. We compute the force-dependent piecewise membrane deflection and bending as well as modes of stored energy in three major regions of the system: body of the tether, membrane-cytoskeleton attachment zone, and the transition zone between the two. We apply our method to three cells: cochlear outer hair cells (OHCs), human embryonic kidney (HEK) cells, and Chinese hamster ovary (CHO) cells. OHCs have a special system of pillars connecting the membrane and the cytoskeleton, and HEK and CHO cells have the membrane-cytoskeleton adhesion arrangement via bonds (e.g., PIP2), which is common to many other cells. We also present a validation of our model by using experimental data on CHO and HEK cells. The proposed method can be an effective tool in the analyses of experiments to probe the properties of cellular membranes.

  11. Localization of Membrane-Associated Proteins in Vesicular Stomatitis Virus by Use of Hydrophobic Membrane Probes and Cross-Linking Reagents

    Science.gov (United States)

    Zakowski, Jack J.; Wagner, Robert R.

    1980-01-01

    The location of membrane-associated proteins of vesicular stomatitis virus was investigated by using two monofunctional and three bifunctional probes that differ in the degree to which they partition into membranes and in their specific group reactivity. Two hydrophobic aryl azide probes, [125I]5-iodonaphthyl-1-azide and [3H]pyrenesulfonylazide, readily partitioned into virion membrane and, when activated to nitrenes by UV irradiation, formed stable covalent adducts to membrane constituents. Both of these monofunctional probes labeled the glyco-protein G and matrix M proteins, but [125I]5-iodonaphthyl-1-azide also labeled the nucleocapsid N protein and an unidentified low-molecular-weight component. Protein labeling of intact virions was unaffected by the presence of cytochrome c or glutathione, but disruption of membrane by sodium dodecyl sulfate greatly enhanced the labeling of all viral proteins except G. Labeling of G protein was essentially restricted to the membrane-embedded, thermolysin-resistant tail fragment. Three bifunctional reagents, tartryl diazide, dimethylsuberimidate, and 4,4′-dithiobisphenylazide, were tested for their capacity to cross-link proteins to membrane phospholipids of virions grown in the presence of [3H]palmitate. Only G and M proteins of intact virions were labeled with 3H-phospholipid by these cross-linkers; the reactions were not affected by cytochrome c but were abolished by disruption of virus with sodium dodecyl sulfate. Dimethylsuberimidate, which reacts with free amino groups, cross-linked 3H-phospholipid to both G and M protein. In contrast, the hydrophilic tartryl diazide cross-linked phospholipid primarily to the M protein, whereas the hydrophobic 4,4′-dithiobisphenylazide cross-linked phospholipid primarily to the intrinsic G protein. These data support the hypothesis that the G protein traverses the virion membrane and that the M protein is membrane associated but does not penetrate very deeply, if at all. PMID:6255216

  12. The Effect of Interphase Structures in Nanodielectrics

    Science.gov (United States)

    Raetzke, Stephanie; Kindersberger, Josef

    The interface between the polymer and the filler particles influences the properties of dielectric materials. To understand how interfaces act, they should be considered as layers rather than interfaces. Therefore the term interphase is more appropriate for the polymer layer around a filler particle where the polymer chains are chemically and/or physically bound to the particle surface. The interphase is characterized by an ordered polymer structure around the particles. This paper discusses the influence of the ordered polymer structure around the particles on the polymer properties with regard to explain the effect of nano particles on material properties. In this paper also a model is given how to estimate the maximum interphase fraction depending on particle diameter and interphase thickness. It is postulated that the most significant results can be achieved at this maximum.

  13. Fluorescence lifetime imaging of membrane lipid order with a ratiometric fluorescent probe.

    Science.gov (United States)

    Kilin, Vasyl; Glushonkov, Oleksandr; Herdly, Lucas; Klymchenko, Andrey; Richert, Ludovic; Mely, Yves

    2015-05-19

    To monitor the lateral segregation of lipids into liquid-ordered (Lo) and -disordered (Ld) phases in lipid membranes, environment-sensitive dyes that partition in both phases but stain them differently have been developed. Of particular interest is the dual-color F2N12S probe, which can discriminate the two phases through the ratio of its two emission bands. These bands are associated with the normal (N(∗)) and tautomer (T(∗)) excited-state species that result from an excited-state intramolecular proton transfer. In this work, we investigated the potency of the time-resolved fluorescence parameters of F2N12S to discriminate lipid phases in model and cell membranes. Both the long and mean lifetime values of the T(∗) form of F2N12S were found to differ by twofold between Ld and Lo phases as a result of the restriction in the relative motions of the two aromatic moieties of F2N12S imposed by the highly packed Lo phase. This differed from the changes in the ratio of the two emission bands between the two phases, which mainly resulted from the decreased hydration of the N(∗) form in the Lo phase. Importantly, the strong difference in lifetimes between the two phases was preserved when cholesterol was added to the Ld phase. The two phases could be imaged with high contrast by fluorescence lifetime imaging microscopy (FLIM) on giant unilamellar vesicles. FLIM images of F2N12S-labeled live HeLa cells confirmed that the plasma membrane was mainly in the Lo-like phase. Furthermore, the two phases were found to be homogeneously distributed all over the plasma membrane, indicating that they are highly mixed at the spatiotemporal resolution of the FLIM setup. Finally, FLIM could also be used to sensitively monitor the change in lipid phase upon cholesterol depletion and apoptosis.

  14. Probing the interaction between nanoparticles and lipid membranes by quartz crystal microbalance with dissipation monitoring

    Science.gov (United States)

    Yousefi, Nariman; Tufenkji, Nathalie

    2016-12-01

    There is increasing interest in using quartz crystal microbalance with dissipation monitoring (QCM-D) to investigate the interaction of nanoparticles (NPs) with model surfaces. The high sensitivity, ease of use and the ability to monitor interactions in real-time has made it a popular technique for colloid chemists, biologists, bioengineers and biophysicists. QCM-D has been recently used to probe the interaction of NPs with supported lipid bilayers (SLBs) as model cell membranes. The interaction of NPs with SLBs is highly influenced by the quality of the lipid bilayers. Unlike many surface sensitive techniques, using QCM-D, the quality of SLBs can be assessed in real-time, hence QCM-D studies on SLB-NP interactions are less prone to the artefacts arising from bilayers that are not well formed. The ease of use and commercial availability of a wide range of sensor surfaces also have made QCM-D a versatile tool for studying NP interactions with lipid bilayers. In this review, we summarize the state-of-the-art on QCM-D based techniques for probing the interactions of NPs with lipid bilayers.

  15. Interphase cytogenetics in pathology: principles, methods, and applications of fluorescence in situ hybridization (FISH).

    Science.gov (United States)

    Werner, M; Wilkens, L; Aubele, M; Nolte, M; Zitzelsberger, H; Komminoth, P

    1997-01-01

    Characteristic chromosome aberrations have been identified in various tumors. Fluorescence in situ hybridization (FISH) using specific probes that are generated by vector cloning or in vitro amplification and labeled with fluorescent dyes allow for the detection of these genetic changes in interphase cells. This technique, that is also referred to as "interphase cytogenetics", can be performed in cytological preparations as well as in sections of routinely formaldehyde-fixed and paraffin-embedded tissue. In cancer research and diagnostics, interphase cytogenetics by FISH is used to detect numerical chromosome changes and structural aberrations, e.g., translocations, deletions, or amplifications. In this technical overview, we explain the principles of the FISH method and provide protocols for FISH in cytological preparations and paraffin sections. Moreover, possible applications of FISH are discussed.

  16. Dominant Microbial Composition and Its Vertical Distribution in Saline Meromictic Lake Kaiike (Japan) as Revealed by Quantitative Oligonucleotide Probe Membrane Hybridization

    OpenAIRE

    Koizumi, Yoshikazu; Kojima, Hisaya; Fukui, Manabu

    2004-01-01

    Vertical distributions of dominant bacterial populations in saline meromictic Lake Kaiike were investigated throughout the water column and sediment by quantitative oligonucleotide probe membrane hybridization. Three oligonucleotide probes specific for the small-subunit (SSU) rRNA of three groups of Chlorobiaceae were newly designed. In addition, three general domain (Bacteria, Archaea, and Eukarya)-specific probes, two δ-Proteobacteria-specific probes, a Chlorobiaceae-specific probe, and a C...

  17. Dynamic Viral Glycoprotein Machines: Approaches for Probing Transient States That Drive Membrane Fusion

    Directory of Open Access Journals (Sweden)

    Natalie K. Garcia

    2016-01-01

    Full Text Available The fusion glycoproteins that decorate the surface of enveloped viruses undergo dramatic conformational changes in the course of engaging with target cells through receptor interactions and during cell entry. These refolding events ultimately drive the fusion of viral and cellular membranes leading to delivery of the genetic cargo. While well-established methods for structure determination such as X-ray crystallography have provided detailed structures of fusion proteins in the pre- and post-fusion fusion states, to understand mechanistically how these fusion glycoproteins perform their structural calisthenics and drive membrane fusion requires new analytical approaches that enable dynamic intermediate states to be probed. Methods including structural mass spectrometry, small-angle X-ray scattering, and electron microscopy have begun to provide new insight into pathways of conformational change and fusion protein function. In combination, the approaches provide a significantly richer portrait of viral fusion glycoprotein structural variation and fusion activation as well as inhibition by neutralizing agents. Here recent studies that highlight the utility of these complementary approaches will be reviewed with a focus on the well-characterized influenza virus hemagglutinin fusion glycoprotein system.

  18. Directly probing redox-linked quinones in photosystem II membrane fragments via UV resonance Raman scattering.

    Science.gov (United States)

    Chen, Jun; Yao, Mingdong; Pagba, Cynthia V; Zheng, Yang; Fei, Liping; Feng, Zhaochi; Barry, Bridgette A

    2015-01-01

    In photosynthesis, photosystem II (PSII) harvests sunlight with bound pigments to oxidize water and reduce quinone to quinol, which serves as electron and proton mediators for solar-to-chemical energy conversion. At least two types of quinone cofactors in PSII are redox-linked: QA, and QB. Here, we for the first time apply 257-nm ultraviolet resonance Raman (UVRR) spectroscopy to acquire the molecular vibrations of plastoquinone (PQ) in PSII membranes. Owing to the resonance enhancement effect, the vibrational signal of PQ in PSII membranes is prominent. A strong band at 1661 cm(-1) is assigned to ring CC/CO symmetric stretch mode (ν8a mode) of PQ, and a weak band at 469 cm(-1) to ring stretch mode. By using a pump-probe difference UVRR method and a sample jet technique, the signals of QA and QB can be distinguished. A frequency difference of 1.4 cm(-1) in ν8a vibrational mode between QA and QB is observed, corresponding to ~86 mV redox potential difference imposed by their protein environment. In addition, there are other PQs in the PSII membranes. A negligible anharmonicity effect on their combination band at 2130 cm(-1) suggests that the 'other PQs' are situated in a hydrophobic environment. The detection of the 'other PQs' might be consistent with the view that another functional PQ cofactor (not QA or QB) exists in PSII. This UVRR approach will be useful to the study of quinone molecules in photosynthesis or other biological systems.

  19. Statistical methods in interphase cytogenetics: an experimental approach.

    Science.gov (United States)

    Kibbelaar, R E; Kok, F; Dreef, E J; Kleiverda, J K; Cornelisse, C J; Raap, A K; Kluin, P M

    1993-10-01

    In situ hybridization (ISH) techniques on interphase cells, or interphase cytogenetics, have powerful potential clinical and biological applications, such as detection of minimal residual disease, early relapse, and the study of clonal evolution and expansion in neoplasia. Much attention has been paid to issues related to ISH data acquisition, i.e., the numbers, colors, intensities, and spatial relationships of hybridization signals. The methodology concerning data analysis, which is of prime importance for clinical applications, however, is less well investigated. We have studied the latter for the detection of small monosomic and trisomic cell populations using various mixtures of human female and male cells. With a chromosome X specific probe, the male cells stimulated monosomic subpopulations of 0, 1, 5, 10, 50, 90, 95, 99, and 100%. Analogously, when a (7 + Y) specific probe combination was used, containing a mixture of chromosome No. 7 and Y-specific DNA, the male cells simulated trisomic cell populations. Probes specific for chromosomes Nos. 1, 7, 8, and 9 were used for estimation of ISH artifacts. Three statistical tests, the Kolmogorov-Smirnov test, the multiple-proportion test, and the z'-max test, were applied to the empirical data using the control data as a reference for ISH artifacts. The Kolmogorov-Smirnov test was found to be inferior for discrimination of small monosomic or trisomic cell populations. The other two tests showed that when 400 cells were evaluated, and using selected control probes, monosomy X could be detected at a frequency of 5% aberrant cells, and trisomy 7 + Y at a frequency of 1%.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. Chemiluminescence-imaging detection of DNA on a solid-phase membrane by using a peroxidase-labeled macromolecular probe.

    Science.gov (United States)

    Azam, Md Golam; Yamasuji, Mutsumi; Krawczyk, Tomasz; Shibata, Takayuki; Kabashima, Tsutomu; Kai, Masaaki

    2015-07-01

    We have developed a novel method for sensitive chemiluminescence (CL)-imaging detection of DNA by using a macromolecular probe synthesized by attaching multiple molecules of horseradish peroxidase (HRP) and biotin in dextran backbone. The probe formed a macromolecular assembly by binding to streptavidin which specifically recognized biotinylated complementary DNA, which was hybridized to a target DNA on a solid-phase membrane. This methodology was applied to CL-imaging detection of a synthetic telomere DNA (TTAGGG)10 and human telomere DNA by using the CL probe comprising of dextranT2000 (MW=ca. 2000kDa) bonded to approximately 42 molecules of HRP and 210 molecules of biotin. The human telomere DNA in a small number of buccal mucous cells (ca. 70 cell numbers) of cheek tissue was quantitatively determined by the proposed CL detection method that afforded approximately 10 times higher sensitivity than that of the conventional CL method using commercially available HRP-avidin probe.

  1. A triterpene oleanolic acid conjugate with 3-hydroxyflavone derivative as a new membrane probe with two-color ratiometric response.

    Science.gov (United States)

    Turkmen, Zeynep; Klymchenko, Andrey S; Oncul, Sule; Duportail, Guy; Topcu, Gulacti; Demchenko, Alexander P

    2005-07-29

    We report on the synthesis by coupling of a triterpenoid oleanolic acid with 4'-diethylamino-3-hydroxyflavone (FE) to produce an environment-sensitive biomembrane probe with two-band ratiometric response in fluorescence emission. The synthesized compound (probe FOT) was tested in a series of model solvents and demonstrated the response to solvent polarity and intermolecular hydrogen bonding very similar to that of parent probe FE. Meantime when incorporated into lipid bilayer membranes, it showed new features differing in response between lipids of different surface charges as well as between glycerophospholipids and sphingomyelin. We observed that in the conditions of coexistence of rafts and non-raft structures the probe is excluded from the rafts.

  2. Interphase tuning for stronger and tougher composites.

    Science.gov (United States)

    Livanov, Konstantin; Yang, Lin; Nissenbaum, Asaf; Wagner, H Daniel

    2016-05-27

    The development of composite materials that are simultaneously strong and tough is one of the most active topics of current material science. Observations of biological structural materials show that adequate introduction of reinforcements and interfaces, or interphases, at different scales usually improves toughness, without reduction in strength. The prospect of interphase properties tuning may lead to further increases in material toughness. Here we use evaporation-driven self-assembly (EDSA) to deposit a thin network of multi-wall carbon nanotubes on ceramic surfaces, thereby generating an interphase reinforcing layer in a multiscale laminated ceramic composite. Both strength and toughness are improved by up to 90%, while keeping the overall volume fraction of nanotubes in a composite below 0.012%, making it a most effective toughening and reinforcement technique.

  3. Interphase tailoring in graphite-epoxy composites

    Science.gov (United States)

    Subramanian, R. V.; Sanadi, A. R.; Crasto, A. S.

    1988-01-01

    The fiber-matrix interphase in graphite fiber-epoxy matrix composites is presently modified through the electrodeposition of a coating of the polymer poly(styrene-comaleic anhydride), or 'SMA' on the graphite fibers; optimum conditions have been established for the achievement of the requisite thin, uniform coatings, as verified by SEM. A single-fiber composite test has shown the SMA coating to result in an interfacial shear strength to improve by 50 percent over commercially treated fibers without sacrifice in impact strength. It is suggested that the epoxy resin's superior penetration into the SMA interphase results in a tougher fiber/matrix interface which possesses intrinsic energy-absorbing mechanisms.

  4. Diffusion studies on permeable nitroxyl spin probe through lipid bilayer membrane

    Energy Technology Data Exchange (ETDEWEB)

    Benial, A. Milton Franklin; Meenakumari, V. [Department of Physics, NMSSVN College, Nagamalai, Madurai-625019 (India); Ichikawa, Kazuhiro; Yamada, Ken-ichi; Utsumi, Hideo, E-mail: hideo.utsumi.278@m.kyushu-u.ac.jp [Department of Bio-functional Science, Kyushu University, Fukuoka (Japan); Hyodo, Fuminori [Innovation Center for Medical Redox Navigation, Kyushu University, Fukuoka (Japan); Jawahar, A. [Department of Chemistry, NMSSVN College, Nagamalai, Madurai-625 019 (India)

    2014-04-24

    Electron spin resonance (ESR) studies were carried out for 2mM {sup 14}N labeled deutrated permeable 3- methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl (MC-PROXYL) in pure water, 1 mM, 2 mM, 3 mM and 4 mM concentration of MC-PROXYL in 300 mM concentration of liposomal solution by using a L-band ESR spectrometer. The ESR parameters such as linewidth, hyperfine coupling constant, g-factor, partition parameter and permeability were reported. The partition parameter and permeability values indicate the maximum spin distribution in the lipid phase at 2 mM concentration. This study illustrates that ESR can be used to differentiate between the intra and extra-membrane water by loading the liposome vesicles with a lipid-permeable nitroxyl spin probe. From the ESR results, the radical concentration was optimized as 2 mM in liposomal solution for ESR phantom studies and experiments.

  5. Site-specific interaction between α-synuclein and membranes probed by NMR-observed methionine oxidation rates.

    Science.gov (United States)

    Maltsev, Alexander S; Chen, Jue; Levine, Rodney L; Bax, Ad

    2013-02-27

    α-Synuclein (αS) is an intrinsically disordered protein that is water-soluble but also can bind negatively charged lipid membranes while adopting an α-helical conformation. Membrane affinity is increased by post-translational N-terminal acetylation, a common modification in all eukaryotic cells. In the presence of lipid vesicles containing a small fraction of peroxidized lipids, the N-terminal Met residues in αS (Met1 and Met5) rapidly oxidize while reducing the toxic lipid hydroperoxide to a nonreactive lipid hydroxide, whereas C-terminal Met residues remain unaffected. Met oxidation can be probed conveniently and quantitatively by NMR spectroscopy. The results show that oxidation of Met1 reduces the rate of oxidation of Met5 and vice versa as a result of decreased membrane affinity of the partially oxidized protein. The effect of Met oxidation on the αS-membrane affinity extends over large distances, as in the V49M mutant, oxidation of Met1 and Met5 strongly impacts the oxidation rate of Met49 and vice versa. When not bound to membrane, oxidized Met1 and Met5 of αS are excellent substrates for methionine sulfoxide reductase (Msr), thereby providing an efficient vehicle for water-soluble Msr enzymes to protect the membrane against oxidative damage.

  6. Response of an environment-sensitive intramolecular charge transfer probe towards solubilization of liposome membranes by a non-ionic detergent: Association and dissociation kinetics

    Science.gov (United States)

    Paul, Bijan Kumar; Guchhait, Nikhil

    2012-10-01

    The present report describes an endeavor to follow the solubilization of DMPC and DMPG liposome membranes by a non-ionic detergent Triton X-100 on the lexicon of environment-sensitive intramolecular charge transfer (ICT) photophysics of an extrinsic molecular probe 5-(4-dimethylamino-phenyl)-penta-2, 4-dienoic acid methyl ester (DPDAME). The prospective applicability of the probe to function as a reporter for detergent-sequestered solubilization of liposome membranes is argued on the basis of comparison of the spectral properties of the probe in various environments. Fluorescence anisotropy study delineates the degree of motional restriction imposed on the probe in different microheterogeneous assemblies. The kinetics of association of the probe with the liposome membranes and the dissociation kinetics of TX-100-sequestered solubilization process of the liposomes have been monitored by the stopped-flow fluorescence technique and the results are rationalized in relevance to fluorescence anisotropy study.

  7. Monitoring Biophysical Properties of Lipid Membranes by Environment-Sensitive Fluorescent Probes

    OpenAIRE

    Demchenko, Alexander P.; Mély, Yves; Duportail, Guy; Klymchenko, Andrey S

    2009-01-01

    We review the main trends in the development of fluorescence probes to obtain information about the structure, dynamics, and interactions in biomembranes. These probes are efficient for studying the microscopic analogs of viscosity, polarity, and hydration, as well as the molecular order, environment relaxation, and electrostatic potentials at the sites of their location. Progress is being made in increasing the information content and spatial resolution of the probe responses. Multichannel e...

  8. Model for probing membrane-cortex adhesion by micropipette aspiration and fluctuation spectroscopy

    CERN Document Server

    Alert, Ricard; Brugués, Jan; Sens, Pierre

    2016-01-01

    We propose a model for membrane-cortex adhesion which couples membrane deformations, hydrodynamics and kinetics of membrane-cortex ligands. In its simplest form, the model gives explicit predictions for the critical pressure for membrane detachment and for the value of adhesion energy. We show that these quantities exhibit a significant dependence on the active acto-myosin stresses. The model provides a simple framework to access quantitative information on cortical activity by means of micropipette experiments. We also extend the model to incorporate fluctuations and show that detailed information on the stability of membrane-cortex coupling can be obtained by a combination of micropipette aspiration and fluctuation spectroscopy measurements.

  9. Dependence of Z Parameter for Tensile Strength of Multi-Layered Interphase in Polymer Nanocomposites to Material and Interphase Properties

    Science.gov (United States)

    Zare, Yasser; Rhee, Kyong Yop

    2017-01-01

    In this work, the Z interphase parameter which determines the tensile strength of interphase layers in polymer nanocomposites is presented as a function of various material and interphase properties. In this regard, the simple Pukanszky model for tensile strength of polymer nanocomposites is applied and the dependency of Z to different characteristics of constituents and interphase are illustrated by contour plots. The interphase strength ( σ i) and B interfacial parameter in Pukanszky model show direct links with Z parameter. Also, it is found that the volume fractions of nanoparticles and interphase reveal dissimilar effects on Z. A high Z is obtained by a low nanoparticle volume fraction and high content of interphase, but the best values of Z are associated with the level of B parameter.

  10. Probing peptide and protein insertion in a biomimetic S-layer supported lipid membrane platform.

    Science.gov (United States)

    Damiati, Samar; Schrems, Angelika; Sinner, Eva-Kathrin; Sleytr, Uwe B; Schuster, Bernhard

    2015-01-27

    The most important aspect of synthetic lipid membrane architectures is their ability to study functional membrane-active peptides and membrane proteins in an environment close to nature. Here, we report on the generation and performance of a biomimetic platform, the S-layer supported lipid membrane (SsLM), to investigate the structural and electrical characteristics of the membrane-active peptide gramicidin and the transmembrane protein α-hemolysin in real-time using a quartz crystal microbalance with dissipation monitoring in combination with electrochemical impedance spectroscopy. A shift in membrane resistance is caused by the interaction of α-hemolysin and gramicidin with SsLMs, even if only an attachment onto, or functional channels through the lipid membrane, respectively, are formed. Moreover, the obtained results did not indicate the formation of functional α-hemolysin pores, but evidence for functional incorporation of gramicidin into this biomimetic architecture is provided.

  11. Structure and dynamics of interphase chromosomes.

    Directory of Open Access Journals (Sweden)

    Angelo Rosa

    Full Text Available During interphase chromosomes decondense, but fluorescent in situ hybridization experiments reveal the existence of distinct territories occupied by individual chromosomes inside the nuclei of most eukaryotic cells. We use computer simulations to show that the existence and stability of territories is a kinetic effect that can be explained without invoking an underlying nuclear scaffold or protein-mediated interactions between DNA sequences. In particular, we show that the experimentally observed territory shapes and spatial distances between marked chromosome sites for human, Drosophila, and budding yeast chromosomes can be reproduced by a parameter-free minimal model of decondensing chromosomes. Our results suggest that the observed interphase structure and dynamics are due to generic polymer effects: confined Brownian motion conserving the local topological state of long chain molecules and segregation of mutually unentangled chains due to topological constraints.

  12. Proteomics of a fuzzy organelle: interphase chromatin

    Science.gov (United States)

    Kustatscher, Georg; Hégarat, Nadia; Wills, Karen L H; Furlan, Cristina; Bukowski-Wills, Jimi-Carlo; Hochegger, Helfrid; Rappsilber, Juri

    2014-01-01

    Chromatin proteins mediate replication, regulate expression, and ensure integrity of the genome. So far, a comprehensive inventory of interphase chromatin has not been determined. This is largely due to its heterogeneous and dynamic composition, which makes conclusive biochemical purification difficult, if not impossible. As a fuzzy organelle, it defies classical organellar proteomics and cannot be described by a single and ultimate list of protein components. Instead, we propose a new approach that provides a quantitative assessment of a protein's probability to function in chromatin. We integrate chromatin composition over a range of different biochemical and biological conditions. This resulted in interphase chromatin probabilities for 7635 human proteins, including 1840 previously uncharacterized proteins. We demonstrate the power of our large-scale data-driven annotation during the analysis of cyclin-dependent kinase (CDK) regulation in chromatin. Quantitative protein ontologies may provide a general alternative to list-based investigations of organelles and complement Gene Ontology. PMID:24534090

  13. Barriers to the Migration of Interphase Boundaries.

    Science.gov (United States)

    1984-01-06

    neceeay and Identify by block number) CFerrite, carbide, interphase boundary structure, nucleation, growth, solute drag effect, barrier, bainite ...Third Three Years (1980-1983) 8 B. Personnel and Supplemental Support Situations 10 C. The Proeutectoid Ferrite and Bainite Reactions in Fe-C-X...C. Fig. 13 Optical micrographs of ferrite/ bainite morphology round the bay of Fe-0.19% C-2.30% Mo at early stages of transformation. Bay temperature

  14. An EPR spin-probe and spin-trap study of the free radicals produced by plant plasma membranes

    Directory of Open Access Journals (Sweden)

    GORAN BACIC

    2005-02-01

    Full Text Available Plant plasma membranes are known to produce superoxide radicals, while the production of hydroxyl radical is thought to occur only in the cell wall. In this work it was demonstrated using combined spin-trap and spin-probe EPR spectroscopic techniques, that plant plasma membranes do produce superoxide and hydroxyl radicals but by kinetically different mechanisms. The results show that superoxide and hydroxyl radicals can be detected by DMPO spin-trap and that the mechanisms and location of their production can be differentiated using the reduction of spin-probes Tempone and 7-DS. It was shown that the mechanism of production of oxygen reactive species is NADH dependent and diphenylene iodonium inhibited. The kinetics of the reduction of Tempone, combined with scavengers or the absence of NADH indicates that hydroxyl radicals are produced by a mechanism independent of that of superoxide production. It was shown that a combination of the spin-probe and spin-trap technique can be used in free radical studies of biological systems, with a number of advantages inherent to them.

  15. Interphase cytogenetics of workers exposed to benzene

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, L.; Wang, Yunxia; Venkatesh, P. [Univ. of California, Berkeley, CA (United States)] [and others

    1996-12-01

    Fluorescence in situ hybridization (FISH) is a powerful new technique that allows numerical chromosome aberrations (aneuploidy) to be detected in interphase cells. In previous studies, FISH has been used to demonstrate that the benzene metabolites hydroquinone and 1,2,4-benzenetriol induce aneuploidy of chromosomes 7 and 9 in cultures of human cells. In the present study, we used an interphase FISH procedure to perform cytogenetic analyses on the blood cells of 43 workers exposed to benzene (median=31 ppm, 8-hr time-weighted average) and 44 matched controls from Shanghai, China. High benzene exposure (>31 ppm, n=22) increased the hyperdiploid frequency of chromosome 9 (p<0.01), but lower exposure (<31 ppm, n=21) did not. Trisomy 9 was the major form of benzene-induced hyperdiploidy. The level of hyperdiploidy in exposed workers correlated with their urinary phenol level (r= 0.58, p < 0.0001), a measure of internal benzene close. A significant correlation was also found between hyperdiploicly and decreased absolute lymphocyte count, an indicator of benzene hematotoxicity, in the exposed group (r=-0.44, p=0.003) but not in controls (r=-0.09, P=0.58). These results show that high benzene exposure induces aneuploidy of chromosome 9 in nondiseased individuals, with trisomy being the most prevalent form. They further highlight the usefulness of interphase cytogenetics and FISH for the rapid and sensitive detection of aneuploidy in exposed human populations. 35 refs., 3 figs., 2 tabs.

  16. A microfluidic platform for probing single cell plasma membranes using optically trapped Smart Droplet Microtools (SDMs).

    Science.gov (United States)

    Lanigan, Peter M P; Ninkovic, Tanja; Chan, Karen; de Mello, Andrew J; Willison, Keith R; Klug, David R; Templer, Richard H; Neil, Mark A A; Ces, Oscar

    2009-04-21

    We recently introduced a novel platform based upon optically trapped lipid coated oil droplets (Smart Droplet Microtools-SDMs) that were able to form membrane tethers upon fusion with the plasma membrane of single cells. Material transfer from the plasma membrane to the droplet via the tether was seen to occur. Here we present a customised version of the SDM approach based upon detergent coated droplets deployed within a microfluidic format. These droplets are able to differentially solubilise the plasma membrane of single cells with spatial selectivity and without forming membrane tethers. The microfluidic format facilitates separation of the target cells from the bulk SDM population and from downstream analysis modules. Material transfer from the cell to the SDM was monitored by tracking membrane localized EGFP.

  17. Can pyrene probes be used to measure lateral pressure profiles of lipid membranes? Perspective through atomistic simulations

    DEFF Research Database (Denmark)

    Franova, M. D.; Vattulainen, I.; Ollila, O. H. S.

    2014-01-01

    The lateral pressure profile of lipid bilayers has gained a lot of attention, since changes in the pressure profile have been suggested to shift the membrane protein conformational equilibrium. This relation has been mostly studied with theoretical methods, especially with molecular dynamics...... determinant of the excimer/monomer fluorescence ratio. Thus, the results do not support the usage of di-pyr-PC molecules to measure the shape of the lateral pressure profile. We yet discuss how the probes could potentially be exploited to gain qualitative insight of the changes in pressure profile when lipid...... simulations, since established methods to measure the lateral pressure profile experimentally have not been available. The only experiments that have attempted to gauge the lateral pressure profile have been done by using di-pyrenyl-phosphatidylcholine (di-pyr-PC) probes. In these experiments, the excimer...

  18. Visualization of lipid domains of lipid domains in giant unilamellar vesicles using an environment-sensitive membrane probe based on 3-hydroxyflavone

    DEFF Research Database (Denmark)

    Klymchenko, Andrey; Oncul, Sule; Didier, Pascal

    2009-01-01

    of the photoselection with the Ld phase indicated no predominant orientation of the probe in the Ld phase. Comparison of the present results with those reported previously for F2N12S in living cells suggests a high content of the Lo phase in the outer leaflet of the cell plasma membranes. Taking into account the high......We characterized the recently introduced environment-sensitive fluorescent membrane probe based on 3-hydroxyflavone, F2N12S, in model lipid membranes displaying liquid disordered (Ld) phase, liquid ordered (Lo) phase, or their coexistence. Steady-state fluorescence studies in large unilamellar...... vesicles show that the probe dual emission drastically changes with the lipid bilayer phase, which can be correlated with the difference in their hydration. Using two-photon excitation microscopy on giant unilamellar vesicles, the F2N12S probe was found to bind both Ld and Lo phases, allowing visualization...

  19. Self-assembling properties of porphyrinic photosensitizers and their effect on membrane interactions probed by NMR spectroscopy.

    Science.gov (United States)

    Vermathen, Martina; Marzorati, Mattia; Bigler, Peter

    2013-06-13

    Aggregation and membrane penetration of porphyrinic photosensitizers play crucial roles for their efficacy in photodynamic therapy. The current study was aimed at comparing the aggregation behavior of selected photosensitizers and correlating it with membrane affinity. Self-assembling properties of 15 amphiphilic free-base chlorin and porphyrin derivatives bearing carboxylate substituents were studied in phosphate buffered saline (PBS) by (1)H NMR spectroscopy, making use of ring current induced aggregation shifts. All compounds exhibited aggregation in PBS to a different degree with dimers or oligomers showing slow aggregate growth over time. Aggregate structures were proposed on the basis of temperature dependent chemical shift changes. All chlorin compounds revealed similar aggregation maps with their hydrophobic sides overlapping and their carboxylate groups protruding toward the exterior. In contrast, for the porphyrin compounds, the carboxylate groups were located in overlapping regions. Membrane interactions were probed using 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayer vesicles and 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC) micelles as models. The chlorin derivatives had higher membrane affinity and were all monomerized by DHPC micelles as opposed to the porphyrin compounds. The observed differences were attributed to the different aggregate structures proposed for the chlorin and porphyrin derivatives. Free accessibility of the carboxylate groups seemed to promote initial surface interaction with phospholipid bilayers and micelles.

  20. Membrane orientation and lateral diffusion of BODIPY-cholesterol as a function of probe structure

    DEFF Research Database (Denmark)

    Solanko, Lukasz Michal; Wüstner, Daniel; Lund, Frederik Wendelboe

    2013-01-01

    -24 of cholesterol (B-P-Chol). Using two-photon fluorescence polarimetry in giant unilamellar vesicles and in the plasma membrane (PM) of living intact and actin-disrupted cells, we show that the BODIPY-groups in B-Chol and B-P-Chol are oriented perpendicular and almost parallel to the bilayer normal......, respectively. B-Chol is in all three membrane systems much stronger oriented than B-P-Chol. Interestingly, we found that the lateral diffusion in the PM was two times slower for B-Chol than for B-P-Chol, although we found no difference in lateral diffusion in model membranes. Stimulated emission depletion...

  1. Dynamic multiple-target tracing to probe spatiotemporal cartography of cell membranes.

    Science.gov (United States)

    Sergé, Arnauld; Bertaux, Nicolas; Rigneault, Hervé; Marguet, Didier

    2008-08-01

    Although the highly dynamic and mosaic organization of the plasma membrane is well-recognized, depicting a resolved, global view of this organization remains challenging. We present an analytical single-particle tracking (SPT) method and tool, multiple-target tracing (MTT), that takes advantage of the high spatial resolution provided by single-fluorophore sensitivity. MTT can be used to generate dynamic maps at high densities of tracked particles, thereby providing global representation of molecular dynamics in cell membranes. Deflation by subtracting detected peaks allows detection of lower-intensity peaks. We exhaustively detected particles using MTT, with performance reaching theoretical limits, and then reconnected trajectories integrating the statistical information from past trajectories. We demonstrate the potential of this method by applying it to the epidermal growth factor receptor (EGFR) labeled with quantum dots (Qdots), in the plasma membrane of live cells. We anticipate the use of MTT to explore molecular dynamics and interactions at the cell membrane.

  2. Mechanisms of nuclear lamina growth in interphase.

    Science.gov (United States)

    Zhironkina, Oxana A; Kurchashova, Svetlana Yu; Pozharskaia, Vasilisa A; Cherepanynets, Varvara D; Strelkova, Olga S; Hozak, Pavel; Kireev, Igor I

    2016-04-01

    The nuclear lamina represents a multifunctional platform involved in such diverse yet interconnected processes as spatial organization of the genome, maintenance of mechanical stability of the nucleus, regulation of transcription and replication. Most of lamina activities are exerted through tethering of lamina-associated chromatin domains (LADs) to the nuclear periphery. Yet, the lamina is a dynamic structure demonstrating considerable expansion during the cell cycle to accommodate increased number of LADs formed during DNA replication. We analyzed dynamics of nuclear growth during interphase and changes in lamina structure as a function of cell cycle progression. The nuclear lamina demonstrates steady growth from G1 till G2, while quantitative analysis of lamina meshwork by super-resolution microscopy revealed that microdomain organization of the lamina is maintained, with lamin A and lamin B microdomain periodicity and interdomain gap sizes unchanged. FRAP analysis, in contrast, demonstrated differences in lamin A and B1 exchange rates; the latter showing higher recovery rate in S-phase cells. In order to further analyze the mechanism of lamina growth in interphase, we generated a lamina-free nuclear envelope in living interphase cells by reversible hypotonic shock. The nuclear envelope in nuclear buds formed after such a treatment initially lacked lamins, and analysis of lamina formation revealed striking difference in lamin A and B1 assembly: lamin A reassembled within 30 min post-treatment, whereas lamin B1 did not incorporate into the newly formed lamina at all. We suggest that in somatic cells lamin B1 meshwork growth is coordinated with replication of LADs, and lamin A meshwork assembly seems to be chromatin-independent process.

  3. Genome architecture: domain organization of interphase chromosomes.

    Science.gov (United States)

    Bickmore, Wendy A; van Steensel, Bas

    2013-03-14

    The architecture of interphase chromosomes is important for the regulation of gene expression and genome maintenance. Chromosomes are linearly segmented into hundreds of domains with different protein compositions. Furthermore, the spatial organization of chromosomes is nonrandom and is characterized by many local and long-range contacts among genes and other sequence elements. A variety of genome-wide mapping techniques have made it possible to chart these properties at high resolution. Combined with microscopy and computational modeling, the results begin to yield a more coherent picture that integrates linear and three-dimensional (3D) views of chromosome organization in relation to gene regulation and other nuclear functions.

  4. SANS study to probe nanoparticle dispersion in nanocomposite membranes of aromatic polyamide and functionalized silica nanoparticles.

    Science.gov (United States)

    Jadav, Ghanshyam L; Aswal, Vinod K; Singh, Puyam S

    2010-11-01

    Silica nanoparticles produced from organically functionalized silicon alkoxide precursors were incorporated into polyamide film to produce a silica-polyamide nanocomposite membrane with enhanced properties. The dispersion of the silica nanoparticles in the nanocomposite membrane was characterized by performing small-angle neutron scattering (SANS) measurements on dilute reactant systems and dilute solution suspensions of the final product. Clear scattering of monodisperse spherical particles of 10-18 A R(g) were observed from dilute solutions of the initial reactant system. These silica nanoparticles initially reacted with diamine monomers of polyamide and subsequently were transformed into polyamide-coated silica nanoparticles; finally nanoparticle aggregates of 27-45 A R(g) were formed. The nanoparticle dispersion of the membrane as the nanosized aggregates is in corroboration with ring- or chain-like assemblies of the nanoparticles dispersed in the bulk polyamide phase as observed by transmission electron microscopy. It is demonstrated that dispersions of silica nanoparticles as the nanosized aggregates in the polyamide phase could be achieved in the nanocomposite membrane with a silica content up to about 2 wt.%. Nanocomposite membranes with higher silica loading approximately 10 wt.% lead to the formation of large aggregates of sizes over 100 A R(g) in addition to the nanosized aggregates.

  5. Fluorescence of nitrobenzoxadiazole (NBD)-labeled lipids in model membranes is connected not to lipid mobility but to probe location.

    Science.gov (United States)

    Amaro, Mariana; Filipe, Hugo A L; Prates Ramalho, J P; Hof, Martin; Loura, Luís M S

    2016-03-14

    Nitrobenzoxadiazole (NBD)-labeled lipids are popular fluorescent membrane probes. However, the understanding of important aspects of the photophysics of NBD remains incomplete, including the observed shift in the emission spectrum of NBD-lipids to longer wavelengths following excitation at the red edge of the absorption spectrum (red-edge excitation shift or REES). REES of NBD-lipids in membrane environments has been previously interpreted as reflecting restricted mobility of solvent surrounding the fluorophore. However, this requires a large change in the dipole moment (Δμ) of NBD upon excitation. Previous calculations of the value of Δμ of NBD in the literature have been carried out using outdated semi-empirical methods, leading to conflicting values. Using up-to-date density functional theory methods, we recalculated the value of Δμ and verified that it is rather small (∼2 D). Fluorescence measurements confirmed that the value of REES is ∼16 nm for 1,2-dioleoyl-sn-glycero-3-phospho-l-serine-N-(NBD) (NBD-PS) in dioleoylphosphatidylcholine vesicles. However, the observed shift is independent of both the temperature and the presence of cholesterol and is therefore insensitive to the mobility and hydration of the membrane. Moreover, red-edge excitation leads to an increased contribution of the decay component with a shorter lifetime, whereas time-resolved emission spectra of NBD-PS displayed an atypical blue shift following excitation. This excludes restrictions to solvent relaxation as the cause of the measured REES and TRES of NBD, pointing instead to the heterogeneous transverse location of probes as the origin of these effects. The latter hypothesis was confirmed by molecular dynamics simulations, from which the calculated heterogeneity of the hydration and location of NBD correlated with the measured fluorescence lifetimes/REES. Globally, our combination of theoretical and experiment-based techniques has led to a considerably improved understanding of

  6. Optical probing of mechanical loss of a Si_{3}N_{4} membrane below 100 mK

    CERN Document Server

    Fischer, R; Assumpção, G G T; Yu, P -L; Cicak, K; Peterson, R W; Simmonds, R W; Regal, C A

    2016-01-01

    We report on low mechanical loss in a high-stress silicon nitride (Si_{3}N_{4}) membrane at temperatures below 100 mK. We isolate a membrane via a phononic shield formed within a supporting silicon frame, and measure the mechanical quality factor of a number of high-tension membrane modes as we vary our dilution refrigerator base temperature between 35 mK and 5 K. At the lowest temperatures, we obtain a maximum quality factor (Q) of 2.3\\times10^{8}, corresponding to a Q-frequency product (QFP) of 3.7\\times10^{14} Hz. These measurements complement the recent observation of improved quality factors of Si_{3}N_{4} at ultralow temperatures via electrical detection. We also observe a dependence of the quality factor on optical heating of the device. By combining exceptional material properties, high tension, advanced isolation and clamping techniques, high-stress mechanical objects are poised to explore a new regime of exceptional quality factors. Such quality factors combined with an optical probe at cryogenic te...

  7. Ionic liquids effects on the permeability of photosynthetic membranes probed by the electrochromic shift of endogenous carotenoids.

    Science.gov (United States)

    Malferrari, Marco; Malferrari, Danilo; Francia, Francesco; Galletti, Paola; Tagliavini, Emilio; Venturoli, Giovanni

    2015-11-01

    Ionic liquids (ILs) are promising materials exploited as solvents and media in many innovative applications, some already used at the industrial scale. The chemical structure and physicochemical properties of ILs can differ significantly according to the specific applications for which they have been synthesized. As a consequence, their interaction with biological entities and toxicity can vary substantially. To select highly effective and minimally harmful ILs, these properties need to be investigated. Here we use the so called chromatophores--protein-phospholipid membrane vesicles obtained from the photosynthetic bacterium Rhodobacter sphaeroides--to assess the effects of imidazolinium and pyrrolidinium ILs, with chloride or dicyanamide as counter anions, on the ionic permeability of a native biological membrane. The extent and modalities by which these ILs affect the ionic conductivity can be studied in chromatophores by analyzing the electrochromic response of endogenous carotenoids, acting as an intramembrane voltmeter at the molecular level. We show that chromatophores represent an in vitro experimental model suitable to probe permeability changes induced in cell membranes by ILs differing in chemical nature, degree of oxygenation of the cationic moiety and counter anion.

  8. Membrane orientation and lateral diffusion of BODIPY-cholesterol as a function of probe structure

    DEFF Research Database (Denmark)

    Solanko, Lukasz Michal; Wüstner, Daniel; Lund, Frederik Wendelboe

    2013-01-01

    -24 of cholesterol (B-P-Chol). Using two-photon fluorescence polarimetry in giant unilamellar vesicles and in the plasma membrane (PM) of living intact and actin-disrupted cells, we show that the BODIPY-groups in B-Chol and B-P-Chol are oriented perpendicular and almost parallel to the bilayer normal...

  9. Interphase Chromosome Conformation and Chromatin-Chromatin Interactions in Human Epithelial Cells Cultured Under Different Gravity Conditions

    Science.gov (United States)

    Zhang, Ye; Wong, Michael; Hada, Megumi; Wu, Honglu

    2015-01-01

    Microgravity has been shown to alter global gene expression patterns and protein levels both in cultured cells and animal models. It has been suggested that the packaging of chromatin fibers in the interphase nucleus is closely related to genome function, and the changes in transcriptional activity are tightly correlated with changes in chromatin folding. This study explores the changes of chromatin conformation and chromatin-chromatin interactions in the simulated microgravity environment, and investigates their correlation to the expression of genes located at different regions of the chromosome. To investigate the folding of chromatin in interphase under various culture conditions, human epithelial cells, fibroblasts, and lymphocytes were fixed in the G1 phase. Interphase chromosomes were hybridized with a multicolor banding in situ hybridization (mBAND) probe for chromosome 3 which distinguishes six regions of the chromosome as separate colors. After images were captured with a laser scanning confocal microscope, the 3-dimensional structure of interphase chromosome 3 was reconstructed at multi-mega base pair scale. In order to determine the effects of microgravity on chromosome conformation and orientation, measures such as distance between homologous pairs, relative orientation of chromosome arms about a shared midpoint, and orientation of arms within individual chromosomes were all considered as potentially impacted by simulated microgravity conditions. The studies revealed non-random folding of chromatin in interphase, and suggested an association of interphase chromatin folding with radiation-induced chromosome aberration hotspots. Interestingly, the distributions of genes with expression changes over chromosome 3 in cells cultured under microgravity environment are apparently clustered on specific loci and chromosomes. This data provides important insights into how mammalian cells respond to microgravity at molecular level.

  10. Use of fluorescent probes to follow membrane traffic in nerve terminals

    Directory of Open Access Journals (Sweden)

    Guatimosim C.

    1998-01-01

    Full Text Available Optical tracers in conjunction with fluorescence microscopy have become widely used to follow the movement of synaptic vesicles in nerve terminals. The present review discusses the use of these optical methods to understand the regulation of exocytosis and endocytosis of synaptic vesicles. The maintenance of neurotransmission depends on the constant recycling of synaptic vesicles and important insights have been gained by visualization of vesicles with the vital dye FM1-43. A number of questions related to the control of recycling of synaptic vesicles by prolonged stimulation and the role of calcium to control membrane internalization are now being addressed. It is expected that optical monitoring of presynaptic activity coupled to appropriate genetic models will contribute to the understanding of membrane traffic in synaptic terminals.

  11. Simultaneous topographic and amperometric membrane mapping using an AFM probe integrated biosensor.

    Science.gov (United States)

    Stanca, Sarmiza Elena; Csaki, Andrea; Urban, Matthias; Nietzsche, Sandor; Biskup, Christoph; Fritzsche, Wolfgang

    2011-02-15

    The investigation of the plasma membrane with intercorrelated multiparameter techniques is a prerequisite for understanding its function. Presented here, is a simultaneous electrochemical and topographic study of the cell membrane using a miniaturized amperometric enzymatic biosensor. The fabrication of this biosensor is also reported. The biosensor combines a scanning force microscopy (AFM) gold-coated cantilever and an enzymatic transducer layer of peroxidases (PODs). When these enzymes are brought in contact with the substrate, the specific redox reaction produces an electric current. The intensity of this current is detected simultaneously with the surface imaging. For sensor characterization, hydroquinone-2-carboxylic acid (HQ) is selected as an intrinsic source of H(2)O(2). HQ has been electrochemically regenerated by the reduction of antraquinone-2-carboxylic acid (AQ). The biosensor reaches the steady state value of the current intensity in 1 ± 0.2s.

  12. Probing Membrane Protein Structure Using Water Polarization Transfer Solid-State NMR

    Science.gov (United States)

    Williams, Jonathan K.; Hong, Mei

    2014-01-01

    Water plays an essential role in the structure and function of proteins, lipid membranes and other biological macromolecules. Solid-state NMR heteronuclear-detected 1H polarization transfer from water to biomolecules is a versatile approach for studying water-protein, water-membrane, and water-carbohydrate interactions in biology. We review radiofrequency pulse sequences for measuring water polarization transfer to biomolecules, the mechanisms of polarization transfer, and the application of this method to various biological systems. Three polarization transfer mechanisms, chemical exchange, spin diffusion and NOE, manifest themselves at different temperatures, magic-angle-spinning frequencies, and pulse irradiations. Chemical exchange is ubiquitous in all systems examined so far, and spin diffusion plays the key role in polarization transfer within the macromolecule. Tightly bound water molecules with long residence times are rare in proteins at ambient temperature. The water polarization-transfer technique has been used to study the hydration of microcrystalline proteins, lipid membranes, and plant cell wall polysaccharides, and to derive atomic-resolution details of the kinetics and mechanism of ion conduction in channels and pumps. Using this approach, we have measured the water polarization transfer to the transmembrane peptide of the influenza M2 protein to obtain information on the structure of this tetrameric proton channel. At short mixing times, the polarization transfer rates are site-specific and depend on the pH, labile protons, sidechain conformation, as well as the radial position of the residues in this four-helix bundle. Despite the multiple dependences, the initial transfer rates reflect the periodic nature of the residue positions from the water-filled pore, thus this technique provides a way of gleaning secondary structure information, helix tilt angle, and the oligomeric structure of membrane proteins. PMID:25228502

  13. Lanthanide recognition: A Ho{sup 3+} potentiometric membrane sensor as a probe for determination of terazosin

    Energy Technology Data Exchange (ETDEWEB)

    Ganjali, Mohammad Reza, E-mail: Ganjali@khayam.ut.ac.ir [Center of Excellence in Electrochemistry, Faculty of Chemistry, Tehran University, Tehran (Iran, Islamic Republic of); Shams, Haniyeh [Department of Chemistry, Islamic Azad University of Shahrerey Branch, Shahrerey (Iran, Islamic Republic of); Faridbod, Farnoush [Center of Excellence in Electrochemistry, Faculty of Chemistry, Tehran University, Tehran (Iran, Islamic Republic of); Hajiaghababaei, Leila [Department of Chemistry, Islamic Azad University of Shahrerey Branch, Shahrerey (Iran, Islamic Republic of); Norouzi, Parviz [Center of Excellence in Electrochemistry, Faculty of Chemistry, Tehran University, Tehran (Iran, Islamic Republic of)

    2009-05-05

    In this study, complexation of N'-(1-pyridin-2-ylmethylene)-2-furohydrazide (NFH) with some metal ions was investigated by conductometry and spectroscopy. Then, a Ho{sup 3+} potentiometric membrane sensor was prepared based on the highly selective complexation between this ionophore and Ho{sup 3+}. These new ionophores are more selective than the previously reported ones. In this work, for the first time, the proposed sensor was applied in indirect determination of the terazocine in its pharmaceutical formulation. The interest in constructing lanthanide sensors arises because they have similar ionic radii to calcium, but a higher charge density, which allows them to be used as probes to find the interactions between Ca{sup 2+} and biologically important molecules.

  14. Intergranular and inter-phased boundaries in the materials; Joints intergranulaires et interphases dans les materiaux

    Energy Technology Data Exchange (ETDEWEB)

    Aslanides, A. [Electricite de France, Dept. CIMA, 77 - Moret sur Loing (France); Backhaus-Ricoult, M. [Centre d' Etudes de Chimie metallurgique, 94 - Vitry-sur-Seine (France); Bayle-Guillemaud, P. [CEA Grenoble, Dept. de Recherche Fondamentale sur la Matiere Condensee, 38 (France)] [and others

    2000-07-01

    This document collects the abstracts of the talks presented during the colloquium J2IM on the intergranular and inter-phased boundaries in the materials. Around the themes of the interfaces behaviour and grain boundaries defects in materials, these days dealt with the microstructure behaviour in many domains such as the interfaces in batteries, the irradiation damages and the special case of the fuel-cladding interactions, the stressed interfaces, the alumina or silicon carbides substrates. (A.L.B.)

  15. Polymer dynamics in nanoconfinement: Interfaces and interphases

    Directory of Open Access Journals (Sweden)

    Krutyeva Margarita

    2015-01-01

    Full Text Available The dynamics of polymers in nanoconfinement was studied by using neutron spectroscopy. A number of pronounced effects on different time and length scales for the polymers confined in nanopores of anodic aluminium oxide were observed. Local segmental dynamics was found to be dependent on the type of the interaction between the solid pore wall and polymer: attractive interactions lead to the formation of a surface layer with the dynamics slowed down as compared to the dynamics of pure polymer; neutral/repulsive interaction do not change the local dynamics. Attractive interactions cause anchoring of polymer segments on the surface creating an interphase between the polymer in close vicinity to the solid surface and pure polymer. In addition, at strong confinement conditions the dilution of the entanglement network is observed.

  16. Probing the potential of apigenin liposomes in enhancing bacterial membrane perturbation and integrity loss.

    Science.gov (United States)

    Banerjee, Kacoli; Banerjee, Shubhadeep; Das, Subhayan; Mandal, Mahitosh

    2015-09-01

    Along with discovery of new antibacterial agents, it is important to develop novel drug delivery systems to effectively deliver drugs within bacterial cells for enhanced therapeutic activity. Liposomes have been extensively investigated as pharmaceutical carriers for improvement of therapeutic index of antimicrobial agents. The aim of this present study was to evaluate the antibacterial activity of free and liposomal formulation of apigenin, a plant based isoflavone and elucidate the mode of action. Distearoylphosphatidylcholine liposomes were prepared having nano-range particle size (104.3±1.8 nm), narrow particle distribution (0.204) and high encapsulation efficiency of apigenin (89.9±2.31%). Antibacterial activity of apigenin and efficacy of liposome-mediated apigenin delivery were determined from minimum inhibitory concentration values. Interaction studies using electron microscopy revealed adherence and fusion of liposomal apigenin with the bacteria causing membrane perturbation through reactive oxygen species generation which was evaluated by epi-fluorescence microscopy and fluorescence activated cell sorting. The interaction of apigenin liposomes with bacterial membrane increased intracellular drug concentration and thus, can be employed to deliver apigenin within cells to augment its antibacterial activity. Increased efficacy and hemocompatibility of this formulation paves way for future evaluation of underlying molecular mechanisms and in vivo testing for enhanced therapeutic effects.

  17. Probe Into the Influence of Crosslinking on CO2 Permeation of Membranes

    Science.gov (United States)

    Li, Jinghui; Chen, Zhuo; Umar, Ahmad; Liu, Yang; Shang, Ying; Zhang, Xiaokai; Wang, Yao

    2017-01-01

    Crosslinking is an effective way to fabricate high-selective CO2 separation membranes because of its unique crosslinking framework. Thus, it is essentially significant to study the influence of crosslinking degree on the permeation selectivities of CO2. Herein, we report a successful and facile synthesis of a series of polyethylene oxide (PEO)-based diblock copolymers (BCP) incorporated with an unique UV-crosslinkable chalcone unit using Reversible Addition-Fragmentation Chain Transfer Polymerization (RAFT) process. The membranes of as-prepared BCPs show superior carbon dioxide (CO2) separation properties as compared to nitrogen (N2) after UV-crosslinking. Importantly, the influence of different proportions of crosslinked chalcone on CO2 selectivities was systematically investigated, which revealed that CO2 selectivities increased obviously with the enhancement of chalcone fractions within a certain limit. Further, the CO2 selectivities of block copolymer with the best block proportion was studied by varying the crosslinking time which confirmed that the high crosslinking degree exhibited a better CO2/N2 (αCO2/N2) selectivities. A possible mechanism model revealing that the crosslinking degree played a key role in the gas separation process was also proposed. PMID:28051190

  18. Structure–performance characterization for carbon molecular sieve membranes using molecular scale gas probes

    KAUST Repository

    Rungta, Meha

    2015-04-01

    © 2015 Elsevier Ltd. All rights reserved. Understanding the relationship between carbon molecular sieve (CMS) pore structure and corresponding gas separation performance enables optimization for a given gas separation application. The final pyrolysis temperature and starting polymer precursor are the two critical parameters in controlling CMS performance. This study considers structure and performance changes of CMS derived from a commercially available polymer precursor at different pyrolysis temperatures. As reviewed in this paper, most traditional characterization methods based on microscopy, X-ray diffraction, spectroscopy, sorption-based pore size distribution measurements etc. provide limited information for relating separation performance to the CMS morphology and structural changes. A useful alternative approach based on different sized gases as molecular scale probes of the CMS pore structure was successfully used here in conjunction with separation data to provide critical insights into the structure-performance relationships of the engineered CMS.

  19. Atomic force microscopy and spectroscopy to probe single membrane proteins in lipid bilayers.

    Science.gov (United States)

    Sapra, K Tanuj

    2013-01-01

    The atomic force microscope (AFM) has opened vast avenues hitherto inaccessible to the biological scientist. The high temporal (millisecond) and spatial (nanometer) resolutions of the AFM are suited for studying many biological processes in their native conditions. The AFM cantilever stylus is aptly termed as a "lab on a tip" owing to its versatility as an imaging tool as well as a handle to manipulate single bonds and proteins. Recent examples assert that the AFM can be used to study the mechanical properties and monitor processes of single proteins and single cells, thus affording insight into important mechanistic details. This chapter specifically focuses on practical and analytical protocols of single-molecule AFM methodologies related to high-resolution imaging and single-molecule force spectroscopy of membrane proteins. Both these techniques are operator oriented, and require specialized working knowledge of the instrument, theoretical, and practical skills.

  20. Membraner

    DEFF Research Database (Denmark)

    Bach, Finn

    2009-01-01

    Notatet giver en kort introduktion til den statiske virkemåde af membraner og membrankonstruktioner......Notatet giver en kort introduktion til den statiske virkemåde af membraner og membrankonstruktioner...

  1. Effects of oxygen on EPR spectra of nitroxide spin-label probes of model membranes

    Science.gov (United States)

    Popp, Carol A.; Hyde, James S.

    The use of a methylpentene polymer, TPX, for construction of sample containers that allow easy equilibration of electron paramagnetic resonance samples with nitrogen is described. The effects of oxygen-dependent shortening of the electron spin relaxation times of nitroxide spin labels were studied in dispersions of dimyristoylphosphatidylcholine (DMPC) and dipalmitoylphosphatidylchohne (DPPC). First-harmonic, in-phase, absorption spectra of deoxygenated samples of 2-(14-carboxytetradecyl)-2-ethyl-4,4-dimethyl-3-oxazolidinyloxyl (16SASL) in DMPC display decreased linewidths and increased peak-to-peak heigths and resolution of 13C splittings. Continuous-wave (cw) saturation studies of 16SASL/DMPC and both lipid- and aqueous-phase components of 2,2,6,6-tetramethyl-piperidinooxyl (Tempo) partitioned into DPPC show that the rf field at which the signal intensity is maximized decreases when aerated samples are equilibrated with nitrogen. Second-harmonic, out-of-phase, absorption (saturation transfer) spectra of deoxygenated samples of 16SASUDMPC at -22°C and 2-(3-carboxypropyl)-4,4-dimethyl-2-tridecyl-3-oxazolidinyloxyl (5SASL) in DPPC at 35°C display increased signal intensity and lineshape changes. Electron-electron double resonance (ELDOR) spectra display much greater ELDOR reduction in signal intensity when a deoxygenated sample of 16SASL/DMPC is used. Our results indicate that the routine use of deoxygenated samples in biologically relevant studies using spin-label probes should be considered.

  2. Nanosqueezed light for probing mitochondria and calcium-induced membrane swelling for study of neuroprotectants

    Science.gov (United States)

    Gourley, Paul L.; Chen, P.; Copeland, R. G.; Hendricks, Judy K.; McDonald, Anthony E.; Keep, M. E.; Karlsson, J. R.

    2004-01-01

    We report a new bioMEMs nanolaser technique for measuring characteristics of small organelles. We have initially applied the method to study mitochondria, a very small (500nm to 1um) organelle containing the respiration apparatus for animal cells. Because the mitochondria are so tiny, it has been difficult to study them using standard light microscope or flow cytometry techniques. We employ a recently discovered a nano-optical transduction method for high-speed analysis of submicron organelles. This ultrasensitive detection of submicron particles uses nano-squeezing of light into photon modes imposed by the ultrasmall organelle dimensions in a submicron laser cavity. In this paper, we report measurements of mitochondria spectra under normal conditions and under high calcium ion gradient conditions that upset membrane homeostasis and lead to organelle swelling and lysis, similar to that observed in the diseased state. The measured spectra are compared with our calculations of the electromagnetic modes in normal and distended mitochondria using multiphysics finite element methods.

  3. A miniature condensed-phase membrane introduction mass spectrometry (CP-MIMS) probe for direct and on-line measurements of pharmaceuticals and contaminants in small, complex samples.

    Science.gov (United States)

    Duncan, Kyle D; Willis, Megan D; Krogh, Erik T; Gill, Christopher G

    2013-06-15

    High-throughput, automated analytical measurements are desirable in many analytical scenarios, as are rapid sample pre-screening techniques to identify 'positive' samples for subsequent measurements using more time-consuming conventional methodologies (e.g., liquid chromatography/mass spectrometry (LC/MS)). A miniature condensed-phase membrane introduction mass spectrometry (CP-MIMS) probe for the direct and continuous, on-line measurement of pharmaceuticals and environmental contaminants in small, complex samples is presented. A miniature polydimethylsiloxane hollow fibre membrane (PDMS-HFM) probe is coupled with an electrospray ionization (ESI) triple quadrupole mass spectrometer. Analytes are transported from the probe to the ESI source by a methanol acceptor phase. The probe can be autosampler mounted and directly inserted in small samples (≥400 μL) allowing continuous and simultaneous pptr-ppb level detection of target analytes (chlorophenols, triclosan, gemfibrozil, nonylphenol) in complex samples (artificial urine, beer, natural water, waste water, plant tissue). The probe has been characterized and optimized for acceptor phase flow rate, sample mixing and probe washing. Signal response times, detection limits and calibration data are given for selected ion monitoring (SIM) and tandem mass spectrometry (MS/MS) measurements of target analytes at trace levels. Comparisons with flow cell type CP-MIMS systems are given. Analyte depletion effects are evaluated for small samples (≥400 μL). On-line measurements in small volumes of complex samples, temporally resolved reaction monitoring and in situ/in vivo demonstrations are presented. The miniature CP-MIMS probe developed was successfully used for the direct, on-line detection of target analytes in small volumes (40 mL to 400 μL) of complex samples at pptr to low ppb levels. The probe can be readily automated as well as deployed for in situ/in vivo monitoring, including reaction monitoring, small sample

  4. Expression-dependent folding of interphase chromatin.

    Directory of Open Access Journals (Sweden)

    Hansjoerg Jerabek

    Full Text Available Multiple studies suggest that chromatin looping might play a crucial role in organizing eukaryotic genomes. To investigate the interplay between the conformation of interphase chromatin and its transcriptional activity, we include information from gene expression profiles into a polymer model for chromatin that incorporates genomic loops. By relating loop formation to transcriptional activity, we are able to generate chromosome conformations whose structural and topological properties are consistent with experimental data. The model particularly allows to reproduce the conformational variations that are known to occur between highly and lowly expressed chromatin regions. As previously observed in experiments, lowly expressed regions of the simulated polymers are much more compact. Due to the changes in loop formation, the distributions of chromatin loops are also expression-dependent and exhibit a steeper decay in highly active regions. As a results of entropic interaction between differently looped parts of the chromosome, we observe topological alterations leading to a preferential positioning of highly transcribed loci closer to the surface of the chromosome territory. Considering the diffusional behavior of the chromatin fibre, the simulations furthermore show that the higher the expression level of specific parts of the chromatin fibre is, the more dynamic they are. The results exhibit that variations of loop formation along the chromatin fibre, and the entropic changes that come along with it, do not only influence the structural parameters on the local scale, but also effect the global chromosome conformation and topology.

  5. Dominant microbial composition and its vertical distribution in saline meromictic Lake Kaiike (Japan) as revealed by quantitative oligonucleotide probe membrane hybridization.

    Science.gov (United States)

    Koizumi, Yoshikazu; Kojima, Hisaya; Fukui, Manabu

    2004-08-01

    Vertical distributions of dominant bacterial populations in saline meromictic Lake Kaiike were investigated throughout the water column and sediment by quantitative oligonucleotide probe membrane hybridization. Three oligonucleotide probes specific for the small-subunit (SSU) rRNA of three groups of Chlorobiaceae were newly designed. In addition, three general domain (Bacteria, Archaea, and Eukarya)-specific probes, two delta-Proteobacteria-specific probes, a Chlorobiaceae-specific probe, and a Chloroflexi-specific probe were used after optimization of their washing conditions. The abundance of the sum of SSU rRNAs hybridizing with probes specific for three groups of Chlorobiaceae relative to total SSU rRNA peaked in the chemocline, accounting for up to 68%. The abundance of the delta-proteobacterial SSU rRNA relative to total SSU rRNA rapidly increased just below the chemocline up to 29% in anoxic water and peaked at the 2- to 3-cm sediment depth at ca. 34%. The abundance of SSU rRNAs hybridizing with the probe specific for the phylum Chloroflexi relative to total SSU rRNA was highest (31 to 54%) in the top of the sediment but then steeply declined with depth and became stable at 11 to 19%, indicating the robust coexistence of sulfate-reducing bacteria and Chloroflexi in the top of the sediment. Any SSU rRNA of Chloroflexi in the water column was under the detection limit. The summation of the signals of group-specific probes used in this study accounted for up to 89% of total SSU rRNA, suggesting that the DGGE-oligonucleotide probe hybridization approach, in contrast to conventional culture-dependent approaches, was very effective in covering dominant populations.

  6. Probing membrane protein interactions with their lipid raft environment using single-molecule tracking and Bayesian inference analysis.

    Directory of Open Access Journals (Sweden)

    Silvan Türkcan

    Full Text Available The statistical properties of membrane protein random walks reveal information on the interactions between the proteins and their environments. These interactions can be included in an overdamped Langevin equation framework where they are injected in either or both the friction field and the potential field. Using a Bayesian inference scheme, both the friction and potential fields acting on the ε-toxin receptor in its lipid raft have been measured. Two types of events were used to probe these interactions. First, active events, the removal of cholesterol and sphingolipid molecules, were used to measure the time evolution of confining potentials and diffusion fields. Second, passive rare events, de-confinement of the receptors from one raft and transition to an adjacent one, were used to measure hopping energies. Lipid interactions with the ε-toxin receptor are found to be an essential source of confinement. ε-toxin receptor confinement is due to both the friction and potential field induced by cholesterol and sphingolipids. Finally, the statistics of hopping energies reveal sub-structures of potentials in the rafts, characterized by small hopping energies, and the difference of solubilization energy between the inner and outer raft area, characterized by higher hopping energies.

  7. Early-Stage Aggregation of Islet Amyloid Polypeptide on Membrane Surfaces Probed by Label-Free Chiral Sum Frequency Generation Spectroscopy

    Science.gov (United States)

    Wang, Zhuguang; Fu, Li; Yan, Elsa

    2013-03-01

    The aggregation of human islet amyloid polypeptide (hIAPP) into fibrils is associated with type II diabetes. It can be catalyzed by interactions with membranes. Recent studies have shown that cytotoxicity arises from the intermediates of aggregation instead of mature fibrils. However, the pathogenic mechanism is still unknown and it remains challenging to probe structures of the intermediates on membrane surfaces due to a lack of biophysical methods that are sensitive to both protein secondary structures and interfaces. Here, we used label-free chiral sum frequency generation spectroscopy (cSFG) to probe the intermediates. Recently, we have discovered cSFG provides highly specific peptide vibrational signatures that can distinguish protein secondary structures at interfaces. Using cSFG, we observed in situ and in real time the aggregation of hIAPP from disordered structures to α-helices and then β-sheets on membrane surfaces. We also obtained the orientation of the β-sheet aggregates inserted into the membranes. We further studied the S20G mutant, which is linked to the early onset of type II diabetes among Asian populations. We compared the mutant with the wild-type hIAPP to evaluate the effect of S20G in the early-stage aggregation on membrane surfaces.

  8. Probing of the combined effect of bisquaternary ammonium antimicrobial agents and acetylsalicylic acid on model phospholipid membranes: differential scanning calorimetry and mass spectrometry studies.

    Science.gov (United States)

    Kasian, N A; Pashynska, V A; Vashchenko, O V; Krasnikova, A O; Gömöry, A; Kosevich, M V; Lisetski, L N

    2014-12-01

    A model molecular biosystem of hydrated dipalmitoylphosphatidylcholine (DPPC) bilayers that mimics cell biomembranes is used to probe combined membranotropic effects of drugs by instrumental techniques of molecular biophysics. Differential scanning calorimetry reveals that doping of the DPPC model membrane with individual bisquaternary ammonium compounds (BQAC) decamethoxinum, ethonium, thionium and acetylsalicylic acid (ASA) leads to lowering of the membrane melting temperature (Tm) pointing to membrane fluidization. Combined application of the basic BQAC and acidic ASA causes an opposite effect on Tm (increase), corresponding to the membrane densification. Thus, modulation of the membranotropic effects upon combined use of the drugs studied can be revealed at the level of model membranes. Formation of noncovalent supramolecular complexes of the individual BQACs and ASA with DPPC molecules, which may be involved in the mechanism of the drug-membrane interaction at the molecular level, is demonstrated by electrospray ionization (ESI) mass spectrometry. In the ternary (DPPC + ASA + BQAC) model systems, the stable complexes of the BQAC dication with the ASA anion, which may be responsible for modulation of the membranotropic effects of the drugs, were recorded by ESI mass spectrometry. The proposed approach can be further developed for preliminary evaluation of the combined effects of the drugs at the level of model lipid membranes prior to tests on living organisms.

  9. Increased binding of a hydrophobic, photolabile probe to Escherichia coli inversely correlates to membrane potential but not adenosine 5'-triphosphate levels.

    Science.gov (United States)

    Wolf, M K; Konisky, J

    1981-01-01

    We describe conditions for a quantitative determination of azidopyrene binding to Escherichia coli cells. In addition, we define conditions whereby irradiation of azidopyrene in the presence of cells leads to irreversible association of probe with cells. This is presumably due to the light-dependent generation of reactive nitrenes and subsequent incorporation of nitrenopyrene moieties into cellular components. These methods allowed us to determine that the amount of azidopyrene bound to cells was inversely correlated with the magnitude of the cellular membrane potential, but was not correlated with high or low adenosine 5-triphosphate levels per se. Cells bound more azidopyrene if the delta psi was low. Cell-bound azidopyrene was found to be entirely associated with the inner and outer membrane. We suggest that the decreased association of hydrophobic probes upon energization of whole cells reflects a rapid transition in structural properties of the cell envelope. PMID:7007317

  10. Impact of humic acids on EYL liposome membranes: ESR method

    Directory of Open Access Journals (Sweden)

    Pytel Barbara

    2015-07-01

    Full Text Available In this paper, the effects of model (commercial and natural (extracted from peat humic substances on the membrane of liposomes formed with egg yolk lecithin (EYL are presented. In our research, mass concentrations of fulvic and humic acids were used, which in relation to lecithin varied from 0% to 13%. To study membrane fluidity, electron spin resonance (EPR was used with two spin probes, penetrating various regions of the lipid bilayer. The effects of model and natural humic substances (humic acids – HAs and fulvic acids – FAs on the lipid membrane in different regions were researched: the lipid-water interphase, and in the middle of the lipid bilayer. It was shown that FA and HA impact the fluidity of liposome membranes in different ways. Increased mass concentrations of HAs decreased membrane fluidity in both acids: extracted from peat and the model. However, increased mass concentration of FAs extracted from peat, decreased membrane fluidity in the surface region, at the same time stiffening the central part of the bilayer. Increasing the concentration of FAs extracted from peat had the opposite effect when compared to model FA. This effect may be related to the complexation of xenobiotics present in the soil environment and their impact on biological membranes.

  11. Growth of the Mammalian Golgi Apparatus during Interphase.

    Science.gov (United States)

    Sin, Alex T-W; Harrison, Rene E

    2016-09-15

    During the cell cycle, genetic materials and organelles are duplicated to ensure that there is sufficient cellular content for daughter cells. While Golgi growth in interphase has been observed in lower eukaryotes, the elaborate ribbon structure of the mammalian Golgi apparatus has made it challenging to monitor. Here we demonstrate the growth of the mammalian Golgi apparatus in its protein content and volume during interphase. Through ultrastructural analyses, physical growth of the Golgi apparatus was revealed to occur by cisternal elongation of the individual Golgi stacks. By examining the timing and regulation of Golgi growth, we established that Golgi growth starts after passage through the cell growth checkpoint at late G1 phase and continues in a manner highly correlated with cell size growth. Finally, by identifying S6 kinase 1 as a major player in Golgi growth, we revealed the coordination between cell size and Golgi growth via activation of the protein synthesis machinery in early interphase.

  12. Nuclear reprogramming by interphase cytoplasm of 2-cell mouse embryos

    Science.gov (United States)

    Kang, Enugu; Wu, Guangming; Ma, Hong; Li, Ying; Tippner-Hedges, Rebecca; Tachibana, Masahito; Sparman, Michelle; Wolf, Don P.; Schöler, Hans; Mitalipov, Shoukhrat

    2014-01-01

    Summary Successful mammalian cloning employing somatic cell nuclear transfer (SCNT) into unfertilized, metaphase II-arrested (MII) oocytes attests to the cytoplasmic presence of reprogramming factors capable of inducing pluripotency in somatic cell nuclei1-3. However, these poorly defined maternal factors presumably decline sharply after fertilization since cytoplasm of pronuclear stage zygotes is reportedly inactive4, 5. Recent evidence suggests that zygotic cytoplasm, if maintained at metaphase (M-phase) can also support derivation of embryonic stem cells (ESCs) following SCNT6-8, albeit at low efficiency. This led to the conclusion that critical oocyte reprogramming factors present in M-phase but not in interphase cytoplasm are “trapped” inside the nucleus during interphase and effectively removed during enucleation9. Here, we investigated the presence of reprogramming activity in the interphase cytoplasm of 2-cell mouse embryos (I2C). First, the presence of candidate reprogramming factors was documented in both intact and enucleated M-phase and interphase zygotes and 2-cell embryos. Consequently, enucleation did not provide a likely explanation for the inability of interphase cytoplasm to induce reprogramming. Then, when we carefully synchronized the cell cycle stage between the transplanted nucleus (ESC, fetal fibroblast or terminally differentiated cumulus cell) and the recipient I2C cytoplasm, the reconstructed SCNT embryos developed into blastocysts and ESCs capable of contributing to traditional germline and tetraploid chimeras. In addition, direct transfer of cloned embryos, reconstructed with ESC nuclei, into recipients resulted in live offspring. Thus, the cytoplasm of I2C supports efficient reprogramming with cell cycle synchronization between the donor nucleus and recipient cytoplasm as the most critical parameter determining success. The ability to utilize interphase cytoplasm in SCNT could impact efforts to generate autologous human ESCs for

  13. Human interphase chromosomes: a review of available molecular cytogenetic technologies

    Directory of Open Access Journals (Sweden)

    Yurov Yuri B

    2010-01-01

    Full Text Available Abstract Human karyotype is usually studied by classical cytogenetic (banding techniques. To perform it, one has to obtain metaphase chromosomes of mitotic cells. This leads to the impossibility of analyzing all the cell types, to moderate cell scoring, and to the extrapolation of cytogenetic data retrieved from a couple of tens of mitotic cells to the whole organism, suggesting that all the remaining cells possess these genomes. However, this is far from being the case inasmuch as chromosome abnormalities can occur in any cell along ontogeny. Since somatic cells of eukaryotes are more likely to be in interphase, the solution of the problem concerning studying postmitotic cells and larger cell populations is interphase cytogenetics, which has become more or less applicable for specific biomedical tasks due to achievements in molecular cytogenetics (i.e. developments of fluorescence in situ hybridization -- FISH, and multicolor banding -- MCB. Numerous interphase molecular cytogenetic approaches are restricted to studying specific genomic loci (regions being, however, useful for identification of chromosome abnormalities (aneuploidy, polyploidy, deletions, inversions, duplications, translocations. Moreover, these techniques are the unique possibility to establish biological role and patterns of nuclear genome organization at suprachromosomal level in a given cell. Here, it is to note that this issue is incompletely worked out due to technical limitations. Nonetheless, a number of state-of-the-art molecular cytogenetic techniques (i.e multicolor interphase FISH or interpahase chromosome-specific MCB allow visualization of interphase chromosomes in their integrity at molecular resolutions. Thus, regardless numerous difficulties encountered during studying human interphase chromosomes, molecular cytogenetics does provide for high-resolution single-cell analysis of genome organization, structure and behavior at all stages of cell cycle.

  14. Using spectral decomposition of the signals from laurdan-derived probes to evaluate the physical state of membranes in live cells [version 2; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Serge Mazeres

    2017-08-01

    Full Text Available Background: We wanted to investigate the physical state of biological membranes in live cells under the most physiological conditions possible. Methods: For this we have been using laurdan, C-laurdan or M-laurdan to label a variety of cells, and a biphoton microscope equipped with both a thermostatic chamber and a spectral analyser. We also used a flow cytometer to quantify the 450/530 nm ratio of fluorescence emissions by whole cells. Results: We find that using all the information provided by spectral analysis to perform spectral decomposition dramatically improves the imaging resolution compared to using just two channels, as commonly used to calculate generalized polarisation (GP. Coupled to a new plugin called Fraction Mapper, developed to represent the fraction of light intensity in the first component in a stack of two images, we obtain very clear pictures of both the intra-cellular distribution of the probes, and the polarity of the cellular environments where the lipid probes are localised. Our results lead us to conclude that, in live cells kept at 37°C, laurdan, and M-laurdan to a lesser extent, have a strong tendency to accumulate in the very apolar environment of intra-cytoplasmic lipid droplets, but label the plasma membrane (PM of mammalian cells ineffectively. On the other hand, C-laurdan labels the PM very quickly and effectively, and does not detectably accumulate in lipid droplets. Conclusions: From using these probes on a variety of mammalian cell lines, as well as on cells from Drosophila and Dictyostelium discoideum, we conclude that, apart from the lipid droplets, which are very apolar, probes in intracellular membranes reveal a relatively polar and hydrated environment, suggesting a very marked dominance of liquid disordered states. PMs, on the other hand, are much more apolar, suggesting a strong dominance of liquid ordered state, which fits with their high sterol contents.

  15. Sexing the human fetus and identification of polyploid nuclei by DNA-DNA in situ hybridisation in interphase nuclei.

    Science.gov (United States)

    West, J D; Gosden, C M; Gosden, J R; West, K M; Davidson, Z; Davidson, C; Nicolaides, K H

    1989-01-01

    Samples of human adult lymphocytes, fetal lymphocytes, amniotic fluid cells, and chorionic villus cells were sexed independently by cytogenetics and DNA-DNA in situ hybridisation to a tritiated Y probe. For the in situ hybridisation analysis, the presence of Y bodies (hybridisation bodies) in 100 interphase nuclei were scored after autoradiography. In all, 82/83 samples were sexed in this way (one technical failure) and 78/82 were sexed by both in situ hybridisation and cytogenetics. There was complete agreement between the two methods. There was a considerable variation (40-100%) in the percentage of interphase nuclei with a hybridisation body among the male samples, but very few nuclei from female samples showed significant hybridisation. In situ hybridisation could be used to sex the conceptus when males but not females are at risk for various X-linked genetic disorders and may also be useful for detecting 45,X/46,XY mosaicism or polyploid/diploid mosaicism. This would be particularly useful for direct preparations of chorionic villus samples, which often prove difficult to analyse cytogenetically but offer the best means of avoiding maternal contamination. Some interphase nuclei had more than one hybridisation body, and this was most commonly found among amniotic fluid cells. Comparison of sizes of nuclei with one or two hybridisation bodies strongly suggested that most of the amniotic fluid cell nuclei with two hybridisation bodies were tetraploid.

  16. Detection of beta-tubulin in the cytoplasm of the interphasic Entamoeba histolytica trophozoites.

    Science.gov (United States)

    Gómez-Conde, Eduardo; Vargas-Mejía, Miguel Ángel; Díaz-Orea, María Alicia; Hernández-Rivas, Rosaura; Cárdenas-Perea, María Elena; Guerrero-González, Tayde; González-Barrios, Juan Antonio; Montiel-Jarquín, Álvaro José

    2016-08-01

    It is known that the microtubules (MT) of Entamoeba histolytica trophozoites form an intranuclear mitotic spindle. However, electron microscopy studies and the employment of anti-beta-tubulin (β-tubulin) antibodies have not exhibited these cytoskeletal structures in the cytoplasm of these parasites. The purpose of this work was to detect β-tubulin in the cytoplasm of interphasic E. histolytica trophozoites. Activated or non-activated HMI-IMSS-strain E. histolytica trophozoites were used and cultured for 72 h at 37 °C in TYI-S-33 medium, and then these were incubated with the anti-β-tubulin antibody of E. histolytica. The anti-β-tubulin antibody reacted with the intranuclear mitotic spindle of E. histolytica-activated trophozoites as control. In contrast, in non-activated interphasic parasites, anti-β-tubulin antibody reacted with diverse puntiform structures in the cytoplasm and with ring-shaped structures localized in the cytoplasm, cellular membrane and endocytic stomas. In this work, for the first time, the presence of β-tubulin is shown in the cytoplasm of E. histolytica trophozoites.

  17. Cell-fusion method to visualize interphase nuclear pore formation.

    Science.gov (United States)

    Maeshima, Kazuhiro; Funakoshi, Tomoko; Imamoto, Naoko

    2014-01-01

    In eukaryotic cells, the nucleus is a complex and sophisticated organelle that organizes genomic DNA to support essential cellular functions. The nuclear surface contains many nuclear pore complexes (NPCs), channels for macromolecular transport between the cytoplasm and nucleus. It is well known that the number of NPCs almost doubles during interphase in cycling cells. However, the mechanism of NPC formation is poorly understood, presumably because a practical system for analysis does not exist. The most difficult obstacle in the visualization of interphase NPC formation is that NPCs already exist after nuclear envelope formation, and these existing NPCs interfere with the observation of nascent NPCs. To overcome this obstacle, we developed a novel system using the cell-fusion technique (heterokaryon method), previously also used to analyze the shuttling of macromolecules between the cytoplasm and the nucleus, to visualize the newly synthesized interphase NPCs. In addition, we used a photobleaching approach that validated the cell-fusion method. We recently used these methods to demonstrate the role of cyclin-dependent protein kinases and of Pom121 in interphase NPC formation in cycling human cells. Here, we describe the details of the cell-fusion approach and compare the system with other NPC formation visualization methods.

  18. Flow-alignment of bicellar lipid mixtures: orientations of probe molecules and membrane-associated biomacromolecules in lipid membranes studied with polarized light

    KAUST Repository

    Kogan, Maxim

    2011-01-01

    Bicelles are excellent membrane-mimicking hosts for a dynamic and structural study of solutes with NMR, but the magnetic fields required for their alignment are hard to apply to optical conditions. Here we demonstrate that bicellar mixtures can be aligned by shear forces in a Couette flow cell, to provide orientation of membrane-bound retinoic acid, pyrene and cytochrome c (cyt c) protein, conveniently studied with linear dichroism spectroscopy. © 2011 The Royal Society of Chemistry.

  19. Peptide-membrane interactions of arginine-tryptophan peptides probed using quartz crystal microbalance with dissipation monitoring.

    Science.gov (United States)

    Rydberg, Hanna A; Kunze, Angelika; Carlsson, Nils; Altgärde, Noomi; Svedhem, Sofia; Nordén, Bengt

    2014-07-01

    Membrane-active peptides include peptides that can cross cellular membranes and deliver macromolecular cargo as well as peptides that inhibit bacterial growth. Some of these peptides can act as both transporters and antibacterial agents. It is desirable to combine the knowledge from these two different fields of membrane-active peptides into design of new peptides with tailored actions, as transporters of cargo or as antibacterial substances, targeting specific membranes. We have previously shown that the position of the amino acid tryptophan in the peptide sequence of three arginine-tryptophan peptides affects their uptake and intracellular localization in live mammalian cells, as well as their ability to inhibit bacterial growth. Here, we use quartz crystal microbalance with dissipation monitoring to assess the induced changes caused by binding of the three peptides to supported model membranes composed of POPC, POPC/POPG, POPC/POPG/cholesterol or POPC/lactosyl PE. Our results indicate that the tryptophan position in the peptide sequence affects the way these peptides interact with the different model membranes and that the presence of cholesterol in particular seems to affect the membrane interaction of the peptide with an even distribution of tryptophans in the peptide sequence. These results give mechanistic insight into the function of these peptides and may aid in the design of membrane-active peptides with specified cellular targets and actions.

  20. Peptide-membrane interactions of arginine-tryptophan peptides probed using quartz crystal microbalance with dissipation monitoring.

    KAUST Repository

    Rydberg, Hanna A

    2014-04-18

    Membrane-active peptides include peptides that can cross cellular membranes and deliver macromolecular cargo as well as peptides that inhibit bacterial growth. Some of these peptides can act as both transporters and antibacterial agents. It is desirable to combine the knowledge from these two different fields of membrane-active peptides into design of new peptides with tailored actions, as transporters of cargo or as antibacterial substances, targeting specific membranes. We have previously shown that the position of the amino acid tryptophan in the peptide sequence of three arginine-tryptophan peptides affects their uptake and intracellular localization in live mammalian cells, as well as their ability to inhibit bacterial growth. Here, we use quartz crystal microbalance with dissipation monitoring to assess the induced changes caused by binding of the three peptides to supported model membranes composed of POPC, POPC/POPG, POPC/POPG/cholesterol or POPC/lactosyl PE. Our results indicate that the tryptophan position in the peptide sequence affects the way these peptides interact with the different model membranes and that the presence of cholesterol in particular seems to affect the membrane interaction of the peptide with an even distribution of tryptophans in the peptide sequence. These results give mechanistic insight into the function of these peptides and may aid in the design of membrane-active peptides with specified cellular targets and actions.

  1. Detection of Listeria monocytogenes by direct colony hybridization on hydrophobic grid-membrane filters by using a chromogen-labeled DNA probe.

    Science.gov (United States)

    Peterkin, P I; Idziak, E S; Sharpe, A N

    1991-02-01

    A DNA probe specific for Listeria monocytogenes was isolated from a beta-hemolytic recombinant clone of an L. monocytogenes gene bank. It was labeled with horseradish peroxidase and used in a direct colony hybridization method on hydrophobic grid-membrane filters for the detection of the organism. Following color development of the chromogen, a commercial counter (HGMF Interpreter) was able to detect and count the organisms electronically. The method gave a positive reaction with 70 L. monocytogenes strains, while showing a negative reaction with 10 strains of other Listeria spp. and with 20 organisms of other genera.

  2. Computer Simulation of the Interphase Boundary Evolution in Ni75AlxV25-x Alloy

    Institute of Scientific and Technical Information of China (English)

    Yongsheng LI; Zheng CHEN; Yanli LU; Yongxin WANG

    2005-01-01

    The interphase boundary evolution of ordered phase in Ni75AlxV25-x alloy during precipitation was simulated on atomic-scale based on the microscopic phase-field dynamic model. The results show that the second phase precipitated from the interphase boundary formed by the first phase and the disordered matrix at high temperature, and from the interphase boundaries of the first phase at low temperature. L12 phase had obvious selective orientation when precipitated from the interphase boundaries of D022. L12 phase nucleated easily at the interphase boundaries formed by [10] and [01] directions of D022 projection along [001] direction, and grew easily at [10] direction. There was no the selective orientation when L12 phase precipitated from the interphase boundary formed by D022 and the disordered matrix. D022 phase had the selective orientation when precipitated from the interphase boundaries of L12, and grew along the [10] direction.

  3. Giant Electric-Field-Induced Strain in PVDF-Based Battery Separator Membranes Probed by Electrochemical Strain Microscopy.

    Science.gov (United States)

    Romanyuk, Konstantin; Costa, Carlos M; Luchkin, Sergey Yu; Kholkin, Andrei L; Lanceros-Méndez, Senentxu

    2016-05-31

    Efficiency of lithium-ion batteries largely relies on the performance of battery separator membrane as it controls the mobility and concentration of Li-ions between the anode and cathode electrodes. Recent advances in electrochemical strain microscopy (ESM) prompted the study of Li diffusion and transport at the nanoscale via electromechanical strain developed under an application of inhomogeneous electric field applied via the sharp ESM tip. In this work, we observed unexpectedly high electromechanical strain developed in polymer membranes based on porous poly(vinylidene fluoride) (PVDF) and poly(vinylidene fluoride-co-chlorotrifluoroethylene) (PVDF-CTFE) and, using it, could study a dynamics of electroosmotic flow of electrolyte inside the pores. We show that, independently of the separator membrane, electric field-induced deformation observed by ESM on wetted membrane surfaces can reach up to 10 nm under a moderate bias of 1 V (i.e., more than an order of magnitude higher than that in best piezoceramics). Such a high strain is explained by the electroosmotic flow in a porous media composed of PVDF. It is shown that the strain-based ESM method can be used to extract valuable information such as average pore size, porosity, elasticity of membrane in electrolyte solvent, and membrane-electrolyte affinity expressed in terms of zeta potential. Besides, such systems can, in principle, serve as actuators even in the absence of apparent piezoelectricity in amorphous PVDF.

  4. Composite sensor membrane

    Science.gov (United States)

    Majumdar, Arun; Satyanarayana, Srinath; Yue, Min

    2008-03-18

    A sensor may include a membrane to deflect in response to a change in surface stress, where a layer on the membrane is to couple one or more probe molecules with the membrane. The membrane may deflect when a target molecule reacts with one or more probe molecules.

  5. Microscopic Chain Motion in Polymer Nanocomposites with Dynamically Asymmetric Interphases

    Science.gov (United States)

    Senses, Erkan; Faraone, Antonio; Akcora, Pinar

    2016-01-01

    Dynamics of the interphase region between matrix and bound polymers on nanoparticles is important to understand the macroscopic rheological properties of nanocomposites. Here, we present neutron scattering investigations on nanocomposites with dynamically asymmetric interphases formed by a high-glass transition temperature polymer, poly(methyl methacrylate), adsorbed on nanoparticles and a low-glass transition temperature miscible matrix, poly(ethylene oxide). By taking advantage of selective isotope labeling of the chains, we studied the role of interfacial polymer on segmental and collective dynamics of the matrix chains from subnanoseconds to 100 nanoseconds. Our results show that the Rouse relaxation remains unchanged in a weakly attractive composite system while the dynamics significantly slows down in a strongly attractive composite. More importantly, the chains disentangle with a remarkable increase of the reptation tube size when the bound polymer is vitreous. The glassy and rubbery states of the bound polymer as temperature changes underpin the macroscopic stiffening of nanocomposites. PMID:27457056

  6. Microscopic Chain Motion in Polymer Nanocomposites with Dynamically Asymmetric Interphases

    Science.gov (United States)

    Senses, Erkan; Faraone, Antonio; Akcora, Pinar

    2016-07-01

    Dynamics of the interphase region between matrix and bound polymers on nanoparticles is important to understand the macroscopic rheological properties of nanocomposites. Here, we present neutron scattering investigations on nanocomposites with dynamically asymmetric interphases formed by a high-glass transition temperature polymer, poly(methyl methacrylate), adsorbed on nanoparticles and a low-glass transition temperature miscible matrix, poly(ethylene oxide). By taking advantage of selective isotope labeling of the chains, we studied the role of interfacial polymer on segmental and collective dynamics of the matrix chains from subnanoseconds to 100 nanoseconds. Our results show that the Rouse relaxation remains unchanged in a weakly attractive composite system while the dynamics significantly slows down in a strongly attractive composite. More importantly, the chains disentangle with a remarkable increase of the reptation tube size when the bound polymer is vitreous. The glassy and rubbery states of the bound polymer as temperature changes underpin the macroscopic stiffening of nanocomposites.

  7. Structural features of membrane-bound glucocerebrosidase and α-synuclein probed by neutron reflectometry and fluorescence spectroscopy.

    Science.gov (United States)

    Yap, Thai Leong; Jiang, Zhiping; Heinrich, Frank; Gruschus, James M; Pfefferkorn, Candace M; Barros, Marilia; Curtis, Joseph E; Sidransky, Ellen; Lee, Jennifer C

    2015-01-01

    Mutations in glucocerebrosidase (GCase), the enzyme deficient in Gaucher disease, are a common genetic risk factor for the development of Parkinson disease and related disorders, implicating the role of this lysosomal hydrolase in the disease etiology. A specific physical interaction exists between the Parkinson disease-related protein α-synuclein (α-syn) and GCase both in solution and on the lipid membrane, resulting in efficient enzyme inhibition. Here, neutron reflectometry was employed as a first direct structural characterization of GCase and α-syn·GCase complex on a sparsely-tethered lipid bilayer, revealing the orientation of the membrane-bound GCase. GCase binds to and partially inserts into the bilayer with its active site most likely lying just above the membrane-water interface. The interaction was further characterized by intrinsic Trp fluorescence, circular dichroism, and surface plasmon resonance spectroscopy. Both Trp fluorescence and neutron reflectometry results suggest a rearrangement of loops surrounding the catalytic site, where they extend into the hydrocarbon chain region of the outer leaflet. Taking advantage of contrasting neutron scattering length densities, the use of deuterated α-syn versus protiated GCase showed a large change in the membrane-bound structure of α-syn in the complex. We propose a model of α-syn·GCase on the membrane, providing structural insights into inhibition of GCase by α-syn. The interaction displaces GCase away from the membrane, possibly impeding substrate access and perturbing the active site. GCase greatly alters membrane-bound α-syn, moving helical residues away from the bilayer, which could impact the degradation of α-syn in the lysosome where these two proteins interact.

  8. Structural Features of Membrane-bound Glucocerebrosidase and α-Synuclein Probed by Neutron Reflectometry and Fluorescence Spectroscopy*

    Science.gov (United States)

    Yap, Thai Leong; Jiang, Zhiping; Heinrich, Frank; Gruschus, James M.; Pfefferkorn, Candace M.; Barros, Marilia; Curtis, Joseph E.; Sidransky, Ellen; Lee, Jennifer C.

    2015-01-01

    Mutations in glucocerebrosidase (GCase), the enzyme deficient in Gaucher disease, are a common genetic risk factor for the development of Parkinson disease and related disorders, implicating the role of this lysosomal hydrolase in the disease etiology. A specific physical interaction exists between the Parkinson disease-related protein α-synuclein (α-syn) and GCase both in solution and on the lipid membrane, resulting in efficient enzyme inhibition. Here, neutron reflectometry was employed as a first direct structural characterization of GCase and α-syn·GCase complex on a sparsely-tethered lipid bilayer, revealing the orientation of the membrane-bound GCase. GCase binds to and partially inserts into the bilayer with its active site most likely lying just above the membrane-water interface. The interaction was further characterized by intrinsic Trp fluorescence, circular dichroism, and surface plasmon resonance spectroscopy. Both Trp fluorescence and neutron reflectometry results suggest a rearrangement of loops surrounding the catalytic site, where they extend into the hydrocarbon chain region of the outer leaflet. Taking advantage of contrasting neutron scattering length densities, the use of deuterated α-syn versus protiated GCase showed a large change in the membrane-bound structure of α-syn in the complex. We propose a model of α-syn·GCase on the membrane, providing structural insights into inhibition of GCase by α-syn. The interaction displaces GCase away from the membrane, possibly impeding substrate access and perturbing the active site. GCase greatly alters membrane-bound α-syn, moving helical residues away from the bilayer, which could impact the degradation of α-syn in the lysosome where these two proteins interact. PMID:25429104

  9. Sticholysin II: a pore-forming toxin as a probe to recognize sphingomyelin in artificial and cellular membranes.

    Science.gov (United States)

    Garcia, Paloma Sanchez; Chieppa, Gabriele; Desideri, Alessandro; Cannata, Stefano; Romano, Elena; Luly, Paolo; Rufini, Stefano

    2012-10-01

    Sphingomyelin is a major component of membrane rafts, and also is a precursor of many bioactive molecules. The sphingomyelin plays important biological roles and alterations of its metabolism are the basis of some genetic disorders such as the Niemann Pick disease. A complete understanding of its biological role is frustrated by the lack of efficient tools for its recognition in the cell. Sticholysin II (StnII) is a 20 kDa protein from the sea-anemone Stichodactyla helianthus which shows a cytotoxic activity by forming oligomeric aqueous pores in the cell plasma membrane. A recent NMR analysis indicates that the sticholysin II binds specifically to sphingomyelin by two domains that recognize respectively the hydrophilic (i.e. phosphorylcholine) and the hydrophobic (i.e. ceramide) moieties of the molecule. Aim of our research has been to verify the possible employ of an antibody against the StnII to investigate the localization and the dynamics of sphingomyelin in cell membranes. For this purpose, we developed a monoclonal antibody (named A10) against the toxin and we tested its ability to bind StnII after binding to sphingomyelin. A10 antibody is able to recognize the sticholysin II both in its native form and after SDS treatment, being the protein still suitable for many analytic techniques such as ELISA, western blotting and immunofluorescence. The high affinity of the toxin for the sphingomyelin in cell membranes has been demonstrated by microscopic immuno-localization and western blot analysis; both methods confirmed that sphingomyelin is the molecular acceptor for StnII also in cell membranes. Finally, we studied the specificity of the toxin for sphingomyelin by a cell membrane-double labelling method, using cholera toxin, specific for the ganglioside GM1, and sticholysin II. The results obtained show that there is no cross-reactivity between the two toxins, confirming that sticholysin II is able to discriminate among membrane domains with sphingomyelin with

  10. Characterization of M-laurdan, a versatile probe to explore order in lipid membranes [v2; ref status: indexed, http://f1000r.es/4on

    Directory of Open Access Journals (Sweden)

    Serge Mazeres

    2014-11-01

    Full Text Available Microdomains corresponding to localized partition of lipids between ordered and less ordered environments are the subject of intensive investigations, because of their putative participation in modulating cellular responses. One popular approach in the field consists in labelling membranes with solvatochromic fluorescent probes such as laurdan and C-laurdan. In this report, we describe a high-yield procedure for the synthesis of laurdan, C-laurdan and two new fluorophores, called MoC-laurdan and M-laurdan, as well as their extensive photophysical characterization. We find that the latter probe, M-laurdan, is particularly suited to discriminate lipid phases independently of the chemical nature of the lipids, as measured by both fluorescence Generalized Polarization (GP and anisotropy in large unilamellar vesicles made of various lipid compositions. In addition, staining of live cells with M-laurdan shows a good stability over time without any apparent toxicity, as well as a wider distribution in the various cell compartments than the other probes.

  11. Comparison of the hydrophobic grid-membrane filter DNA probe method and the Health Protection Branch standard method for the detection of Listeria monocytogenes in foods.

    Science.gov (United States)

    Yan, W; Malik, M N; Peterkin, P I; Sharpe, A N

    1996-07-01

    The standard Health Protection Branch (HPB) method for the detection of L. monocytogenes in foods involves lengthy enrichment, selection and biochemical testing, requiring up to 8 days to complete. A hydrophobic grid-membrane filter (HGMF) method employing a digoxigenin-labelled listeriolysin O probe required 5 days to complete, and included an image-analysis system for electronic data acquisition. A total of 200 food samples encompassing 8 high-risk food groups (soft and semi-soft cheeses, packaged raw vegetables, frozen cooked shrimp, ground poultry, ground pork, ground beef, jellied meats, and pâté) were screened for the presence of L. monocytogenes by the two methods. Overall, 32 (16%) and 30 (15%) of the naturally-contaminated food samples tested positive for L. monocytogenes by the HPB and DNA methods, respectively. The DNA probe method was highly specific in discriminating L. monocytogenes from other Listeria spp. present in 50 of the samples tested. Results showed 94% sensitivity and 100% specificity between the two methods. The HGMF DNA probe method is an efficient and reliable alternative to the HPB standard method for detecting L. monocytogenes in foods.

  12. Dynamics of a Room Temperature Ionic Liquid in Supported Ionic Liquid Membranes vs the Bulk Liquid: 2D IR and Polarized IR Pump-Probe Experiments.

    Science.gov (United States)

    Shin, Jae Yoon; Yamada, Steven A; Fayer, Michael D

    2017-01-11

    Supported ionic liquid membranes (SILMs) are membranes that have ionic liquids impregnated in their pores. SILMs have been proposed for advanced carbon capture materials. Two-dimensional infrared (2D IR) and polarization selective IR pump-probe (PSPP) techniques were used to investigate the dynamics of reorientation and spectral diffusion of the linear triatomic anion, SeCN(-), in poly(ether sulfone) (PES) membranes and room-temperature ionic liquid (RTIL), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EmimNTf2). The dynamics in the bulk EmimNTf2 were compared to its dynamics in the SILM samples. Two PES membranes, PES200 and PES30, have pores with average sizes, ∼300 nm and ∼100 nm, respectively. Despite the relatively large pore sizes, the measurements reveal that the reorientation of SeCN(-) and the RTIL structural fluctuations are substantially slower in the SILMs than in the bulk liquid. The complete orientational randomization, slows from 136 ps in the bulk to 513 ps in the PES30. 2D IR measurements yield three time scales for structural spectral diffusion (SSD), that is, the time evolution of the liquid structure. The slowest decay constant increases from 140 ps in the bulk to 504 ps in the PES200 and increases further to 1660 ps in the PES30. The results suggest that changes at the interface propagate out and influence the RTIL structural dynamics even more than a hundred nanometers from the polymer surface. The differences between the IL dynamics in the bulk and in the membranes suggest that studies of bulk RTIL properties may be poor guides to their use in SILMs in carbon capture applications.

  13. FANCA safeguards interphase and mitosis during hematopoiesis in vivo.

    Science.gov (United States)

    Abdul-Sater, Zahi; Cerabona, Donna; Potchanant, Elizabeth Sierra; Sun, Zejin; Enzor, Rikki; He, Ying; Robertson, Kent; Goebel, W Scott; Nalepa, Grzegorz

    2015-12-01

    The Fanconi anemia (FA/BRCA) signaling network controls multiple genome-housekeeping checkpoints, from interphase DNA repair to mitosis. The in vivo role of abnormal cell division in FA remains unknown. Here, we quantified the origins of genomic instability in FA patients and mice in vivo and ex vivo. We found that both mitotic errors and interphase DNA damage significantly contribute to genomic instability during FA-deficient hematopoiesis and in nonhematopoietic human and murine FA primary cells. Super-resolution microscopy coupled with functional assays revealed that FANCA shuttles to the pericentriolar material to regulate spindle assembly at mitotic entry. Loss of FA signaling rendered cells hypersensitive to spindle chemotherapeutics and allowed escape from the chemotherapy-induced spindle assembly checkpoint. In support of these findings, direct comparison of DNA crosslinking and anti-mitotic chemotherapeutics in primary FANCA-/- cells revealed genomic instability originating through divergent cell cycle checkpoint aberrations. Our data indicate that FA/BRCA signaling functions as an in vivo gatekeeper of genomic integrity throughout interphase and mitosis, which may have implications for future targeted therapies in FA and FA-deficient cancers.

  14. Promoters active in interphase are bookmarked during mitosis by ubiquitination.

    Science.gov (United States)

    Arora, Mansi; Zhang, Jie; Heine, George F; Ozer, Gulcin; Liu, Hui-wen; Huang, Kun; Parvin, Jeffrey D

    2012-11-01

    We analyzed modification of chromatin by ubiquitination in human cells and whether this mark changes through the cell cycle. HeLa cells were synchronized at different stages and regions of the genome with ubiquitinated chromatin were identified by affinity purification coupled with next-generation sequencing. During interphase, ubiquitin marked the chromatin on the transcribed regions of ∼70% of highly active genes and deposition of this mark was sensitive to transcriptional inhibition. Promoters of nearly half of the active genes were highly ubiquitinated specifically during mitosis. The ubiquitination at the coding regions in interphase but not at promoters during mitosis was enriched for ubH2B and dependent on the presence of RNF20. Ubiquitin labeling of both promoters during mitosis and transcribed regions during interphase, correlated with active histone marks H3K4me3 and H3K36me3 but not a repressive histone modification, H3K27me3. The high level of ubiquitination at the promoter chromatin during mitosis was transient and was removed within 2 h after the cells exited mitosis and entered the next cell cycle. These results reveal that the ubiquitination of promoter chromatin during mitosis is a bookmark identifying active genes during chromosomal condensation in mitosis, and we suggest that this process facilitates transcriptional reactivation post-mitosis.

  15. Formation of chromosomal domains in interphase by loop extrusion

    Science.gov (United States)

    Fudenberg, Geoffrey

    While genomes are often considered as one-dimensional sequences, interphase chromosomes are organized in three dimensions with an essential role for regulating gene expression. Recent studies have shown that Topologically Associating Domains (TADs) are fundamental structural and functional building blocks of human interphase chromosomes. Despite observations that architectural proteins, including CTCF, demarcate and maintain the borders of TADs, the mechanisms underlying TAD formation remain unknown. Here we propose that loop extrusion underlies the formation TADs. In this process, cis-acting loop-extruding factors, likely cohesins, form progressively larger loops, but stall at TAD boundaries due to interactions with boundary proteins, including CTCF. This process dynamically forms loops of various sizes within but not between TADs. Using polymer simulations, we find that loop extrusion can produce TADs as determined by our analyses of the highest-resolution experimental data. Moreover, we find that loop extrusion can explain many diverse experimental observations, including: the preferential orientation of CTCF motifs and enrichments of architectural proteins at TAD boundaries; TAD boundary deletion experiments; and experiments with knockdown or depletion of CTCF, cohesin, and cohesin-loading factors. Together, the emerging picture from our work is that TADs are formed by rapidly associating, growing, and dissociating loops, presenting a clear framework for understanding interphase chromosomal organization.

  16. Acoustic profilometry of interphases in epoxy due to segregation and diffusion using Brillouin microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Mueller, U; Bactavatchalou, R; Baller, J; Philipp, M; Sanctuary, R; Zielinski, B; Krueger, J K [Laboratoire de Physique des Materiaux, Universite du Luxembourg, 162A, Avenue de la Faiencerie, L-1115 Luxembourg (Luxembourg); Alnot, P; Possart, W [Laboratoire Europeen de Recherche Universitaire Saarland-Lorraine (Germany)], E-mail: mail@tauron.de

    2008-02-15

    Reactive network forming polymer systems like epoxies are of huge technological interest because of their adhesive properties based on specific interactions with a large variety of materials. These specific interactions alter the morphology of the epoxy within areas determined by the correlation length of these interactions. The changed morphology leads to interphases with altered (mechanical) properties. Besides these surface-induced interphases, bulk interphases do occur due to segregation, crystallization, diffusion, etc. A new experimental technique to characterize such mechanical interphases is {mu}-Brillouin spectroscopy ({mu}-BS). With {mu}-BS, we studied interphases and their formation in epoxies due to segregation of the constituent components and due to selective diffusion of one component. In the latter case, we will demonstrate the influence of changing the boundary conditions of the diffusion process on the shape of the interphase.

  17. Towards a full karyotype screening of interphase cells: 'FISH and chip' technology

    Energy Technology Data Exchange (ETDEWEB)

    Weier, Heinz-Ulli G.; Munne, Santiago; Lersch, Robert A.; Hsieh, H.-Ben; Smida, Jan; Chen, Xiao-Ning; Korenberg, Julie R.; Pedersen, Roger A.; Fung, Jingley

    2003-06-23

    Numerical chromosome aberrations are incompatible with normal human development. Our laboratories develop hybridization based screening tools that generate a maximum of cytogenetic information for each polar body or blastomere analyzed. The methods are developed considering that the abnormality might require preparation of case-specific probes and that only one or two cells will be available for diagnosis, most of which might be in the interphase stage. Further more, assay efficiencies have to be high, since there is typically not enough time to repeat an experiment or reconfirm a result prior to fertilization or embryo transfer. Structural alterations are delineated with break point-spanning probes. When screening for numerical abnormalities, we apply a Spectral Imaging-based approach to simultaneously score as many as ten different chromosome types in individual inter phase cells. Finally, DNA micro-arrays are under development to score all of the human chromosomes in a single experiment and to increase the resolution with which micro-deletions can be delineated.

  18. [Interphase cytogenetics of the breast tumors with fluorescence in situ hybridization (FISH) on cytologic preparation--its practice and clinical applications].

    Science.gov (United States)

    Shibuya, M; Osamura, R Y

    1996-05-01

    Fluorescence in situ hybridization (FISH) study with the chromosome specific probes is performed in the interphase nuclei of the routinely processed cytologic preparation of the breast tumors. Numerical aberrations on the chromosomes 1, 3, 11 or 17 were detected in more than 80% of the malignant tumors, but not in the benign tumors. Marked heterogeneity of the polysomies is noted in the malignant tumor cells. A few malignant cases revealed monosomy of chromosome 17. No apparent correlation between the numerical abnormalities and the histological features in malignant tumors is identified. These results suggest that the interphase cytogenetics with FISH for the breast tumors may be useful for differential diagnosis of malignancy. The practice and the clinical applications of the FISH study are discussed.

  19. THE USE OF INFRARED SPECTROSCOPY FOR FOLLOWING DRUG-MEMBRANE INTERACTIONS: PROBING PACLITAXEL (TAXOL-CELL PHOSPHOLIPID SURFACE RECOGNITION

    Directory of Open Access Journals (Sweden)

    Erhan Süleymanoglu

    2009-01-01

    Full Text Available Over the past two decades, of the several new chemotherapeutic agents, taxol (Paclitaxel has played a crucial role in the treatment of various malignancies, including those of the ovary, breast, lung, head and neck, esophagus, as well as Kaposi's sarcoma. Despite its well documented mechanisms of action causing cell cycle arrest and apoptosis following microtubule stabilization, further details still remain to be clarified. Alterations of lipid membrane composition of cancer cells as compared with normal cells are well established. In addition, the mechanisms of drug resistance, which severely limit the effectiveness of cancer chemotherapy are undertaken by membrane located proteins such as multidrug resistance (MDR-1 or P-glycoprotein (Pgp. On the other hand, recent chemotherapeutic regimens employ anticancer drug induced apoptosis, during which dynamic structural changes occur in cellular dynamics characterizing cell death phase leading to fragmentation into membrane-bound apoptotic bodies. Thus, cell membranes represent an attractive research field in cellular carcinogenesis and cancer therapy. Besides DNA, plasma membrane is considered as the most important target for many antineoplastic drugs. However, its role in chemotherapy-induced cell death is not well understood. Hence, it is interesting to study the molecular interactions of the anticancer drugs in phospholipid environment. Both cell biological and biotechnological aspects are aimed. By further clarifying the precise mechanisms of taxol-lipid interactions, better understanding of its pharmacological targets can be obtained. Moreover, gaining further insights on such drug-lipid interactions would encourage the design of novel lipid based antitumor drug formulations with improved bioavailability properties and decreased toxic side effects. The currently employed analytical approaches to follow drug-cell or drug-membrane interactions are limited by either the requirement of experienced

  20. Spatially resolved characterization of catalyst-coated membranes by distance-controlled scanning mass spectrometry utilizing catalytic methanol oxidation as gas-solid probe reaction.

    Science.gov (United States)

    Li, Nan; Assmann, Jens; Schuhmann, Wolfgang; Muhler, Martin

    2007-08-01

    The spatially resolved catalytic activity of a catalyst-coated membrane (CCM), which is the essential part of PEM fuel cells, was visualized rapidly without any damage by a distance-controlled scanning mass spectrometer with an improved resolution of 250 microm. Methanol oxidation was identified as a suitable gas-solid probe reaction for the characterization of local catalytic activity. In addition, defects were manually generated in the CCM to simulate inhomogeneous coating and pinholes. The measurements successfully demonstrated that catalytically active and less active regions can be clearly distinguished. Simultaneously, the local topography was recorded, providing additional information on the location of the scratches and pinholes. The catalytic results were highly reproducible due to the constant-distance feedback loop rendering scanning mass spectrometry a promising tool for the quantitative quality control of CCMs.

  1. Dynamics and regulation of plant interphase microtubules: a comparative view.

    Science.gov (United States)

    Hashimoto, Takashi

    2003-12-01

    Microtubule and actin cytoskeletons are fundamental to a variety of cellular activities within eukaryotic organisms. Extensive information on the dynamics and functions of microtubules, as well as on their regulatory proteins, have been revealed in fungi and animals, and corresponding pictures are now slowly emerging in plants. During interphase, plant cells contain highly dynamic cortical microtubules that organize into ordered arrays, which are apparently regulated by distinct groups of microtubule regulators. Comparison with fungal and animal microtubules highlights both conserved and unique mechanisms for the regulation of the microtubule cytoskeleton in plants.

  2. Interphase fluorescence in situ hybridization and reverse transcription polymerase chain reaction as a diagnostic aid for synovial sarcoma.

    Science.gov (United States)

    Shipley, J; Crew, J; Birdsall, S; Gill, S; Clark, J; Fisher, C; Kelsey, A; Nojima, T; Sonobe, H; Cooper, C; Gusterson, B

    1996-02-01

    Identification of the t(X;18)(p11.2;q11.2) that is associated with a high proportion of synovial sarcoma can be a useful diagnostic aid. The translocation results in fusion of the SYT gene on chromosome 18 to either the SSX1 or the SSX2 gene, two homologous genes within Xp11.2. Two-color interphase fluorescence in situ hybridization and reverse transcription polymerase chain reaction were assessed as approaches to identify the rearrangement in well characterized cases. The presence of the translocation, and the specific chromosome X gene disrupted, were inferred from the configuration of signals from chromosome-specific centromere probes, paints, and markers flanking each gene in preparations of interphase nuclei. Rearrangement was found in two cell lines and eight of nine tumor samples, including analysis of five touch imprints. This was consistent with cytogenetic data in four cases and reverse transcription polymerase chain reaction analysis using primers known to amplify both SYT-SSX1 and SYT-SSX2 transcripts. The transcripts were distinguished by restriction with LspI and SmaI. Contrary to previous suggestions, there was no obvious correlation between histological subtype and involvement of the SSX1 or SSX2 gene. These approaches could also be applied to the identification of tumor-free margins and metastatic disease.

  3. Protective Oxide Coating for Ionic Conductive Solid Electrolyte Interphase.

    Science.gov (United States)

    Kim, Yong Su; Kim, Seong Heon; Kim, Gyusung; Heo, Sung; Mun, Jinsoo; Han, Sungsoo; Jung, Heechul; Kyoung, Yong Koo; Yun, Dong Jin; Baek, Woon Joong; Doo, Seokgwang

    2016-11-16

    To employ Li-based batteries to their full potential in a wide range of energy-storage applications, their capacity and performance stability must be improved. Si is a viable anode material for Li-based batteries in electric vehicles due to its high theoretical capacity and good economic feasibility. However, it suffers from physical and chemical degradation, leading to unstable electrochemical performance and preventing its incorporation in new Li-based battery systems. Herein, we applied a poly(vinyl alcohol)-PO4 protective coating for Si-graphite anodes and confirmed an improvement in the electrochemical performance. The experimental results revealed that the polymer acts as a binder to alleviate the pulverization of the electrode. Furthermore, the oxide coating reduces the loss of Li2O, which has high ionic conductivity, during operation, resulting in the formation of a stable solid electrolyte interphase. Our findings suggest that a stable and ion-conducting anode/interphase can be developed by applying an oxide and polymer coating in combined approach. Therefore, this study is expected to provide a basis for the further development and design of high-performance Li-based battery systems.

  4. Repo-Man/PP1 regulates heterochromatin formation in interphase

    Science.gov (United States)

    de Castro, Inês J.; Budzak, James; Di Giacinto, Maria L.; Ligammari, Lorena; Gokhan, Ezgi; Spanos, Christos; Moralli, Daniela; Richardson, Christine; de las Heras, Jose I.; Salatino, Silvia; Schirmer, Eric C.; Ullman, Katharine S.; Bickmore, Wendy A.; Green, Catherine; Rappsilber, Juri; Lamble, Sarah; Goldberg, Martin W.; Vinciotti, Veronica; Vagnarelli, Paola

    2017-01-01

    Repo-Man is a protein phosphatase 1 (PP1) targeting subunit that regulates mitotic progression and chromatin remodelling. After mitosis, Repo-Man/PP1 remains associated with chromatin but its function in interphase is not known. Here we show that Repo-Man, via Nup153, is enriched on condensed chromatin at the nuclear periphery and at the edge of the nucleopore basket. Repo-Man/PP1 regulates the formation of heterochromatin, dephosphorylates H3S28 and it is necessary and sufficient for heterochromatin protein 1 binding and H3K27me3 recruitment. Using a novel proteogenomic approach, we show that Repo-Man is enriched at subtelomeric regions together with H2AZ and H3.3 and that depletion of Repo-Man alters the peripheral localization of a subset of these regions and alleviates repression of some polycomb telomeric genes. This study shows a role for a mitotic phosphatase in the regulation of the epigenetic landscape and gene expression in interphase. PMID:28091603

  5. Tetrameric structure of centromeric nucleosomes in interphase Drosophila cells.

    Directory of Open Access Journals (Sweden)

    Yamini Dalal

    2007-08-01

    Full Text Available Centromeres, the specialized chromatin structures that are responsible for equal segregation of chromosomes at mitosis, are epigenetically maintained by a centromere-specific histone H3 variant (CenH3. However, the mechanistic basis for centromere maintenance is unknown. We investigated biochemical properties of CenH3 nucleosomes from Drosophila melanogaster cells. Cross-linking of CenH3 nucleosomes identifies heterotypic tetramers containing one copy of CenH3, H2A, H2B, and H4 each. Interphase CenH3 particles display a stable association of approximately 120 DNA base pairs. Purified centromeric nucleosomal arrays have typical "beads-on-a-string" appearance by electron microscopy but appear to resist condensation under physiological conditions. Atomic force microscopy reveals that native CenH3-containing nucleosomes are only half as high as canonical octameric nucleosomes are, confirming that the tetrameric structure detected by cross-linking comprises the entire interphase nucleosome particle. This demonstration of stable half-nucleosomes in vivo provides a possible basis for the instability of centromeric nucleosomes that are deposited in euchromatic regions, which might help maintain centromere identity.

  6. Integrin-linked kinase regulates interphase and mitotic microtubule dynamics.

    Directory of Open Access Journals (Sweden)

    Simin Lim

    Full Text Available Integrin-linked kinase (ILK localizes to both focal adhesions and centrosomes in distinct multiprotein complexes. Its dual function as a kinase and scaffolding protein has been well characterized at focal adhesions, where it regulates integrin-mediated cell adhesion, spreading, migration and signaling. At the centrosomes, ILK regulates mitotic spindle organization and centrosome clustering. Our previous study showed various spindle defects after ILK knockdown or inhibition that suggested alteration in microtubule dynamics. Since ILK expression is frequently elevated in many cancer types, we investigated the effects of ILK overexpression on microtubule dynamics. We show here that overexpressing ILK in HeLa cells was associated with a shorter duration of mitosis and decreased sensitivity to paclitaxel, a chemotherapeutic agent that suppresses microtubule dynamics. Measurement of interphase microtubule dynamics revealed that ILK overexpression favored microtubule depolymerization, suggesting that microtubule destabilization could be the mechanism behind the decreased sensitivity to paclitaxel, which is known to stabilize microtubules. Conversely, the use of a small molecule inhibitor selective against ILK, QLT-0267, resulted in suppressed microtubule dynamics, demonstrating a new mechanism of action for this compound. We further show that treatment of HeLa cells with QLT-0267 resulted in higher inter-centromere tension in aligned chromosomes during mitosis, slower microtubule regrowth after cold depolymerization and the presence of a more stable population of spindle microtubules. These results demonstrate that ILK regulates microtubule dynamics in both interphase and mitotic cells.

  7. Influences of interphase on dynamic effective properties of composites reinforced by dispersed spherical particles

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    The influences of interphase on dynamic effective properties of composites reinforced by randomly dispersed spherical particles were studied. A thin homogeneous elastic interphase with different shear and bulk moduli, located between the reinforced particle and the host matrix, was introduced to model the interfacial bonding state. The effects of such an interphase on the coherent plane waves were studied numerically. Numerical simulations were carried out for SiC-Al composites with four typical cases of interphase. It was found that the property of interphase has significant influences on the effective propagation constants of coherent waves and the dynamic effective elastic moduli of the composites. The influences on the coherent longitudinal wave and the coherent shear waves were different and dependent upon the frequency range. Moreover, several imperfect interface models, i.e., the spring model, mass model, and spring-mass model, were studied numerically and compared with the interphase model. It was found that the spring model is a more suitable model than the mass model for the light and weak interphase whereas the mass model is a more suitable model than the spring model for the heavy and strong interphase.

  8. Atomic force microscopy: a versatile tool to probe the physical and chemical properties of supported membranes at the nanoscale.

    Science.gov (United States)

    Picas, Laura; Milhiet, Pierre-Emmanuel; Hernández-Borrell, Jordi

    2012-12-01

    Atomic force microscopy (AFM) was developed in the 1980s following the invention of its precursor, scanning tunneling microscopy (STM), earlier in the decade. Several modes of operation have evolved, demonstrating the extreme versatility of this method for measuring the physicochemical properties of samples at the nanoscopic scale. AFM has proved an invaluable technique for visualizing the topographic characteristics of phospholipid monolayers and bilayers, such as roughness, height or laterally segregated domains. Implemented modes such as phase imaging have also provided criteria for discriminating the viscoelastic properties of different supported lipid bilayer (SLB) regions. In this review, we focus on the AFM force spectroscopy (FS) mode, which enables determination of the nanomechanical properties of membrane models. The interpretation of force curves is presented, together with newly emerging techniques that provide complementary information on physicochemical properties that may contribute to our understanding of the structure and function of biomembranes. Since AFM is an imaging technique, some basic indications on how real-time AFM imaging is evolving are also presented at the end of this paper. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  9. Accuracy Assessment of Interphase Fluorescence In-Situ Hybridization on Uncultured Amniotic Fluid Cells

    Directory of Open Access Journals (Sweden)

    Hamideh Karimi

    2007-01-01

    Full Text Available Background: Parental anxiety while waiting for the results of amniocentesis has been investigatedby many authors. It seems that the implementation of faster techniques such as fluorescence in-situhybridization (FISH will have some benefits in reducing this anxiety. Besides the patients' attitudesto choosing this method, gynecologists who are the persons responsible for treatment, must feelcomfortable about prescribing FISH techniques.Materials and Methods: This study, using a simple methodology, was undertaken to evaluate theresults of FISH tests on the amniotic fluid from 40 pregnant women undergoing cesarean surgery.Two sets of probes including X/Y cocktail and 13, 21 and 18 were applied on different slides.Results: The results of FISH tests were compared with the reports of the pediatrician about thehealth condition of the newborn. Complete conformity between the two sets of findings, haveconvinced our gynecologists of the benefit of prescribing this method to reduce the anxiety ofpatients at risk of having abnormal offspring due to chromosomal anuploidies.Conclusion: As has been documented by many authors, conventional chromosome analysis hasgreat advantages over fluorescence in situ hybridization of interphase amniocytes, but reducing theanxiety of parents is a good reason for employing the FISH technique.

  10. [Prostate cancers and potential precancerous conditions: DNA cytometric investigations and interphase cytogenetics].

    Science.gov (United States)

    Baretton, G; Vogt, T; Valina, C; Schneiderbanger, K; Löhrs, U

    1993-01-01

    The topic of this investigation was to compare precancerous lesions of the prostate (prostatic intraepithelial neoplasia -PIN- and atypical hyperplasia -AH-) and invasive carcinomas concerning DNA ploidy (image cytometry/ICM) and morphologically feasible chromosomal aberrations (interphase cytogenetics/NISH). The aim was to find clues to formal pathogenesis of prostatic cancer. Prostatic tissue of 76 patients (76 areas with carcinoma, 71 with PIN, and 12 with AH) was examined by means of ICM. In 44 cases of coincidental PIN and carcinoma, the gradings of PIN and carcinoma correlated. C-values, 2,5c-exceeding-rate, and aneuploidy rate turned out to increase in PIN and carcinoma with increasing grading (P < 0.01). In some of these cases NISH was carried out in serial sections by applying centromer-(X,Y,1,7,8,10,17,18) and telomer-(1p) specific DNA probes. The result of this approach was an increase in the number of chromosomal aberrations and chromosomes involved correlating with the grading. Our conclusion is that PIN 1 could be regarded as the precancerous lesion mainly to higher differentiated carcinomas, whereas PIN 2 and 3 should be considered a preneoplastic condition mainly of moderately and low differentiated carcinomas.

  11. Accuracy Assessment of Interphase Fluorescence In-Situ Hybridization on Uncultured Amniotic Fluid Cells

    Directory of Open Access Journals (Sweden)

    Hamid Gourabi

    2008-01-01

    Full Text Available Background: Parental anxiety while waiting for the results of amniocentesis has been investigatedby many authors. It seems that the implementation of faster techniques such as fluorescence in-situhybridization (FISH will have some benefits in reducing this anxiety. Besides the patients' attitudesto choosing this method, gynecologists who are the persons responsible for treatment, must feelcomfortable about prescribing FISH techniques.Materials and Methods: This study, using a simple methodology, was undertaken to evaluate theresults of FISH tests on the amniotic fluid from 40 pregnant women undergoing cesarean surgery.Two sets of probes including X/Y cocktail and 13, 21 and 18 were applied on different slides.Results: The results of FISH tests were compared with the reports of the pediatrician about thehealth condition of the newborn. Complete conformity between the two sets of findings, haveconvinced our gynecologists of the benefit of prescribing this method to reduce the anxiety ofpatients at risk of having abnormal offspring due to chromosomal anuploidies.Conclusion: As has been documented by many authors, conventional chromosome analysis hasgreat advantages over fluorescence in situ hybridization of interphase amniocytes, but reducing theanxiety of parents is a good reason for employing the FISH technique.

  12. Designer interphases for the lithium-oxygen electrochemical cell

    KAUST Repository

    Choudhury, Snehashis

    2017-04-20

    An electrochemical cell based on the reversible oxygen reduction reaction: 2Li+ + 2e− + O2 ↔ Li2O2, provides among the most energy dense platforms for portable electrical energy storage. Such Lithium-Oxygen (Li-O2) cells offer specific energies competitive with fossil fuels and are considered promising for electrified transportation. Multiple, fundamental challenges with the cathode, anode, and electrolyte have limited practical interest in Li-O2 cells because these problems lead to as many practical shortcomings, including poor rechargeability, high overpotentials, and specific energies well below theoretical expectations. We create and study in-situ formation of solid-electrolyte interphases (SEIs) based on bromide ionomers tethered to a Li anode that take advantage of three powerful processes for overcoming the most stubborn of these challenges. The ionomer SEIs are shown to protect the Li anode against parasitic reactions and also stabilize Li electrodeposition during cell recharge. Bromine species liberated during the anchoring reaction also function as redox mediators at the cathode, reducing the charge overpotential. Finally, the ionomer SEI forms a stable interphase with Li, which protects the metal in high Gutmann donor number liquid electrolytes. Such electrolytes have been reported to exhibit rare stability against nucleophilic attack by Li2O2 and other cathode reaction intermediates, but also react spontaneously with Li metal anodes. We conclude that rationally designed SEIs able to regulate transport of matter and ions at the electrolyte/anode interface provide a promising platform for addressing three major technical barriers to practical Li-O2 cells.

  13. Validation of interphase fluorescence in situ hybridization (iFISH for multiple myeloma using CD138 positive cells

    Directory of Open Access Journals (Sweden)

    Renata Kiyomi Kishimoto

    2016-06-01

    Full Text Available ABSTRACT BACKGROUND: Multiple myeloma is a plasma cell neoplasm with acquired genetic abnormalities of clinical and prognostic importance. Multiple myeloma differs from other hematologic malignancies due to a high fraction of low proliferating malignant plasma cells and the paucity of plasma cells in bone marrow aspiration samples, making cytogenetic analysis a challenge. An abnormal karyotype is found in only one-third of patients with multiple myeloma and interphase fluorescence in situ hybridization is the most useful test for studying the chromosomal abnormalities present in almost 90% of cases. However, it is necessary to study the genetic abnormalities in plasma cells after their identification or selection by morphology, immunophenotyping or sorting. Other challenges are the selection of the most informative FISH panel and determining cut-off levels for FISH probes. This study reports the validation of interphase fluorescence in situ hybridization using CD138 positive cells, according to proposed guidelines published by the European Myeloma Network (EMN in 2012. METHOD: Bone marrow samples from patients with multiple myeloma were used to standardize a panel of five probes [1q amplification, 13q14 deletion, 17p deletion, t(4;14, and t(14;16] in CD138+ cells purified by magnetic cell sorting. RESULTS: This test was validated with a low turnaround time and good reproducibility. Five of six samples showed genetic abnormalities. Monosomy/deletion 13 plus t(4;14 were found in two cases. CONCLUSION: This technique together with magnetic cell sorting is effective and can be used in the routine laboratory practice. In addition, magnetic cell sorting provides a pure plasma cell population that allows other molecular and genomic studies.

  14. Synchronization of interphase events depends neither on mitosis nor on cdk1.

    Science.gov (United States)

    Laronne, Ayelet; Rotkopf, Shay; Hellman, Asaf; Gruenbaum, Yosef; Porter, Andrew C G; Brandeis, Michael

    2003-09-01

    Human HT2-19 cells with a conditional cdk1 mutation stop dividing upon cdk1 inactivation and undergo multiple rounds of endoreplication. We show herein that major cell cycle events remain synchronized in these endoreplicating cells. DNA replication alternates with gap phases and cell cycle-specific cyclin E expression is maintained. Centrosomes duplicate in synchrony with chromosome replication, giving rise to polyploid cells with multiple centrosomes. Centrosome migration, a typical prophase event, also takes place in endoreplicating cells. The timing of these events is unaffected by cdk1 inactivation compared with normally dividing cells. Nuclear lamina breakdown, in contrast, previously shown to be dependent on cdk1, does not take place in endoreplicating HT2-19 cells. Moreover, breakdown of all other major components of the nuclear lamina, like the inner nuclear membrane proteins and nuclear pore complexes, seems also to depend on cdk1. Interestingly, the APC/C ubiquitin ligase is activated in these endoreplicating cells by fzr but not by fzy. The oscillations of interphase events are thus independent of cdk1 and of mitosis but may depend on APC/Cfzr activity.

  15. Tuning the Solid Electrolyte Interphase for Selective Li- and Na-Ion Storage in Hard Carbon

    Energy Technology Data Exchange (ETDEWEB)

    Soto, Fernando A. [Department of Chemical Engineering, Texas A& M University, College Station TX 77843-3122 USA; Yan, Pengfei [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Engelhard, Mark H. [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Marzouk, Asma [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 5825 Doha Qatar; Wang, Chongmin [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Xu, Guiliang [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue Argonne IL 60439 USA; Chen, Zonghai [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue Argonne IL 60439 USA; Amine, Khalil [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue Argonne IL 60439 USA; Liu, Jun [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Sprenkle, Vincent L. [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; El-Mellouhi, Fedwa [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 5825 Doha Qatar; Balbuena, Perla B. [Department of Chemical Engineering, Texas A& M University, College Station TX 77843-3122 USA; Li, Xiaolin [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA

    2017-03-07

    Solid-electrolyte interphase (SEI) films with controllable properties are highly desirable for improving battery performance. In this paper, a combined experimental and theoretical approach is used to study SEI films formed on hard carbon in Li- and Na-ion batteries. It is shown that a stable SEI layer can be designed by precycling an electrode in a desired Li- or Na-based electrolyte, and that ionic transport can be kinetically controlled. Selective Li- and Na-based SEI membranes are produced using Li- or Na-based electrolytes, respectively. The Na-based SEI allows easy transport of Li ions, while the Li-based SEI shuts off Na-ion transport. Na-ion storage can be manipulated by tuning the SEI layer with film-forming electrolyte additives, or by preforming an SEI layer on the electrode surface. The Na specific capacity can be controlled to < 25 mAh g(-1); approximate to 1/10 of the normal capacity (250 mAh g(-1)). Unusual selective/ preferential transport of Li ions is demonstrated by preforming an SEI layer on the electrode surface and corroborated with a mixed electrolyte. This work may provide new guidance for preparing good ion-selective conductors using electrochemical approaches.

  16. Tuning the Solid Electrolyte Interphase for Selective Li- and Na-Ion Storage in Hard Carbon

    Energy Technology Data Exchange (ETDEWEB)

    Soto, Fernando A. [Department of Chemical Engineering, Texas A& M University, College Station TX 77843-3122 USA; Yan, Pengfei [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Engelhard, Mark H. [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Marzouk, Asma [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 5825 Doha Qatar; Wang, Chongmin [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Xu, Guiliang [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue Argonne IL 60439 USA; Chen, Zonghai [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue Argonne IL 60439 USA; Amine, Khalil [Chemical Sciences and Engineering Division, Argonne National Laboratory, 9700 South Cass Avenue Argonne IL 60439 USA; Liu, Jun [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; Sprenkle, Vincent L. [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA; El-Mellouhi, Fedwa [Qatar Environment and Energy Research Institute, Hamad Bin Khalifa University, P.O. Box 5825 Doha Qatar; Balbuena, Perla B. [Department of Chemical Engineering, Texas A& M University, College Station TX 77843-3122 USA; Li, Xiaolin [Pacific Northwest National Laboratory, 902 Battelle Boulevard Richland WA 99354 USA

    2017-03-07

    Solid-electrolyte interphase (SEI) with controllable properties are highly desirable to improve battery performance. In this paper, we use a combined experimental and simulation approach to study the SEI formation on hard carbon in Li and Na-ion batteries. We show that with proper additives, stable SEI can be formed on hard carbon by pre-cycling the electrode materials in Li or Na-ion electrolyte. Detailed mechanistic studies suggest that the ion transport in the SEI layer is kinetically controlled and can be tuned by the applied voltage. Selective Na and Li-ion SEI membranes are produced using the Na or Li-ion based electrolytes respectively. The large Na ion SEI allows easy transport of Li ions, while the small Li ion SEI shuts off the Na-ion transport. Na-ion storage can be manipulated by tuning the SEI with film-forming electrolyte additives or preforming a SEI on the electrodes’ surface. The Na specific capacity can be controlled to <25 mAh/g, ~1/10 of the normal capacity (250 mAh/g). Unusual selective/preferential transport of Li-ion is demonstrated by preforming a SEI on the electrode’s surface and corroborated with a mixed electrolyte. This work may provide new guidance for preparing good ion selective conductors using electrochemical approaches in the future.

  17. Interphase for ceramic matrix composites reinforced by non-oxide ceramic fibers

    Science.gov (United States)

    DiCarlo, James A. (Inventor); Bhatt, Ramakrishna (Inventor); Morscher, Gregory N. (Inventor); Yun, Hee-Mann (Inventor)

    2008-01-01

    A ceramic matrix composite material is disclosed having non-oxide ceramic fibers, which are formed in a complex fiber architecture by conventional textile processes; a thin mechanically weak interphase material, which is coated on the fibers; and a non-oxide or oxide ceramic matrix, which is formed within the interstices of the interphase-coated fiber architecture. During composite fabrication or post treatment, the interphase is allowed to debond from the matrix while still adhering to the fibers, thereby providing enhanced oxidative durability and damage tolerance to the fibers and the composite material.

  18. Final Report: Interphase Analysis and Control in Fiber Reinforced Thermoplastic Composites

    Energy Technology Data Exchange (ETDEWEB)

    Jon J. Kellar; William M. Cross; Lidvin Kjerengtroen

    2009-03-14

    This research program builds upon a multi-disciplinary effort in interphase analysis and control in thermoplastic matrix polymer matrix composites (PMC). The research investigates model systems deemed of interest by members of the Automotive Composites Consortium (ACC) as well as samples at the forefront of PMC process development (DRIFT and P4 technologies). Finally, the research investigates, based upon the fundamental understanding of the interphases created during the fabrication of thermoplastic PMCs, the role the interphase play in key bulk properties of interest to the automotive industry.

  19. Diabetes Mellitus/HIV Interphase: A Series of 10 Cases | Otieno ...

    African Journals Online (AJOL)

    Diabetes Mellitus/HIV Interphase: A Series of 10 Cases. ... transaminase (ALT), aspartate transaminase (AST), serum lipase and amylase levels. ... early enough, escpecially where a family history of diabetes and other risk factors occur.

  20. Models that include supercoiling of topological domains reproduce several known features of interphase chromosomes.

    Science.gov (United States)

    Benedetti, Fabrizio; Dorier, Julien; Burnier, Yannis; Stasiak, Andrzej

    2014-03-01

    Understanding the structure of interphase chromosomes is essential to elucidate regulatory mechanisms of gene expression. During recent years, high-throughput DNA sequencing expanded the power of chromosome conformation capture (3C) methods that provide information about reciprocal spatial proximity of chromosomal loci. Since 2012, it is known that entire chromatin in interphase chromosomes is organized into regions with strongly increased frequency of internal contacts. These regions, with the average size of ∼1 Mb, were named topological domains. More recent studies demonstrated presence of unconstrained supercoiling in interphase chromosomes. Using Brownian dynamics simulations, we show here that by including supercoiling into models of topological domains one can reproduce and thus provide possible explanations of several experimentally observed characteristics of interphase chromosomes, such as their complex contact maps.

  1. Role of Interphase in the Mechanical Behavior of Silica/Epoxy Resin Nanocomposites

    Directory of Open Access Journals (Sweden)

    Yi Hua

    2015-06-01

    Full Text Available A nanoscale representative volume element has been developed to investigate the effect of interphase geometry and property on the mechanical behavior of silica/epoxy resin nanocomposites. The role of interphase–matrix bonding was also examined. Results suggested that interphase modulus and interfacial bonding conditions had significant influence on the effective stiffness of nanocomposites, while its sensitivities with respect to both the thickness and the gradient property of the interphase was minimal. The stiffer interphase demonstrated a higher load-sharing capacity, which also increased the stress distribution uniformity within the resin nanocomposites. Under the condition of imperfect interfacial bonding, the effective stiffness of nanocomposites was much lower, which was in good agreement with the documented experimental observations. This work could shed some light on the design and manufacturing of resin nanocomposites.

  2. Visual test of subparts per billion-level mercuric ion with a gold nanoparticle probe after preconcentration by hollow fiber supported liquid membrane.

    Science.gov (United States)

    Tan, Zhi-qiang; Liu, Jing-fu

    2010-05-15

    With the combination of the gold nanoparticle (AuNP)-based visual test with hollow fiber supported liquid membrane (HFSLM) extraction, a highly sensitive and selective method was developed for field detection of mercuric ion (Hg(2+)) in environmental waters. Hg(2+) in water samples was extracted through HFSLM and trapped in the aqueous acceptor and then visually detected based on the red-to-blue color change of 3-mercaptopropionic acid-functionalized AuNP (MPA-AuNP) probe. The highest extraction efficiency of Hg(2+) was obtained by using a 600 mL sample (pH 8.0, 2.0% (w/v) NaCl), approximately 35 microL of acceptor (10 mM of 2,6-pyridinedicarboxylic acid, pH 4.0) filled in the lumen of a polypropylene hollow fiber tubing (55 cm in length, 50 microm wall thickness, 280 microm inner diameter), a liquid membrane of 2.0% (w/v) trioctycphosphine oxide in undecane, and a shaking rate of 250 rpm. The chromegenic reaction was conducted by incubating the mixture of MPA-AuNP stock solution (12 microL, 15 nM), Tris-borate buffer solution (18 microL, 0.2 M, pH 9.5), and acceptor (30 microL) at 30 degrees C for 1 h. The detection limit can be adjusted to 0.8 microg/L Hg(2+) (corresponding to an enrichment factor of approximately 1000 in the HFSLM) and 2.0 microg/L Hg(2+) (the U.S. Environmental Protection Agency limit of [Hg(2+)] for drinkable water) by using extraction times of 3 and 1 h, respectively. The proposed method is extremely specific for Hg(2+) with tolerance to at least 1000-fold of other environmentally relevant heavy and transition metal ions and was successfully applied to detect Hg(2+) in a certified reference water sample, as well as real river, lake, and tap water samples.

  3. Interphase Death of Chinese Hamster Ovary Cells Exposed to Accelerated Heavy Ions

    Directory of Open Access Journals (Sweden)

    P. Mehnati

    2007-06-01

    Full Text Available Introduction: Heavy ions are nucleus of elements of iron, argon, carbon and neon that all carry positive electrical charges. For these particles to be useful in radiotherapy they need to accelerated to high energy by more than thousand mega volts. Also the cosmic environment is considered to be a complicated mixture of highly energetic photons and heavy ions such as iron. Therefore, the health risks to astronauts during long mission should be considered.  Materials and Methods: The induction of interphase death was tested on Chinese hamster ovary cells by exposing them to accelerated heavy ions (carbon, neon, argon and iron of 10-2000 linear energy transfers (LETs. The fraction of cells that underwent interphase death was determined by observing individual cells with time-lapse photography (direct method as well as by the indirect method of counting cells undergoing interphase death made visible by the addition of caffeine (indirect method. Results: The interphase death due to the exposure to X- rays is increased linearly as the dose exceeds the threshold dose of 10 Gy. Whereas the interphase death increases at a higher rate due to the exposure to high LET heavy ions and no threshold dose was observed. The range of LET values corresponding to the maximum RBE for the interphase death is 120-230 keV/µm. The probability of inducing the interphase death by a single heavy ion traversing through the nucleus is about 0.04-0.08. Discussion and Conclusion: The relative biological effectiveness (RBE of heavy ions as compared to X- rays as determined at the 50% level of induction is increased with LET. It reached a maximum value at a LET of approximately 230 keV/µm and then decreased with further increase in LET. The range of LET values corresponding to the maximum RBE appears to be narrower for interphase death than for reproductive death.

  4. Modification of carbon fiber / epoxy matrix interphase in a composite material : Design of a self-healing interphase by introducing thermally reversible Diels-Alder adducts

    OpenAIRE

    2014-01-01

    A thermally self-healable carbon/epoxy interphase was designed based on Diels-Alder (D-A) thermally reversible covalent bonds. The D-A modified interphase was formed between maleimide groups grafted on carbon fiber surface and furan groups introduced into epoxy network. The self-healing ability was characterized by a micromechanical approach using the micro-droplet debonding test. In this work, carbon fiber surface underwent a three-step treatment to graft maleimide groups, including HNO3 oxi...

  5. Interphase chromosome positioning in in vitro porcine cells and ex vivo porcine tissues

    Directory of Open Access Journals (Sweden)

    Foster Helen A

    2012-11-01

    Full Text Available Abstract Background In interphase nuclei of a wide range of species chromosomes are organised into their own specific locations termed territories. These chromosome territories are non-randomly positioned in nuclei which is believed to be related to a spatial aspect of regulatory control over gene expression. In this study we have adopted the pig as a model in which to study interphase chromosome positioning and follows on from other studies from our group of using pig cells and tissues to study interphase genome re-positioning during differentiation. The pig is an important model organism both economically and as a closely related species to study human disease models. This is why great efforts have been made to accomplish the full genome sequence in the last decade. Results This study has positioned most of the porcine chromosomes in in vitro cultured adult and embryonic fibroblasts, early passage stromal derived mesenchymal stem cells and lymphocytes. The study is further expanded to position four chromosomes in ex vivo tissue derived from pig kidney, lung and brain. Conclusions It was concluded that porcine chromosomes are also non-randomly positioned within interphase nuclei with few major differences in chromosome position in interphase nuclei between different cell and tissue types. There were also no differences between preferred nuclear location of chromosomes in in vitro cultured cells as compared to cells in tissue sections. Using a number of analyses to ascertain by what criteria porcine chromosomes were positioned in interphase nuclei; we found a correlation with DNA content.

  6. [Molecular cytogenetic methods for studying interphase chromosomes in human brain cells].

    Science.gov (United States)

    Iurov, I Iu; Vorsanova, S G; Solov'ev, I V; Iurov, Iu B

    2010-09-01

    One of the main genetic factors determining the functional activity of the genome in somatic cells, including brain nerve cells, is the spatial organization of chromosomes in the interphase nucleus. For a long time, no studies of human brain cells were carried out until high-resolution methods of molecular cytogenetics were developed to analyze interphase chromosomes in nondividing somatic cells. The purpose of the present work was to assess the potential of high-resolution methods of interphase molecular cytogenetics for studying chromosomes and the nuclear organization in postmitotic brain cells. A high efficiency was shown by such methods as multiprobe and quantitative fluorescence in situ hybridization (Multiprobe FISH and QFISH), ImmunoMFISH (analysis of the chromosome organization in different types of brain cells), and interphase chromosome-specific multicolor banding (ICS-MCB). These approaches allowed studying the nuclear organization depending on the gene composition and types of repetitive DNA of specific chromosome regions in certain types of brain cells (in neurons and glial cells, in particular). The present work demonstrates a high potential of interphase molecular cytogenetics for studying the structural and functional organizations of the cell nucleus in highly differentiated nerve cells. Analysis of interphase chromosomes of brain cells in the normal and pathological states can be considered as a promising line of research in modern molecular cytogenetics and cell neurobiology, i. e., molecular neurocytogenetics.

  7. Molecular cytogenetics in metaphase and interphase cells for cancer and genetic research, diagnosis and prognosis. Application in tissue sections and cell suspensions.

    Science.gov (United States)

    Mühlmann, Maria

    2002-06-30

    As the pioneer among molecular cytogenetics techniques, fluorescence in situ hybridization (FISH) allows identification of specific sequences in a structurally preserved cell, in metaphase or interphase. This technique, based on the complementary double-stranded nature of DNA, hybridizes labeled specific DNA (probe). The probe, bound to the target, will be developed into a fluorescent signal. The fact that the signal can be detected clearly, even when fixed in interphase, improves the accuracy of the results, since in some cases it is extremely difficult to obtain mitotic samples. FISH is still used mostly in research, but there are diagnostic applications. New nomenclature is being developed in order to define many of the aberrations that were not distinguished before FISH. Prenatal diagnosis of aneuploidies and malignancies are promptly detected with FISH, which is very useful in critical cases. In some tumors, where chromosomal abnormalities are too complicated to classify manually, the technique of comparative genomic hybridization (CGH), a competitive FISH, allows examiners to determine complete or partial gain or loss of chromosomes. CGH results allow the classification of many tumor cell lines and along with other complementary techniques, like microdissection-FISH, PRINS, etc., increase the possibility of choosing an appropriate treatment for cancer patients.

  8. Enhanced molecular dynamics for simulating porous interphase layers in batteries.

    Energy Technology Data Exchange (ETDEWEB)

    Zimmerman, Jonathan A.; Wong, Bryan Matthew; Jones, Reese E.; Templeton, Jeremy Alan; Lee, Jonathan (Rice University, Houston, TX)

    2009-10-01

    Understanding charge transport processes at a molecular level using computational techniques is currently hindered by a lack of appropriate models for incorporating anistropic electric fields in molecular dynamics (MD) simulations. An important technological example is ion transport through solid-electrolyte interphase (SEI) layers that form in many common types of batteries. These layers regulate the rate at which electro-chemical reactions occur, affecting power, safety, and reliability. In this work, we develop a model for incorporating electric fields in MD using an atomistic-to-continuum framework. This framework provides the mathematical and algorithmic infrastructure to couple finite element (FE) representations of continuous data with atomic data. In this application, the electric potential is represented on a FE mesh and is calculated from a Poisson equation with source terms determined by the distribution of the atomic charges. Boundary conditions can be imposed naturally using the FE description of the potential, which then propagates to each atom through modified forces. The method is verified using simulations where analytical or theoretical solutions are known. Calculations of salt water solutions in complex domains are performed to understand how ions are attracted to charged surfaces in the presence of electric fields and interfering media.

  9. Rheology at the Interface and the Role of the Interphase in Reactive Functionalized Multilayer Polymers in Coextrusion Process

    Science.gov (United States)

    Lamnawar, Khalid; Maazouz, Abderrahim

    2008-07-01

    Coextrusion technologies are commonly used to produce multilayered composite sheets or films for a large range of applications from food packaging to optics. The contrast of rheological properties between layers can lead to interfacial instabilities during flow. Important theoretical and experimental advances regarding the stability of compatible and incompatible polymers have, during the last decades, been made using a mechanical approach. However, few research efforts have been dedicated to the physicochemical affinity between the neighboring layers. The present study deals with the influence of this affinity on interfacial instabilities for functionalized incompatible polymers. Polyamide (PA6)/polyethylene grafted with glycidyl methacrylate (PE-GMA) was used as a reactive system and PE/PA6 as a non reactive one. Two grades of polyamide (PA6) were used in order to change the viscosity and elasticity ratios between PE (or PE-GMA) and PA6. It was experimentally confirmed, in this case, that weak disturbance can be predicted by considering an interphase of non-zero thickness (corresponding to an interdiffusion/reaction zone) instead of a purely geometrical interface between the two reactive layers. According to the rheological investigations from previous work which the interphase effect can be probed, an experimental strategy was here formulated to optimize the process by listing the parameters that controlled the stability of the reactive multilayer flows. Hence, based on this analysis, guidelines for a stable coextrusion of reactive functionalized polymers can be provided coupling the classical parameters (viscosity, elasticity and layer ratios) and the physicochemical affinity at the polymer/polymer interface.

  10. Proximity Within Interphase Chromosome Contributes to the Breakpoint Distribution in Radiation-Induced Intrachromosomal Exchanges

    Science.gov (United States)

    Zhang, Ye; Uhlemeyer, Jimmy; Hada, Megumi; Asaithamby, A.; Chen, David J.; Wu, Honglu

    2015-01-01

    Previously, we reported that breaks involved in chromosome aberrations were clustered in several regions of chromosome3 in human mammary epithelial cells after exposures to either low-or high-LET radiation. In particular, breaks in certain regions of the chromosome tended to rejoin with each other to form an intrachromosome exchange event. This study tests the hypothesis that proximity within a single chromosome in interphase cell nuclei contributes to the distribution of radiation-induced chromosome breaks. Chromosome 3 in G1 human mammary epithelial cells was hybridized with the multicolor banding in situ hybridization (mBAND) probes that distinguish the chromosome in six differently colored regions, and the location of these regions was measured with a laser confocal microscope. Results of the study indicated that, on a multi-mega base pair scale of the DNA, the arrangement of chromatin was non-random. Both telomere regions tended to be located towards the exterior of the chromosome domain, whereas the centromere region towards the interior. In addition, the interior of the chromosome domain was preferentially occupied by the p-arm of the chromatin, which is consistent with our previous finding of intrachromosome exchanges involving breaks on the p-arm and in the centromere region of chromosome3. Other factors, such as the fragile sites in the 3p21 band and gene regulation, may also contribute to the breakpoint distribution in radiation-induced chromosome aberrations. Further investigations suggest that the 3D chromosome folding is cell type and culture condition dependent.

  11. New image analysis methods for 3D visualization and assessment of mapping distance for chromosomes in interphase nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Ikizyan, I.; Burde, S.; Leary, J.F. (Univ. of Rochester, NY (United States))

    1993-01-01

    Confocal microscopy (Meridian Instruments, Inc.) images of interphase nuclei with portions or entire chromosomes singley- or doubly-labeled by fluorescence in situ hybridization were analyzed with newly-developed software on an 80486 PC equipped with an autostereoscopic display (Dimension Technologies, Inc.). The computer display is hologram-like with the ability to address points in 3D space using the associated mouse. Software was developed which allowed for reduction of background by a 19 voxel (3x3x3 voxel cube without corner voxels) median filtering algorithm followed by rendering of a 3D surface and skeleton figure of a chromosome. Visualization at multiple viewing angles by animation allows approximate coordinate locations to be obtained with a 3D mouse to guide the process thereby reducing significantly the required calculation times. Two biological applications under development include (1) correct counting of a given chromosome's copy number using centromere/chromosome-specific probes, and (2) visualization of painted chromosomes and subregion-specific probes at different locations on that chromosome for physical mapping. In either application, real-world distances within each confocal plane and between planes are calculable to give physical mapping distances in three dimensions and along the chromosome.

  12. Impact of NAPL architecture on interphase mass transfer: A pore network study

    Science.gov (United States)

    Agaoglu, Berken; Scheytt, Traugott; Copty, Nadim K.

    2016-09-01

    Interphase mass transfer in porous media is commonly modeled using Sherwood number expressions that are developed in terms of fluid and porous medium properties averaged over some representative elementary volume (REV). In this work the influence of sub-grid scale properties on interphase mass transfer was investigated using a two-dimensional pore network model. The focus was on assessing the impact of (i) NAPL saturation, (ii) interfacial area (iii) NAPL spatial distribution at the pore scale, (iv) grain size heterogeneity, (v) REV or domain size and (vi) pore scale heterogeneity of the porous media on interphase mass transfer. Variability of both the mass transfer coefficient that explicitly accounts for the interfacial area and the mass transfer coefficient that lumps the interfacial area was examined. It was shown that pore scale NAPL distribution and its orientation relative to the flow direction have significant impact on flow bypassing and the interphase mass transfer coefficient. This results in a complex non-linear relationship between interfacial area and the REV-based interphase mass transfer rate. Hence, explicitly accounting for the interfacial area does not eliminate the uncertainty of the mass transfer coefficient. It was also shown that, even for explicitly defined flow patterns, changing the domain size over which the mass transfer process is defined influences the extent of NAPL bypassing and dilution and, consequently, the interphase mass transfer. It was also demonstrated that the spatial variability of pore scale parameters such as pore throat diameters may result in different rates of interphase mass transfer even for the same pore size distribution index.

  13. Mobile Probing and Probes

    DEFF Research Database (Denmark)

    2013-01-01

    Mobile probing is a method, developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time and space......). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings point...... to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face). The development...

  14. Mobile Probing and Probes

    DEFF Research Database (Denmark)

    2012-01-01

    Mobile probing is a method, which has been developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time...... and space). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings...... point to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face...

  15. Mobile Probing and Probes

    DEFF Research Database (Denmark)

    2012-01-01

    Mobile probing is a method, which has been developed for learning about digital work situations, as an approach to discover new grounds. The method can be used when there is a need to know more about users and their work with certain tasks, but where users at the same time are distributed (in time...... and space). Mobile probing was inspired by the cultural probe method, and was influenced by qualitative interview and inquiry approaches. The method has been used in two subsequent projects, involving school children (young adults at 15-17 years old) and employees (adults) in a consultancy company. Findings...... point to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face...

  16. Characterizing the interphase dielectric constant of polymer composite materials: Effect of chemical coupling agents

    Science.gov (United States)

    Todd, Michael G.; Shi, Frank G.

    2003-10-01

    Recent research into the dielectric characteristics of polymer-ceramic composites has shown that the interphase region of the composite can have a dielectric constant significantly different from that of the polymer phase due to covalent bonding of the polymer molecules to the surface of the filler particles. Chemical coupling agents and surfactants such as functional silanes, organotitanates, organometallic chelating agents, phosphate esters, and various ionic and nonionic organic esters are commonly employed to enhance the compatibility between the polymer phase and dispersed filler phase of composite systems. Using experimental data and molecular dipole polarization calculations, we determine the effect of such coupling agents on the interphase dielectric constant. Our results show that the addition of functional silane coupling agents or nonionic surfactants at concentrations of 0.5 wt % or less of the total organics of a polymer-ceramic composite system has significant effects on the dielectric constant of the interphase region, yet has little or no effect on the dielectric constant values of the polymer phase. Furthermore, the chemical bonding of the coupling agents to the ceramic filler particles determine the dielectric constant of the interphase region as predicted by chemical polarization calculations. These results are fully consistent with experimental evidence and further validate the use of molecular polarization calculations of composite interphase regions to determine and predict the overall effective dielectric properties of packaging materials for a wide range of electrical, electronic, and rf applications.

  17. The use of interphase FISH for prenatal diagnosis of Pallister-Killian syndrome.

    Science.gov (United States)

    Mowery-Rushton, P A; Stadler, M P; Kochmar, S J; McPherson, E; Surti, U; Hogge, W A

    1997-03-01

    Pallister-Killian syndrome (tetrasomy 12p) is a relatively rare aneuploidy syndrome characterized by the presence of mosaicism for an isochromosome 12p [i(12p)]. We report two new cases diagnosed following chorionic villus sampling and an abnormal ultrasound, respectively. Fluorescent in situ hybridization (FISH) was used to enumerate the number of interphase cells containing the isochromosome. The results of these studies illustrate the importance of the use of interphase FISH to detect the presence of the i(12p) in uncultured, non-dividing cells. A review of the literature identified 23 additional cases of Pallister-Killian syndrome diagnosed prenatally. Approximately 50 per cent of these cases were associated with the presence of a congenital diaphragmatic hernia. We suggest that a perinatal-lethal form of Pallister-Killian syndrome is underdiagnosed and recommend that all cases of prenatally detected diaphragmatic hernia be tested for Pallister-Killian syndrome using interphase FISH on uncultured amniocytes.

  18. Combined fluorescent-chromogenic in situ hybridization for identification and laser microdissection of interphase chromosomes.

    Directory of Open Access Journals (Sweden)

    Nerea Paz

    Full Text Available Chromosome territories constitute the most conspicuous feature of nuclear architecture, and they exhibit non-random distribution patterns in the interphase nucleus. We observed that in cell nuclei from humans with Down Syndrome two chromosomes 21 frequently localize proximal to one another and distant from the third chromosome. To systematically investigate whether the proximally positioned chromosomes were always the same in all cells, we developed an approach consisting of sequential FISH and CISH combined with laser-microdissection of chromosomes from the interphase nucleus and followed by subsequent chromosome identification by microsatellite allele genotyping. This approach identified proximally positioned chromosomes from cultured cells, and the analysis showed that the identity of the chromosomes proximally positioned varies. However, the data suggest that there may be a tendency of the same chromosomes to be positioned close to each other in the interphase nucleus of trisomic cells. The protocol described here represents a powerful new method for genome analysis.

  19. Third-strand in situ hybridization (TISH) to non-denatured metaphase spreads and interphase nuclei.

    Science.gov (United States)

    Johnson, M D; Fresco, J R

    1999-07-01

    A methodology has been developed for binding oligodeoxyribonucleotide 'third strands' to duplex DNA targets in fixed but not additionally denatured metaphase spreads and interphase nuclei under conditions found to be optimal in solution. Third-strand in situ hybridization (TISH) at pH 6.0 of a psoralen- and biotin-modified 16-nucleotide homopyrimidine third strand to a unique multicopy target sequence in human chromosome 17 alpha-satellite (D17Z1 locus) is described. UVA-photofixed third strands, rendered fluorescent by fluorescein isothiocyanate-labeled avidin, are reproducibly centromere-specific for chromosome 17, and visible without amplification of the signal in lymphocyte and somatic cell hybrid spreads and interphase nuclei. Two third-strand-specific D17Z1 haplotypes were identified. TISH has potential diagnostic, biochemical, and flow cytometric applicability to native metaphase and interphase chromatin.

  20. On the matrix-particle interphase in epoxy-based composites

    Energy Technology Data Exchange (ETDEWEB)

    Tognana, S., E-mail: stognana@exa.unicen.edu.a [IFIMAT - Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, B7000GHG Tandil (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas, Tandil (Argentina); Salgueiro, W. [IFIMAT - Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, B7000GHG Tandil (Argentina); Somoza, A. [IFIMAT - Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399, B7000GHG Tandil (Argentina); Comision de Investigaciones Cientificas de la Provincia de Buenos Aires, Tandil (Argentina)

    2010-04-16

    A study on the interphase morphology in epoxy-based composites is presented. Composite samples containing a volume fraction of aluminum particles (typical sizes of 100 {mu}m ca.) between 0% and 30% were prepared. As main experimental technique, differential scanning calorimetry (DSC) was used. Specifically, from the thermograms obtained for each composite, the differences between the heat flow at temperatures above and below the glass transition temperature were determined. From these data, for each composite, and following ideas suggested in the literature, the different thicknesses and volumetric fractions of interphase were estimated. The results obtained show that both morphological parameters strongly increase for a filler volume fraction above 15%. On the other hand, using positron annihilation lifetime spectroscopy technique, additional evidence allowed us to confirm the presence of an interphase region in the composites and estimate the associated free volume which was smaller than that corresponding to the epoxy matrix.

  1. Spectroscopic investigation of the binding interactions of a membrane potential molecule in various supramolecular confined environments: contrasting behavior of surfactant molecules in relocation or release of the probe between nanocarriers and DNA surface.

    Science.gov (United States)

    Ghosh, Surajit; Banik, Debasis; Roy, Arpita; Kundu, Niloy; Kuchlyan, Jagannath; Sarkar, Nilmoni

    2014-12-01

    The fluorescence and optical properties of membrane potential probes are widely used to measure cellular transmembrane potentials. Hemicyanine dyes are also able to bind to membranes. The spectral properties of these molecules depend upon the charge shift from the donor moiety to the acceptor moiety. Changes in their spectral properties, i.e. absorption and emission maxima or intensities, are helpful in characterizing model membranes, microheterogeneous media, etc. In this article, we have demonstrated the binding interaction of a membrane potential probe, 1-ethyl-2-(4-(p-dimethylaminophenyl)-1,3-butadienyl)-pyridinium perchlorate (LDS 698), with various supramolecular confined environments. The larger dipole moment in the ground state compared to the excited state is a unique feature of hemicyanine dyes. Due to this unique feature, red shifts in the absorption maxima are observed in hydrophobic environments, compared with bulk solvent. On addition of surfactants and CT DNA to an aqueous solution containing LDS 698, significant increase in the emission intensity along with the quantum yield and lifetime indicate partition of the probe molecules into organized assemblies. In the case of the sodium dodecyl sulfate (SDS)-water system, due to interactions between the cationic LDS 698 and the anionic dodecyl sulfate moiety, the fluorescence intensity at ∼666 nm decreases and an additional peak at ∼590 nm appears at premicellar concentration (∼0.20 mM-4.50 mM). But at ∼5.50 mM SDS concentration, the absorbance in the higher wavelength region increases again, indicating encapsulation of the probe in micellar aggregates. This observation indicates that the premicellar aggregation behavior of SDS can also be judged by observing the changes in the UV-vis and fluorescence spectral patterns. The temperature dependent study also indicates that non-radiative deactivation of the dye molecules is highly restricted in the DNA micro-environment, compared with micelles

  2. Nuclear reprogramming by interphase cytoplasm of two-cell mouse embryos.

    Science.gov (United States)

    Kang, Eunju; Wu, Guangming; Ma, Hong; Li, Ying; Tippner-Hedges, Rebecca; Tachibana, Masahito; Sparman, Michelle; Wolf, Don P; Schöler, Hans R; Mitalipov, Shoukhrat

    2014-05-01

    Successful mammalian cloning using somatic cell nuclear transfer (SCNT) into unfertilized, metaphase II (MII)-arrested oocytes attests to the cytoplasmic presence of reprogramming factors capable of inducing totipotency in somatic cell nuclei. However, these poorly defined maternal factors presumably decline sharply after fertilization, as the cytoplasm of pronuclear-stage zygotes is reportedly inactive. Recent evidence suggests that zygotic cytoplasm, if maintained at metaphase, can also support derivation of embryonic stem (ES) cells after SCNT, albeit at low efficiency. This led to the conclusion that critical oocyte reprogramming factors present in the metaphase but not in the interphase cytoplasm are 'trapped' inside the nucleus during interphase and effectively removed during enucleation. Here we investigated the presence of reprogramming activity in the cytoplasm of interphase two-cell mouse embryos (I2C). First, the presence of candidate reprogramming factors was documented in both intact and enucleated metaphase and interphase zygotes and two-cell embryos. Consequently, enucleation did not provide a likely explanation for the inability of interphase cytoplasm to induce reprogramming. Second, when we carefully synchronized the cell cycle stage between the transplanted nucleus (ES cell, fetal fibroblast or terminally differentiated cumulus cell) and the recipient I2C cytoplasm, the reconstructed SCNT embryos developed into blastocysts and ES cells capable of contributing to traditional germline and tetraploid chimaeras. Last, direct transfer of cloned embryos, reconstructed with ES cell nuclei, into recipients resulted in live offspring. Thus, the cytoplasm of I2C supports efficient reprogramming, with cell cycle synchronization between the donor nucleus and recipient cytoplasm as the most critical parameter determining success. The ability to use interphase cytoplasm in SCNT could aid efforts to generate autologous human ES cells for regenerative

  3. Mobile Probing and Probes

    DEFF Research Database (Denmark)

    2013-01-01

    to mobile probing being a flexible method for uncovering the unknowns, as a way of getting rich data to the analysis and design phases. On the other hand it is difficult to engage users to give in depth explanations, which seem easier in synchronous dialogs (whether online or face2face). The development...

  4. INTERACTION OF A SCREW DISLOCATION IN THE INTERPHASE LAYER WITH THE INCLUSION AND MATRIX

    Institute of Scientific and Technical Information of China (English)

    蒋持平; 刘又文; 徐耀玲

    2003-01-01

    The interaction of a screw dislocation in the interphase layer with the circular inhomogeneity and matrix was dealt with. An efficient method for multiply connected regions was developed by combining the sectionally subholomorphic function theory, Schwarz symmetric principle and Cauchy integral technique. The Hilbert problem of the complex potentials for three material regions was reduced to a functional equation in the complex potential of the interphase layer, resulting in an explicit series solution. By using the present solution the interaction energy and force acting dislocation were evaluated and discussed.

  5. Laser uv microirradiation of interphase nuclei and post-treatment with caffeine. A new approach to establish the arrangement of interphase chromosomes

    Energy Technology Data Exchange (ETDEWEB)

    Zorn, C.; Cremer, T.; Cremer, C.; Zimmer, J.

    1976-12-29

    Laser uv microirradiation of Chinese hamster interphase cells combined with caffeine post-treatment produced different patterns of chromosome damage in mitosis following irradiation of a small area of the nucleus that may be classified in three categories: (I) intact metaphase figures, (II) chromosome damage confined to a small area of the metaphase spread, (III) mitotic figures with damage on all chromosomes. Category III might be the consequence of a non-localized distortion of nuclear metabolism. By contrast, category II may reflect localized DNA damage induced by microirradiation, which could not be efficiently repaired due to the effect of caffeine. If this interpretation is right, in metaphase figures of category II chromosome damage should occur only at the irradiation site. The effect might then be used to investigate neighbourhood relationships of individual chromosomes in the interphase nucleus.

  6. Probing the roles of Ca(2+) and Mg(2+) in humic acids-induced ultrafiltration membrane fouling using an integrated approach.

    Science.gov (United States)

    Wang, Long-Fei; He, Dong-Qin; Chen, Wei; Yu, Han-Qing

    2015-09-15

    Membrane fouling induced by natural organic matter (NOM) negatively affects the performance of ultrafiltration (UF) technology in producing drinking water. Divalent cation is found to be an important factor that affects the NOM-induced membrane fouling process. In this work, attenuated total reflection-Fourier transformation infrared spectroscopy (ATR-FTIR) coupled with quartz crystal microbalance (QCM), assisted by isothermal titration calorimetry (ITC), is used to explore the contribution of Mg(2+) and Ca(2+), the two abundant divalent cations in natural water, to the UF membrane fouling caused by humic acid (HA) at a molecular level. The results show that Ca(2+) exhibited superior performance in accelerating fouling compared to Mg(2+). The hydrophobic polyethersulfone (PES) membrane exhibited greater complexation with HA in the presence of Mg(2+) and Ca(2+), compared to the hydrophilic cellulose membrane, as evidenced by the more intense polysaccharide C-O, aromatic C=C and carboxylic C=O bands in the FTIR spectra. The QCM and ITC measurements provide quantitative evidence to support that Ca(2+) was more effective than Mg(2+) in binding with HA and accumulating foulants on the membrane surfaces. The higher charge neutralization capacity and more favorable binding ability of Ca(2+) were found to be responsible for its greater contribution to the NOM-induced membrane fouling than Mg(2+). This work offers a new insight into the mechanism of cation-mediated NOM-induced membrane fouling process, and demonstrates that such an integrated ATR-FTIR/QCM/ITC approach could be a useful tool to explore other complicated interaction processes in natural and engineered environments.

  7. Synthesis of Photoactivatable Phospholipidic Probes

    Institute of Scientific and Technical Information of China (English)

    Qing PENG; Fan Qi QU; Yi XIA; Jie Hua ZHOU; Qiong You WU; Ling PENG

    2005-01-01

    We synthesized and characterized photoactivatable phospholipidic probes 1-3. These probes have the perfluorinated aryl azide function at the polar head of phospholipid. They are stable in dark and become highly reactive upon photoirradiation. The preliminary results suggest that they are promising tools to study the topology of membrane proteins and protein-lipid interactions using photolabeling approach.

  8. [Detection of mixed lymphoid chimerism after allogeneic bone marrow transplantation: demonstration by interphase cytogenetics in paraffin-embedded tissue].

    Science.gov (United States)

    Friedrich, T; Ott, G; Kalla, J; Helbig, W; Schwenke, H; Kubel, M; Pönisch, W; Feyer, P; Friedrich, A

    1994-01-01

    In bone marrow transplantation (BMT) the detection of residual host lymphoid or haematopoietic cells surviving conditioning therapy is because of its association to graft-versus-host disease, graft-versus-leukemia reaction, and relapse of leukemia a matter of great interest. We studied the occurrence of this mixed lymphoid chimerism (MC) in the formol-fixed lymphatic tissue of lymph nodes and spleen from 21 autopsies after allogeneic sex-mismatched BMT (5 females, 16 males, survival 5 to 1140 days after BMT). In situ hybridisation with biotinylated centromer-specific anti-X- and anti-Y-chromosome probes was performed on pepsin-digested paraffin sections. The number of double X-, single X-, and Y-chromosome bearing cells was analysed microscopically. Because of artefacts only 14 cases remained for valid investigation. MC was detected in 6 cases (5 out of 11 males 5 days to 840 days and 1 out of 3 females 76 days after BMT). MC occurred after whole body irradiation with 10 Gy (n = 5) and 7 Gy (n = 1). In 1 autopsy relapse of leukemia caused host cell infiltration. Cases with MC did not express histological signs of acute or chronic graft-versus-host disease, but 5 out of 8 with complete lymphoid chimerism did. The sensitivity of interphase cytogenetics on paraffin embedded tissue is low.

  9. Chromosomal Rearrangements in Post-Chernobyl Papillary Thyroid Carcinomas: Evaluation by Spectral Karyotyping and Automated Interphase FISH

    Directory of Open Access Journals (Sweden)

    Ludwig Hieber

    2011-01-01

    Full Text Available Structural genomic rearrangements are frequent findings in human cancers. Therefore, papillary thyroid carcinomas (PTCs were investigated for chromosomal aberrations and rearrangements of the RET proto-oncogene. For this purpose, primary cultures from 23 PTC have been established and metaphase preparations were analysed by spectral karyotyping (SKY. In addition, interphase cell preparations of the same cases were investigated by fluorescence in situ hybridisation (FISH for the presence of RET/PTC rearrangements using RET-specific DNA probes. SKY analysis of PTC revealed structural aberrations of chromosome 11 and several numerical aberrations with frequent loss of chromosomes 20, 21, and 22. FISH analysis for RET/PTC rearrangements showed prevalence of this rearrangement in 72% (16 out of 22 of cases. However, only subpopulations of tumour cells exhibited this rearrangement indicating genetic heterogeneity. The comparison of visual and automated scoring of FISH signals revealed concordant results in 19 out of 22 cases (87% indicating reliable scoring results using the optimised scoring parameter for RET/PTC with the automated Metafer4 system. It can be concluded from this study that genomic rearrangements are frequent in PTC and therefore important events in thyroid carcinogenesis.

  10. Cell cycle regulation of dynein association with membranes modulates microtubule-based organelle transport.

    Science.gov (United States)

    Niclas, J; Allan, V J; Vale, R D

    1996-05-01

    Cytoplasmic dynein is a minus end-directed microtubule motor that performs distinct functions in interphase and mitosis. In interphase, dynein transports organelles along microtubules, whereas in metaphase this motor has been implicated in mitotic spindle formation and orientation as well as chromosome segregation. The manner in which dynein activity is regulated during the cell cycle, however, has not been resolved. In this study, we have examined the mechanism by which organelle transport is controlled by the cell cycle in extracts of Xenopus laevis eggs. Here, we show that photocleavage of the dynein heavy chain dramatically inhibits minus end-directed organelle transport and that purified dynein restores this motility, indicating that dynein is the predominant minus end-directed membrane motor in Xenopus egg extracts. By measuring the amount of dynein associated with isolated membranes, we find that cytoplasmic dynein and its activator dynactin detach from the membrane surface in metaphase extracts. The sevenfold decrease in membrane-associated dynein correlated well with the eightfold reduction in minus end-directed membrane transport observed in metaphase versus interphase extracts. Although dynein heavy or intermediate chain phosphorylation did not change in a cell cycle-dependent manner, the dynein light intermediate chain incorporated approximately 12-fold more radiolabeled phosphate in metaphase than in interphase extracts. These studies suggest that cell cycle-dependent phosphorylation of cytoplasmic dynein may regulate organelle transport by modulating the association of this motor with membranes.

  11. Stable morphology, but dynamic internal reorganisation, of interphase human chromosomes in living cells.

    Directory of Open Access Journals (Sweden)

    Iris Müller

    Full Text Available Despite the distinctive structure of mitotic chromosomes, it has not been possible to visualise individual chromosomes in living interphase cells, where chromosomes spend over 90% of their time. Studies of interphase chromosome structure and dynamics use fluorescence in-situ hybridisation (FISH on fixed cells, which potentially damages structure and loses dynamic information. We have developed a new methodology, involving photoactivation of labelled histone H3 at mitosis, to visualise individual and specific human chromosomes in living interphase cells. Our data revealed bulk chromosome volume and morphology are established rapidly after mitosis, changing only incrementally after the first hour of G1. This contrasted with the behaviour of specific loci on labelled chromosomes, which showed more progressive reorganisation, and revealed that "looping out" of chromatin from chromosome territories is a dynamic state. We measured considerable heterogeneity in chromosome decondensation, even between sister chromatids, which may reflect local structural impediments to decondensation and could potentially amplify transcriptional noise. Chromosome structure showed tremendous resistance to inhibitors of transcription, histone deacetylation and chromatin remodelling. Together, these data indicate steric constraints determine structure, rather than innate chromosome architecture or function-driven anchoring, with interphase chromatin organisation governed primarily by opposition between needs for decondensation and the space available for this to happen.

  12. Epithelial tricellular junctions act as interphase cell shape sensors to orient mitosis.

    Science.gov (United States)

    Bosveld, Floris; Markova, Olga; Guirao, Boris; Martin, Charlotte; Wang, Zhimin; Pierre, Anaëlle; Balakireva, Maria; Gaugue, Isabelle; Ainslie, Anna; Christophorou, Nicolas; Lubensky, David K; Minc, Nicolas; Bellaïche, Yohanns

    2016-02-25

    The orientation of cell division along the long axis of the interphase cell--the century-old Hertwig's rule--has profound roles in tissue proliferation, morphogenesis, architecture and mechanics. In epithelial tissues, the shape of the interphase cell is influenced by cell adhesion, mechanical stress, neighbour topology, and planar polarity pathways. At mitosis, epithelial cells usually adopt a rounded shape to ensure faithful chromosome segregation and to promote morphogenesis. The mechanisms underlying interphase cell shape sensing in tissues are therefore unknown. Here we show that in Drosophila epithelia, tricellular junctions (TCJs) localize force generators, pulling on astral microtubules and orienting cell division via the Dynein-associated protein Mud independently of the classical Pins/Gαi pathway. Moreover, as cells round up during mitosis, TCJs serve as spatial landmarks, encoding information about interphase cell shape anisotropy to orient division in the rounded mitotic cell. Finally, experimental and simulation data show that shape and mechanical strain sensing by the TCJs emerge from a general geometric property of TCJ distributions in epithelial tissues. Thus, in addition to their function as epithelial barrier structures, TCJs serve as polarity cues promoting geometry and mechanical sensing in epithelial tissues.

  13. Demonstrating the Effect of Interphase Mass Transfer in a Transparent Fluidized Bed Reactor

    Science.gov (United States)

    Saayman, Jean; Nicol, Willie

    2011-01-01

    A demonstration experiment is described that employs the ozone decomposition reaction at ambient conditions on Fe2O3 impregnated Fluidized Catalytic Cracking (FCC) catalyst. Using a two-dimensional see-through column the importance of interphase mass transfer is clearly illustrated by the significant difference in ozone conversion between the…

  14. Demonstrating the Effect of Interphase Mass Transfer in a Transparent Fluidized Bed Reactor

    Science.gov (United States)

    Saayman, Jean; Nicol, Willie

    2011-01-01

    A demonstration experiment is described that employs the ozone decomposition reaction at ambient conditions on Fe2O3 impregnated Fluidized Catalytic Cracking (FCC) catalyst. Using a two-dimensional see-through column the importance of interphase mass transfer is clearly illustrated by the significant difference in ozone conversion between the…

  15. Three-Dimensional Organization of Chromosome Territories and the Human Interphase Cell Nucleus

    NARCIS (Netherlands)

    T.A. Knoch (Tobias); C. Münkel (Christian); J. Langowski (Jörg)

    1998-01-01

    textabstractTo study the three-dimensional organization of chromosome territories and the human interphase cell nucleus we developed models which could be compared to experiments. Despite the successful linear sequencing of the human genome its 3D-organization is widely unknown. Using Monte Carl

  16. Three-dimensional organization of chromosome territories in the human interphase cell nucleus

    NARCIS (Netherlands)

    T.A. Knoch (Tobias); C. Münkel (Christian); J. Langowski (Jörg)

    1999-01-01

    markdownabstractTo study the three-dimensional organization of chromosome territories and the human interphase cell nucleus we developed models which could be compared to experiments. Despite the successful linear sequencing of the human genome its 3D-organization is widely unknown. Using Monte Carl

  17. The use of an interphase to improve the transverse properties of unidirectional glass fibre reinforced polymer composites

    Science.gov (United States)

    Ellis, Keith

    The aim of the project was to improve the transverse mechanical properties of unidirectional glass fibre reinforced plastics (G.R.P.)* In addition it was intended that the longitudinal mechanical properties should not be Significantly a result of the transverse improvement The scientific and commercial literature were consulted to determine the most feasible means of improving the transverse properties. Four possible methods were identified, the most promising of which was interfacial modification. Interfacial modification involves the introduction of a third material ("the interphase" ) at the interface between the fibre and the matrix. For this project the interphase material was selected to be compliant or rubbery in nature. The Kies model for predicting the magnification of strain in the resin between fibres was extended to include an interphase. The model was developed for two modes of applied stress. The first was pure tension acting transverse to the fibre axis. The second was shear in the plane transverse to the fibre axis. A novel apparatus was constructed to manufacture composites with a compliant interphase. The apparatus combined a self-regulating coating technique with filament winding to give a continuous production facility. A range of mechanical tests were performed on composites both with and without an interphase. Presence of an interphase improved the following properties: transverse flexural strength, interlaminar and intralaminar shear strength , and transverse fiexural fracture energy. No improvement was noted for pure transverse tension. These results indicated that the interphase acted beneficially only when the composite was stressed in a predominantly shear mode. Conclusions from mechanical test results were supported by S.E.M. fractography. Considerable deformation of the interphase was found in composite tested in shear. This deformation was absent in composite tested in tension. It was postulated that these differences between behaviour

  18. Methods of fiber surface grafting for interphase design and tailored composite response

    Science.gov (United States)

    Arnold, Jesse Judson

    1997-11-01

    The objective of this research was to develop methods of fiber surface grafting for interphase formation, and to experimentally evaluate and model these interphases in order to further elucidate their role in fiber-reinforced composites. Surface modification by sp{60}Co gamma irradiation was used initially to graft acrylic polymers on the surface of ultra-high modulus (UHMPE) fibers. This technique utilized low dose rates and low total doses, and achieved grafting with retention of the exceptional UHMPE properties. The surface properties of the fibers were evaluated using fourier transform infra-red spectroscopy (FTIR), electron spectroscopy for chemical analysis (ESCA), and mechanical tests and dynamic mechanical spectrometry (DMS) of discontinuous fiber composites. Depending on the glass transition temperature, Tg, and chemical structure of the graft, the fiber/matrix adhesion and the interfacial failure mechanism was tailored to provide either enhanced reinforcement or toughening. Using a three-phase block model, the DMS characteristics of the composites were modeled and the reinforcement efficiencies extrapolated as a function of surface treatment. The model successfully predicts the tan delta response of the composite and the appearance of additional loss dispersions associated with the interphase. However, the interactions between the high-energy gamma radiation and the fiber and grafts yield interphases that are difficult to characterize and control. The hydroperoxidation grafting method was subsequently developed, which permitted the grafting of tethered, linear chains by a free radical-type polymerization. Poly(styrene-stat-acrylonitrile) was grafted initially, in which the nitrogen in acrylonitrile was used as a marker to verify grafting and to estimate the grafting efficiency by ESCA analysis. Tapping modesp{TM} atomic force microscopy (TMAFM) images of the grafted fibers revealed a nodular surface topography with dimensions that were correlated to the

  19. Structural Elucidation of the Cell-Penetrating Penetratin Peptide in Model Membranes at the Atomic Level: Probing Hydrophobic Interactions in the Blood-Brain Barrier.

    Science.gov (United States)

    Bera, Swapna; Kar, Rajiv K; Mondal, Susanta; Pahan, Kalipada; Bhunia, Anirban

    2016-09-06

    Cell-penetrating peptides (CPPs) have shown promise in nonpermeable therapeutic drug delivery, because of their ability to transport a variety of cargo molecules across the cell membranes and their noncytotoxicity. Drosophila antennapedia homeodomain-derived CPP penetratin (RQIKIWFQNRRMKWKK), being rich in positively charged residues, has been increasingly used as a potential drug carrier for various purposes. Penetratin can breach the tight endothelial network known as the blood-brain barrier (BBB), permitting treatment of several neurodegenerative maladies, including Alzheimer's disease, Parkinson's disease, and Huntington's disease. However, a detailed structural understanding of penetratin and its mechanism of action is lacking. This study defines structural features of the penetratin-derived peptide, DK17 (DRQIKIWFQNRRMKWKK), in several model membranes and describes a membrane-induced conformational transition of the DK17 peptide in these environments. A series of biophysical experiments, including high-resolution nuclear magnetic resonance spectroscopy, provides the three-dimensional structure of DK17 in different membranes mimicking the BBB or total brain lipid extract. Molecular dynamics simulations support the experimental results showing preferential binding of DK17 to particular lipids at atomic resolution. The peptide conserves the structure of the subdomain spanning residues Ile6-Arg11, despite considerable conformational variation in different membrane models. In vivo data suggest that the wild type, not a mutated sequence, enters the central nervous system. Together, these data highlight important structural and functional attributes of DK17 that could be utilized in drug delivery for neurodegenerative disorders.

  20. Identification of interphase functions for the NIMA kinase involving microtubules and the ESCRT pathway.

    Directory of Open Access Journals (Sweden)

    Meera Govindaraghavan

    2014-03-01

    Full Text Available The Never in Mitosis A (NIMA kinase (the founding member of the Nek family of kinases has been considered a mitotic specific kinase with nuclear restricted roles in the model fungus Aspergillus nidulans. By extending to A. nidulans the results of a synthetic lethal screen performed in Saccharomyces cerevisiae using the NIMA ortholog KIN3, we identified a conserved genetic interaction between nimA and genes encoding proteins of the Endosomal Sorting Complex Required for Transport (ESCRT pathway. Absence of ESCRT pathway functions in combination with partial NIMA function causes enhanced cell growth defects, including an inability to maintain a single polarized dominant cell tip. These genetic insights suggest NIMA potentially has interphase functions in addition to its established mitotic functions at nuclei. We therefore generated endogenously GFP-tagged NIMA (NIMA-GFP which was fully functional to follow its interphase locations using live cell spinning disc 4D confocal microscopy. During interphase some NIMA-GFP locates to the tips of rapidly growing cells and, when expressed ectopically, also locates to the tips of cytoplasmic microtubules, suggestive of non-nuclear interphase functions. In support of this, perturbation of NIMA function either by ectopic overexpression or through partial inactivation results in marked cell tip growth defects with excess NIMA-GFP promoting multiple growing cell tips. Ectopic NIMA-GFP was found to locate to the plus ends of microtubules in an EB1 dependent manner, while impairing NIMA function altered the dynamic localization of EB1 and the cytoplasmic microtubule network. Together, our genetic and cell biological analyses reveal novel non-nuclear interphase functions for NIMA involving microtubules and the ESCRT pathway for normal polarized fungal cell tip growth. These insights extend the roles of NIMA both spatially and temporally and indicate that this conserved protein kinase could help integrate cell

  1. Identification of interphase functions for the NIMA kinase involving microtubules and the ESCRT pathway.

    Directory of Open Access Journals (Sweden)

    Meera Govindaraghavan

    2014-03-01

    Full Text Available The Never in Mitosis A (NIMA kinase (the founding member of the Nek family of kinases has been considered a mitotic specific kinase with nuclear restricted roles in the model fungus Aspergillus nidulans. By extending to A. nidulans the results of a synthetic lethal screen performed in Saccharomyces cerevisiae using the NIMA ortholog KIN3, we identified a conserved genetic interaction between nimA and genes encoding proteins of the Endosomal Sorting Complex Required for Transport (ESCRT pathway. Absence of ESCRT pathway functions in combination with partial NIMA function causes enhanced cell growth defects, including an inability to maintain a single polarized dominant cell tip. These genetic insights suggest NIMA potentially has interphase functions in addition to its established mitotic functions at nuclei. We therefore generated endogenously GFP-tagged NIMA (NIMA-GFP which was fully functional to follow its interphase locations using live cell spinning disc 4D confocal microscopy. During interphase some NIMA-GFP locates to the tips of rapidly growing cells and, when expressed ectopically, also locates to the tips of cytoplasmic microtubules, suggestive of non-nuclear interphase functions. In support of this, perturbation of NIMA function either by ectopic overexpression or through partial inactivation results in marked cell tip growth defects with excess NIMA-GFP promoting multiple growing cell tips. Ectopic NIMA-GFP was found to locate to the plus ends of microtubules in an EB1 dependent manner, while impairing NIMA function altered the dynamic localization of EB1 and the cytoplasmic microtubule network. Together, our genetic and cell biological analyses reveal novel non-nuclear interphase functions for NIMA involving microtubules and the ESCRT pathway for normal polarized fungal cell tip growth. These insights extend the roles of NIMA both spatially and temporally and indicate that this conserved protein kinase could help integrate cell

  2. [Clinical value of interphase fluorescent in situ hybridization in diagnosis of core-binding factor acute myelocytic leukemia].

    Science.gov (United States)

    Yang, Hui; Fan, Lei; Qiu, Hai-Rong; Wang, Rong; Zhang, Jian-Fu; Wu, Yu-Jie; Li, Jian-Yong; Liu, Peng

    2011-10-01

    The purpose of this study was to evaluate the clinical value of interphase fluorescence in situ hybridization (I-FISH) in diagnosis of core-binding factor acute myelocytic leukemia (CBF AML). The cytogenetic characteristics in leukemia cells from 82 cases of AML-M(2) and 43 cases of AML-M(4)/M(5) were detected by using I-FISH with AML1-ETO double color double fusion probe and double color break point isolated gene probe CBFβ-MYH11, and the detected results were compared with results detected by conventional cytogenetic R banding technique (CC). The results indicated that AML1-ETO fusion gene was detected in 30.5% cases (25/82) by FISH, and t(8;21)(q22;q22) karyotypic aberrations was found in 28.0% cases (23/82) by CC method. Among 25 FISH positive cases, typical FISH positive signal pattern (1R1G2F) was displayed in 22 cases and atypical signal pattern (1R2G1F and 2R1G2F) was found in the other 3 cases. Among all 43 AML-M(4)/M(5) cases, the CBFβ-MYH11 fusion gene was detected in 23.3% cases (10/43) by FISH, which sensitivity was significant higher than that by CC method (2/43) (p < 0.05). It is concluded that some insufficiency of CC technique can be compensated by FISH, and combination of I-FISH with CC technique play a crucial role in diagnosis of CBF AML and in monitoring of minimal residual disease.

  3. Biodosimetry of heavy ions by interphase chromosome painting

    Science.gov (United States)

    Durante, M.; Kawata, T.; Nakano, T.; Yamada, S.; Tsujii, H.

    1998-11-01

    We report measurements of chromosomal aberrations in peripheral blood lymphocytes from cancer patients undergoing radiotherapy treatment. Patients with cervix or esophageal cancer were treated with 10 MV X-rays produced at a LINAC accelerator, or high-energy carbon ions produced at the HIMAC accelerator at the National Institute for Radiological Sciences (NIRS) in Chiba. Blood samples were obtained before, during, and after the radiation treatment. Chromosomes were prematurely condensed by incubation in calyculin A. Aberrations in chromosomes 2 and 4 were scored after fluorescence in situ hybridization with whole-chromosome probes. Pre-treatment samples were exposed in vitro to X-rays, individual dose-response curves for the induction of chromosomal aberrations were determined, and used as calibration curves to calculate the effective whole-body dose absorbed during the treatment. This calculated dose, based on the calibration curve relative to the induction of reciprocal exchanges, has a sharp increase after the first few fractions of the treatment, then saturates at high doses. Although carbon ions are 2-3 times more effective than X-rays in tumor sterilization, the effective dose was similar to that of X-ray treatment. However, the frequency of complex-type chromosomal exchanges was much higher for patients treated with carbon ions than X-ray.

  4. Mechanical characterization of Si-C(O) fiber/SiC (CVI) matrix composites with a BN-interphase

    Energy Technology Data Exchange (ETDEWEB)

    Prouhet, S.; Camus, G.; Labrugere, C.; Guette, A. (Lab. des Composites Thermostructuraux, Pessac (France)); Martin, E. (Univ. de Bordeaux, Talence (France). Lab. de Genie Mechanique de l' IUT A)

    1994-03-01

    The mechanical behavior of three CVI-processed 2D woven SiC/BN/SiC composite materials with different initial BN interphase thicknesses has been investigated by means of tensile and impact tests. The results have established the efficiency of a BN interphase in promoting a nonlinear/noncatastrophic tensile behavior and high impact resistance. The effect of the initial BN interphase thickness on the resulting mechanical behavior has also been demonstrated. AES and TEM has revealed the presence of a SiO[sub 2]/C double layer at the BN/fiber interface, which might result from a decomposition undergone by the Si-C(O) Nicalon fiber during processing. It has been suggested that the influence of the initial BN interphase thickness on the mechanical properties of the composites results from both changes occurring in the composition and morphology of the interfacial zones and modifications of the interfacial forces due to accommodation of the radial residual clamping stress.

  5. Chromosome mapping by FISH to metaphase and interphase nuclei. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Trask, B.

    1997-08-01

    The overall specific aims of this project were: (1) to determine the large-scale structure of interphase and metaphase chromosomes, in order to establish new capabilities for genome mapping by fluorescence in situ hybridization (FISH); (2) to detect chromosome abnormalities associated with genetic disease and map DNA sequences relative to them in order to facilitate the identification of new genes with disease-causing mutations; (3) to establish medium resolution physical maps of selected chromosomal regions using a combined metaphase and interphase mapping strategy and to corroborate physical and genetic maps and integrate these maps with the cytogenetic map; (4) to analyze the polymorphism and sequence evolution of subtelomeric regions of human chromosomes; (5) to establish a state-of-the-art FISH and image processing facility in the Department of Molecular Biotechnology, University of Washington, in order to map DNA sequences rapidly and accurately to benefit the Human Genome Project.

  6. A model for interphase precipitation based on finite interface solute drag theory

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, R., E-mail: okamoto.riki@nsc.co.jp [Department of Materials Science and Engineering, KTH (Royal Institute of Technology), SE-10044 Stockholm (Sweden)] [Steel Products Lab.-1, Nippon Steel Corporation, 20-1, Shintomi, Futtu-shi, Chiba-ken 476-8686 (Japan); Agren, J. [Department of Materials Science and Engineering, KTH (Royal Institute of Technology), SE-10044 Stockholm (Sweden)

    2010-08-15

    A model for interphase precipitation with the ledge mechanism, based on a eutectoid reaction, has been developed and combined with the finite interface solute drag model and a numerical solution of the diffusion equations inside the migrating phase interface. In the model, niobium flows in two directions, i.e. perpendicular to the direction of the ledge migration by eutectoid-like reaction and simultaneously parallel to the direction of the ledge migration inside the ledge interface. The difference between ledge transformation and typical phase transformation is compared using this model and the effects of row spacing, temperature and segregation energy are discussed. The calculation results using the model are compared with experimental results and the critical driving force for interphase precipitation is evaluated. The estimations of the niobium carbide precipitation using this model are in good agreement with experimental results.

  7. Multiscale modeling of microscale fiber reinforced composites with nano-engineered interphases

    CERN Document Server

    Kundalwalal, S I; Wardle, B L

    2015-01-01

    This study is focused on the mechanical properties and stress transfer behavior of multiscale composite containing nano- and micro-scale fillers. A novel concept has been proposed to exploit the remarkable mechanical properties of carbon nanotubes (CNTs) to improve the stress transfer through the interphases, enabling their additional functionalities not available otherwise at the microscale. The distinctive feature of construction of this composite is such that CNTs are dispersed around the microscale fiber to modify fiber-matrix interfacial adhesion. Accordingly, models are developed for hybrid composites. First, molecular dynamics simulations in conjunction with the Mori-Tanaka method are used to determine the effective elastic properties of nano-engineered interphase layer comprised of CNT bundles and epoxy. Subsequently, a micromechanical pull-out model is developed for the resulting multiscale composite and its stress transfer behavior is studied for different orientations of CNT bundles. The current pu...

  8. Micromechanics Modeling of Functionally Graded Interphase Regions in Carbon Nanotube-Polymer Composites

    Science.gov (United States)

    Seidel, Gary D.; Lagoudas, Dimitris C.; Frankland, Sarah Jane V.; Gates, Thomas S.

    2006-01-01

    The effective elastic properties of a unidirectional carbon fiber/epoxy lamina in which the carbon fibers are coated with single-walled carbon nanotubes are modeled herein through the use of a multi-scale method involving the molecular dynamics/equivalent continuum and micromechanics methods. The specific lamina representative volume element studied consists of a carbon fiber surrounded by a region of epoxy containing a radially varying concentration of carbon nanotubes which is then embedded in the pure epoxy matrix. The variable concentration of carbon nanotubes surrounding the carbon fiber results in a functionally graded interphase region as the properties of the interphase region vary according to the carbon nanotube volume fraction. Molecular dynamics and equivalent continuum methods are used to assess the local effective properties of the carbon nanotube/epoxy comprising the interphase region. Micromechanics in the form of the Mori-Tanaka method are then applied to obtain the global effective properties of the graded interphase region wherein the carbon nanotubes are randomly oriented. Finally, the multi-layer composite cylinders micromechanics approach is used to obtain the effective lamina properties from the lamina representative volume element. It was found that even very small quantities of carbon nanotubes (0.36% of lamina by volume) coating the surface of the carbon fibers in the lamina can have a significant effect (8% increase) on the transverse properties of the lamina (E22, k23, G23 and G12) with almost no affect on the lamina properties in the fiber direction (E11 and v12).

  9. Combined Fluorescent-Chromogenic In Situ Hybridization for Identification and Laser Microdissection of Interphase Chromosomes

    OpenAIRE

    Nerea Paz; Amaia Zabala; Félix Royo; África García-Orad; Zugaza, José L.; Parada, Luis A.

    2013-01-01

    Chromosome territories constitute the most conspicuous feature of nuclear architecture, and they exhibit non-random distribution patterns in the interphase nucleus. We observed that in cell nuclei from humans with Down Syndrome two chromosomes 21 frequently localize proximal to one another and distant from the third chromosome. To systematically investigate whether the proximally positioned chromosomes were always the same in all cells, we developed an approach consisting ...

  10. Chromosomes at Work: Organization of Chromosome Territories in the Interphase Nucleus.

    Science.gov (United States)

    Fritz, Andrew J; Barutcu, A Rasim; Martin-Buley, Lori; van Wijnen, André J; Zaidi, Sayyed K; Imbalzano, Anthony N; Lian, Jane B; Stein, Janet L; Stein, Gary S

    2016-01-01

    The organization of interphase chromosomes in chromosome territories (CTs) was first proposed more than one hundred years ago. The introduction of increasingly sophisticated microscopic and molecular techniques, now provide complementary strategies for studying CTs in greater depth than ever before. Here we provide an overview of these strategies and how they are being used to elucidate CT interactions and the role of these dynamically regulated, nuclear-structure building blocks in directly supporting nuclear function in a physiologically responsive manner.

  11. Exclusion of NFAT5 from mitotic chromatin resets its nucleo-cytoplasmic distribution in interphase.

    Directory of Open Access Journals (Sweden)

    Anaïs Estrada-Gelonch

    Full Text Available BACKGROUND: The transcription factor NFAT5 is a major inducer of osmoprotective genes and is required to maintain the proliferative capacity of cells exposed to hypertonic stress. In response to hypertonicity, NFAT5 translocates to the nucleus, binds to regulatory regions of osmoprotective genes and activates their transcription. Besides stimulus-specific regulatory mechanisms, the activity of transcription factors in cycling cells is also regulated by the passage through mitosis, when most transcriptional processes are downregulated. It was not known whether mitosis could be a point of control for NFAT5. METHODOLOGY/PRINCIPAL FINDINGS: Using confocal microscopy we observed that NFAT5 was excluded from chromatin during mitosis in both isotonic and hypertonic conditions. Analysis of NFAT5 deletions showed that exclusion was mediated by the carboxy-terminal domain (CTD. NFAT5 mutants lacking this domain showed constitutive binding to mitotic chromatin independent of tonicity, which caused them to localize in the nucleus and remain bound to chromatin in the subsequent interphase without hypertonic stimulation. We analyzed the contribution of the CTD, DNA binding, and nuclear import and export signals to the subcellular localization of this factor. Our results indicated that cytoplasmic localization of NFAT5 in isotonic conditions required both the exclusion from mitotic DNA and active nuclear export in interphase. Finally, we identified several regions within the CTD of NFAT5, some of them overlapping with transactivation domains, which were separately capable of causing its exclusion from mitotic chromatin. CONCLUSIONS/SIGNIFICANCE: Our results reveal a multipart mechanism regulating the subcellular localization of NFAT5. The transactivating module of NFAT5 switches its function from an stimulus-specific activator of transcription in interphase to an stimulus-independent repressor of binding to DNA in mitosis. This mechanism, together with export

  12. Interphase and magnetotransport of LSMO-PMMA nanocomposites obtained by a sonochemical method

    Energy Technology Data Exchange (ETDEWEB)

    Romero, Mariano [Centro NanoMat/Cryssmat Lab/Cátedra de Física – DETEMA – Facultad de Química – Universidad de la República (Uruguay); Centro Interdisciplinario de Nanotecnología, Química y Física de Materiales – Universidad de la República (Uruguay); Pardo, Helena, E-mail: hpardo@fq.edu.uy [Centro NanoMat/Cryssmat Lab/Cátedra de Física – DETEMA – Facultad de Química – Universidad de la República (Uruguay); Centro Interdisciplinario de Nanotecnología, Química y Física de Materiales – Universidad de la República (Uruguay); Faccio, Ricardo [Centro NanoMat/Cryssmat Lab/Cátedra de Física – DETEMA – Facultad de Química – Universidad de la República (Uruguay); Centro Interdisciplinario de Nanotecnología, Química y Física de Materiales – Universidad de la República (Uruguay); Tumelero, Milton A. [Laboratorio de filmes finos e superficies – Departamento de Física – Universidad Federal de Santa Catarina, Florianópolis (Brazil); and others

    2015-05-15

    In this report, we studied the structural, microstructural and compositional trends in a manganite-polymethylmethacrilate (LSMO-PMMA) nanocomposite prepared by a sonochemical method focusing in the study of its interphase and its correlation with magnetotransport. Differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Raman scattering and X-ray powder diffraction (XRPD) studies showed evidence of PMMA reactivity with partial decomposition at the LSMO nanoparticles interface. Additionally, grazing incidence small angle X-ray scattering (GISAXS) and high resolution transmission electron microscopy (HRTEM) showed information about the microstructure and the separation between nanoparticles in these nanocomposite materials. An enhancement in the low field magnetoresistance (LFMR) respect to pure LSMO was observed for a 20% weight fraction addition of PMMA in the high temperature regime (205–305 K) probably due to the increase in the magnetic disorder at the grain boundaries caused by the ultrasonic treatment. Nevertheless, lower PMMA weight fraction addition showed no enhancement in LFMR respect to pure LSMO, probably in agreement with the higher decomposition rate observed at the interphase. - Highlights: • We report the synthesis of LSMO-PMMA nanocomposites by a sonochemical method. • Compositional and microstructural trends were obtained from the interphase. • This method showed long-range homogeneity and enhancement of grain boundary disorder. • The enhancement on the LFMR respect to pure manganite was obtained at higher temperatures.

  13. Amorphous/crystal and polymer/filler interphases in biocomposites from poly(butylene succinate)

    Energy Technology Data Exchange (ETDEWEB)

    Signori, Francesca [Consiglio Nazionale delle Ricerche - Istituto per i Processi Chimico-Fisici (CNR-IPCF), Via G. Moruzzi 1, I-56124 Pisa (Italy); Pelagaggi, Martina [Universita di Pisa - Dipartimento di Chimica e Chimica Industriale, Via Risorgimento 35, I-56126 Pisa (Italy); Bronco, Simona [Consiglio Nazionale delle Ricerche - Istituto per i Processi Chimico-Fisici (CNR-IPCF), Via G. Moruzzi 1, I-56124 Pisa (Italy); Righetti, Maria Cristina, E-mail: righetti@ipcf.cnr.it [Consiglio Nazionale delle Ricerche - Istituto per i Processi Chimico-Fisici (CNR-IPCF), Via G. Moruzzi 1, I-56124 Pisa (Italy)

    2012-09-10

    Highlights: Black-Right-Pointing-Pointer The existence of intermolecular interactions between poly(butylene succinate) and hemp fibres was proved from specific heat capacities data. Black-Right-Pointing-Pointer Different degrees of mobility of the poly(butylene succinate) amorphous segments were evidenced at the amorphous/crystal interphase. Black-Right-Pointing-Pointer Devitrification of the rigid amorphous fraction in poly(butylene succinate) was found to occur before and simultaneously with the fusion. - Abstract: Poly(butylene succinate)-hemp composites (PBS-hemp), with hemp content in the range 0-40 wt.%, were prepared in the melt and characterized. This paper focuses on the detailed analysis of the thermal behaviour of the PBS-hemp composites, investigated by differential scanning calorimetry (DSC), to enlighten the polymer/fibre interphase features. The occurrence of specific intermolecular interactions between PBS and hemp was assessed from specific heat capacity data. Different degrees of mobility of the PBS amorphous segments were found at the amorphous/crystal interphases. A broadening of the bulk glass transition was observed, and attributed to the presence of polymer segments slightly constrained. Moreover, a rigid amorphous fraction that devitrifies at temperatures higher than the bulk glass transition, partly before the melting region and partly simultaneously with the fusion, was observed and quantified, and attributed to the presence of major constraints probably occurring in geometrically restricted areas.

  14. Oxygen as a paramagnetic probe for nuclear magnetic resonance: structure and paramagnetic profile of a lipid bilayer/membrane model system

    Energy Technology Data Exchange (ETDEWEB)

    Al-Abdul Wahid, M.S

    2005-07-01

    Paramagnetic contact shifts and relaxation rate enhancements from molecular oxygen dissolved in a model membrane, were studied by nuclear magnetic resonance spectroscopy. The model membrane system was an isotropic bicelle formed using 1-myristelaidoyl-2-myristoyl-d27-sn- glycero-3-phosphocholine (MLMPC), a custom phospholipid, and 1-2-dihexanoyl-d22-sn-glycero-3-phosphocholine (DHPC). The {sup 13}C and {sup 1}H spectra of MLMPC were assigned. Molecular oxygen was delivered at external pressures of 20 and 50 atm. Paramagnetic contact shifts were found to scale with the oxygen solubility gradient in the lipid bilayer, were found to be invariant to temperature changes in the region studied (288K to 331K), and scaled linearly with changes in oxygen pressure. Relaxation rate enhancements from oxygen were low in the headgroup region and increased to a roughly constant rate in the acyl chain region. Rates were comparable to values predicted by simple thermodynamic theories which take into account the observed gradients in diffusion rates and solubility of oxygen in bilayers. (author)

  15. Photosynthetic reaction center functionalized nano-composite films: effective strategies for probing and exploiting the photo-induced electron transfer of photosensitive membrane protein.

    Science.gov (United States)

    Lu, Yidong; Xu, Jingjing; Liu, Baohong; Kong, Jilie

    2007-02-15

    Photosynthetic reaction center (RC), a robust transmembrane pigment-protein complex, works as the crucial component participating the primary event of the photo-electrochemical conversion in bacteria. Sparked by the high photo-induced charge separation yield (ca. 100%) of RC, great interests have been aroused to fabricate versatile RC-functionalized nano-composite films for exploring the initial photosynthetic electron transfer (ET) of RC, and thus exploiting well-designed bio-photoelectric converters. In this review, we classify and summarize the current status about the concepts and methods of constructing RC-immobilized nano-composite films or devices for probing the photo-induced ET, and applying to novel bioelectronics if it is possible.

  16. The Kemp elimination in membrane mimetic reaction media. Probing catalytic properties of cationic vesicles formed from a double-tailed amphiphile and linear long-tailed alcohols or alkyl pyranosides.

    Science.gov (United States)

    Klijn, Jaap E; Engberts, Jan B F N

    2004-06-21

    Vesicles formed from synthetic, double-tailed amphiphiles are often used as mimics for biological membranes. However, biological membranes are a complex mixture of various compounds. In the present paper we describe a first attempt to study the importance of additives on vesicular catalysis. The rate-determining deprotonation of 5-nitrobenzisoxazole (Kemp elimination) by hydroxide ion is efficiently catalysed by vesicles formed from dimethyldi-n-octadecylammonium chloride (C(18)C(18)(+)) as a result of (partial) dehydration of the reactants (especially the hydroxide ion) at the vesicular binding sites. Gradual addition of linear alcohols, such as n-decanol (C(10)OH), n-octadecanol (C(18)OH) and batyl alcohol (C(18)GlyOH) leads to a decrease in the observed catalysis. By contrast, gradual addition of oleyl alcohol, n-dodecyl-beta-glucoside (C(12)Glu) and n-dodecyl-beta-maltoside (C(12)Mal) leads to an increase in the observed catalysis. A detailed kinetic analysis, taking into account substrate binding site polarities, counterion binding percentages and binding affinity of the kinetic probe, suggests that the catalytic changes depend strongly on subtle changes in the structure of the additive. Whereas the C(12)Glu-induced effect can be explained by an increase in the vesicular rate constant, the effect of C(12)Mal can only be explained by an increase in the binding constant of the kinetic probe. However, for these pyranoside-containing vesicles others factors, such as a more extensive dehydration of the hydroxide ion, and micelle formation have to be considered. For the linear alcohols, besides a decrease in the counterion binding, changes in the vesicular rate constant and the binding constant should be taken into account. These two parameters change to a different extent for the different alcohols. The kinetic analysis is supported by differential scanning calorimetry (DSC), E(T)(30) absorbance data and Nile Red, Laurdan, ANS and pyrene fluorescence measurements

  17. Chromosome-specific DNA Repeat Probes

    Energy Technology Data Exchange (ETDEWEB)

    Baumgartner, Adolf; Weier, Jingly Fung; Weier, Heinz-Ulrich G.

    2006-03-16

    In research as well as in clinical applications, fluorescence in situ hybridization (FISH) has gained increasing popularity as a highly sensitive technique to study cytogenetic changes. Today, hundreds of commercially available DNA probes serve the basic needs of the biomedical research community. Widespread applications, however, are often limited by the lack of appropriately labeled, specific nucleic acid probes. We describe two approaches for an expeditious preparation of chromosome-specific DNAs and the subsequent probe labeling with reporter molecules of choice. The described techniques allow the preparation of highly specific DNA repeat probes suitable for enumeration of chromosomes in interphase cell nuclei or tissue sections. In addition, there is no need for chromosome enrichment by flow cytometry and sorting or molecular cloning. Our PCR-based method uses either bacterial artificial chromosomes or human genomic DNA as templates with {alpha}-satellite-specific primers. Here we demonstrate the production of fluorochrome-labeled DNA repeat probes specific for human chromosomes 17 and 18 in just a few days without the need for highly specialized equipment and without the limitation to only a few fluorochrome labels.

  18. Probing Structural Dynamics and Topology of the KCNE1 Membrane Protein in Lipid Bilayers via Site-Directed Spin Labeling and Electron Paramagnetic Resonance Spectroscopy.

    Science.gov (United States)

    Sahu, Indra D; Craig, Andrew F; Dunagan, Megan M; Troxel, Kaylee R; Zhang, Rongfu; Meiberg, Andrew G; Harmon, Corrinne N; McCarrick, Robert M; Kroncke, Brett M; Sanders, Charles R; Lorigan, Gary A

    2015-10-20

    KCNE1 is a single transmembrane protein that modulates the function of voltage-gated potassium channels, including KCNQ1. Hereditary mutations in the genes encoding either protein can result in diseases such as congenital deafness, long QT syndrome, ventricular tachyarrhythmia, syncope, and sudden cardiac death. Despite the biological significance of KCNE1, the structure and dynamic properties of its physiologically relevant native membrane-bound state are not fully understood. In this study, the structural dynamics and topology of KCNE1 in bilayered lipid vesicles was investigated using site-directed spin labeling (SDSL) and electron paramagnetic resonance (EPR) spectroscopy. A 53-residue nitroxide EPR scan of the KCNE1 protein sequence including all 27 residues of the transmembrane domain (45-71) and 26 residues of the N- and C-termini of KCNE1 in lipid bilayered vesicles was analyzed in terms of nitroxide side-chain motion. Continuous wave-EPR spectral line shape analysis indicated the nitroxide spin label side-chains located in the KCNE1 TMD are less mobile when compared to the extracellular region of KCNE1. The EPR data also revealed that the C-terminus of KCNE1 is more mobile when compared to the N-terminus. EPR power saturation experiments were performed on 41 sites including 18 residues previously proposed to reside in the transmembrane domain (TMD) and 23 residues of the N- and C-termini to determine the topology of KCNE1 with respect to the 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (POPG) lipid bilayers. The results indicated that the transmembrane domain is indeed buried within the membrane, spanning the width of the lipid bilayer. Power saturation data also revealed that the extracellular region of KCNE1 is solvent-exposed with some of the portions partially or weakly interacting with the membrane surface. These results are consistent with the previously published solution NMR

  19. Simultaneous localization of MLL, AF4 and ENL genes in interphase nuclei by 3D-FISH: MLL translocation revisited

    Directory of Open Access Journals (Sweden)

    Sun Jian-Sheng

    2006-01-01

    Full Text Available Abstract Background Haematological cancer is characterised by chromosomal translocation (e.g. MLL translocation in acute leukaemia and two models have been proposed to explain the origins of recurrent reciprocal translocation. The first, established from pairs of translocated genes (such as BCR and ABL, considers the spatial proximity of loci in interphase nuclei (static "contact first" model. The second model is based on the dynamics of double strand break ends during repair processes (dynamic "breakage first" model. Since the MLL gene involved in 11q23 translocation has more than 40 partners, the study of the relative positions of the MLL gene with both the most frequent partner gene (AF4 and a less frequent partner gene (ENL, should elucidate the MLL translocation mechanism. Methods Using triple labeling 3D FISH experiments, we have determined the relative positions of MLL, AF4 and ENL genes, in two lymphoblastic and two myeloid human cell lines. Results In all cell lines, the ENL gene is significantly closer to the MLL gene than the AF4 gene (with P value loci would indicate a greater probability of the occurrence of t(11;19(q23;p13.3 compared to t(4;11(q21;q23. However this is in contradiction to the epidemiology of 11q23 translocation. Conclusion The simultaneous multi-probe hybridization in 3D-FISH is a new approach in addressing the correlation between spatial proximity and occurrence of translocation. Our observations are not consistent with the static "contact first" model of translocation. The recently proposed dynamic "breakage first" model offers an attractive alternative explanation.

  20. Probe Storage

    NARCIS (Netherlands)

    Gemelli, Marcellino; Abelmann, Leon; Engelen, Johan B.C.; Khatib, Mohammed G.; Koelmans, Wabe W.; Zaboronski, Olog; Campardo, Giovanni; Tiziani, Federico; Laculo, Massimo

    2011-01-01

    This chapter gives an overview of probe-based data storage research over the last three decades, encompassing all aspects of a probe recording system. Following the division found in all mechanically addressed storage systems, the different subsystems (media, read/write heads, positioning, data chan

  1. Cultural probes

    DEFF Research Database (Denmark)

    Madsen, Jacob Østergaard

    2016-01-01

    The aim of this study was thus to explore cultural probes (Gaver, Boucher et al. 2004), as a possible methodical approach, supporting knowledge production on situated and contextual aspects of occupation.......The aim of this study was thus to explore cultural probes (Gaver, Boucher et al. 2004), as a possible methodical approach, supporting knowledge production on situated and contextual aspects of occupation....

  2. Effects of aneuploidy on genome structure, expression, and interphase organization in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Bruno Huettel

    2008-10-01

    Full Text Available Aneuploidy refers to losses and/or gains of individual chromosomes from the normal chromosome set. The resulting gene dosage imbalance has a noticeable affect on the phenotype, as illustrated by aneuploid syndromes, including Down syndrome in humans, and by human solid tumor cells, which are highly aneuploid. Although the phenotypic manifestations of aneuploidy are usually apparent, information about the underlying alterations in structure, expression, and interphase organization of unbalanced chromosome sets is still sparse. Plants generally tolerate aneuploidy better than animals, and, through colchicine treatment and breeding strategies, it is possible to obtain inbred sibling plants with different numbers of chromosomes. This possibility, combined with the genetic and genomics tools available for Arabidopsis thaliana, provides a powerful means to assess systematically the molecular and cytological consequences of aberrant numbers of specific chromosomes. Here, we report on the generation of Arabidopsis plants in which chromosome 5 is present in triplicate. We compare the global transcript profiles of normal diploids and chromosome 5 trisomics, and assess genome integrity using array comparative genome hybridization. We use live cell imaging to determine the interphase 3D arrangement of transgene-encoded fluorescent tags on chromosome 5 in trisomic and triploid plants. The results indicate that trisomy 5 disrupts gene expression throughout the genome and supports the production and/or retention of truncated copies of chromosome 5. Although trisomy 5 does not grossly distort the interphase arrangement of fluorescent-tagged sites on chromosome 5, it may somewhat enhance associations between transgene alleles. Our analysis reveals the complex genomic changes that can occur in aneuploids and underscores the importance of using multiple experimental approaches to investigate how chromosome numerical changes condition abnormal phenotypes and

  3. Wetting properties of model interphases coated with defined organic functional groups

    Science.gov (United States)

    Woche, Susanne K.; Goebel, Marc-O.; Guggenberger, Georg; Tunega, Daniel; Bachmann, Joerg

    2013-04-01

    Surface properties of soil particles are of particular interest regarding transport of water and sorption of solutes, especially hazardous xenobiotic species. Wetting properties (e.g. determined by contact angle, CA), governed by the functional groups exposed, are crucial to understand sorption processes in water repellent soils as well as for the geometry of water films sustaining microbial processes on the pore scale. Natural soil particle surfaces are characterized by a wide variety of mineralogical and chemical compounds. Their composition is almost impossible to identify in full. Hence, in order to get a better understanding about surface properties, an option is the usage of defined model surfaces, whereas the created surface should be comparable to natural soil interphases. We exposed smooth glass surfaces to different silane compounds, resulting in a coating covalently bound to the surface and exhibiting defined organic functional groups towards the pore space. The wetting properties as evaluated by CA and the surface free energy (SFE), calculated according to the Acid-Base Theory, were found to be a function of the specific functional group. Specifically, the treated surfaces showed a large variation of CA and SFE as function of chain length and polarity of the organic functional group. The study of wetting properties was accompanied by XPS analysis for selective detection of chemical compounds of the interphase. As the reaction mechanism of the coating process is known, the resulting interphase structure can be modeled based on energetic considerations. A next step is to use same coatings for the defined modification of the pore surfaces of porous media to study transport and sorption processes in complex three phase systems.

  4. Artificial solid electrolyte interphase with in-situ formed porosity for enhancing lithiation of silicon wafer

    Science.gov (United States)

    Lin, Jie; Guo, Jianlai; Liu, Chang; Guo, Hang

    2016-12-01

    In order to utilize silicon wafer as electrode and substrate for integrated lithium-ion batteries, a composite film with in-situ formed porosity (lithium phosphorous oxynitride/tin oxide, LiPON/SnO2) is fabricated and directly exploited as the artificial solid electrolyte interphase film. Without the compromise of Coulombic efficiency, the capacity and cycle performance of silicon wafer are both developed, resulting from the reduced resistance and the dynamically stable coating. This work provides guidance to enhance the lithiation of bulk silicon, and the strategy of surface modification can be applied to other advanced materials or fields.

  5. Controlled Interphase Power Controller (IPC on the Base of Squashed Transformer

    Directory of Open Access Journals (Sweden)

    AMBROS, T.

    2007-11-01

    Full Text Available One of the perspective technical decisions in the field of management of modes of the electrical networks and systems are the Flexible Alternating Power Transmission Systems (FACTS or Power Controllers. Most perspective of them is Interphase Power Controller (IPC on the base of non-controllable phase-shifting transformer with the three working windings connected in 'delta' and constant shifting angle of 600. The analyses of its characteristics and working modes which are done in this paper are shone, then using multi-windings controllable transformer allows essentially to damage the required power of the phase-shifting transformer.

  6. Catalysis of the interphase reaction of. cap alpha. -methylstyrene with formaldehyde by alkylbenzenesulfonic acids

    Energy Technology Data Exchange (ETDEWEB)

    Sharf, V.Z.; Kasymova, K.A.; Litvin, E.F.

    1986-11-10

    Alkylbenzenesulfonic acids accelerate condensation of ..cap alpha..-methylstyrene with formaldehyde (on conversion per acid group) significantly more strongly than sulfuric and oxalic acids. The observed event is due to interphase transfer under conditions of acid catalysts (Prins reaction). Schemes which include transfer of the olefin to the aqueous phase and formaldehyde to the organic phase were proposed. The catalytic cycle includes the formation of an ion pair of the alkylbenzenesulfonic acid with formaldehyde due to the occurrence of the reaction in the organic phase.

  7. Lithium batteries: Improving solid-electrolyte interphases via underpotential solvent electropolymerization

    Science.gov (United States)

    Kasmaee, Laleh Majari; Aryanfar, Asghar; Chikneyan, Zarui; Hoffmann, Michael R.; Colussi, Agustín J.

    2016-09-01

    Understanding the mechanism of formation of solid-electrolyte interphases (SEI) is key to the prospects of lithium metal batteries (LMB). Here, we investigate via cyclic voltammetry, impedance spectroscopy and chronoamperometry the role of kinetics in controlling the properties of the SEI generated from the reduction of propylene carbonate (PC, a typical solvent in LMB). Our observations are consistent with the operation of a radical chain PC electropolymerization into polymer units whose complexity increases at lower initiation rates. As proof-of-concept, we show that slow initiation rates via one-electron PC reduction at underpotentials consistently yields compact, electronically insulating, Li+-conducting, PC-impermeable SEI films.

  8. Control of Regime of Unified Interphase Power Controller by the Use of Rotary Transformer

    Directory of Open Access Journals (Sweden)

    Kalinin L.P.

    2015-12-01

    Full Text Available Interphase Power Controller (IPC has some properties of the source of the current. The use of these technical devices in electrical networks, in addition to optimization of the flow distribution, contributes to limiting of short-circuit currents and limits the level of distribution of electromechanical transients between energy systems. The increase of IPC controllability allows assigning some control function upon them and ensuring a more favorable operation of the energy system generators. We have studied a variant of such a device, which is controlled by a rotary phase-shifting transformer using the asynchronous electric machines with locked phase-wound rotor.

  9. Biophysical assays to probe the mechanical properties of the interphase cell nucleus: substrate strain application and microneedle manipulation.

    Science.gov (United States)

    Lombardi, Maria L; Zwerger, Monika; Lammerding, Jan

    2011-09-14

    In most eukaryotic cells, the nucleus is the largest organelle and is typically 2 to 10 times stiffer than the surrounding cytoskeleton; consequently, the physical properties of the nucleus contribute significantly to the overall biomechanical behavior of cells under physiological and pathological conditions. For example, in migrating neutrophils and invading cancer cells, nuclear stiffness can pose a major obstacle during extravasation or passage through narrow spaces within tissues.(1) On the other hand, the nucleus of cells in mechanically active tissue such as muscle requires sufficient structural support to withstand repetitive mechanical stress. Importantly, the nucleus is tightly integrated into the cellular architecture; it is physically connected to the surrounding cytoskeleton, which is a critical requirement for the intracellular movement and positioning of the nucleus, for example, in polarized cells, synaptic nuclei at neuromuscular junctions, or in migrating cells.(2) Not surprisingly, mutations in nuclear envelope proteins such as lamins and nesprins, which play a critical role in determining nuclear stiffness and nucleo-cytoskeletal coupling, have been shown recently to result in a number of human diseases, including Emery-Dreifuss muscular dystrophy, limb-girdle muscular dystrophy, and dilated cardiomyopathy.(3) To investigate the biophysical function of diverse nuclear envelope proteins and the effect of specific mutations, we have developed experimental methods to study the physical properties of the nucleus in single, living cells subjected to global or localized mechanical perturbation. Measuring induced nuclear deformations in response to precisely applied substrate strain application yields important information on the deformability of the nucleus and allows quantitative comparison between different mutations or cell lines deficient for specific nuclear envelope proteins. Localized cytoskeletal strain application with a microneedle is used to complement this assay and can yield additional information on intracellular force transmission between the nucleus and the cytoskeleton. Studying nuclear mechanics in intact living cells preserves the normal intracellular architecture and avoids potential artifacts that can arise when working with isolated nuclei. Furthermore, substrate strain application presents a good model for the physiological stress experienced by cells in muscle or other tissues (e.g., vascular smooth muscle cells exposed to vessel strain). Lastly, while these tools have been developed primarily to study nuclear mechanics, they can also be applied to investigate the function of cytoskeletal proteins and mechanotransduction signaling.

  10. Detection of illegitimate rearrangement within the immunoglobulin locus on 14q32.3 in B-cell malignancies using end-sequenced probes

    DEFF Research Database (Denmark)

    Silahtaroglu, Asli; Poulsen, Tim; Giselø, Claus

    2001-01-01

    in the literature or at http://www.biologia.uniba.it/rmc/. Validation, orientation, and overlap of these probes were confirmed using interphase-, metaphase-, and fiber-FISH. We have identified seven BAC end-sequenced probes (3087C18, 47P23, 76N15, 12F16, 101G24, 112H5, and 151B17) covering 612 kb of the distal IGHV...

  11. Single- and Multilayered Inter-phases in SiC/SiC Composites Exposed to Severe Environmental Conditions: An Overview

    Energy Technology Data Exchange (ETDEWEB)

    Naslain, R.R.; Pailler, R.J.F.; Lamon, J.L. [Univ Bordeaux, LCTS, F-33600 Pessac (France)

    2010-07-01

    Pyrocarbon (PyC), the common interphase for SiC/SiC, is not stable under severe environmental conditions. It could be replaced by boron nitride more resistant to oxidation but poorly compatible with nuclear applications. Other materials, such as ternary carbides seem promising but their use in SiC/SiC has not been demonstrated. The most efficient way to improve the behavior of PyC interphase in severe environments is to replace part of PyC by a material displaying a better compatibility, such as SiC itself. Issues related to the design and behavior of layered inter-phases are reviewed with a view to demonstrate their interest in high-temperature nuclear reactors. (authors)

  12. Stable cycling of double-walled silicon nanotube battery anodes through solid–electrolyte interphase control

    KAUST Repository

    Wu, Hui

    2012-03-25

    Although the performance of lithium ion-batteries continues to improve, their energy density and cycle life remain insufficient for applications in consumer electronics, transport and large-scale renewable energy storage 1-5. Silicon has a large charge storage capacity and this makes it an attractive anode material, but pulverization during cycling and an unstable solid-electrolyte interphase has limited the cycle life of silicon anodes to hundreds of cycles 6-11. Here, we show that anodes consisting of an active silicon nanotube surrounded by an ion-permeable silicon oxide shell can cycle over 6,000 times in half cells while retaining more than 85% of their initial capacity. The outer surface of the silicon nanotube is prevented from expansion by the oxide shell, and the expanding inner surface is not exposed to the electrolyte, resulting in a stable solid-electrolyte interphase. Batteries containing these double-walled silicon nanotube anodes exhibit charge capacities approximately eight times larger than conventional carbon anodes and charging rates of up to 20C (a rate of 1C corresponds to complete charge or discharge in one hour). © 2012 Macmillan Publishers Limited. All rights reserved.

  13. Quantitative comparison of a human cancer cell surface proteome between interphase and mitosis.

    Science.gov (United States)

    Özlü, Nurhan; Qureshi, Mohammad H; Toyoda, Yusuke; Renard, Bernhard Y; Mollaoglu, Gürkan; Özkan, Nazlı E; Bulbul, Selda; Poser, Ina; Timm, Wiebke; Hyman, Anthony A; Mitchison, Timothy J; Steen, Judith A

    2015-01-13

    The cell surface is the cellular compartment responsible for communication with the environment. The interior of mammalian cells undergoes dramatic reorganization when cells enter mitosis. These changes are triggered by activation of the CDK1 kinase and have been studied extensively. In contrast, very little is known of the cell surface changes during cell division. We undertook a quantitative proteomic comparison of cell surface-exposed proteins in human cancer cells that were tightly synchronized in mitosis or interphase. Six hundred and twenty-eight surface and surface-associated proteins in HeLa cells were identified; of these, 27 were significantly enriched at the cell surface in mitosis and 37 in interphase. Using imaging techniques, we confirmed the mitosis-selective cell surface localization of protocadherin PCDH7, a member of a family with anti-adhesive roles in embryos. We show that PCDH7 is required for development of full mitotic rounding pressure at the onset of mitosis. Our analysis provided basic information on how cell cycle progression affects the cell surface. It also provides potential pharmacodynamic biomarkers for anti-mitotic cancer chemotherapy.

  14. A Plastic-Crystal Electrolyte Interphase for All-Solid-State Sodium Batteries.

    Science.gov (United States)

    Gao, Hongcai; Xue, Leigang; Xin, Sen; Park, Kyusung; Goodenough, John B

    2017-05-08

    The development of all-solid-state rechargeable batteries is plagued by a large interfacial resistance between a solid cathode and a solid electrolyte that increases with each charge-discharge cycle. The introduction of a plastic-crystal electrolyte interphase between a solid electrolyte and solid cathode particles reduces the interfacial resistance, increases the cycle life, and allows a high rate performance. Comparison of solid-state sodium cells with 1) solid electrolyte Na3 Zr2 (Si2 PO4 ) particles versus 2) plastic-crystal electrolyte in the cathode composites shows that the former suffers from a huge irreversible capacity loss on cycling whereas the latter exhibits a dramatically improved electrochemical performance with retention of capacity for over 100 cycles and cycling at 5 C rate. The application of a plastic-crystal electrolyte interphase between a solid electrolyte and a solid cathode may be extended to other all-solid-state battery cells. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Imaging the interphase of carbon fiber composites using transmission electron microscopy:Preparations by focused ion beam, ion beam etching, and ultramicrotomy

    Institute of Scientific and Technical Information of China (English)

    Wu Qing; Li Min; Gu Yizhuo; Wang Shaokai; Zhang Zuoguang

    2015-01-01

    Three sample preparation techniques, focused ion beam (FIB), ion beam (IB) etching, and ultramicrotomy (UM) were used in comparison to analyze the interphase of carbon fiber/epoxy composites using transmission electron microscopy. An intact interphase with a relatively uniform thickness was obtained by FIB, and detailed chemical analysis of the interphase was investigated by electron energy loss spectroscopy. It shows that the interphase region is 200 nm wide with an increasing oxygen-to-carbon ratio from 10% to 19% and an almost constant nitrogen-to-carbon ratio of about 3%. However, gallium implantation of FIB tends to hinder fine structure analysis of the interphase. For IB etching, the interphase region is observed with transition morphology from amorphous resin to nano-crystalline carbon fiber, but the uneven sample thickness brings difficulty for quantitative chemical analysis. Moreover, UM tends to cause damage and/or deformation on the interphase. These results are meaningful for in-depth understanding on the interphase characteristic of carbon fiber composites.

  16. Mobile probes

    DEFF Research Database (Denmark)

    2016-01-01

    A project investigating the effectiveness of a collection of online resources for teachers' professional development used mobile probes as a data collection method. Teachers received questions and tasks on their mobile in a dialogic manner while in their everyday context as opposed to in an inter......A project investigating the effectiveness of a collection of online resources for teachers' professional development used mobile probes as a data collection method. Teachers received questions and tasks on their mobile in a dialogic manner while in their everyday context as opposed...... to in an interview. This method provided valuable insight into the contextual use, i.e. how did the online resource transfer to the work practice. However, the research team also found that mobile probes may provide the scaffolding necessary for individual and peer learning at a very local (intra-school) community...... level. This paper is an initial investigation of how the mobile probes process proved to engage teachers in their efforts to improve teaching. It also highlights some of the barriers emerging when applying mobile probes as a scaffold for learning....

  17. The probe rules in single particle tracking

    DEFF Research Database (Denmark)

    Clausen, Mathias P.; Lagerholm, B. Christoffer

    2011-01-01

    techniques it has been determined that the organization of native plasma membranes is heterogeneous over a very large range of spatial and temporal scales. The observed heterogeneities in the organization have the practical consequence that the SPT results in investigations of native plasma membranes....... The focus of this review is on the impact that the SPT probe has on the experimental results in SPT....

  18. Conductivity Probe

    Science.gov (United States)

    2008-01-01

    The Thermal and Electrical Conductivity Probe (TECP) for NASA's Phoenix Mars Lander took measurements in Martian soil and in the air. The needles on the end of the instrument were inserted into the Martian soil, allowing TECP to measure the propagation of both thermal and electrical energy. TECP also measured the humidity in the surrounding air. The needles on the probe are 15 millimeters (0.6 inch) long. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  19. Bioelectrochemistry II: Membrane Phenomena,

    Science.gov (United States)

    1984-12-11

    techniques for studying protein-lipid interactions and molecular movements in membranes. He discussed spin labels, fluorescent probes, NMR studies and recent...transduction in chloroplasts . Re reviewed the components and reactions at the two reaction centers In photosynthesis, and carefully correlated the structure...particularly useful for considering biological problems involving charge movement (e.g., ion transport, energy transduction, and electrical excitation

  20. Interphase fluorescence in situ hybridization analysis detects a much higher rate of thyroid tumors with clonal cytogenetic deviations of the main cytogenetic subgroups than conventional cytogenetics.

    Science.gov (United States)

    Drieschner, Norbert; Rippe, Volkhard; Laabs, Anne; Dittberner, Lea; Nimzyk, Rolf; Junker, Klaus; Rommel, Birgit; Kiefer, Yvonne; Belge, Gazanfer; Bullerdiek, Jörn; Sendt, Wolfgang

    2011-07-01

    In benign thyroid lesions, three main cytogenetic subgroups, characterized by trisomy 7 or structural aberrations involving either chromosomal region 19q13.4 or 2p21, can be distinguished by conventional cytogenetics (CC). As a rule, these aberrations seem to be mutually exclusive. Interphase fluorescence in situ hybridization (I-FISH) analysis on benign as well as malignant thyroid neoplasias has been performed in the past, but rarely in combination with CC. In the present paper, we have analyzed 161 benign thyroid lesions both with CC and I-FISH on touch preparations by using a multi-target, triple-color FISH assay as well as dual-color break-apart probes for detection of the main cytogenetic subgroups. Within the samples, I-FISH detected tumors belonging to either of the subgroups more frequently than CC (23 vs. 11.4%), either due to small subpopulations of aberrant cells or to cryptic chromosomal rearrangements (three cases). Thus, I-FISH seems to be more sensitive than CC, particularly in the detection of subpopulations of cells harboring cytogenetic aberrations that may be overlooked by CC. In summary, I-FISH on touch preparations of benign thyroid lesions seems to be a favorable method for cytogenetic subtyping of thyroid lesions.

  1. Pollution Probe.

    Science.gov (United States)

    Chant, Donald A.

    This book is written as a statement of concern about pollution by members of Pollution Probe, a citizens' anti-pollution group in Canada. Its purpose is to create public awareness and pressure for the eventual solution to pollution problems. The need for effective government policies to control the population explosion, conserve natural resources,…

  2. Analytic and computational micromechanics of clustering and interphase effects in carbon nanotube composites.

    Energy Technology Data Exchange (ETDEWEB)

    Seidel, Gary D.; Hammerand, Daniel Carl; Lagoudas, Dimitris C. (Texas A& M University, College Station, TX)

    2006-01-01

    Effective elastic properties for carbon nanotube reinforced composites are obtained through a variety of micromechanics techniques. Using the in-plane elastic properties of graphene, the effective properties of carbon nanotubes are calculated utilizing a composite cylinders micromechanics technique as a first step in a two-step process. These effective properties are then used in the self-consistent and Mori-Tanaka methods to obtain effective elastic properties of composites consisting of aligned single or multi-walled carbon nanotubes embedded in a polymer matrix. Effective composite properties from these averaging methods are compared to a direct composite cylinders approach extended from the work of Hashin and Rosen (1964) and Christensen and Lo (1979). Comparisons with finite element simulations are also performed. The effects of an interphase layer between the nanotubes and the polymer matrix as result of functionalization is also investigated using a multi-layer composite cylinders approach. Finally, the modeling of the clustering of nanotubes into bundles due to interatomic forces is accomplished herein using a tessellation method in conjunction with a multi-phase Mori-Tanaka technique. In addition to aligned nanotube composites, modeling of the effective elastic properties of randomly dispersed nanotubes into a matrix is performed using the Mori-Tanaka method, and comparisons with experimental data are made. Computational micromechanical analysis of high-stiffness hollow fiber nanocomposites is performed using the finite element method. The high-stiffness hollow fibers are modeled either directly as isotropic hollow tubes or equivalent transversely isotropic effective solid cylinders with properties computed using a micromechanics based composite cylinders method. Using a representative volume element for clustered high-stiffness hollow fibers embedded in a compliant matrix with the appropriate periodic boundary conditions, the effective elastic properties

  3. Interphase APC/C-Cdc20 inhibition by cyclin A2-Cdk2 ensures efficient mitotic entry

    DEFF Research Database (Denmark)

    Hein, Jamin B; Nilsson, Jakob

    2016-01-01

    Proper cell-cycle progression requires tight temporal control of the Anaphase Promoting Complex/Cyclosome (APC/C), a large ubiquitin ligase that is activated by one of two co-activators, Cdh1 or Cdc20. APC/C and Cdc20 are already present during interphase but APC/C-Cdc20 regulation during...

  4. The effect of the inter-phase delay interval in the spontaneous object recognition test for pigs

    DEFF Research Database (Denmark)

    Kornum, Birgitte Rahbek; Thygesen, Kristin Sjølie; Nielsen, Thomas Rune

    2007-01-01

    In the neuroscience community interest for using the pig is growing. Several disease models have been developed creating a need for validation of behavioural paradigms in these animals. Here, we report the effect of different inter-phase delay intervals on the performance of Göttingen minipigs in...

  5. In situ methods to localize transgenes and transcripts in interphase nuclei: a tool for transgenic plant research

    Directory of Open Access Journals (Sweden)

    Shaw Peter

    2006-11-01

    Full Text Available Abstract Genetic engineering of commercially important crops has become routine in many laboratories. However, the inability to predict where a transgene will integrate and to efficiently select plants with stable levels of transgenic expression remains a limitation of this technology. Fluorescence in situ hybridization (FISH is a powerful technique that can be used to visualize transgene integration sites and provide a better understanding of transgene behavior. Studies using FISH to characterize transgene integration have focused primarily on metaphase chromosomes, because the number and position of integration sites on the chromosomes are more easily determined at this stage. However gene (and transgene expression occurs mainly during interphase. In order to accurately predict the activity of a transgene, it is critical to understand its location and dynamics in the three-dimensional interphase nucleus. We and others have developed in situ methods to visualize transgenes (including single copy genes and their transcripts during interphase from different tissues and plant species. These techniques reduce the time necessary for characterization of transgene integration by eliminating the need for time-consuming segregation analysis, and extend characterization to the interphase nucleus, thus increasing the likelihood of accurate prediction of transgene activity. Furthermore, this approach is useful for studying nuclear organization and the dynamics of genes and chromatin.

  6. Dynamic behaviour of interphases and its implication on high-energy-density cathode materials in lithium-ion batteries

    Science.gov (United States)

    Li, Wangda; Dolocan, Andrei; Oh, Pilgun; Celio, Hugo; Park, Suhyeon; Cho, Jaephil; Manthiram, Arumugam

    2017-01-01

    Undesired electrode–electrolyte interactions prevent the use of many high-energy-density cathode materials in practical lithium-ion batteries. Efforts to address their limited service life have predominantly focused on the active electrode materials and electrolytes. Here an advanced three-dimensional chemical and imaging analysis on a model material, the nickel-rich layered lithium transition-metal oxide, reveals the dynamic behaviour of cathode interphases driven by conductive carbon additives (carbon black) in a common nonaqueous electrolyte. Region-of-interest sensitive secondary-ion mass spectrometry shows that a cathode-electrolyte interphase, initially formed on carbon black with no electrochemical bias applied, readily passivates the cathode particles through mutual exchange of surface species. By tuning the interphase thickness, we demonstrate its robustness in suppressing the deterioration of the electrode/electrolyte interface during high-voltage cell operation. Our results provide insights on the formation and evolution of cathode interphases, facilitating development of in situ surface protection on high-energy-density cathode materials in lithium-based batteries. PMID:28443608

  7. Flow Cytometric Applicability of Fluorescent Vitality Probes on Phytoplankton

    NARCIS (Netherlands)

    Peperzak, L.; Brussaard, C.P.D.

    2011-01-01

    The applicability of six fluorescent probes (four esterase probes: acetoxymethyl ester of Calcein [Calcein-AM], 5-chloromethylfluorescein diacetate [CMFDA], fluorescein diacetate [FDA], and 2',7'-dichlorofluorescein diacetate [H(2)DCFDA]; and two membrane probes: bis-(1,3-dibutylbarbituric acid) tri

  8. Mapping residual organics and carbonate at grain boundaries and the amorphous interphase in mouse incisor enamel.

    Science.gov (United States)

    Gordon, Lyle M; Joester, Derk

    2015-01-01

    Dental enamel has evolved to resist the most grueling conditions of mechanical stress, fatigue, and wear. Adding insult to injury, it is exposed to the frequently corrosive environment of the oral cavity. While its hierarchical structure is unrivaled in its mechanical resilience, heterogeneity in the distribution of magnesium ions and the presence of Mg-substituted amorphous calcium phosphate (Mg-ACP) as an intergranular phase have recently been shown to increase the susceptibility of mouse enamel to acid attack. Herein we investigate the distribution of two important constituents of enamel, residual organic matter and inorganic carbonate. We find that organics, carbonate, and possibly water show distinct distribution patterns in the mouse enamel crystallites, at simple grain boundaries, and in the amorphous interphase at multiple grain boundaries. This has implications for the resistance to acid corrosion, mechanical properties, and the mechanism by which enamel crystals grow during amelogenesis.

  9. [Chromosome territories in the interphase nucleus in normal or pathological condition].

    Science.gov (United States)

    Lavrov, A V; Vol'dgorn, Ia I; Bochkov, N P

    2011-01-01

    The non-random arrangement of chromosomes in the interphase nucleus was observed for the first time in the late XIX century. However, considerable progress in studying chromosome territories became possible only in the end of the XX century mainly due to advances in microscopy and molecular biology. At present, chromosome territories are believed to play an important role in epigenetic regulation of genome activity during various cell processes including but not limited to cell cycle, differentiation, stress response. 3D structure of genome also plays an important role in pathogenesis of various hereditary diseases and cancer. This article describes main provisions of the chromosome territory theory and current trends toward further development of human genetics based on the new knowledge about the role of chromosome territories.

  10. Effect of Microstructure of Cementite on Interphase Stress State in Carbon Steel

    Institute of Scientific and Technical Information of China (English)

    CHE Lei; GOTOH Masahide; HORIMOTO Yoshiaki; HIROSE Yukio

    2007-01-01

    The experiments related to stress states of ferrite and cementite in carbon steels were carried out including in situ four-point bending and tensile test by X-ray diffraction technique. Stresses in the cementite phase can be measured by conventional X-ray diffraction instrument after a specific treatment on the specimen surface. In order to estimate the stress states in two phases, the X-ray elastic constants of two phases in single-phase state (PXEC) are determined by the experimental X-ray elastic constants of them in composite state (CXEC). The effects of volume fraction and particle size of spheroidal cementite on the interphase stress state are estimated. The experimental results are in good agreement with the theoretical relationships reported in the previous studies.

  11. The Centrosome Undergoes Plk1-Independent Interphase Maturation during Inflammation and Mediates Cytokine Release.

    Science.gov (United States)

    Vertii, Anastassiia; Ivshina, Maria; Zimmerman, Wendy; Hehnly, Heidi; Kant, Shashi; Doxsey, Stephen

    2016-05-23

    Cytokine production is a necessary event in the immune response during inflammation and is associated with mortality during sepsis, autoimmune disorders, cancer, and diabetes. Stress-activated MAP kinase signaling cascades that mediate cytokine synthesis are well established. However, the downstream fate of cytokines before they are secreted remains elusive. We report that pro-inflammatory stimuli lead to recruitment of pericentriolar material, specifically pericentrin and γ-tubulin, to the centrosome. This is accompanied by enhanced microtubule nucleation and enrichment of the recycling endosome component FIP3, all of which are hallmarks of centrosome maturation during mitosis. Intriguingly, centrosome maturation occurs during interphase in an MLK-dependent manner, independent of the classic mitotic kinase, Plk1. Centrosome disruption by chemical prevention of centriole assembly or genetic ablation of pericentrin attenuated interleukin-6, interleukin-10, and MCP1 secretion, suggesting that the centrosome is critical for cytokine production. Our results reveal a function of the centrosome in innate immunity.

  12. Interphases, gelation, vitrification, porous glasses and the generalized Cauchy relation: epoxy/silica nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Philipp, M; Mueller, U; Jimenez Rioboo, R J; Baller, J; Sanctuary, R; Krueger, J K [Laboratoire de Physique des Materiaux, University of Luxembourg, 162A avenue de la Faiencerie, L-1511 Luxembourg (Luxembourg); Possart, W [Fachbereich Werkstoffwissenschaften, Universitaet des Saarlandes, D-66123 Saarbruecken (Germany)], E-mail: martine.philipp@uni.lu

    2009-02-15

    The generalized Cauchy relation (gCR) of epoxy/silica nano-composites does not show either the chemically induced sol-gel transition or the chemically induced glass transition in the course of polymerization. Astonishingly, by varying the silica nanoparticles' concentration between 0 and 25 vol% in the composites, the Cauchy parameter A of the gCR remains universal and can be determined from the pure epoxy's elastic moduli. Air-filled porous silica glasses are considered as models for percolated silica particles. A longitudinal modulus versus density representation evidences the aforementioned transition phenomena during polymerization of the epoxy/silica nanocomposites. The existence of optically and mechanically relevant interphases is discussed.

  13. Local properties of a functionally graded interphase between cementum and dentin.

    Science.gov (United States)

    Ho, Sunita P; Balooch, Mehdi; Marshall, Sally J; Marshall, Grayson W

    2004-09-01

    The study of natural interfaces may provide information necessary to engineer functionally graded biomaterials for bioengineering applications. In this study, the mechanical, structural, and chemical composition variations associated with a region between cementum and dentin were studied with the use of nanoindentation, microindentation, optical microscopy, and Raman microspectroscopy techniques. Three-millimeter-thick transverse sections (N = 5) were obtained from the apical one-third of the roots of sterilized human molars. The samples were ultrasectioned at room temperature with the use of a diamond knife and an ultramicrotome. Longitudinal ground sections of 100 microm thickness were prepared and stained with von Kossa stain to determine the mineralized regions within the molar roots. Raman microspectroscopy was used to determine the relative inorganic content, mainly apatite (PO4(3-)nu1 mode at 960 cm(-1)) and organic content, mainly collagen (C--H stretch at 2940 cm(-1)) between cementum and dentin bulk tissues. The microindentation and nanoindentation results indicated a gradual transition in hardness from cementum to dentin over a width ranging from 100 to 200 microm. However, the variation in hardness data for cementum and dentin by nanoindentation was larger (0.62 +/- 0.21, 0.77 +/- 0.14 GPa) than from microindentation (0.49 +/- 0.03, 0.69 +/- 0.07 GPa). Within the 100 to 200 microm region there was a 10 to 50 microm fibrillar hydrophilic cementum-dentin junction (CDJ) with mechanical properties significantly lower than either the cementum or the dentin side of CDJ. Light microscopy revealed a 100 to 200 microm translucent region between cementum and dentin. Raman microspectroscopy results showed a variation in organic and inorganic composition 80 to 140 microm wide. It was concluded that a morphologically and biomechanically different CDJ lies within a wider cementum-dentin interphase. Hence, cementum, dentin, and the interphase can be classified as a

  14. Drug-induced premature chromosome condensation (PCC) protocols: cytogenetic approaches in mitotic chromosome and interphase chromatin.

    Science.gov (United States)

    Gotoh, Eisuke

    2015-01-01

    Chromosome analysis is a fundamental technique which is used in wide areas of cytogenetic study including karyotyping species, hereditary diseases diagnosis, or chromosome biology study. Chromosomes are usually prepared from mitotic cells arrested by colcemid block protocol. However, obtaining mitotic chromosomes is often hampered under several circumstances. As a result, cytogenetic analysis will be sometimes difficult or even impossible in such cases. Premature chromosome condensation (PCC) (see Note 1) is an alternative method that has proved to be a unique and useful way in chromosome analysis. Former, PCC has been achieved following cell fusion method (cell-fusion PCC) mediated either by fusogenic viruses (e.g., Sendai virus) or cell fusion chemicals (e.g., polyethylene glycol), but the cell fusion PCC has several drawbacks. The novel drug-induced PCC using protein phosphatase inhibitors was introduced about 20 years ago. This method is much simpler and easier even than the conventional mitotic chromosome preparation protocol use with colcemid block and furthermore obtained PCC index (equivalent to mitotic index for metaphase chromosome) is usually much higher than colcemid block method. Moreover, this method allows the interphase chromatin to be condensed to visualize like mitotic chromosomes. Therefore drug-induced PCC has opened the way for chromosome analysis not only in metaphase chromosomes but also in interphase chromatin. The drug-induced PCC has thus proven the usefulness in cytogenetics and other cell biology fields. For this second edition version, updated modifications/changes are supplemented in Subheadings 2, 3, and 4, and a new section describing the application of PCC in chromosome science fields is added with citation of updated references.

  15. Membrane dynamics

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

    Current topics include membrane-protein interactions with regard to membrane deformation or curvature sensing by BAR domains. Also, we study the dynamics of membrane tubes of both cells and simple model membrane tubes. Finally, we study membrane phase behavior which has important implications...... for the lateral organization of membranes as wells as for physical properties like bending, permeability and elasticity...

  16. Patterning and lifetime of plasma membrane-localized cellulose synthase is dependent on actin organization in Arabidopsis interphase cells

    NARCIS (Netherlands)

    Sampathkumar, A.; Gutierrez, R.; McFarlane, H.E.; Bringmann, M.; Lindeboom, J.J.; Emons, A.M.C.; Samuels, L.; Ketelaar, T.; Ehrhardt, D.W.; Persson, S.

    2013-01-01

    The actin and microtubule cytoskeletons regulate cell shape across phyla, from bacteria to metazoans. In organisms with cell walls, the wall acts as a primary constraint of shape, and generation of specific cell shape depends on cytoskeletal organization for wall deposition and/or cell expansion. In

  17. Methods of staining target chromosomal DNA employing high complexity nucleic acid probes

    Energy Technology Data Exchange (ETDEWEB)

    Gray, Joe W.; Pinkel, Daniel; Kallioniemi, Ol' li-Pekka; Kallioniemi, Anne; Sakamoto, Masaru

    2006-10-03

    Methods and compositions for staining based upon nucleic acid sequence that employ nucleic acid probes are provided. Said methods produce staining patterns that can be tailored for specific cytogenetic analyses. Said probes are appropriate for in situ hybridization and stain both interphase and metaphase chromosomal material with reliable signals. The nucleic acid probes are typically of a complexity greater than 50 kb, the complexity depending upon the cytogenetic application. Methods and reagents are provided for the detection of genetic rearrangements. Probes and test kits are provided for use in detecting genetic rearrangements, particularly for use in tumor cytogenetics, in the detection of disease related loci, specifically cancer, such as chronic myelogenous leukemia (CML), retinoblastoma, ovarian and uterine cancers, and for biological dosimetry. Methods and reagents are described for cytogenetic research, for the differentiation of cytogenetically similar but genetically different diseases, and for many prognostic and diagnostic applications.

  18. Durability of polymer matrix composites for infrastructure: The role of the interphase

    Science.gov (United States)

    Verghese, Kandathil Nikhil Eapen

    1999-12-01

    As fiber reinforced polymer matrix composites find greater use in markets such as civil infrastructure and ground transportation, the expectations placed on these materials are ever increasing. The overall cost and reliability have become the drivers of these high performance materials and have led to the disappearance of resins such as bismaleimides (BMI). cyanate esters and other high performance polyimides and epoxys. In their place polymers, such polyester and vinylester have arisen. The reinforcing fiber scenario has also undergone changes from the high quality and performance assured IM7 and AS4 to cheaper and hybrid systems consisting of both glass and low cost carbon. Manufacturing processes have had their share of changes too with processes such as pultrusion and other mass production techniques replacing hand lay-up and resin transfer molding. All of this has however come with little or no concession on material performance. The motivation of the present research has therefore been to try to improve the properties of these low cost composites by better understanding the constituent materials (fiber and matrix) and the region that lies in-between them namely the interphase. In order to achieve this. working with controls is necessary and the present discourse therefore deals with the AS4 fiber system from Hexcel Corporation and the vinyl ester resin, Derakane 441-400 from The Dow Chemical Company. The following eight chapters sum up the work done thus far on composites made with sized fibers and the above mentioned resin and fiber systems. They are in the form of publications that have either been accepted. submitted or going to be submitted to various peer reviewed journals. The sizings used have been poly(vinylpyrrolidone) PVP and Polyhydroxyether (Phenoxy) thermoplastic polymers and G' an industrial sizing material supplied by Hexcel. A number of issues have been addressed ranging from viscoelastic relaxation to enviro-mechanical durability. Chapter 1

  19. EDITORIAL: Probing the nanoworld Probing the nanoworld

    Science.gov (United States)

    Miles, Mervyn

    2009-10-01

    In nanotechnology, it is the unique properties arising from nanometre-scale structures that lead not only to their technological importance but also to a better understanding of the underlying science. Over the last twenty years, material properties at the nanoscale have been dominated by the properties of carbon in the form of the C60 molecule, single- and multi-wall carbon nanotubes, nanodiamonds, and recently graphene. During this period, research published in the journal Nanotechnology has revealed the amazing mechanical properties of such materials as well as their remarkable electronic properties with the promise of new devices. Furthermore, nanoparticles, nanotubes, nanorods, and nanowires from metals and dielectrics have been characterized for their electronic, mechanical, optical, chemical and catalytic properties. Scanning probe microscopy (SPM) has become the main characterization technique and atomic force microscopy (AFM) the most frequently used SPM. Over the past twenty years, SPM techniques that were previously experimental in nature have become routine. At the same time, investigations using AFM continue to yield impressive results that demonstrate the great potential of this powerful imaging tool, particularly in close to physiological conditions. In this special issue a collaboration of researchers in Europe report the use of AFM to provide high-resolution topographical images of individual carbon nanotubes immobilized on various biological membranes, including a nuclear membrane for the first time (Lamprecht C et al 2009 Nanotechnology 20 434001). Other SPM developments such as high-speed AFM appear to be making a transition from specialist laboratories to the mainstream, and perhaps the same may be said for non-contact AFM. Looking to the future, characterisation techniques involving SPM and spectroscopy, such as tip-enhanced Raman spectroscopy, could emerge as everyday methods. In all these advanced techniques, routinely available probes will

  20. Labeling the plasma membrane with TMA-DPH.

    Science.gov (United States)

    Chazotte, Brad

    2011-05-01

    INTRODUCTION TMA-DPH (trimethylamine-diphenylhexatriene) is a fluorescent membrane probe that has classically been used to label the outer leaflet of a membrane bilayer, to label the outer leaflet of the plasma membrane in cells, and to report on membrane dynamics using the techniques of fluorescence polarization and/or fluorescence lifetime. This probe has also been used to follow exocytosis and endocytosis of labeled plasma membranes. The interaction of the aqueous environment with mitochondrial inner membrane dynamics has also been studied following the fluorescence polarization and the lifetime of TMA-DPH. This protocol describes the use of TMA-DPH to label the plasma membrane.

  1. Analysis of Protein-Membrane Interactions

    DEFF Research Database (Denmark)

    Kemmer, Gerdi Christine

    Cellular membranes are complex structures, consisting of hundreds of different lipids and proteins. These membranes act as barriers between distinct environments, constituting hot spots for many essential functions of the cell, including signaling, energy conversion, and transport. These functions....... Discovered interactions were then probed on the level of the membrane using liposome-based assays. In the second part, a transmembrane protein was investigated. Assays to probe activity of the plasma membrane ATPase (Arabidopsis thaliana H+ -ATPase isoform 2 (AHA2)) in single liposomes using both giant...... are implemented by soluble proteins reversibly binding to, as well as by integral membrane proteins embedded in, cellular membranes. The activity and interaction of these proteins is furthermore modulated by the lipids of the membrane. Here, liposomes were used as model membrane systems to investigate...

  2. Influence of helium atoms on the shear behavior of the fiber/matrix interphase of SiC/SiC composite

    Science.gov (United States)

    Jin, Enze; Du, Shiyu; Li, Mian; Liu, Chen; He, Shihong; He, Jian; He, Heming

    2016-10-01

    Silicon carbide has many attractive properties and the SiC/SiC composite has been considered as a promising candidate for nuclear structural materials. Up to now, a computational investigation on the properties of SiC/SiC composite varying in the presence of nuclear fission products is still missing. In this work, the influence of He atoms on the shear behavior of the SiC/SiC interphase is investigated via Molecular Dynamics simulation following our recent paper. Calculations are carried out on three dimensional models of graphite-like PyC/SiC interphase and amorphous PyC/SiC interphase with He atoms in different regions (the SiC region, the interface region and the PyC region). In the graphite-like PyC/SiC interphase, He atoms in the SiC region have little influence on the shear strength of the material, while both the shear strength and friction strength may be enhanced when they are in the PyC region. Low concentration of He atoms in the interface region of the graphite-like PyC/SiC interphase increases the shear strength, while there is a reduction of shear strength when the He concentration is high due to the switch of sliding plane. In the amorphous PyC/SiC interphase, He atoms can cause the reduction of the shear strength regardless of the regions that He atoms are located. The presence of He atoms may significantly alter the structure of SiC/SiC in the interface region. The influence of He atoms in the interface region is the most significant, leading to evident shear strength reduction of the amorphous PyC/SiC interphase with increasing He concentration. The behaviors of the interphases at different temperatures are studied as well. The dependence of the shear strengths of the two types of interphases on temperatures is studied as well. For the graphite-like PyC/SiC interphase, it is found strongly related to the regions He atoms are located. Combining these results with our previous study on pure SiC/SiC system, we expect this work may provide new insight

  3. Development of a zinc oxide nanowire interphase for enhanced structural composites

    Science.gov (United States)

    Ehlert, Gregory John

    Continuous fiber reinforced polymers (CFRPs) form the backbone of the high strength, low density material systems that will be central to the next generation of transportation vehicles. CFRPs, with a compliant matrix between relatively stiff fibers, localize stress at the interface between the two different phases to cause the interface to dominate many bulk material properties. As such, the two phase composite design problem generally has three selections; fiber, matrix and the interface between the two. This work has developed a unique ZnO nanowire interphase to improve the properties of the interface. Whiskerization, the deposition of an array of whiskers on the surface of a fiber, enables enhancement of the interfacial properties by causing fibers to interlock thus allowing the formation of a graded interface to reduce the stress concentration between the two phases. Whiskerization techniques have existed for some time; however ZnO nanowires offer a radical departure from existing technologies because ZnO nanowires can be deposited at low temperatures (90 °C) aqueous solutions. The high performance afforded by ZnO nanowires is documented for the first time in this work. This work will demonstrate the ability of a ZnO nanowire interphase to reinforce the interface of both aramid and carbon fiber composites. The interfacial shear strength of single fiber aramid composites is enhanced by 41% and single carbon fiber composite are improved by 110% with this process. Lamina scale testing on unidirectional carbon fiber composites demonstrates a 37% increase in shear strength and a 38% increase in shear modulus for the affected fibers. Given that ZnO nanowires are grown directly onto the underlying fiber, the interface between the nanowires and fiber will have low surface area and minimal interlocking, which implies that the chemical adhesion of the nanowires is strong. This work develops new functionalization procedures that directly control the interface chemistry

  4. Screening far red probes for use on optical biochip devices

    Science.gov (United States)

    Njoh, Kerenza L.; Patterson, Laurence H.; Pors, Klaus; Zloh, Mire; Ameer-Beg, Simon; Summers, Huw; Matthews, Daniel; Errington, Rachel J.; Smith, Paul J.

    2006-02-01

    In situ spectral analysis can be used to understand the targeting and interaction of agents in cellular compartments. A range of novel red excitable fluorescent probes, related to the anthraquinone family of anti-cancer agents, were designed for their DNA affinic properties and their ability to enter and penetrate living cells. We report on the spectral features of these probes, both in solution and bound within intact cells, to identify unique fluorescent signatures that exploit their use in bioassays on optical biochip devices. The probes demonstrated red shifted emission spectra and increased 2 photon lifetime, with minimal fluorescent enhancement, upon binding to DNA. Spectral confocal laser scanning microscopy revealed complex emission profiles representing the bound (nuclear) and unbound (cytoplasmic) fractions of the DNA probes within live interphase, mitotic and apoptotic cells. Analysis of the emission peaks encoded the spectra to provide cell compartment recognition and profiles for cells in different cell states. Sampling the entire emission spectra of these probes for cell locating, even in the presence of unbound molecules, provides good signal-to-noise in biochip devices. Furthermore, by sampling the fluorescence output at specific spectral windows we can obtain high spatial information without imaging. The technological challenge is to integrate these fluorophores and appropriate detection capacity onto an optical biochip platform with microfluidic systems for cell handling.

  5. Probing the nano-bio interface with nanoplasmonic optical probes

    Science.gov (United States)

    Yu, X.; Wu, Linxi; Khanehzar, Ali; Feizpour, Amin; Xu, Fangda; Reinhard, Björn M.

    2014-08-01

    Noble metal nanoparticles have large cross-sections in both optical and electron microscopy and plasmon coupling between noble metal nanoparticles facilitate the characterization of subdiffraction limit separations through spectral analysis of the scattered light in Plasmon Coupling Microscopy (PCM). The size compatibility of noble metal nanoparticles together with the ability to encode specific functionality in a rational fashion by control of the nanoparticle surface makes noble metal nanoparticles unique probes for a broad range of biological processes. Recent applications of the technology include i.) characterization of cellular heterogeneity in nanomaterial uptake and processing through macrophages, ii.) testing the role of viral membrane lipids in mediating viral binding and trafficking, and iii.) characterizing the spatial organization of cancer biomarkers in plasma membranes. This paper reviews some of these applications and introduces the physical and material science principles underlying them. We will also introduce the use of membrane wrapped noble metal nanoparticles, which combine the superb photophysical properties of a nanoparticle core with the biological functionality of a membrane, as probes in PCM.

  6. Custom-made Microdialysis Probe Design.

    Science.gov (United States)

    Lietsche, Jana; Gorka, Jan; Hardt, Stefanie; Karas, Michael; Klein, Jochen

    2015-07-21

    Microdialysis is a commonly used technique in neuroscience research. Therefore commercial probes are in great demand to monitor physiological, pharmacological and pathological changes in cerebrospinal fluid. Unfortunately, commercial probes are expensive for research groups in public institutions. In this work, a probe assembly is explained in detail to build a reliable, concentric, custom-made microdialysis probe for less than $10. The microdialysis probe consists of a polysulfone membrane with a molecular cut-off of 30 kDa. Probe in vitro recoveries of substances with different molecular weight (in the range of 100-1,600 Da) and different physicochemical properties are compared. The probe yields an in vitro recovery of approximately 20% for the small compounds glucose, lactate, acetylcholine and ATP. In vitro recoveries for neuropeptides with a molecular weight between 1,000-1,600 Da amount to 2-6%. Thus, while the higher molecular weight of the neuropeptides lowered in vitro recovery values, dialysis of compounds in the lower range (up to 500 Da) of molecular weights has no great impact on the in vitro recovery rate. The present method allows utilization of a dialysis membrane with other cut-off value and membrane material. Therefore, this custom-made probe assembly has the advantage of sufficient flexibility to dialyze substances in a broad molecular weight range. Here, we introduce a microdialysis probe with an exchange length of 2 mm, which is applicable for microdialysis in mouse and rat brain regions. However, dimensions of the probe can easily be adapted for larger exchange lengths to be used in larger animals.

  7. Studies on the Effects of Interphase Heat Exchange during Thermal Explosion in a Combustible Dusty Gas with General Arrhenius Reaction-Rate Laws

    OpenAIRE

    K. S. Adegbie; F. I. Alao

    2012-01-01

    A mathematical model for thermal explosion in a combustible dusty gas containing fuel droplets with general Arrhenius reaction-rate laws, convective and radiative heat losses, and interphase heat exchange between gas and inert solid particles is investigated. The objective of the study is to examine the effects of interphase heat exchange between the gas and solid particles on (i) ignition of reacting gas, (ii) accumulation of heat by the solid particles during combustion process (iii) evapor...

  8. Nanoscale multilayered and porous carbide interphases prepared by pressure-pulsed reactive chemical vapor deposition for ceramic matrix composites

    Energy Technology Data Exchange (ETDEWEB)

    Jacques, S., E-mail: jacques@lcts.u-bordeaux1.fr [LCTS, University of Bordeaux 1, CNRS, Herakles-Safran, CEA, 3 allee de la Boetie, F-33600 Pessac (France); Jouanny, I.; Ledain, O.; Maillé, L.; Weisbecker, P. [LCTS, University of Bordeaux 1, CNRS, Herakles-Safran, CEA, 3 allee de la Boetie, F-33600 Pessac (France)

    2013-06-15

    In Ceramic Matrix Composites (CMCs) reinforced by continuous fibers, a good toughness is achieved by adding a thin film called “interphase” between the fiber and the brittle matrix, which acts as a mechanical fuse by deflecting the matrix cracks. Pyrocarbon (PyC), with or without carbide sub-layers, is typically the material of choice to fulfill this role. The aim of this work was to study PyC-free nanoscale multilayered carbide coatings as interphases for CMCs. Nanoscale multilayered (SiC–TiC){sub n} interphases were deposited by pressure-Pulsed Chemical Vapor Deposition (P-CVD) on single filament Hi-Nicalon fibers and embedded in a SiC matrix sheath. The thicknesses of the carbide interphase sub-layers could be made as low as a few nanometers as evidenced by scanning and transmission electron microscopy. By using the P-ReactiveCVD method (P-RCVD), in which the TiC growth involves consumption of SiC, it was not only possible to obtain multilayered (SiC–TiC){sub n} films but also TiC films with a porous multilayered microstructure as a result of the Kirkendall effect. The porosity in the TiC sequences was found to be enhanced when some PyC was added to SiC prior to total RCVD consumption. Because the porosity volume fraction was still not high enough, the role of mechanical fuse of the interphases could not be evidenced from the tensile curves, which remained fully linear even when chemical attack of the fiber surface was avoided.

  9. International Conference Intergranular and Interphase Boundaries (9th) (IIB󈨦) Held in Prague, Czech Republic, 6 - 9 July 1998

    Science.gov (United States)

    2007-11-02

    thermomechanical processing steps on the segregation behaviour . P217 SEGREGATION AT INTERPHASE BOUNDARIES IN OXIDE - DISPERSION STRENGTHENED FERRITIC...metallurgy Fe-Cr ferritic steel strengthened by disperse TiO 2 particles is studied by Auger electron spectroscopy as a function of annealing time...technique. All specimens were doped with various Bi bulk concentrations and annealed at various temperatures. We studied the segregation by energy dispersive

  10. Bivalence Mn5O8 with hydroxylated interphase for high-voltage aqueous sodium-ion storage

    OpenAIRE

    Shan, Xiaoqiang; Charles, Daniel S.; Lei, Yinkai; Qiao, Ruimin; Wang, Guofeng; Yang, Wanli; Feygenson, Mikhail; Su, Dong; Teng, Xiaowei

    2016-01-01

    Aqueous electrochemical energy storage devices have attracted significant attention owing to their high safety, low cost and environmental friendliness. However, their applications have been limited by a narrow potential window (∼1.23 V), beyond which the hydrogen and oxygen evolution reactions occur. Here we report the formation of layered Mn5O8 pseudocapacitor electrode material with a well-ordered hydroxylated interphase. A symmetric full cell using such electrodes demonstrates a stable po...

  11. A time-series method for automated measurement of changes in mitotic and interphase duration from time-lapse movies.

    Directory of Open Access Journals (Sweden)

    Frederic D Sigoillot

    Full Text Available BACKGROUND: Automated time-lapse microscopy can visualize proliferation of large numbers of individual cells, enabling accurate measurement of the frequency of cell division and the duration of interphase and mitosis. However, extraction of quantitative information by manual inspection of time-lapse movies is too time-consuming to be useful for analysis of large experiments. METHODOLOGY/PRINCIPAL FINDINGS: Here we present an automated time-series approach that can measure changes in the duration of mitosis and interphase in individual cells expressing fluorescent histone 2B. The approach requires analysis of only 2 features, nuclear area and average intensity. Compared to supervised learning approaches, this method reduces processing time and does not require generation of training data sets. We demonstrate that this method is as sensitive as manual analysis in identifying small changes in interphase or mitotic duration induced by drug or siRNA treatment. CONCLUSIONS/SIGNIFICANCE: This approach should facilitate automated analysis of high-throughput time-lapse data sets to identify small molecules or gene products that influence timing of cell division.

  12. Analysis of chromosome positions in the interphase nucleus of Chinese hamster cells by laser-UV-microirradiation experiments

    Energy Technology Data Exchange (ETDEWEB)

    Cremer, T.; Baumann, H.; Cremer, C.; Schneider, T.; Hens, L.; Kirsch-Volders, M.

    1982-01-01

    Unsynchronized cells of an essentially diploid strain of female Chinese hamster cells derived from lung tissue (CHL) were laser-UV-microirradiated (lambda=257 nm) in the nucleus either at its central part or at its periphery. After 7-9 h postincubation with 0.5 mM caffeine, chromosome preparations were made in situ. Twenty-one and 29 metaphase spreads, respectively, with partial chromosome shattering (PCS) obtained after microirradiation at these two nuclear sites, were Q-banded and analyzed in detail. A positive correlation was observed between the frequency of damage of chromosomes and both their DNA content and length at metaphase. No significant difference was observed between the frequencies of damage obtained for individual chromosomes at either site of microirradiation. The frequency of joint damage of homologous chromosomes was low as compared to nonhomologous ones. Considerable variation was noted in different cells in the combination of jointly shattered chromosomes. Evidence which justifies an interpretation of these data in terms of an interphase arrangement of chromosome territories is discussed. Our data strongly argue against somatic pairing as a regular event, and suggest a considerable variability of chromosome positions in different nuclei. However, present data do not exclude the possibility of certain non-random chromosomal arrangements in CHL-nuclei. The interphase chromosome distribution revealed by these experiments is compared with centromere-centromere, centromere-center and angle analyses of metaphase spreads and the relationship between interphase and metaphase arrangements of chromosomes is discussed.

  13. The Kemp elimination in membrane mimetic reaction media. Probing catalytic properties of cationic vesicles formed from a double-tailed amphiphile and linear long-tailed alcohols or alkyl pyranosides

    NARCIS (Netherlands)

    Klijn, JE; Engberts, JBFN

    2004-01-01

    Vesicles formed from synthetic, double-tailed amphiphiles are often used as mimics for biological membranes. However, biological membranes are a complex mixture of various compounds. In the present paper we describe a first attempt to study the importance of additives on vesicular catalysis. The rat

  14. Polymeric artificial solid/electrolyte interphases for Li-ion batteries

    Directory of Open Access Journals (Sweden)

    Nae-Lih Wu

    2015-12-01

    Full Text Available During the operation of Li-ion batteries (LIBs, solvent and electrolyte decomposition takes place at the electrode surface to form a so-called solid-electrode interphase (SEI passivating-layer. The physical structure and chemical composition of the SEI exert profound effects on various aspects of the electrode performance of the batteries. A new concept of forming polymeric artificial SEIs (A-SEIs based on rational design of multifunctional polymer-blend coating to achieve favorable electrode/A-SEI/electrolyte interfacial properties is described. Three examples using binary and ternary polymer blends to form mechanically robust and highly Li-ion permeable surface coatings with selected functionalities in the cases of graphite and silicon–graphite composite electrodes have demonstrated greatly enhanced capacity, rate and cycle performance. Given the rich chemistry available from polymer blends, this surface preconditioning approach holds great promise for improving the performance of various negative electrodes to meet the requirements for advanced LIBs.

  15. Low-cost, environmentally friendly route for producing CFRP laminates with microfibrillated cellulose interphase

    Directory of Open Access Journals (Sweden)

    B. E. B. Uribe

    2017-01-01

    Full Text Available In this paper, a cost-effective and eco-friendly method to improve mechanical performance in continuous carbon fiber-reinforced polymer (CFRP matrix composites is presented. Unsized fiber fabric preforms are coated with self-assembling sugarcane bagasse microfibrillated cellulose, and undergo vacuum-assisted liquid epoxy resin infusion to produce solid laminates after curing at ambient temperature. Quasi-static tensile, flexural and short beam testing at room temperature indicated that the stiffness, ultimate strength and toughness at ultimate load of the brand-new two-level hierarchical composite are substantially higher than in baseline, unsized fiber-reinforced epoxy laminate. Atomic force microscopy for height and phase imaging, along with scanning electron microscopy for the fracture surface survey, revealed a 400 nm-thick fiber/matrix interphase wherein microfibrillated cellulose exerts strengthening and toughening roles in the hybrid laminate. Market expansion of this class of continuous fiber-reinforced-polymer matrix composites exhibiting remarkable mechanical performance/cost ratios is thus conceivable.

  16. Single-drop reactive extraction/extractive reaction with forced convective diffusion and interphase mass transfer

    Science.gov (United States)

    Kleinman, Leonid S.; Red, X. B., Jr.

    1995-01-01

    An algorithm has been developed for time-dependent forced convective diffusion-reaction having convection by a recirculating flow field within the drop that is hydrodynamically coupled at the interface with a convective external flow field that at infinity becomes a uniform free-streaming flow. The concentration field inside the droplet is likewise coupled with that outside by boundary conditions at the interface. A chemical reaction can take place either inside or outside the droplet, or reactions can take place in both phases. The algorithm has been implemented, and for comparison results are shown here for the case of no reaction in either phase and for the case of an external first order reaction, both for unsteady behavior. For pure interphase mass transfer, concentration isocontours, local and average Sherwood numbers, and average droplet concentrations have been obtained as a function of the physical properties and external flow field. For mass transfer enhanced by an external reaction, in addition to the above forms of results, we present the enhancement factor, with the results now also depending upon the (dimensionless) rate of reaction.

  17. Degradation of the solid electrolyte interphase induced by the deposition of manganese ions

    Science.gov (United States)

    Shin, Hosop; Park, Jonghyun; Sastry, Ann Marie; Lu, Wei

    2015-06-01

    The deposition of manganese ions dissolved from the cathode onto the interface between the solid electrolyte interphase (SEI) and graphite causes severe capacity fading in manganese oxide-based cells. The evolution of the SEI layer containing these Mn compounds and the corresponding instability of the layer are thoroughly investigated by artificially introducing soluble Mn ions into a 1 mol L-1 LiPF6 electrolyte solution. Deposition of dissolved Mn ions induces an oxygen-rich SEI layer that results from increased electrolyte decomposition, accelerating SEI growth. The spatial distribution of Mn shows that dissolved Mn ions diffuse through the porous layer and are deposited mostly at the inorganic layer/graphite interface. The Mn compound deposited on the anode, identified as MnF2, originates from a metathesis reaction between LiF and dissolved Mn ion. It is confirmed that ion-exchange reaction occurs in the inorganic layer, converting SEI species to Mn compounds. Some of the Mn is observed inside the graphite; this may cause surface structural disordering in the graphite, limiting lithium-ion intercalation. The continuous reaction that occurs at the inorganic layer/graphite interfacial regions and the modification of the original SEI layer in the presence of Mn ions are critically related to capacity fade and impedance rise currently plaguing Li-ion cells.

  18. Single-drop reactive extraction/extractive reaction with forced convective diffusion and interphase mass transfer

    Science.gov (United States)

    Kleinman, Leonid S.; Reed, X. B., Jr.

    1995-01-01

    An algorithm has been developed for the forced convective diffusion-reaction problem for convection inside and outside a droplet by a recirculating flow field hydrodynamically coupled at the droplet interface with an external flow field that at infinity becomes a uniform streaming flow. The concentration field inside the droplet is likewise coupled with that outside by boundary conditions at the interface. A chemical reaction can take place either inside or outside the droplet or reactions can take place in both phases. The algorithm has been implemented and results are shown here for the case of no reaction and for the case of an external first order reaction, both for unsteady behavior. For pure interphase mass transfer, concentration isocontours, local and average Sherwood numbers, and average droplet concentrations have been obtained as a function of the physical properties and external flow field. For mass transfer enhanced by an external reaction, in addition to the above forms of results, we present the enhancement factor, with the results now also depending upon the (dimensionless) rate of reaction.

  19. The rapid interphase chromosome assay (RICA implementation: comparison with other PCC methods

    Directory of Open Access Journals (Sweden)

    Sommer Sylwester

    2015-12-01

    Full Text Available A report is presented on the advantages of the rapid interphase chromosome assay (RICA and the difficulties that may be met while implementing this method for application in biological dosimetry. The RICA test can be applied on unstimulated human lymphocytes; this is an advantage in comparison with the dicentric chromosomes or micronucleus tests. In the former two tests, stimulated lymphocytes are examined and hence, 48 h more are needed to obtain cells traversing the cell cycle. Due to the use of unstimulated nondividing cells, higher numbers of cells are available for RICA analysis than for dicentric chromosomes or micronuclei tests. Moreover, the method can be applied after exposure to ionizing radiation doses in excess of 5 Gy. Such doses cause a significant cell cycle delay or result in the loss of G2 phase and mitotic cells because of apoptosis. Therefore, the traditional biodosimetry based on the evaluation of the incidence of damage to chromosomes is very difficult to carry out. This is due to the lack of an adequate number of mitotic cells for analysis. RICA is free of this disadvantage. An automatic microscope can be used to retrieve cell images; automatic image analysis can also be used.

  20. Evidence of Chromosomal Instability in Prostate Cancer Determined by Spectral Karyotyping (SKY and Interphase FISH Analysis

    Directory of Open Access Journals (Sweden)

    Ben Beheshti

    2001-01-01

    Full Text Available The way in which cytogenetic aberrations develop in prostate cancer (Cap is poorly understood. Spectral karyotype (SKY analysis of Cap cell lines has shown that they have unstable karyotypes and also have features associated with chromosomal instability (CIN. To accurately determine the incidence of de novo structural and numerical aberrations in vitro in Cap, we performed SKY analysis of three independent clones derived from one representative cell line, DU145. The frequent generation of new chromosomal rearrangements and a wide variation in the number of structural aberrations within two to five passages suggested that this cell line exhibited some of the features associated with a CIN phenotype. To study numerical cell-to-cell variation, chromosome 8 aneusomy was assessed in the LNCaP, DU145, and PC-3 cell lines and a patient cohort of 15 Cap primary tumors by interphase fluorescence in situ hybridization (FISH. This analysis showed that a high frequency of numerical alteration affecting chromosome 8 was present in both in vitro and in Cap tissues. In comparison to normal controls, the patient cohort had a statistically significant (P<.05, greater frequency of cells with one and three centromere 8 copies. These data suggest that a CIN-like process may be contributing towards the generation of de novo numerical and structural chromosome abnormalities in Cap.

  1. Effect of zwitterion on the lithium solid electrolyte interphase in ionic liquid electrolytes

    Science.gov (United States)

    Byrne, N.; Howlett, P. C.; MacFarlane, D. R.; Smith, M. E.; Howes, A.; Hollenkamp, A. F.; Bastow, T.; Hale, P.; Forsyth, M.

    An understanding of the solid electrolyte interphase (SEI) that forms on the lithium-metal surface is essential to the further development of rechargeable lithium-metal batteries. Currently, the formation of dendrites during cycling, which can lead to catastrophic failure of the cell, has mostly halted research on these power sources. The discovery of ionic liquids as electrolytes has rekindled the possibility of safe, rechargeable, lithium-metal batteries. The current limitation of ionic liquid electrolytes, however, is that when compared with conventional non-aqueous electrolytes the device rate capability is limited. Recently, we have shown that the addition of a zwitterion such as N-methyl- N-(butyl sulfonate) pyrrolidinium resulted in enhancement of the achievable current densities by 100%. It was also found that the resistance of the SEI layer in the presence of a zwitterion is 50% lower. In this study, a detailed chemical and electrochemical analysis of the SEI that forms in both the presence and absence of a zwitterion has been conducted. Clear differences in the chemical nature and also the thickness of the SEI are observed and these may account for the enhancement of operating current densities.

  2. In Situ Chemical Imaging of Solid-Electrolyte Interphase Layer Evolution in Li–S Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Nandasiri, Manjula I.; Camacho-Forero, Luis E.; Schwarz, Ashleigh M.; Shutthanandan, Vaithiyalingam; Thevuthasan, Suntharampillai; Balbuena, Perla B.; Mueller, Karl T.; Murugesan, Vijayakumar

    2017-05-16

    Parasitic reactions of electrolyte and polysulfide with the Li-anode in lithium sulfur (Li-S) batteries lead to the for-mation of solid electrolyte interphase (SEI) layers, which are the major reason behind severe capacity fading in these systems. Despite numerous studies, the evolution mechanism of the SEI layer and specific roles of polysulfides and oth-er electrolyte components are still unclear. We report an in-situ X-ray photoelectron spectroscopy (XPS) and chemical imaging analysis combined with ab initio molecular dynamics (AIMD) computational modeling to gain fundamental understanding regarding the evolution of SEI layers on Li-anodes within Li-S batteries. A multi-modal approach in-volving AIMD modeling and in-situ XPS characterization uniquely reveals the chemical identity and distribution of active participants in parasitic reactions as well as the SEI layer evolution mechanism. The SEI layer evolution has three major stages: the formation of a primary composite mixture phase involving stable lithium compounds (Li2S, LiF, Li2O etc); and formation of a secondary matrix type phase due to cross interaction between reaction products and elec-trolyte components, which is followed by a highly dynamic mono-anionic polysulfide (i.e. LiS5) fouling process. These new molecular-level insights into the SEI layer evolution on Li- anodes are crucial for delineating effective strategies for the development of Li–S batteries.

  3. Effect of water on solid electrolyte interphase formation in Li-ion batteries

    Science.gov (United States)

    Saito, M.; Fujita, M.; Aoki, Y.; Yoshikawa, M.; Yasuda, K.; Ishigami, R.; Nakata, Y.

    2016-03-01

    Time-of-flight-elastic recoil detection analysis (TOF-ERDA) with 20 MeV Cu ions has been applied to measure the depth profiles of solid electrolyte interphase (SEI) layers on the negative electrode of lithium ion batteries (LIB). In order to obtain quantitative depth profiles, the detector efficiency was first assessed, and the test highlighted a strong mass and energy dependence of the recoiled particles, especially H and He. Subsequently, we prepared LIB cells with different water contents in the electrolyte, and subjected them to different charge-discharge cycle tests. TOF-ERDA, X-ray photoelectron spectrometry (XPS), gas chromatography (GC), ion chromatography (IC), and 1H nuclear magnetic resonance (1H NMR) were applied to characterize the SEI region of the negative electrode. The results showed that the SEI layer is formed after 300 cycle tests, and a 500 ppm water concentration in the electrolyte does not appear to cause significant differences in the elemental and organic content of the SEI.

  4. Highly Quantitative Electrochemical Characterization of Non-Aqueous Electrolytes & Solid Electrolyte Interphases

    Energy Technology Data Exchange (ETDEWEB)

    Sergiy V. Sazhin; Kevin L. Gering; Mason K. Harrup; Harry W. Rollins

    2012-10-01

    The methods to measure solid electrolyte interphase (SEI) electrochemical properties and SEI formation capability of non-aqueous electrolyte solutions are not adequately addressed in the literature. And yet, there is a strong demand in new electrolyte generations that promote stabilized SEIs and have an influence to resolve safety, calendar life and other limitations of Li-ion batteries. To fill this gap, in situ electrochemical approach with new descriptive criteria for highly quantitative characterization of SEI and electrolytes is proposed. These criteria are: SEI formation capacity, SEI corrosion rate, SEI maintenance rate, and SEI kinetic stability. These criteria are associated with battery parameters like irreversible capacity, self-discharge, shelf-life, power, etc. Therefore, they are especially useful for electrolyte development and standard fast screening, allowing a skillful approach to narrow down the search for the best electrolyte. The characterization protocol also allows retrieving information on interfacial resistance for SEI layers and the electrochemical window of electrolytes, the other important metrics of characterization. The method validation was done on electrolyte blends containing phosphazenes, developed at Idaho National Laboratory, as 1.2M LiPF6 [80 % EC-MEC (2:8) (v/v) + 20% Phosphazene variety] (v/v), which were targeted for safer electrolyte variations.

  5. Artificial Solid Electrolyte Interphase to Address the Electrochemical Degradation of Silicon Electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Dudney, Nancy J [ORNL; Nanda, Jagjit [ORNL; Liang, Chengdu [ORNL; Li, Juchuan [ORNL

    2014-01-01

    Electrochemical degradation on Si anodes prevents them from being successfully used in lithium-ion full cells. Unlike the case of graphite anodes, natural solid electrolyte interphase (SEI) films generated from carbonate electrolyte do not self-passivate on Si and causes continuous electrolyte decomposition. In this work we aim at solving the issue of electrochemical degradation by fabricating artificial SEI films using a solid electrolyte material, lithium phosphor oxynitride (Lipon), that conducts Li ions and blocks electrons. For Si anodes coated with Lipon of 50 nm or thicker, significant effect is observed in suppressing the electrolyte decomposition, while Lipon of thinner than 40 nm has little effect. Ionic and electronic conductivity measurement reveals that the artificial SEI is effective when it is a pure ionic conductor, and the electrolyte decomposition is not suppressed when the artificial SEI is a mixed electronic-ionic conductor. The critical thickness for this transition in conducting behavior is found to be 40~50 nm. This work provides guidance for designing artificial SEI for high capacity lithium-ion battery electrodes using solid electrolyte materials.

  6. Quantifying lithium in the solid electrolyte interphase layer and beyond using Lithium- Nuclear Reaction Analysis technique

    Science.gov (United States)

    Schulz, Adam; Bakhru, Hassaram; DeRosa, Don; Higashiya, Seiichiro; Rane-Fondacaro, Manisha; Haldar, Pradeep

    2017-08-01

    Accurate knowledge of lithium content within the solid electrolyte interphase (SEI) layer and anode would significantly enhance the current understanding of the lithium ion battery (LIB) degradation mechanisms, enabling knowledge-based improvements in the technology. For the first time, we have demonstrated the capabilities of highly selective Lithium Nuclear Reaction Analysis (Li-NRA) as a non-destructive depth profiling technique for quantifying Li within the SEI and anode without accurate knowledge of the composition, which is unavailable with other depth profiling techniques. The Li-NRA technique detects the gamma radiation resulting from a nuclear reaction at characteristic resonance energy between an incident high-energy proton and Li. The intensity of γ-ray is directly proportional to the Li content, and the energy of the incident proton is increased stepwise to depth profile the sample. We performed Li-NRA on the carbonaceous negative electrodes of commercial LIB coin cells at varying states of charge (SOC) and states of health (SOH) conditions. We used three simple models for the composition of SEI and anode material to show concurrence between theoretical and experimental value for Li content at varying SOC conditions, estimated the average SEI layer thickness, and correlated the residual Li content within the SOH samples with electrochemical data.

  7. 间期荧光原位杂交检测血液病染色体三体8%Use of interphase fluorescence in situ hybridization for diction of trisomy 8 in hematologic disorders

    Institute of Scientific and Technical Information of China (English)

    程淑琴; 陈成坚; 谢伟成; 谢必霞; 黄朝辉; 曹小龙

    2008-01-01

    目的 探讨间期荧光原位杂交(FISH)技术在检测血液病染色体三体8中的价值.方法 用荧光素直接标记的8号染色体着丝粒探针对77例血液病患者进行间期FISH检测,并与常规细胞遗传学方法(CC)进行比较分析.结果 FISH法三体8的检出率较传统吉姆萨显带高,或在吉姆萨显带无法分析时提供结果.结论 FISH检测三体8的敏感性高于常规核型分析,在小克隆检测方面有其优越性.%Objective To explore the value of interphase fluorescence in situ hybridization(FISH) in the detection of trisomy 8 in patients with hematologic disorders. Methods Seventy-seven patients were vestigated by directly labeled centrome DNA probes specific for 8 chromosome. The results were compared with that of conventional cytogenetic (CC) analysis. Results The proportion of trisomy 8 of 77 cases of hematologic disorders detected by FISH is higher than by G-banding karyotyping and FISH could offer the result when conventional cytogenetic methods failed to diagnose. Conclusion Interphase FISH is more sensitive in the detection of trisomy 8 than CC, and FISH displays its superiority in the detection of small clone.

  8. Membrane reactor. Membrane reactor

    Energy Technology Data Exchange (ETDEWEB)

    Shindo, Y.; Wakabayashi, K. (National Chemical Laboratory for Industry, Tsukuba (Japan))

    1990-08-05

    Many reaction examples were introduced of membrane reactor, to be on the point of forming a new region in the field of chemical technology. It is a reactor to exhibit excellent function, by its being installed with membrane therein, and is generally classified into catalyst function type and reaction promotion type. What firstly belongs to the former is stabilized zirconia, where oxygen, supplied to the cathodic side of membrane with voltage, impressed thereon, becomes O {sup 2 {minus}} to be diffused through the membrane and supplied, as variously activated oxygenous species, on the anodic side. Examples with many advantages can be given such as methane coupling, propylene oxidation, methanating reaction of carbon dioxide, etc. Apart, palladium film and naphion film also belong to the former. While examples of the latter comprise, among others, decomposition of hydrogen sulfide by porous glass film and dehydrogenation of cyclohexane or palladium alloy film, which are expected to be developed and materialized in the industry. 33 refs., 8 figs.

  9. Mecanobiología de la interfase hueso-implante dental Mechanobiology of bone-dental implant interphase

    Directory of Open Access Journals (Sweden)

    Juan Carlos Vanegas Acosta

    2010-03-01

    Full Text Available La osteointegración es la conexión estructural y funcional entre el hueso y un implante. Cuando un implante se inserta en el hueso, se crea la denominada interfase hueso-implante, una zona de unión entre la superficie del biomaterial del implante y el hueso circundante. La cicatrización de esta interfase depende de las condiciones biológicas del hueso, las características de diseño del implante y la distribución de cargas entre hueso e implante. En este artículo se hace una revisión del proceso de cicatrización de la interfase hueso-implante para el caso de un implante dental. El objetivo es describir la secuencia de eventos biológicos iniciados con la lesión causada por la inserción del implante y que concluyen con la formación de nuevo hueso en la interfase. Esta descripción incluye una novedosa clasificación de los fenómenos mecánicos que intervienen durante el proceso de cicatrización de los tejidos lesionados. Esta descripción mecanobiológica de la interfase hueso-implante dental se utiliza para determinar las características más relevantes a tener en cuenta en la formulación de un modelo matemático de la osteointegración de implantes dentales.The osteointegration is the structural and functional connection between bone and implant. When an implant is inserted in bone, it creates the so-called bone-implant interphase, a joint zone between implant biomaterial surface and the surrounding bone. The healing of this interphase depends on bone biological conditions, characteristic of implant design and the distribution of loads between bone and implant. The aim of present article is to review of healing process of bone-implant interphase for a dental implant and also to describe the sequence of biological events beginning with lesion caused by implant insertion and leading to the formation of a new bone in the interphase. This description includes a novel classification of mechanical phenomena present in the healing

  10. Biobased Membrane

    NARCIS (Netherlands)

    Koenders, E.A.B.; Zlopasa, J.; Picken, S.J.

    2015-01-01

    The present invention is in the field of a composition for forming a bio-compatible membrane applicable to building material, such as concrete, cement, etc., to a meth od of applying said composition for forming a bio-compatible membrane, a biocompatible membrane, use of said membrane for various pu

  11. Membrane fusion

    DEFF Research Database (Denmark)

    Bendix, Pól Martin

    2015-01-01

    At Stanford University, Boxer lab, I worked on membrane fusion of small unilamellar lipid vesicles to flat membranes tethered to glass surfaces. This geometry closely resembles biological systems in which liposomes fuse to plasma membranes. The fusion mechanism was studied using DNA zippering...... between complementary strands linked to the two apposing membranes closely mimicking the zippering mechanism of SNARE fusion complexes....

  12. Lateral proton transfer between the membrane and a membrane protein.

    Science.gov (United States)

    Ojemyr, Linda; Sandén, Tor; Widengren, Jerker; Brzezinski, Peter

    2009-03-17

    Proton transport across biological membranes is a key step of the energy conservation machinery in living organisms, and it has been proposed that the membrane itself plays an important role in this process. In the present study we have investigated the effect of incorporation of a proton transporter, cytochrome c oxidase, into a membrane on the protonation kinetics of a fluorescent pH-sensitive probe attached at the surface of the protein. The results show that proton transfer to the probe was slightly accelerated upon attachment at the protein surface (approximately 7 x 1010 s(-1) M(-1), compared to the expected value of (1-2) x 10(10) s(-1) M(-1)), which is presumably due to the presence of acidic/His groups in the vicinity. Upon incorporation of the protein into small unilamellar phospholipid vesicles the rate increased by more than a factor of 400 to approximately 3 x 10(13) s(-1) M(-1), which indicates that the protein-attached probe is in rapid protonic contact with the membrane surface. The results indicate that the membrane acts to accelerate proton uptake by the membrane-bound proton transporter.

  13. Data Mining Empowers the Generation of a Novel Class of Chromosome-specific DNA Probes

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Hui; Weier, Heinz-Ulrich G.; Kwan, Johnson; Wang, Mei; O' Brien, Benjamin

    2011-03-08

    Probes that allow accurate delineation of chromosome-specific DNA sequences in interphase or metaphase cell nuclei have become important clinical tools that deliver life-saving information about the gender or chromosomal make-up of a product of conception or the probability of an embryo to implant, as well as the definition of tumor-specific genetic signatures. Often such highly specific DNA probes are proprietary in nature and have been the result of extensive probe selection and optimization procedures. We describe a novel approach that eliminates costly and time consuming probe selection and testing by applying data mining and common bioinformatics tools. Similar to a rational drug design process in which drug-protein interactions are modeled in the computer, the rational probe design described here uses a set of criteria and publicly available bioinformatics software to select the desired probe molecules from libraries comprised of hundreds of thousands of probe molecules. Examples describe the selection of DNA probes for the human X and Y chromosomes, both with unprecedented performance, but in a similar fashion, this approach can be applied to other chromosomes or species.

  14. Proximal Probes Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Proximal Probes Facility consists of laboratories for microscopy, spectroscopy, and probing of nanostructured materials and their functional properties. At the...

  15. Freely turning over palmitate in erythrocyte membrane proteins is not responsible for the anchoring of lipid rafts to the spectrin skeleton: a study with bio-orthogonal chemical probes.

    Science.gov (United States)

    Ciana, Annarita; Achilli, Cesare; Hannoush, Rami N; Risso, Angela; Balduini, Cesare; Minetti, Giampaolo

    2013-03-01

    Erythrocyte lipid rafts are anchored to the underlying spectrin membrane skeleton [A. Ciana, C. Achilli, C. Balduini, G. Minetti, On the association of lipid rafts to the spectrin skeleton in human erythrocytes, Biochim. Biophys. Acta 1808 (2011) 183-190]. The nature of this linkage and the molecules involved are poorly understood. The interaction is sensitive to the increase in pH and ionic strength induced by carbonate. Given the role of palmitoylation in modulating the partitioning of certain proteins between various sub-cellular compartments and the plasma membrane, we asked whether palmitoylation of p55, a peripheral protein located at the junctional complex between spectrin-actin-protein 4.1 that anchors the membrane skeleton to the lipid bilayer via the transmembrane protein glycophorin C, could contribute to the anchoring of lipid rafts to the membrane skeleton. We adopted a new, non-radioactive method for studying protein palmitoylation, based on bio-orthogonal chemical analogues of fatty acids, containing an omega-alkynyl group, to metabolically label cell proteins, which are then revealed by a "click chemistry" reaction of the alkynyl moiety with an azide-containing reporter tag. We show that the membrane localization and palmitoylation levels of p55 did not change after carbonate treatment. 2-bromopalmitate and cerulenin, two known palmitoylation inhibitors, completely inhibited p55 palmitoylation, and protein palmitoyl thioesterase-1 (PPT1) reduced it, without affecting the association between lipid rafts and membrane-skeleton, indicating, on the one hand, that p55 palmitoylation is enzymatic, and, on the other, that it is not involved in the modulation of the linkage of lipid rafts to the membrane-skeleton.

  16. Segregation of solute atoms to interphase boundaries in GdNi{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Murray, Ryan; Banerjee, Debashis; Collins, Gary S., E-mail: collins@wsu.edu [Washington State University, Department of Physics and Astronomy (United States); Zacate, Matthew O. [Northern Kentucky University, Department of Physics and Geology (United States)

    2017-11-15

    Lattice locations of {sup 111}In impurity probe atoms in intermetallic GdNi{sub 2} were studied as a function of alloy composition and temperature using perturbed angular correlation spectroscopy (PAC). Measurements were made on a pair of samples that were richer and poorer in Gd. Three nuclear quadrupole interaction signals were detected and their equilibrium site fractions were measured up to 700 {sup ∘}C. Two signals have well-defined electric field gradients (EFGs) and are attributed to In-probes on Gd- and Ni-sites in a well-ordered lattice. A third signal exhibiting strong inhomogeneous broadening was observed at low temperature in Gd-richer samples. This is attributed to segregation of the In-probes to phase boundaries (PB) of minor volume fractions of the neighboring GdNi phase. A measurement made on a stoichiometric GdNi sample exhibited the same inhomogeneously broadened signal, indicating that In-probes prefer to occupy PB and/or grain boundary sites in GdNi rather than the well-defined Gd- and Ni-sites. Changes in site fractions were reversible above 300 {sup ∘}C, indicating that probe atoms equilibrate among all lattice locations within a time period of one day. Thus, PB sites provide lower enthalpy environments for In-probes than either crystallographic site in GdNi{sub 2}. Enthalpy differences between the levels were determined from measurements of temperature dependences of ratios of site fractions. The enthalpy of transfer of In-probes from the Gd- to Ni-sublattice, which is coupled to intrinsic disorder in the compound, was found to be much smaller in the Gd-richer sample than in the Gd-poorer sample. This can be explained by differing temperature dependences of intrinsic defect concentrations at the two compositions. Among those probes that remain within the GdNi{sub 2} phase, there is a temperature dependence of the ratio of site fractions of In-probes on Gd- and Ni-sites. Taking this into account, a macroscopic segregation enthalpy is

  17. Interphase cytogenetic analysis of prostatic carcinomas by use of nonisotopic in situ hybridization.

    Science.gov (United States)

    Baretton, G B; Valina, C; Vogt, T; Schneiderbanger, K; Diebold, J; Löhrs, U

    1994-08-15

    To gain a better understanding of chromosomal aberrations in direct correlation with histology, we studied tumor material from 35 patients (36 regions) with primary prostate carcinoma by nonisotopic in situ hybridization. Nine biotinylated DNA probes were used on serial paraffin sections (centromer-specific probes for X, Y, 1, 7, 8, 10, 17, and 18, and a telomer-specific probe for 1p; ONCOR). Of the 324 hybridized sections, 94% were suitable for evaluation. In 34 of the 35 cases (35 of 36 regions) 1-8 chromosomal aberrations were detected. Chromosome X showed supernumerary centromer copies in 44% of cases. The probes for chromosomes 1, 1p, 10, and 18 demonstrated deletions in 25, 23, 40 and 58% of cases, respectively. Gains as well as deletions were present for Y, 7, 8, and 17 in 31, 25, 36, and 58% of cases, respectively. In 27% of cases discordant copy numbers of the centromer- and the telomer-specific probes for chromosome 1 were observed. No aberration which might be specific for prostate cancer could be established. The rate of aneusomy increased significantly with histological grade. Intratumoral heterogeneity of chromosomal aberrations was revealed in one case. Due to the higher sensitivity of nonisotopic in situ hybridization, aneusomic cases outnumbered cases with cytometrically determined DNA aneuploidy. In view of published results of metaphase preparations, the high frequency of aneusomy and some of the chromosomal aberrations detected by nonisotopic in situ hybridization were unexpected.

  18. Differential localization of cytoplasmic myosin II isoforms A and B in avian interphase and dividing embryonic and immortalized cardiomyocytes and other cell types in vitro

    Science.gov (United States)

    Conrad, A. H.; Jaffredo, T.; Conrad, G. W.; Spooner, B. S. (Principal Investigator)

    1995-01-01

    Two principal isoforms of cytoplasmic myosin II, A and B (CMIIA and CMIIB), are present in different proportions in different tissues. Isoform-specific monoclonal and polyclonal antibodies to avian CMIIA and CMIIB reveal the cellular distributions of these isoforms in interphase and dividing embryonic avian cardiac, intestinal epithelial, spleen, and dorsal root ganglia cells in primary cell culture. Embryonic cardiomyocytes react with antibodies to CMIIB but not to CMIIA, localize CMIIB in stress-fiber-like-structures during interphase, and markedly concentrate CMIIB in networks in the cleavage furrow during cytokinesis. In contrast, cardiac fibroblasts localize both CMIIA and CMIIB in stress fibers and networks during interphase, and demonstrate slight and independently regulated concentration of CMIIA and CMIIB in networks in their cleavage furrows. V-myc-immortalized cardiomyocytes, an established cell line, have regained the ability to express CMIIA, as well as CMIIB, and localize both CMIIA and CMIIB in stress fibers and networks in interphase cells and in cleavage furrows in dividing cells. Conversely, some intestinal epithelial, spleen, and dorsal root ganglia interphase cells express only CMIIA, organized primarily in networks. Of these, intestinal epithelial cells express both CMIIA and CMIIB when they divide, whereas some dividing cells from both spleen and dorsal root ganglia express only CMIIA and concentrate it in their cleavage furrows. These results suggest that within a given tissue, different cell types express different isoforms of CMII, and that cells expressing either CMIIA or CMIIB alone, or simultaneously, can form a cleavage furrow and divide.

  19. 5 prime -Azido-(3,6- sup 3 H sub 2 )-1-naphthylphthalamic acid, a photoactivatable probe for naphthylphthalamic acid receptor proteins from higher plants: Identification of a 23-kDa protein from maize coleoptile plasma membranes

    Energy Technology Data Exchange (ETDEWEB)

    Zettl, R.; Feldwisch, J.; Schell, J.; Palme, K. (Max-Planck-Inst. fuer Zuechtungsforschung, Koeln (West Germany)); Boland, W. (Univ. Karlsruhe (West Germany))

    1992-01-15

    1-Naphthylphthalamic acid (NPA) is a specific inhibitor of polar auxin transport that blocks carrier mediated auxin efflux from plant cells. To allow identification of the NPA receptor thought to be part of the auxin efflux carrier, the authors have synthesized a tritiated, photolabile NPA analogue, 5{prime}-azido-(3,6-{sup 3}H{sub 2})NPA (({sup 3}H{sub 2})N{sub 3}NPA). This analogue was used to identify NPA-binding proteins in fractions highly enriched for plasma membrane vesicles isolated from maize coleoptiles (Zea mays L.). Competition studies showed that binding of ({sup 3}H{sub 2})N{sub 3}NPA to maize plasma membrane vesicles was blocked by nonradioactive NPA but not by benzoic acid. After incubation of plasma membrane vesicles with ({sup 3}H{sub 2})N{sub 3}NPA and exposure to UV light, they observed specific photoaffinity labeling of a protein with an apparent molecular mass of 23 kDa. Pretreatment of the plasma membrane vesicles with indole-3-acetic acid or with the auxin-transport inhibitors NPA and 2,3,5-triiodobenzoic acid strongly reduced specific labeling of this protein. This 23-kDa protein was also labeled by addition of 5-azido-(7-{sup 3}H)indole-3-acetic acid to plasma membranes prior to exposure to UV light. The 23-kDa protein was solubilized from plasma membranes by 1% Triton X-100. The possibility that this 23-kDa polypeptide is part of the auxin efflux carrier system is discussed.

  20. SAP-like domain in nucleolar spindle associated protein mediates mitotic chromosome loading as well as interphase chromatin interaction

    Energy Technology Data Exchange (ETDEWEB)

    Verbakel, Werner, E-mail: werner.verbakel@chem.kuleuven.be [Laboratory of Biomolecular Dynamics, Katholieke Universiteit Leuven, Celestijnenlaan 200G, Bus 2403, 3001 Heverlee (Belgium); Carmeliet, Geert, E-mail: geert.carmeliet@med.kuleuven.be [Laboratory of Experimental Medicine and Endocrinology, Katholieke Universiteit Leuven, Herestraat 49, Bus 902, 3000 Leuven (Belgium); Engelborghs, Yves, E-mail: yves.engelborghs@fys.kuleuven.be [Laboratory of Biomolecular Dynamics, Katholieke Universiteit Leuven, Celestijnenlaan 200G, Bus 2403, 3001 Heverlee (Belgium)

    2011-08-12

    Highlights: {yields} The SAP-like domain in NuSAP is a functional DNA-binding domain with preference for dsDNA. {yields} This SAP-like domain is essential for chromosome loading during early mitosis. {yields} NuSAP is highly dynamic on mitotic chromatin, as evident from photobleaching experiments. {yields} The SAP-like domain also mediates NuSAP-chromatin interaction in interphase nucleoplasm. -- Abstract: Nucleolar spindle associated protein (NuSAP) is a microtubule-stabilizing protein that localizes to chromosome arms and chromosome-proximal microtubules during mitosis and to the nucleus, with enrichment in the nucleoli, during interphase. The critical function of NuSAP is underscored by the finding that its depletion in HeLa cells results in various mitotic defects. Moreover, NuSAP is found overexpressed in multiple cancers and its expression levels often correlate with the aggressiveness of cancer. Due to its localization on chromosome arms and combination of microtubule-stabilizing and DNA-binding properties, NuSAP takes a special place within the extensive group of spindle assembly factors. In this study, we identify a SAP-like domain that shows DNA binding in vitro with a preference for dsDNA. Deletion of the SAP-like domain abolishes chromosome arm binding of NuSAP during mitosis, but is not sufficient to abrogate its chromosome-proximal localization after anaphase onset. Fluorescence recovery after photobleaching experiments revealed the highly dynamic nature of this NuSAP-chromatin interaction during mitosis. In interphase cells, NuSAP also interacts with chromatin through its SAP-like domain, as evident from its enrichment on dense chromatin regions and intranuclear mobility, measured by fluorescence correlation spectroscopy. The obtained results are in agreement with a model where NuSAP dynamically stabilizes newly formed microtubules on mitotic chromosomes to enhance chromosome positioning without immobilizing these microtubules. Interphase Nu

  1. Chromosomal imbalances detected in primary bone tumors by comparative genomic hybridization and interphase fluorescence in situ hybridization

    OpenAIRE

    Baruffi Marcelo Razera; Engel Edgard Edward; Squire Jeremy Andrew; Tone Luis Gonzaga; Rogatto Silvia Regina

    2003-01-01

    We applied a combination of comparative genomic hybridization (CGH) and fluorescence in situ hybridization (FISH), to characterize the genetic aberrations in three osteosarcomas (OS) and one Ewing's sarcoma. CGH identified recurrent chromosomal losses at 10p14-pter and gains at 8q22.3-24.1 in OS. Interphase FISH allowed to confirm 8q gain in two cases. A high amplification level of 11q12-qter was detected in one OS. The Ewing's sarcoma showed gain at 1p32-36.1 as the sole chromosome alteratio...

  2. Membranous nephropathy

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/000472.htm Membranous nephropathy To use the sharing features on this page, please enable JavaScript. Membranous nephropathy is a kidney disorder that leads to changes ...

  3. Probe tip heating assembly

    Science.gov (United States)

    Schmitz, Roger William; Oh, Yunje

    2016-10-25

    A heating assembly configured for use in mechanical testing at a scale of microns or less. The heating assembly includes a probe tip assembly configured for coupling with a transducer of the mechanical testing system. The probe tip assembly includes a probe tip heater system having a heating element, a probe tip coupled with the probe tip heater system, and a heater socket assembly. The heater socket assembly, in one example, includes a yoke and a heater interface that form a socket within the heater socket assembly. The probe tip heater system, coupled with the probe tip, is slidably received and clamped within the socket.

  4. A model for interphase chromosomes and evaluation of radiation-induced aberrations

    Science.gov (United States)

    Holley, W. R.; Mian, I. S.; Park, S. J.; Rydberg, B.; Chatterjee, A.

    2002-01-01

    We have developed a theoretical model for evaluating radiation-induced chromosomal exchanges by explicitly taking into account interphase (G(0)/G(1)) chromosome structure, nuclear organization of chromosomes, the production of double-strand breaks (DSBs), and the subsequent rejoinings in a faithful or unfaithful manner. Each of the 46 chromosomes for human lymphocytes (40 chromosomes for mouse lymphocytes) is modeled as a random polymer inside a spherical volume. The chromosome spheres are packed randomly inside a spherical nucleus with an allowed overlap controlled by a parameter Omega. The rejoining of DSBs is determined by a Monte Carlo procedure using a Gaussian proximity function with an interaction range parameter sigma. Values of Omega and sigma have been found which yield calculated results of interchromosomal aberration frequencies that agree with a wide range of experimental data. Our preferred solution is one with an interaction range of 0.5 microm coupled with a relatively small overlap parameter of 0.675 microm, which more or less confirms previous estimates. We have used our model with these parameter values and with resolution or detectability limits to calculate yields of translocations and dicentrics for human lymphocytes exposed to low-LET radiation that agree with experiments in the dose range 0.09 to 4 Gy. Five different experimental data sets have been compared with the theoretical results. Essentially all of the experimental data fall between theoretical curves corresponding to resolution limits of 1 Mbp and 20 Mbp, which may reflect the fact that different investigators use different limits for sensitivity or detectability. Translocation yields for mouse lymphocytes have also been calculated and are in good agreement with experimental data from 1 cGy to 10 cGy. There is also good agreement with recent data on complex aberrations. Our model is expected to be applicable to both low- and high-LET radiation, and we include a sample prediction of

  5. Firing membranes

    NARCIS (Netherlands)

    Kappert, Emiel Jan

    2015-01-01

    Thermal processing is commonly employed to alter the chemistry and microstructure of membrane layers. It can shape, strengthen, and give functionality to a membrane. A good understanding of the processes taking place during the thermal processing of a membrane material allows for optimization and tu

  6. Computational modeling of elastic properties of carbon nanotube/polymer composites with interphase regions. Part I: Micro-structural characterization and geometric modeling

    KAUST Repository

    Han, Fei

    2014-01-01

    A computational strategy to predict the elastic properties of carbon nanotube-reinforced polymer composites is proposed in this two-part paper. In Part I, the micro-structural characteristics of these nano-composites are discerned. These characteristics include networks/agglomerations of carbon nanotubes and thick polymer interphase regions between the nanotubes and the surrounding matrix. An algorithm is presented to construct three-dimensional geometric models with large amounts of randomly dispersed and aggregated nanotubes. The effects of the distribution of the nanotubes and the thickness of the interphase regions on the concentration of the interphase regions are demonstrated with numerical results. © 2013 Elsevier B.V. All rights reserved.

  7. Studies on the Effects of Interphase Heat Exchange during Thermal Explosion in a Combustible Dusty Gas with General Arrhenius Reaction-Rate Laws

    Directory of Open Access Journals (Sweden)

    K. S. Adegbie

    2012-01-01

    Full Text Available A mathematical model for thermal explosion in a combustible dusty gas containing fuel droplets with general Arrhenius reaction-rate laws, convective and radiative heat losses, and interphase heat exchange between gas and inert solid particles is investigated. The objective of the study is to examine the effects of interphase heat exchange between the gas and solid particles on (i ignition of reacting gas, (ii accumulation of heat by the solid particles during combustion process (iii evaporation of the liquid fuel droplets, and (iv consumption of reacting gas concentration. The equations governing the physical model with realistic assumptions are stated and nondimensionalised leading to an intractable system of first-order coupled nonlinear differential equations, which is not amenable to exact methods of solution. Therefore, we present numerical solutions as well as different qualitative effects of varying interphase heat exchange parameter. Graphs and Table feature prominently to explain the results obtained.

  8. Membrane Biophysics

    CERN Document Server

    Ashrafuzzaman, Mohammad

    2013-01-01

    Physics, mathematics and chemistry all play a vital role in understanding the true nature and functioning of biological membranes, key elements of living processes. Besides simple spectroscopic observations and electrical measurements of membranes we address in this book the phenomena of coexistence and independent existence of different membrane components using various theoretical approaches. This treatment will be helpful for readers who want to understand biological processes by applying both simple observations and fundamental scientific analysis. It provides a deep understanding of the causes and effects of processes inside membranes, and will thus eventually open new doors for high-level pharmaceutical approaches towards fighting membrane- and cell-related diseases.

  9. Investigation of interphase effects in silica-polystyrene nanocomposites based on a hybrid molecular-dynamics-finite-element simulation framework

    Science.gov (United States)

    Pfaller, Sebastian; Possart, Gunnar; Steinmann, Paul; Rahimi, Mohammad; Müller-Plathe, Florian; Böhm, Michael C.

    2016-05-01

    A recently developed hybrid method is employed to study the mechanical behavior of silica-polystyrene nanocomposites (NCs) under uniaxial elongation. The hybrid method couples a particle domain to a continuum domain. The region of physical interest, i.e., the interphase around a nanoparticle (NP), is treated at molecular resolution, while the surrounding elastic continuum is handled with a finite-element approach. In the present paper we analyze the polymer behavior in the neighborhood of one or two nanoparticle(s) at molecular resolution. The coarse-grained hybrid method allows us to simulate a large polymer matrix region surrounding the nanoparticles. We consider NCs with dilute concentration of NPs embedded in an atactic polystyrene matrix formed by 300 chains with 200 monomer beads. The overall orientation of polymer segments relative to the deformation direction is determined in the neighborhood of the nanoparticle to investigate the polymer response to this perturbation. Calculations of strainlike quantities give insight into the deformation behavior of a system with two NPs and show that the applied strain and the nanoparticle distance have significant influence on the deformation behavior. Finally, we investigate to what extent a continuum-based description may account for the specific effects occurring in the interphase between the polymer matrix and the NPs.

  10. Visualization and Characterization of High-Order Chromatin Fibers under Light Microscope during Interphase and Mitotic Stages in Plants

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Using genomic in situ hybridization with genomic DNA.high-order chromatin fibers were successfully exhibited under a light microscope through the cell cycle in barley,rice,maize and field bean.From the interphase to prophase and metaphase of mitosis,the fibers were basically similar.Each was estimated to be around 200 nm in diameter,but the strength of signals was not the same along the fiber length.Through the cell cycle a series of dynamic distribution changes occurred in the fibers.In the interphase,they were unraveled.At the early prophase they were arranged with parallel and mirror symmetry.During late-prophase and metaphase,the fibers were bundled and became different visible chromosomes.The parallel coiling and mirror symmetry structures were visible clearly until the metaphase.In anaphase they disappeared.During telophase,in peripheral regions of congregated chromosome group,borderlines of the chromosomes disappeared and the fibers were unraveled.This demonstrated that mitotic chromosomes are assembled and organized by parallel and adjacent coiling of the fibers and the fibers should be the highest order structure for DNA coiling.

  11. The use of premature chromosome condensation to study in interphase cells the influence of environmental factors on human genetic material

    Directory of Open Access Journals (Sweden)

    Vasiliki I. Hatzi

    2006-01-01

    Full Text Available Nowadays, there is a constantly increasing concern regarding the mutagenic and carcinogenic potential of a variety of harmful environmental factors to which humans are exposed in their natural and anthropogenic environment. These factors exert their hazardous potential in humans' personal (diet, smoking, pharmaceuticals, cosmetics and occupational environment that constitute part of the anthropogenic environment. It is well known that genetic damage due to these factors has dramatic implications for human health. Since most of the environmental genotoxic factors induce arrest or delay in cell cycle progression, the conventional analysis of chromosomes at metaphase may underestimate their genotoxic potential. Premature Chromosome Condensation (PCC induced either by means of cell fusion or specific chemicals, enables the microscopic visualization of interphase chromosomes whose morphology depends on the cell cycle stage, as well as the analysis of structural and numerical aberrations at the G1 and G2 phases of the cell cycle. The PCC has been successfully used in problems involving cell cycle analysis, diagnosis and prognosis of human leukaemia, assessment of interphase chromosome malformations resulting from exposure to radiation or chemicals, as well as elucidation of the mechanisms underlying the conversion of DNA damage into chromosomal damage. In this report, particular emphasis is given to the advantages of the PCC methodology used as an alternative to conventional metaphase analysis in answering questions in the fields of radiobiology, biological dosimetry, toxicogenetics, clinical cytogenetics and experimental therapeutics.

  12. Electrolyte Volume Effects on Electrochemical Performance and Solid Electrolyte Interphase in Si-Graphite/NMC Lithium-Ion Pouch Cells

    Energy Technology Data Exchange (ETDEWEB)

    An, Seong Jin; Li, Jianlin; Daniel, Claus; Meyer, Harry M.; Trask, Stephen E.; Polzin, Bryant J.; Wood, David L.

    2017-05-23

    This study aims to explore the correlations between electrolyte volume, electrochemical performance, and properties of the solid electrolyte interphase in pouch cells with Si-graphite composite anodes. The electrolyte is 1.2 M LiPF6 in ethylene carbonate:ethylmethyl carbonate with 10 wt.% fluoroethylene carbonate. Single layer pouch cells (100 mAh) were constructed with 15 wt.% Si-graphite / LiNi0.5Mn0.3CO0.2O2 electrodes. It is found that a minimum electrolyte volume factor of 3.1 times the total pore volume of cell components (cathode, anode, and separator) is needed for better cycling stability. Less electrolyte causes increases in ohmic and charge transfer resistances. Lithium dendrites are observed when the electrolyte volume factor is low. The resistances from the anodes become significant as the cells are discharged. Solid electrolyte interphase thickness grows as the electrolyte volume factor increases and is non-uniform after cycling.

  13. Bivalence Mn5O8 with hydroxylated interphase for high-voltage aqueous sodium-ion storage

    Science.gov (United States)

    Shan, Xiaoqiang; Charles, Daniel S.; Lei, Yinkai; Qiao, Ruimin; Wang, Guofeng; Yang, Wanli; Feygenson, Mikhail; Su, Dong; Teng, Xiaowei

    2016-11-01

    Aqueous electrochemical energy storage devices have attracted significant attention owing to their high safety, low cost and environmental friendliness. However, their applications have been limited by a narrow potential window (~1.23 V), beyond which the hydrogen and oxygen evolution reactions occur. Here we report the formation of layered Mn5O8 pseudocapacitor electrode material with a well-ordered hydroxylated interphase. A symmetric full cell using such electrodes demonstrates a stable potential window of 3.0 V in an aqueous electrolyte, as well as high energy and power performance, nearly 100% coulombic efficiency and 85% energy efficiency after 25,000 charge-discharge cycles. The interplay between hydroxylated interphase on the surface and the unique bivalence structure of Mn5O8 suppresses the gas evolution reactions, offers a two-electron charge transfer via Mn2+/Mn4+ redox couple, and provides facile pathway for Na-ion transport via intra-/inter-layer defects of Mn5O8.

  14. Bivalence Mn5O8 with hydroxylated interphase for high-voltage aqueous sodium-ion storage.

    Science.gov (United States)

    Shan, Xiaoqiang; Charles, Daniel S; Lei, Yinkai; Qiao, Ruimin; Wang, Guofeng; Yang, Wanli; Feygenson, Mikhail; Su, Dong; Teng, Xiaowei

    2016-11-15

    Aqueous electrochemical energy storage devices have attracted significant attention owing to their high safety, low cost and environmental friendliness. However, their applications have been limited by a narrow potential window (∼1.23 V), beyond which the hydrogen and oxygen evolution reactions occur. Here we report the formation of layered Mn5O8 pseudocapacitor electrode material with a well-ordered hydroxylated interphase. A symmetric full cell using such electrodes demonstrates a stable potential window of 3.0 V in an aqueous electrolyte, as well as high energy and power performance, nearly 100% coulombic efficiency and 85% energy efficiency after 25,000 charge-discharge cycles. The interplay between hydroxylated interphase on the surface and the unique bivalence structure of Mn5O8 suppresses the gas evolution reactions, offers a two-electron charge transfer via Mn(2+)/Mn(4+) redox couple, and provides facile pathway for Na-ion transport via intra-/inter-layer defects of Mn5O8.

  15. Membrane fouling and wetting in membrane distillation and their mitigation by novel membranes with special wettability.

    Science.gov (United States)

    Wang, Zhangxin; Lin, Shihong

    2017-04-01

    Membrane distillation (MD) has been identified as a promising technology to desalinate the hypersaline wastewaters from fracking and other industries. However, conventional hydrophobic MD membranes are highly susceptible to fouling and/or wetting by the hydrophobic and/or amphiphilic constituents in these wastewaters of complex compositions. This study systematically investigates the impact of the surface wetting properties on the membrane wetting and/or fouling behaviors in MD. Specifically, we compare the wetting and fouling resistance of three types of membranes of different wetting properties, including hydrophobic and omniphobic membranes as well as composite membranes with a hydrophobic substrate and a superhydrophilic top surface. We challenged the MD membranes with hypersaline feed solutions that contained a relatively high concentration of crude oil with and without added synthetic surfactants, Triton X-100. We found that the composite membranes with superhydrophilic top surface were robustly resistant to oil fouling in the absence of Triton X-100, but were subject to pore wetting in the presence of Triton X-100. On the other hand, the omniphobic membranes were easily fouled by oil-in-water emulsion without Triton X-100, but successfully sustained stable MD performance with Triton X-100 stabilized oil-in-water emulsion as the feed solution. In contrast, the conventional hydrophobic membranes failed readily regardless whether Triton X-100 was present, although via different mechanisms. These findings are corroborated by contact angle measures as well as oil-probe force spectroscopy. This study provides a holistic picture regarding how a hydrophobic membrane fails in MD and how we can leverage membranes with special wettability to prevent membrane failure in MD operations. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Hydrothermal stability of microporous silica and niobia-silica membranes

    NARCIS (Netherlands)

    Boffa, V.; Blank, David H.A.; ten Elshof, Johan E.

    2008-01-01

    The hydrothermal stability of microporous niobia–silica membranes was investigated and compared with silica membranes. The membranes were exposed to hydrothermal conditions at 150 and 200 °C for 70 h. The change of pore structure before and after exposure to steam was probed by single-gas permeation

  17. Mobile Game Probes

    DEFF Research Database (Denmark)

    Borup Lynggaard, Aviaja

    2006-01-01

    This paper will examine how probes can be useful for game designers in the preliminary phases of a design process. The work is based upon a case study concerning pervasive mobile phone games where Mobile Game Probes have emerged from the project. The new probes are aimed towards a specific target...... group and the goal is to specify the probes so they will cover the most relevant areas for our project. The Mobile Game Probes generated many interesting results and new issues occurred, since the probes came to be dynamic and favorable for the process in new ways....

  18. Non-toxic fluorescent phosphonium probes to detect mitochondrial potential

    Science.gov (United States)

    Šarić, Ana; Crnolatac, Ivo; Bouillaud, Frédéric; Sobočanec, Sandra; Mikecin, Ana-Matea; Mačak Šafranko, Željka; Delgeorgiev, Todor; Piantanida, Ivo; Balog, Tihomir; Petit, Patrice X.

    2017-03-01

    We evaluated our phosphonium-based fluorescent probes for selective staining of mitochondria. Currently used probes for monitoring mitochondrial membrane potential show varying degrees of interference with cell metabolism, photo-induced damage and probe binding. Here presented probes are characterised by highly efficient cellular uptake and specific accumulation in mitochondria. Fluorescent detection of the probes was accomplished using flow cytometry and confocal microscopy imaging of yeast and mammalian cells. Toxicity analysis (impedimetry—xCELLigence for the cellular proliferation and Seahorse technology for respiratory properties) confirms that these dyes exhibit no-toxicity on mitochondrial or cellular functioning even for long time incubation. The excellent chemical and photophysical stability of the dyes makes them promising leads toward improved fluorescent probes. Therefore, the probes described here offer to circumvent the problems associated with existing-probe’s limitations.

  19. Lipid membranes on nanostructured silicon.

    Energy Technology Data Exchange (ETDEWEB)

    Slade, Andrea Lynn; Lopez, Gabriel P. (University of New Mexico, Albuquerque, NM); Ista, Linnea K. (University of New Mexico, Albuquerque, NM); O' Brien, Michael J. (University of New Mexico, Albuquerque, NM); Sasaki, Darryl Yoshio; Bisong, Paul (University of New Mexico, Albuquerque, NM); Zeineldin, Reema R. (University of New Mexico, Albuquerque, NM); Last, Julie A.; Brueck, Stephen R. J. (University of New Mexico, Albuquerque, NM)

    2004-12-01

    A unique composite nanoscale architecture that combines the self-organization and molecular dynamics of lipid membranes with a corrugated nanotextured silicon wafer was prepared and characterized with fluorescence microscopy and scanning probe microscopy. The goal of this project was to understand how such structures can be assembled for supported membrane research and how the interfacial interactions between the solid substrate and the soft, self-assembled material create unique physical and mechanical behavior through the confinement of phases in the membrane. The nanometer scale structure of the silicon wafer was produced through interference lithography followed by anisotropic wet etching. For the present study, a line pattern with 100 nm line widths, 200 nm depth and a pitch of 360 nm pitch was fabricated. Lipid membranes were successfully adsorbed on the structured silicon surface via membrane fusion techniques. The surface topology of the bilayer-Si structure was imaged using in situ tapping mode atomic force microscopy (AFM). The membrane was observed to drape over the silicon structure producing an undulated topology with amplitude of 40 nm that matched the 360 nm pitch of the silicon structure. Fluorescence recovery after photobleaching (FRAP) experiments found that on the microscale those same structures exhibit anisotropic lipid mobility that was coincident with the silicon substructure. The results showed that while the lipid membrane maintains much of its self-assembled structure in the composite architecture, the silicon substructure indeed influences the dynamics of the molecular motion within the membrane.

  20. Properties of Ultrasound Probes

    OpenAIRE

    Rusina, M.

    2015-01-01

    This work deals with the measurement properties of ultrasound probes. Ultrasound probes and their parameters significantly affect the quality of the final image. In this work there are described the possibility of measuring the spatial resolution, sensitivity of the probe and measuring the length of the dead zone. Ultrasound phantom ATS Multi Purpose Phantom Type 539 was used for measurements.

  1. Approaches leading to the Three-Dimensional Organization of the Human Interphase Nucleus: Simulations, FISH, Chromatin Labelling in vivo, Fractal Analysis, Carbon Ion Irradiation

    NARCIS (Netherlands)

    T.A. Knoch (Tobias)

    2000-01-01

    textabstractDespite the successful linear sequencing of the human genome its three-dimensional structure is widely unknown, although it is important for gene regulation and replication. For a long time the interphase nucleus has been viewed as a 'spaghetti soup' of DNA without much internal stru

  2. Approaches leading to the Three-Dimensional Organization of the Human Interphase Nucleus: Simulations, FISH, Chromatin Labelling in vivo, Fractal Analysis, Carbon Ion Irradiation

    NARCIS (Netherlands)

    T.A. Knoch (Tobias)

    2000-01-01

    textabstractDespite the successful linear sequencing of the human genome its three-dimensional structure is widely unknown, although it is important for gene regulation and replication. For a long time the interphase nucleus has been viewed as a 'spaghetti soup' of DNA without much internal struc

  3. Optimized Fast-FISH with a-satellite probes: acceleration by microwave activation

    Directory of Open Access Journals (Sweden)

    Durm M.

    1997-01-01

    Full Text Available It has been shown for several DNA probes that the recently introduced Fast-FISH (fluorescence in situ hybridization technique is well suited for quantitative microscopy. For highly repetitive DNA probes the hybridization (renaturation time and the number of subsequent washing steps were reduced considerably by omitting denaturing chemical agents (e.g., formamide. The appropriate hybridization temperature and time allow a clear discrimination between major and minor binding sites by quantitative fluorescence microscopy. The well-defined physical conditions for hybridization permit automatization of the procedure, e.g., by a programmable thermal cycler. Here, we present optimized conditions for a commercially available X-specific a-satellite probe. Highly fluorescent major binding sites were obtained for 74oC hybridization temperature and 60 min hybridization time. They were clearly discriminated from some low fluorescent minor binding sites on metaphase chromosomes as well as in interphase cell nuclei. On average, a total of 3.43 ± 1.59 binding sites were measured in metaphase spreads, and 2.69 ± 1.00 in interphase nuclei. Microwave activation for denaturation and hybridization was tested to accelerate the procedure. The slides with the target material and the hybridization buffer were placed in a standard microwave oven. After denaturation for 20 s at 900 W, hybridization was performed for 4 min at 90 W. The suitability of a microwave oven for Fast-FISH was confirmed by the application to a chromosome 1-specific a-satellite probe. In this case, denaturation was performed at 630 W for 60 s and hybridization at 90 W for 5 min. In all cases, the results were analyzed quantitatively and compared to the results obtained by Fast-FISH. The major binding sites were clearly discriminated by their brightness

  4. Free-standing biomimetic polymer membrane imaged with atomic force microscopy

    DEFF Research Database (Denmark)

    Rein, Christian; Pszon-Bartosz, Kamila Justyna; Jensen, Karin Bagger Stibius

    2011-01-01

    Fluid polymeric biomimetic membranes are probed with atomic force microscopy (AFM) using probes with both normal tetrahedrally shaped tips and nanoneedle-shaped Ag2Ga rods. When using nanoneedle probes, the collected force volume data show three distinct membrane regions which match the expected...... membrane structure when spanning an aperture in a hydrophobic scaffold. The method used provides a general method for mapping attractive fluid surfaces. In particular, the nanoneedle probing allows for characterization of free-standing biomimetic membranes with thickness on the nanometer scale suspended...

  5. Subcellular Microanatomy by 3D Deconvolution Brightfield Microscopy: Method and Analysis Using Human Chromatin in the Interphase Nucleus

    Directory of Open Access Journals (Sweden)

    Paul Joseph Tadrous

    2012-01-01

    Full Text Available Anatomy has advanced using 3-dimensional (3D studies at macroscopic (e.g., dissection, injection moulding of vessels, radiology and microscopic (e.g., serial section reconstruction with light and electron microscopy levels. This paper presents the first results in human cells of a new method of subcellular 3D brightfield microscopy. Unlike traditional 3D deconvolution and confocal techniques, this method is suitable for general application to brightfield microscopy. Unlike brightfield serial sectioning it has subcellular resolution. Results are presented of the 3D structure of chromatin in the interphase nucleus of two human cell types, hepatocyte and plasma cell. I show how the freedom to examine these structures in 3D allows greater morphological discrimination between and within cell types and the 3D structural basis for the classical “clock-face” motif of the plasma cell nucleus is revealed. Potential for further applications discussed.

  6. Mapping residual organics and carbonate at grain boundaries and in the amorphous interphase in mouse incisor enamel

    Directory of Open Access Journals (Sweden)

    Lyle M Gordon

    2015-03-01

    Full Text Available Dental enamel has evolved to resist the most grueling conditions of mechanical stress, fatigue, and wear. Adding insult to injury, it is exposed to the frequently corrosive environment of the oral cavity. While its hierarchical structure is unrivaled in its mechanical resilience, heterogeneity in the distribution of magnesium ions and the presence of Mg-substituted amorphous calcium phosphate (Mg-ACP as an intergranular phase have recently been shown to increase the susceptibility of mouse enamel to acid attack. Herein we investigate the distribution of two important constituents of enamel, residual organic matter and inorganic carbonate. We find that organics, carbonate, and possibly water show distinct distribution patterns in the mouse enamel crystallites, at simple grain boundaries, and in the amorphous interphase at multiple grain boundaries. This has implications for the resistance to acid corrosion, mechanical properties, and the mechanism by which enamel crystals grow during amelogenesis.

  7. Computational modeling of elastic properties of carbon nanotube/polymer composites with interphase regions. Part II: Mechanical modeling

    KAUST Repository

    Han, Fei

    2014-01-01

    We present two modeling approaches for predicting the macroscopic elastic properties of carbon nanotubes/polymer composites with thick interphase regions at the nanotube/matrix frontier. The first model is based on local continuum mechanics; the second one is based on hybrid local/non-local continuum mechanics. The key computational issues, including the peculiar homogenization technique and treatment of periodical boundary conditions in the non-local continuum model, are clarified. Both models are implemented through a three-dimensional geometric representation of the carbon nanotubes network, which has been detailed in Part I. Numerical results are shown and compared for both models in order to test convergence and sensitivity toward input parameters. It is found that both approaches provide similar results in terms of homogenized quantities but locally can lead to very different microscopic fields. © 2013 Elsevier B.V. All rights reserved.

  8. Chromosomal imbalances detected in primary bone tumors by comparative genomic hybridization and interphase fluorescence in situ hybridization

    Directory of Open Access Journals (Sweden)

    Baruffi Marcelo Razera

    2003-01-01

    Full Text Available We applied a combination of comparative genomic hybridization (CGH and fluorescence in situ hybridization (FISH, to characterize the genetic aberrations in three osteosarcomas (OS and one Ewing's sarcoma. CGH identified recurrent chromosomal losses at 10p14-pter and gains at 8q22.3-24.1 in OS. Interphase FISH allowed to confirm 8q gain in two cases. A high amplification level of 11q12-qter was detected in one OS. The Ewing's sarcoma showed gain at 1p32-36.1 as the sole chromosome alteration. These studies demonstrate the value of molecular cytogenetic methods in the characterization of recurrent genomic alterations in bone tumor tissue.

  9. Novel phosphamide additive to improve thermal stability of solid electrolyte interphase on graphite anode in lithium-ion batteries.

    Science.gov (United States)

    Cao, Xia; Li, Yixiao; Li, Xiubin; Zheng, Jianming; Gao, Jun; Gao, Yuxing; Wu, Xiaobiao; Zhao, Yufen; Yang, Yong

    2013-11-27

    In this communication, a novel electrolyte additive, N,N-diallyic-diethyoxyl phosphamide (DADEPA), is described for the first time to improve the thermal stability of lithiated graphite anode in Li-ion batteries. The differential scanning calorimetry (DSC) measurement demonstrated that when the graphite was lithiated in the 5% DADEPA-containing electrolyte, the heat generation decreased sharply by half as compared with the reference, whereas the onset temperature for the main exothermic process was postponed by 20 °C. Electrochemical and XPS analyses indicated that the distinctive improvement in thermal safety came from a new interfacial chemistry, in which phosphorus-containing ingredients was embedded during the initial forming of the interphase.

  10. First-principles study of interphase Ni3Sn in Sn-Ni alloy for anode of lithium ion battery

    Institute of Scientific and Technical Information of China (English)

    Hou Xian-Hua; Hu She-Jun; Li Wei-Shan; Ru Qiang; Yu Hong-Wen; Huang Zhao-Wen

    2008-01-01

    This paper investigates the mechanism of Li insertion into interphase NiaSn in Ni-Sn alloy for the anode of lithium ion battery by means of the first-principles plane-wave pseudopotential.Compared with other phases,it is found that the Ni3Sn has larger relative expansion ratio and lower electrochemical potential,with its specific plateaus voltage around 0.3 eV when lithium atoms are filled in all octahedral interstitial sites.and the relative expansion ratio increasing dramatically when the lithiated phase transits from octahedral interstitial sites to tetrahedral interstitial sites.So this phase is a devastating phase for whole alloy electrode materials.

  11. Direct visualization of solid electrolyte interphase formation in lithium-ion batteries with in situ electrochemical transmission electron microscopy.

    Science.gov (United States)

    Unocic, Raymond R; Sun, Xiao-Guang; Sacci, Robert L; Adamczyk, Leslie A; Alsem, Daan Hein; Dai, Sheng; Dudney, Nancy J; More, Karren L

    2014-08-01

    Complex, electrochemically driven transport processes form the basis of electrochemical energy storage devices. The direct imaging of electrochemical processes at high spatial resolution and within their native liquid electrolyte would significantly enhance our understanding of device functionality, but has remained elusive. In this work we use a recently developed liquid cell for in situ electrochemical transmission electron microscopy to obtain insight into the electrolyte decomposition mechanisms and kinetics in lithium-ion (Li-ion) batteries by characterizing the dynamics of solid electrolyte interphase (SEI) formation and evolution. Here we are able to visualize the detailed structure of the SEI that forms locally at the electrode/electrolyte interface during lithium intercalation into natural graphite from an organic Li-ion battery electrolyte. We quantify the SEI growth kinetics and observe the dynamic self-healing nature of the SEI with changes in cell potential.

  12. Determination of the Solid Electrolyte Interphase Structure Grown on a Silicon Electrode Using a Fluoroethylene Carbonate Additive

    Energy Technology Data Exchange (ETDEWEB)

    Baldwin, J K. [Los Alamos National Laboratory (LANL); Veith, Gabriel M. [ORNL; Browning, Jim [ORNL; Doucet, Mathieu [ORNL; Vacaliuc, Bogdan [ORNL; Sacci, Robert L. [ORNL

    2017-07-01

    In this work we explore how an electrolyte additive (fluorinated ethylene carbonate – FEC) mediates the thickness and composition of the solid electrolyte interphase formed over a silicon anode in situ as a function of state-of-charge and cycle. We show the FEC condenses on the surface at open circuit voltage then is reduced to C-O containing polymeric species around 0.9 V (vs. Li/Li+). The resulting film is about 50 Å thick. Upon lithiation the SEI thickens to 70 Å and becomes more organic-like. With delithiation the SEI thins by 13 Å and becomes more inorganic in nature, consistent with the formation of LiF. This thickening/thinning is reversible with cycling and shows the SEI is a dynamic structure. We compare the SEI chemistry and thickness to 280 Å thick SEI layers produced without FEC and provide a mechanism for SEI formation using FEC additives.

  13. pMD-Membrane: A Method for Ligand Binding Site Identification in Membrane-Bound Proteins.

    Directory of Open Access Journals (Sweden)

    Priyanka Prakash

    2015-10-01

    Full Text Available Probe-based or mixed solvent molecular dynamics simulation is a useful approach for the identification and characterization of druggable sites in drug targets. However, thus far the method has been applied only to soluble proteins. A major reason for this is the potential effect of the probe molecules on membrane structure. We have developed a technique to overcome this limitation that entails modification of force field parameters to reduce a few pairwise non-bonded interactions between selected atoms of the probe molecules and bilayer lipids. We used the resulting technique, termed pMD-membrane, to identify allosteric ligand binding sites on the G12D and G13D oncogenic mutants of the K-Ras protein bound to a negatively charged lipid bilayer. In addition, we show that differences in probe occupancy can be used to quantify changes in the accessibility of druggable sites due to conformational changes induced by membrane binding or mutation.

  14. Tensile strain mapping in flat germanium membranes

    Energy Technology Data Exchange (ETDEWEB)

    Rhead, S. D., E-mail: S.Rhead@warwick.ac.uk; Halpin, J. E.; Myronov, M.; Patchett, D. H.; Allred, P. S.; Wilson, N. R.; Leadley, D. R. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Shah, V. A. [Department of Physics, University of Warwick, Coventry, CV4 7AL (United Kingdom); Department of Engineering, University of Warwick, Coventry, CV4 7AL (United Kingdom); Kachkanov, V.; Dolbnya, I. P. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE (United Kingdom); Reparaz, J. S. [ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona) (Spain); Sotomayor Torres, C. M. [ICN2 - Institut Catala de Nanociencia i Nanotecnologia, Campus UAB, 08193 Bellaterra (Barcelona) (Spain)

    2014-04-28

    Scanning X-ray micro-diffraction has been used as a non-destructive probe of the local crystalline quality of a thin suspended germanium (Ge) membrane. A series of reciprocal space maps were obtained with ∼4 μm spatial resolution, from which detailed information on the strain distribution, thickness, and crystalline tilt of the membrane was obtained. We are able to detect a systematic strain variation across the membranes, but show that this is negligible in the context of using the membranes as platforms for further growth. In addition, we show evidence that the interface and surface quality is improved by suspending the Ge.

  15. Condensin II Regulates Interphase Chromatin Organization Through the Mrg-Binding Motif of Cap-H2.

    Science.gov (United States)

    Wallace, Heather A; Klebba, Joseph E; Kusch, Thomas; Rogers, Gregory C; Bosco, Giovanni

    2015-03-09

    The spatial organization of the genome within the eukaryotic nucleus is a dynamic process that plays a central role in cellular processes such as gene expression, DNA replication, and chromosome segregation. Condensins are conserved multi-subunit protein complexes that contribute to chromosome organization by regulating chromosome compaction and homolog pairing. Previous work in our laboratory has shown that the Cap-H2 subunit of condensin II physically and genetically interacts with the Drosophila homolog of human MORF4-related gene on chromosome 15 (MRG15). Like Cap-H2, Mrg15 is required for interphase chromosome compaction and homolog pairing. However, the mechanism by which Mrg15 and Cap-H2 cooperate to maintain interphase chromatin organization remains unclear. Here, we show that Cap-H2 localizes to interband regions on polytene chromosomes and co-localizes with Mrg15 at regions of active transcription across the genome. We show that co-localization of Cap-H2 on polytene chromosomes is partially dependent on Mrg15. We have identified a binding motif within Cap-H2 that is essential for its interaction with Mrg15, and have found that mutation of this motif results in loss of localization of Cap-H2 on polytene chromosomes and results in partial suppression of Cap-H2-mediated compaction and homolog unpairing. Our data are consistent with a model in which Mrg15 acts as a loading factor to facilitate Cap-H2 binding to chromatin and mediate changes in chromatin organization. Copyright © 2015 Wallace et al.

  16. Effects of copper amine treatments on mechanical, biological and surface/interphase properties of poly (vinyl chloride)/wood composites

    Science.gov (United States)

    Jiang, Haihong

    2005-11-01

    The copper ethanolamine (CuEA) complex was used as a wood surface modifier and a coupling agent for wood-PVC composites. Mechanical properties of composites, such as unnotched impact strength, flexural strength and flexural toughness, were significantly increased, and fungal decay weight loss was dramatically decreased by wood surface copper amine treatments. It is evident that copper amine was a very effective coupling agent and decay inhibitor for PVC/wood flour composites, especially in high wood flour loading level. A DSC study showed that the heat capacity differences (DeltaCp) of composites before and after PVC glass transition were reduced by adding wood particles. A DMA study revealed that the movements of PVC chain segments during glass transition were limited and obstructed by the presence of wood molecule chains. This restriction effect became stronger by increasing wood flour content and by using Cu-treated wood flour. Wood flour particles acted as "physical cross-linking points" inside the PVC matrix, resulting in the absence of the rubbery plateau of PVC and higher E', E'' above Tg, and smaller tan delta peaks. Enhanced mechanical performances were attributed to the improved wetting condition between PVC melts and wood surfaces, and the formation of a stronger interphase strengthened by chemical interactions between Cu-treated wood flour and the PVC matrix. Contact angles of PVC solution drops on Cu-treated wood surfaces were decreased dramatically compared to those on the untreated surfaces. Acid-base (polar), gammaAB, electron-acceptor (acid) (gamma +), electron-donor (base) (gamma-) surface energy components and the total surface energies increased after wood surface Cu-treatments, indicating a strong tendency toward acid-base or polar interactions. Improved interphase and interfacial adhesion were further confirmed by measuring interfacial shear strength between wood and the PVC matrix.

  17. Suppressing membrane height fluctuations leads to a membrane-mediated interaction among proteins.

    Science.gov (United States)

    Sapp, Kayla; Maibaum, Lutz

    2016-11-01

    Membrane-induced interactions can play a significant role in the spatial distribution of membrane-bound proteins. We develop a model that combines a continuum description of lipid bilayers with a discrete particle model of proteins to probe the emerging structure of the combined membrane-protein system. Our model takes into account the membrane's elastic behavior, the steric repulsion between proteins, and the quenching of membrane shape fluctuations due to the presence of the proteins. We employ coupled Langevin equations to describe the dynamics of the system. We show that coupling to the membrane induces an attractive interaction among proteins, which may contribute to the clustering of proteins in biological membranes. We investigate the lateral protein diffusion and find that it is reduced due to transient fluctuations in membrane shape.

  18. Suppressing membrane height fluctuations leads to a membrane-mediated interaction among proteins

    Science.gov (United States)

    Sapp, Kayla; Maibaum, Lutz

    2016-11-01

    Membrane-induced interactions can play a significant role in the spatial distribution of membrane-bound proteins. We develop a model that combines a continuum description of lipid bilayers with a discrete particle model of proteins to probe the emerging structure of the combined membrane-protein system. Our model takes into account the membrane's elastic behavior, the steric repulsion between proteins, and the quenching of membrane shape fluctuations due to the presence of the proteins. We employ coupled Langevin equations to describe the dynamics of the system. We show that coupling to the membrane induces an attractive interaction among proteins, which may contribute to the clustering of proteins in biological membranes. We investigate the lateral protein diffusion and find that it is reduced due to transient fluctuations in membrane shape.

  19. Detection of Membrane Fluidity in Submitochondrial Particles of Platelets and Erythrocyte Membranes from Mexican Patients with Alzheimer Disease by Intramolecular Excimer Formation of 1,3 Dipyrenylpropane

    Directory of Open Access Journals (Sweden)

    G.G. Ortiz

    2008-01-01

    Full Text Available It has been suggested that mitochondrial dysfunction and defects in membrane structure could be implied in AD pathogenesis. The aim of the present work was the study of membrane fluidity in submitochondrial platelet particles and erythrocyte membranes from Mexican patients. Blood samples were obtained from 30 patients with Alzheimer disease and 30 aged-matched control subjects. Membrane fluidity determinations were done using a very low concentration of the fluorescent dipyrenylpropane probe incorporated in both types of membranes. This probe is able to give excimer and monomer fluorescence, therefore it can be used to monitor fluidity changes in biological membranes.

  20. Dual action of BPC194 : a membrane active peptide killing bacterial cells

    NARCIS (Netherlands)

    Moiset, Gemma; Cirac, Anna D; Stuart, Marc C A; Marrink, Siewert-Jan; Sengupta, Durba; Poolman, Bert

    2013-01-01

    Membrane active peptides can perturb the lipid bilayer in several ways, such as poration and fusion of the target cell membrane, and thereby efficiently kill bacterial cells. We probe here the mechanistic basis of membrane poration and fusion caused by membrane-active, antimicrobial peptides. We

  1. Potential use of buccal smears for rapid diagnosis of autosomal trisomy or chromosomal sex in newborn infants using DNA probes

    Energy Technology Data Exchange (ETDEWEB)

    Harris, C.; Clark, K.; Lazarski, K. [Univ. of Wisconsin, Madison, WI (United States); Wilkerson, C. [Univ. of Wisconsin Medical School, Madison, WI (United States); Meisner, L. [Univ. of Wisconsin, Madison, WI (United States)]|[Univ. of Wisconsin Medical School, Madison, WI (United States)

    1994-12-01

    Buccal smears from 3 women and 1 man were probed with alpha satellite DNA probes for chromosomes 8, 18, X, and Y. Buccal smears were also collected from an adolescent phenotypic female with uterine agenesis, as well as from newborn infants with suspected trisomy 18 and trisomy 21. The clinical cases were confirmed with conventional cytogenetic studies of peripheral lymphocytes. Overall probe efficiency at detecting expected chromosome number in interphase cells was found to be 71% {+-} 6.8%. Higher than expected n-1 signal numbers may be due to karyopyknotic intermediate epithelial cells present in all collected samples. Overall probe efficiency was found to be consistent using alpha satellite and cosmid probes, both of which accurately reflected the modal copy number of the target chromosomes. False trisomy was less than 1%. This study suggests DNA probes can be used in buccal smears for rapid diagnosis of trisomies and chromosomal sex in newborns, but because of high rates of false hydropoploid signals, probed buccal smear specimens may not be accurate at diagnosing mosaicism. 9 refs., 2 figs., 1 tab.

  2. Atom probe crystallography

    National Research Council Canada - National Science Library

    Gault, Baptiste; Moody, Michael P; Cairney, Julie M; Ringer, Simon P

    2012-01-01

    This review addresses new developments in the emerging area of "atom probe crystallography", a materials characterization tool with the unique capacity to reveal both composition and crystallographic...

  3. Viral membrane fusion

    Energy Technology Data Exchange (ETDEWEB)

    Harrison, Stephen C., E-mail: harrison@crystal.harvard.edu

    2015-05-15

    Membrane fusion is an essential step when enveloped viruses enter cells. Lipid bilayer fusion requires catalysis to overcome a high kinetic barrier; viral fusion proteins are the agents that fulfill this catalytic function. Despite a variety of molecular architectures, these proteins facilitate fusion by essentially the same generic mechanism. Stimulated by a signal associated with arrival at the cell to be infected (e.g., receptor or co-receptor binding, proton binding in an endosome), they undergo a series of conformational changes. A hydrophobic segment (a “fusion loop” or “fusion peptide”) engages the target-cell membrane and collapse of the bridging intermediate thus formed draws the two membranes (virus and cell) together. We know of three structural classes for viral fusion proteins. Structures for both pre- and postfusion conformations of illustrate the beginning and end points of a process that can be probed by single-virion measurements of fusion kinetics. - Highlights: • Viral fusion proteins overcome the high energy barrier to lipid bilayer merger. • Different molecular structures but the same catalytic mechanism. • Review describes properties of three known fusion-protein structural classes. • Single-virion fusion experiments elucidate mechanism.

  4. Clinical utility of a DNA probe to 17p11.2 in screening of patients with a peripheral neuropathy

    Energy Technology Data Exchange (ETDEWEB)

    Blancato, J.; Precht, K.; Meck, J. [Georgetown Univ., Hospital, Washington, DC (United States)] [and others

    1994-09-01

    We assessed the usefulness of in situ hybridization with a DNA probe to the area of chromosome 17 at p11.2 as a diagnostic tool for screening for Charcot Marte Tooth 1A (CMT 1A). In situ hybridization with a probe to 17p11.2 was performed on fixed lymphocytes from the following groups of individuals: (1) normal controls; (2) patients evoking a strong clinical suspicion of CMT 1A; and (3) 3 families with an apparent autosomal dominant peripheral neuropathy of unknown diagnoses. Group 2 patients had evidence of demyelination as defined by nerve conduction of less that 50% of the normal mean or terminal latency greater than 50% of the normal mean in conduction studies. Analysis of interphase cells hybridized with a cosmid DNA probe to 17p11.2 requires inclusion of a normal control with each trial and masked observer. Due to the size of the target DNA and the nature of the centromeric heterochromatin, the scoring of this probe is more subjective than centromere probes. For example, if the two 17 chromosomes are decondensed as in interphase, two tandem signals may be visualized as one. Results from duplication positive patients demonstrate a large proportion of cells with two closely aligned, but separate, signals with an additional single signal. Normal results demonstrate a majority of cells with two separate signals representing both normal homologues. None of the 3 families with questionable diagnosis revealed a duplication at the region, reinforcing our belief that a clinical diagnosis is the most discriminating tool available for diagnosis of CMT 1A. We concur with Boylan that molecular analysis for CMT 1A is useful for establishing a diagnosis of CMT 1A, but is not a primary differential diagnostic test. The yield in screening patients without physiologic evidence of demyelination is likely to be low. We further find that the use of in situ hybridization is a simple method of performing the duplication analysis.

  5. Lateral mobility of plasma membrane lipids in dividing Xenopus eggs

    OpenAIRE

    de Laat, S W; Tetteroo, P.A.T.; Bluemink, J.G.; Dictus, W.J.A.G.; Zoelen, E.J.J. van

    1984-01-01

    The lateral mobility of plasma membrane lipids was analyzed during first cleavage of Xaopus Levis eggs by fluorescence photobleaching recovery (FPR) measurements, using the lipid analogs 5-(N-hexadecanoyl)aminofluorescein (“HEDAF”) and 5-(N-tetradecanoyl)aminofluorescein (“TEDAF”) as probes. The preexisting plasma membrane of the animal side showed an inhomogeneous, dotted fluorescence pattern after labeling and the lateral mobility of both probes used was below the detection limits of the FP...

  6. Elastic thickness compressibilty of the red cell membrane.

    OpenAIRE

    Heinrich, V; Ritchie, K; Mohandas, N; Evans, E.

    2001-01-01

    We have used an ultrasensitive force probe and optical interferometry to examine the thickness compressibility of the red cell membrane in situ. Pushed into the centers of washed-white red cell ghosts lying on a coverglass, the height of the microsphere-probe tip relative to its closest approach on the adjacent glass surface revealed the apparent material thickness, which began at approximately 90 nm per membrane upon detection of contact (force approximately 1-2 pN). With further impingement...

  7. BN interphase in composite materials with nicalon Si-C-O fibers and with vitro ceramic matrix of MAS type; L`interphase BN dans les materiaux composites a fibres Si-C-O nicalon et a matrice vitroceramique de type MAS

    Energy Technology Data Exchange (ETDEWEB)

    Ricca, N.

    1994-03-14

    BN has been suggested as an interphase in silica-based glass-ceramic matrix composites with a view to use these materials in oxidizing atmospheres at medium or high temperatures. The matrix had a boron-doped MAS (MgO-Al{sub 2}O{sub 3}-SiO{sub 2}) composition and was prepared from an hydrosol precursor. Pseudo-ID composites were prepared according to a sol impregnations/calcination/hot-pressing route. Chemical and microstructural characterizations of the fiber/matrix interfacial area were conducted by mean of TEM/EELS and AES analyses. The efficiency of BN as a coupling interphase for this particular composite system was successfully demonstrated through tensile tests performed on either as-processed or aged specimens (100 hours at 1000 deg C in air or under argon). In addition, composites maintained in air at 600 deg C, 800 deg C and 900 deg C while simultaneously loaded did not fail after 150 hours or more. Thus, a BN interphase appeared to be compatible with an oxidizing environment (i.e. the oxide matrix and/or air from 600 to 1000 deg C) and should therefore successfully replace the usual carbon interphase at least for use at medium temperatures. (author)

  8. Variation of the interphase heterochromatin in Artemia (Crustacea, Anostraca of the Americas is related to changes in nuclear size and ionic composition of hipersaline habitats

    Directory of Open Access Journals (Sweden)

    M. Parraguez

    Full Text Available Abstract The populations of Artemia (or brine shrimp from the Americas exhibit a wide variation in the amount of interphase heterochromatin. There is interest in understanding how this variation affects different parameters, from the cellular to the organismal levels. This should help to clarify the ability of this organism to tolerate brine habitats regularly subject to strong abiotic changes. In this study, we assessed the amount of interphase heterochromatin per nucleus based on chromocenter number (N-CHR and relative area of chromocenter (R-CHR in two species of Artemia, A. franciscana (Kellog, 1906 (n=9 populations and A. persimilis (Piccinelli and Prosdocimi, 1968 (n=3 populations, to investigate the effect on nuclear size (S-NUC. The relationship of the R-CHR parameter with the ionic composition (IC of brine habitats was also analysed. Our results indicate a significant variation in the amount of heterochromatin both within and between species (ANOVA, p0.05. The R-CHR and IC parameters were associated significantly for the magnesium ion (r= 0.496, p<0.05 and also for the chloride, sodium and calcium ions (r = from -0.705 to -0.478, p<0.05. At species level, a significant association between both parameters was also found in A. franciscana populations, for the sulphate and calcium ions, in contrast to A. persimilis. These findings suggest that the amount of interphase heterochromatin modifies the nuclear size in Artemia. Our data also indicate that change in the amount of interphase heterochromatin is in line with the ionic composition of brines. This would be a species-specific phenomenon, whose occurrence may be involved in the ability of this organism to survive in these environments.

  9. Position of chromosomes 18, 19, 21 and 22 in 3D-preserved interphase nuclei of human and gorilla and white hand gibbon

    OpenAIRE

    Bhatt Samarth; Mrasek Kristin; Hunstig Friederike; Manvelyan Marina; Pellestor Franck; Weise Anja; Liehr Thomas

    2008-01-01

    Abstract Background Even though comparative nuclear architecture studies in hominoids are sparse, nuclear chromosome architecture was shown to be conserved during hominoid evolution. Thus, it is suspected that yet unknown biological mechanisms must underlie this observation. Results Here for the first time a combination of multicolor banding (MCB) and three-dimensional analysis of interphase cells was used to characterize the position and orientation of human chromosomes #18, #19, #21 and #22...

  10. An Investigation of the Structure-Property Relationships for High Performance Thermoplastic Matrix, Carbon Fiber Composites with a Tailored Polyimide Interphase

    OpenAIRE

    Gardner, Slade Havelock II

    1998-01-01

    The aqueous suspension prepregging technique was used to fabricate PEEK and PPS matrix composites with polyimide interphases of tailored properties. The structure-property relationships of Ultem-type polyimide and BisP-BTDA polyimide which were made from various water soluble polyamic acid salts were studied. The molecular weight of the polyimides was shown to be dependant upon the selection of the base used for making the polyamic acid salt. The development of an Ultem-type polyimide with...

  11. Interphase cytogenetics of multicentric renal cell tumours confirm associations of specific aberrations with defined cytomorphologies

    Science.gov (United States)

    Amo-Takyi, B K; Mittermayer, C; Günther, K; Handt, S

    2000-01-01

    To demonstrate associations of certain chromosomal aberrations with defined renal cell tumour (RCT) subtypes, we analysed 239 tumour nephrectomy cases for specimens with multicentric tumours. Chromosomal in situ hybridization was then performed on 15 cases with 34 foci (16 conventional renal cell carcinomas (RCCs), and 18 papillary RCTs (11 carcinomas and seven adenomas) for specific chromosomal aberrations, using α-satellite probes for chromosomes 3, 7 or 17. Particular preference was given to cases which had separate foci with different cytomorphologies. Furthermore, we compared aberrations in relation to tumour size, stage, grade and between different foci in a specimen. Thirty-four cases had multiple tumours. Forty-seven per cent of the multicentric tumours were conventional RCCs and 53% papillary RCTs (against 83% solitary conventional RCCs and 5% solitary papillary RCTs). Three conventional RCCs sized 8 mm (G3), 13 cm (pT2, G2) and 15 cm (pT3b, G3), respectively, revealed monosomy 3, and 13 were disomic. Seventeen papillary RCTs (11 carcinomas and six adenomas) displayed trisomy 17, irrespective of size or grade. Four papillary carcinomas and six papillary adenomas had trisomy 7, and the rest (seven papillary carcinomas and one papillary adenoma) revealed disomy 7. In conclusion, papillary RCTs were tendentially multicentric. Although specific for conventional RCCs heedless of size, monosomy 3 was only observed in high-grade and/or advanced tumours. Trisomy 17 was only detectable in papillary RCTs irrespective of tumour state, showing increased copies with tumour growth. Papillary RCTs also appeared to lose some copies of chromosome 7 with tumour progress, possibly reflecting malignancy. © 2000 Cancer Research Campaign PMID:10780519

  12. In vivo metabolite compartmentalization probed using intracellular GdDTPA

    DEFF Research Database (Denmark)

    Peters, David Alberg; Rowland, Ian

    Fast trans-membrane water exchange enables in- tracellular relaxation enhancement of water by contrast agents in the extracellular space. For me- tabolites not in fast exchange across membranes, intracellular metabolite relaxation enhancement will only occur if the contrast agent and metabolite a...... are in the same compartment. Extracellular contrast has utilized electroporation methods to deliver GdDTPA into the cytosol of rat muscle in vivo in order to probe the intracellular compart- mentalization of MR-visible metabolites....

  13. Advances in molecular imaging of prostate cancer targeting prostate specific membrane antigen with small molecular radionuclide probes%以核素标记前列腺特异性膜抗原小分子抑制剂为探针的前列腺癌分子影像研究进展

    Institute of Scientific and Technical Information of China (English)

    胡四龙(综述); 许晓平; 章英剑(审校)

    2015-01-01

    Prostate speciifc membrane antigen (PSMA) is expressed in normal prostate epithelial cells and strongly up regulated in initial and advanced prostate carcinoma. Therefore, PSMA is an attractive molecular target for the detection of primary and metastatic lesions. It plays an important role in the diagnosis, staging, prognostic evaluation and targeted treatment in prostate carcinoma patients. This review will summarize the progress of small molecular radionuclide probes, which targeted PSMA, for visualizing prostate cancer.%前列腺特异性膜抗原(PSMA)高表达于前列腺癌及其转移灶中,可作为生物分子靶点,在前列腺癌的早期诊断、分期、复发检测、预后判断及靶向治疗中具有重要价值。本文重点综述以核素标记PSMA小分子抑制剂为探针的前列腺癌分子影像研究进展。

  14. Pioneer Jupiter orbiter probe mission 1980, probe description

    Science.gov (United States)

    Defrees, R. E.

    1974-01-01

    The adaptation of the Saturn-Uranus Atmospheric Entry Probe (SUAEP) to a Jupiter entry probe is summarized. This report is extracted from a comprehensive study of Jovian missions, atmospheric model definitions and probe subsystem alternatives.

  15. Probing cell mechanical properties with microfluidic devices

    Science.gov (United States)

    Rowat, Amy

    2012-02-01

    Exploiting flow on the micron-scale is emerging as a method to probe cell mechanical properties with 10-1000x advances in throughput over existing technologies. The mechanical properties of cells and the cell nucleus are implicated in a wide range of biological contexts: for example, the ability of white blood cells to deform is central to immune response; and malignant cells show decreased stiffness compared to benign cells. We recently developed a microfluidic device to probe cell and nucleus mechanical properties: cells are forced to deform through a narrow constrictions in response to an applied pressure; flowing cells through a series of constrictions enables us to probe the ability of hundreds of cells to deform and relax during flow. By tuning the constriction width so it is narrower than the width of the cell nucleus, we can specifically probe the effects of nuclear physical properties on whole cell deformability. We show that the nucleus is the rate-limiting step in cell passage: inducing a change in its shape to a multilobed structure results in cells that transit more quickly; increased levels of lamin A, a nuclear protein that is key for nuclear shape and mechanical stability, impairs the passage of cells through constrictions. We are currently developing a new class of microfluidic devices to simultaneously probe the deformability of hundreds of cell samples in parallel. Using the same soft lithography techniques, membranes are fabricated to have well-defined pore distribution, width, length, and tortuosity. We design the membranes to interface with a multiwell plate, enabling simultaneous measurement of hundreds of different samples. Given the wide spectrum of diseases where altered cell and nucleus mechanical properties are implicated, such a platform has great potential, for example, to screen cells based on their mechanical phenotype against a library of drugs.

  16. Permanent farnesylation of lamin A mutants linked to progeria impairs its phosphorylation at serine 22 during interphase.

    Science.gov (United States)

    Moiseeva, Olga; Lopes-Paciencia, Stéphane; Huot, Geneviève; Lessard, Frédéric; Ferbeyre, Gerardo

    2016-02-01

    Mutants of lamin A cause diseases including the Hutchinson-Gilford progeria syndrome (HGPS) characterized by premature aging. Lamin A undergoes a series of processing reactions, including farnesylation and proteolytic cleavage of the farnesylated C-terminal domain. The role of cleavage is unknown but mutations that affect this reaction lead to progeria. Here we show that interphase serine 22 phosphorylation of endogenous mutant lamin A (progerin) is defective in cells from HGPS patients. This defect can be mimicked by expressing progerin in human cells and prevented by inhibition of farnesylation. Furthermore, serine 22 phosphorylation of non-farnesylated progerin was enhanced by a mutation that disrupts lamin A head to tail interactions. The phosphorylation of lamin A or non-farnesylated progerin was associated to the formation of spherical intranuclear lamin A droplets that accumulate protein kinases of the CDK family capable of phosphorylating lamin A at serine 22. CDK inhibitors compromised the turnover of progerin, accelerated senescence of HGPS cells and reversed the effects of FTI on progerin levels. We discuss a model of progeria where faulty serine 22 phosphorylation compromises phase separation of lamin A polymers, leading to accumulation of functionally impaired lamin A structures.

  17. Component-/structure-dependent elasticity of solid electrolyte interphase layer in Li-ion batteries: Experimental and computational studies

    Science.gov (United States)

    Shin, Hosop; Park, Jonghyun; Han, Sangwoo; Sastry, Ann Marie; Lu, Wei

    2015-03-01

    The mechanical instability of the Solid Electrolyte Interphase (SEI) layer in lithium ion (Li-ion) batteries causes significant side reactions resulting in Li-ion consumption and cell impedance rise by forming further SEI layers, which eventually leads to battery capacity fade and power fade. In this paper, the composition-/structure-dependent elasticity of the SEI layer is investigated via Atomic Force Microscopy (AFM) measurements coupled with X-ray Photoelectron Spectroscopy (XPS) analysis, and atomistic calculations. It is observed that the inner layer is stiffer than the outer layer. The measured Young's moduli are mostly in the range of 0.2-4.5 GPa, while some values above 80 GPa are also observed. This wide variation of the observed elastic modulus is elucidated by atomistic calculations with a focus on chemical and structural analysis. The numerical analysis shows the Young's moduli range from 2.4 GPa to 58.1 GPa in the order of the polymeric, organic, and amorphous inorganic components. The crystalline inorganic component (LiF) shows the highest value (135.3 GPa) among the SEI species. This quantitative observation on the elasticity of individual components of the SEI layer must be essential to analyzing the mechanical behavior of the SEI layer and to optimizing and controlling it.

  18. Oxidation of SiC Fiber-Reinforced SiC Matrix Composites with a BN Interphase

    Science.gov (United States)

    Opila, Elizabeth; Boyd, Meredith K.

    2010-01-01

    SiC-fiber reinforced SiC matrix composites with a BN interphase were oxidized in reduced oxygen partial pressures of oxygen to simulate the environment for hypersonic vehicle leading edge applications. The constituent fibers as well as composite coupons were oxidized in oxygen partial pressures ranging from 1000 ppm O2 to 5% O2 balance argon. Exposure temperatures ranged from 816 C to 1353 C (1500 F to 2450 F). The oxidation kinetics of the coated fibers were monitored by thermogravimetric analysis (TGA). An initial rapid transient weight gain was observed followed by parabolic kinetics. Possible mechanisms for the transient oxidation are discussed. One edge of the composite coupon seal coat was ground off to simulate damage to the composite which allowed oxygen ingress to the interior of the composite. Oxidation kinetics of the coupons were characterized by scanning electron microscopy since the weight changes were minimal. It was found that sealing of the coupon edge by silica formation occurred. Differences in the amount and morphology of the sealing silica as a function of time, temperature and oxygen partial pressure are discussed. Implications for use of these materials for hypersonic vehicle leading edge materials are summarized.

  19. Using electrochemical surface plasmon resonance for in-situ kinetic investigations of solid electrolyte interphase formation in lithium ion battery

    Science.gov (United States)

    Pradanawati, Sylvia Ayu; Wang, Fu-Ming; Su, Chia-Hung

    2016-10-01

    The solid electrolyte interphase (SEI) significantly affects the energy density and safety performance of lithium ion batteries. Previous studies have shown that conventional analyses cannot characterize the real-time molecule interactions of SEI formation on the surface of an electrode. In this study, a novel in situ electrochemical-surface plasmon resonance (EC-SPR) was developed for evaluating the kinetic changes of ionic dissociation, SEI formation, and Li-Au alloying reaction. The novel EC-SPR not only indicates the rates of each reaction stage but also reveals the characteristics of the passivated layers. This research demonstrates that the dissociation rates of ionic clusters are affected by several reactions on the surface of an electrode. The rate and mass of the SEI formation from the reduction of ethylene carbonate (EC) are calculated at 0.004 ngs-1 and 5.858 ng, respectively. The EC-SPR is a powerful tool for further in situ kinetic investigations of different electrolyte and electrode systems.

  20. Systems-level chromosomal parameters represent a suprachromosomal basis for the non-random chromosomal arrangement in human interphase nuclei

    Science.gov (United States)

    Fatakia, Sarosh N.; Mehta, Ishita S.; Rao, Basuthkar J.

    2016-01-01

    Forty-six chromosome territories (CTs) are positioned uniquely in human interphase nuclei, wherein each of their positions can range from the centre of the nucleus to its periphery. A non-empirical basis for their non-random arrangement remains unreported. Here, we derive a suprachromosomal basis of that overall arrangement (which we refer to as a CT constellation), and report a hierarchical nature of the same. Using matrix algebra, we unify intrinsic chromosomal parameters (e.g., chromosomal length, gene density, the number of genes per chromosome), to derive an extrinsic effective gene density matrix, the hierarchy of which is dominated largely by extrinsic mathematical coupling of HSA19, followed by HSA17 (human chromosome 19 and 17, both preferentially interior CTs) with all CTs. We corroborate predicted constellations and effective gene density hierarchy with published reports from fluorescent in situ hybridization based microscopy and Hi-C techniques, and delineate analogous hierarchy in disparate vertebrates. Our theory accurately predicts CTs localised to the nuclear interior, which interestingly share conserved synteny with HSA19 and/or HSA17. Finally, the effective gene density hierarchy dictates how permutations among CT position represents the plasticity within its constellations, based on which we suggest that a differential mix of coding with noncoding genome modulates the same. PMID:27845379

  1. Molecular Mechanisms of Processing Proteome Reorganization of Interphase Chromatin During Stress and Adaptation to Winter in Wheat

    Directory of Open Access Journals (Sweden)

    Ivanov R.S.

    2015-06-01

    Full Text Available Research of fundamental molecular and genetic processes of plant interaction with the environment, is a progressive field of understanding the fundamental problems of stress supramolecular biochemistry of developmental biology. The purpose of the work was the analysis of localization shielded to protease processing proteins of suprastructures of interphase chromatin matrix in the conditions of adaptation during vegetative phase of wheat to stressful environment factors. It is shown that in the conditions of perennial adaptation to cold shock of wheat at the level of chromatin suprastructures tightly bound to the nuclear matrix there is a total shielding of arginine-X sites to protease-processing. Perhaps these are zones that affect to the architecture organization of the cell nucleus that can help to survive in complex environmental conditions. According to the priorities in the study of agricultural plants, put forward by EPIC (The Epigenomics of Plants International Consortium in 2011 for the next decade, was included the point of necessity to understand the molecular basis of the interactions of genotype and environment that change the characteristics of plants in different conditions of the environment. These data will be useful for those who involved in the development of mathematical logic schemes of the theory and practice of biological specificity, and it could be included in the ontology of the stages plant growth and development.

  2. Surface chemistry and morphology of the solid electrolyte interphase on silicon nanowire lithium-ion battery anodes

    KAUST Repository

    Chan, Candace K.

    2009-04-01

    Silicon nanowires (SiNWs) have the potential to perform as anodes for lithium-ion batteries with a much higher energy density than graphite. However, there has been little work in understanding the surface chemistry of the solid electrolyte interphase (SEI) formed on silicon due to the reduction of the electrolyte. Given that a good, passivating SEI layer plays such a crucial role in graphite anodes, we have characterized the surface composition and morphology of the SEI formed on the SiNWs using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). We have found that the SEI is composed of reduction products similar to that found on graphite electrodes, with Li2CO3 as an important component. Combined with electrochemical impedance spectroscopy, the results were used to determine the optimal cycling parameters for good cycling. The role of the native SiO2 as well as the effect of the surface area of the SiNWs on reactivity with the electrolyte were also addressed. © 2009 Elsevier B.V. All rights reserved.

  3. The impact of humic and fulvic acids on the dynamic properties of liposome membranes: the ESR method.

    Science.gov (United States)

    Man, Dariusz; Pisarek, Izabella; Braczkowski, Michał; Pytel, Barbara; Olchawa, Ryszard

    2014-06-01

    This paper presents the results of research on the influence of two fractions of humic substances (HS): fulvic acids (FA) and humic acids (HA), as a function of concentration, on the liposome membranes formed from egg yolk lecithin (EYL). The concentration of HS in relation to EYL changed from 0% to 10% by weight. The influence of HS on various areas of membranes: interphase water-lipid, in the lipid layer just below the polar part of the membrane and in the middle of the lipid bilayer, was investigated by different spin labels (TEMPO, DOXYL 5, DOXYL 16). The study showed that HA slightly decreased the fluidity of the analyzed membranes on the surface layer, while FA significantly liquidated the center of the lipid bilayer. The strong effect of both fractions of HS on the concentration of free radicals as a function of time was also described.

  4. Rapid generation of region-specific probes by chromosome microdissection: Application to the identification of chromosomal rearrangements

    Energy Technology Data Exchange (ETDEWEB)

    Trent, J.M.; Guan, X.Y.; Zang, J.; Meltzer, P.S. (Univ. of Michigan, Ann Arbor (United States))

    1993-01-01

    The authors present results using a novel strategy for chromosome microdissection and direct in vitro amplification of specific chromosomal regions, to identify cryptic chromosome alterations, and to rapidly generate region-specific genomic probes. First, banded chromosomes are microdissected and directly PCR amplified by a procedure which eliminates microchemistry (Meltzer, et al., Nature Genetics, 1:24, 1992). The resulting PCR product can be used for several applications including direct labeling for fluorescent in situ hybridization (FISH) to normal metaphase chromosomes. A second application of this procedure is the extremely rapid generation of chromosome region-specific probes. This approach has been successfully used to determine the derivation of chromosome segments unidentifiable by standard chromosome banding analysis. In selected instances these probes have also been used on interphase nuclei and provides the potential for assessing chromosome abnormalities in a variety of cell lineages. The microdissection probes (which can be generated in <24 hours) have also been utilized in direct library screening and provide the possibility of acquiring a significant number of region-specific probes for any chromosome band. This procedure extends the limits of conventional cytogenetic analysis by providing an extremely rapid source of numerous band-specific probes, and by enabling the direct analysis of essentially any unknown chromosome region.

  5. Visualization of sterol-rich membrane domains with fluorescently-labeled theonellamides.

    Directory of Open Access Journals (Sweden)

    Shinichi Nishimura

    Full Text Available Cholesterol plays important roles in biological membranes. The cellular location where cholesterol molecules work is prerequisite information for understanding their dynamic action. Bioimaging probes for cholesterol molecules would be the most powerful means for unraveling the complex nature of lipid membranes. However, only a limited number of chemical or protein probes have been developed so far for cytological analysis. Here we show that fluorescently-labeled derivatives of theonellamides act as new sterol probes in mammalian cultured cells. The fluorescent probes recognized cholesterol molecules and bound to liposomes in a cholesterol-concentration dependent manner. The probes showed patchy distribution in the plasma membrane, while they stained specific organelle in the cytoplasm. These data suggest that fTNMs will be valuable sterol probes for studies on the role of sterols in the biological membrane under a variety of experimental conditions.

  6. Structural and functional properties of hydration and confined water in membrane interfaces.

    Science.gov (United States)

    Disalvo, E A; Lairion, F; Martini, F; Tymczyszyn, E; Frías, M; Almaleck, H; Gordillo, G J

    2008-12-01

    The scope of the present review focuses on the interfacial properties of cell membranes that may establish a link between the membrane and the cytosolic components. We present evidences that the current view of the membrane as a barrier of permeability that contains an aqueous solution of macromolecules may be replaced by one in which the membrane plays a structural and functional role. Although this idea has been previously suggested, the present is the first systematic work that puts into relevance the relation water-membrane in terms of thermodynamic and structural properties of the interphases that cannot be ignored in the understanding of cell function. To pursue this aim, we introduce a new definition of interphase, in which the water is organized in different levels on the surface with different binding energies. Altogether determines the surface free energy necessary for the structural response to changes in the surrounding media. The physical chemical properties of this region are interpreted in terms of hydration water and confined water, which explain the interaction with proteins and could affect the modulation of enzyme activity. Information provided by several methodologies indicates that the organization of the hydration states is not restricted to the membrane plane albeit to a region extending into the cytoplasm, in which polar head groups play a relevant role. In addition, dynamic properties studied by cyclic voltammetry allow one to deduce the energetics of the conformational changes of the lipid head group in relation to the head-head interactions due to the presence of carbonyls and phosphates at the interphase. These groups are, apparently, surrounded by more than one layer of water molecules: a tightly bound shell, that mostly contributes to the dipole potential, and a second one that may be displaced by proteins and osmotic stress. Hydration water around carbonyl and phosphate groups may change by the presence of polyhydroxylated compounds

  7. Primordial membranes

    DEFF Research Database (Denmark)

    Hanczyc, Martin M; Monnard, Pierre-Alain

    2017-01-01

    Cellular membranes, which are self-assembled bilayer structures mainly composed of lipids, proteins and conjugated polysaccharides, are the defining feature of cell physiology. It is likely that the complexity of contemporary cells was preceded by simpler chemical systems or protocells during the...

  8. Robotic membranes

    DEFF Research Database (Denmark)

    Ramsgaard Thomsen, Mette

    2008-01-01

    , Vivisection and Strange Metabolisms, were developed at the Centre for Information Technology and Architecture (CITA) at the Royal Danish Academy of Fine Arts in Copenhagen as a means of engaging intangible digital data with tactile physical material. As robotic membranes, they are a dual examination...

  9. Detection of illegitimate rearrangement within the immunoglobulin locus on 14q32.3 in B-cell malignancies using end-sequenced probes

    DEFF Research Database (Denmark)

    Silahtaroglu, Asli; Poulsen, Tim; Giselø, Claus

    2001-01-01

    Translocation involving the immunoglobulin heavy chain (IGH) locus is a recurring event in B-cell oncogenesis. The aim of this study was to characterize clones from bacterial artificial chromosome (BAC) libraries and/or bacteriophage P1 artificial chromosome libraries spanning the IGH locus...... for detection of illegitimate rearrangement within the region by fluorescence in situ hybridization (FISH). In silico analysis of the IGH variable (IGHV) DNA sequence (NT_001716.v1) was performed to identify BAC probes located within the IGHV cluster. Clones of the constant (IGHC) cluster were found...... in the literature or at http://www.biologia.uniba.it/rmc/. Validation, orientation, and overlap of these probes were confirmed using interphase-, metaphase-, and fiber-FISH. We have identified seven BAC end-sequenced probes (3087C18, 47P23, 76N15, 12F16, 101G24, 112H5, and 151B17) covering 612 kb of the distal IGHV...

  10. An Ultrasonographic Periodontal Probe

    Science.gov (United States)

    Bertoncini, C. A.; Hinders, M. K.

    2010-02-01

    Periodontal disease, commonly known as gum disease, affects millions of people. The current method of detecting periodontal pocket depth is painful, invasive, and inaccurate. As an alternative to manual probing, an ultrasonographic periodontal probe is being developed to use ultrasound echo waveforms to measure periodontal pocket depth, which is the main measure of periodontal disease. Wavelet transforms and pattern classification techniques are implemented in artificial intelligence routines that can automatically detect pocket depth. The main pattern classification technique used here, called a binary classification algorithm, compares test objects with only two possible pocket depth measurements at a time and relies on dimensionality reduction for the final determination. This method correctly identifies up to 90% of the ultrasonographic probe measurements within the manual probe's tolerance.

  11. Hard probes 2006 Asilomar

    CERN Multimedia

    2006-01-01

    "The second international conference on hard and electromagnetic probes of high-energy nuclear collisions was held June 9 to 16, 2006 at the Asilomar Conference grounds in Pacific Grove, California" (photo and 1/2 page)

  12. Detection of illegitimate rearrangement within the immunoglobulin locus on 14q32.3 in B-cell malignancies using end-sequenced probes.

    Science.gov (United States)

    Poulsen, T S; Silahtaroglu, A N; Gisselø, C G; Gaarsdal, E; Rasmussen, T; Tommerup, N; Johnsen, H E

    2001-11-01

    Translocation involving the immunoglobulin heavy chain (IGH) locus is a recurring event in B-cell oncogenesis. The aim of this study was to characterize clones from bacterial artificial chromosome (BAC) libraries and/or bacteriophage P1 artificial chromosome libraries spanning the IGH locus for detection of illegitimate rearrangement within the region by fluorescence in situ hybridization (FISH). In silico analysis of the IGH variable (IGHV) DNA sequence (NT_001716.v1) was performed to identify BAC probes located within the IGHV cluster. Clones of the constant (IGHC) cluster were found in the literature or at http://www.biologia.uniba.it/rmc/. Validation, orientation, and overlap of these probes were confirmed using interphase-, metaphase-, and fiber-FISH. We have identified seven BAC end-sequenced probes (3087C18, 47P23, 76N15, 12F16, 101G24, 112H5, and 151B17) covering 612 kb of the distal IGHV cluster, which, together with probes covering the IGHC cluster (11771 and 998D24), could be used in interphase nuclei and metaphase chromosome analysis. A visual split of the IGHV and IGHC clusters indicating a translocation was analyzed by dual-color FISH in a series of 21 cell lines of different origins. Translocations were found, as expected, in eight of eight myelomas, four of four lymphomas, none of five leukemias, and none of four Epstein-Barr virus-transformed B-lymphoblastoid cell lines. To summarize, we have established a set of IGHV and IGHC probes that can be used for universal screening of illegitimate rearrangement within the IGH locus in B-cell malignancies. These probes allow for routine FISH analysis to detect this early central oncogenic event. Copyright 2001 Wiley-Liss, Inc.

  13. Sensing lymphoma cells based on a cell-penetrating/apoptosis-inducing/electron-transfer peptide probe

    Energy Technology Data Exchange (ETDEWEB)

    Sugawara, Kazuharu, E-mail: kzsuga@maebashi-it.ac.jp [Maebashi Institute of Technology, Gunma 371-0816 (Japan); Shinohara, Hiroki; Kadoya, Toshihiko [Maebashi Institute of Technology, Gunma 371-0816 (Japan); Kuramitz, Hideki [Department of Environmental Biology and Chemistry, Graduate School of Science and Engineering for Research, University of Toyama, Toyama 930-8555 (Japan)

    2016-06-14

    To electrochemically sense lymphoma cells (U937), we fabricated a multifunctional peptide probe that consists of cell-penetrating/apoptosis-inducing/electron-transfer peptides. Electron-transfer peptides derive from cysteine residue combined with the C-terminals of four tyrosine residues (Y{sub 4}). A peptide whereby Y{sub 4}C is bound to the C-terminals of protegrin 1 (RGGRLCYCRRRFCVCVGR-NH{sub 2}) is known to be an apoptosis-inducing agent against U937 cells, and is referred to as a peptide-1 probe. An oxidation response of the peptide-1 probe has been observed due to a phenolic hydroxyl group, and this response is decreased by the uptake of the peptide probe into the cells. To improve the cell membrane permeability against U937 cells, the RGGR at the N-terminals of the peptide-1 probe was replaced by RRRR (peptide-2 probe). In contrast, RNRCKGTDVQAWY{sub 4}C (peptide-3 probe), which recognizes ovalbumin, was constructed as a control. Compared with the other probes, the change in the peak current of the peptide-2 probe was the greatest at low concentrations and occurred in a short amount of time. Therefore, the cell membrane permeability of the peptide-2 probe was increased based on the arginine residues and the apoptosis-inducing peptides. The peak current was linear and ranged from 100 to 1000 cells/ml. The relative standard deviation of 600 cells/ml was 5.0% (n = 5). Furthermore, the membrane permeability of the peptide probes was confirmed using fluorescent dye. - Highlights: • We constructed a multifunctional peptide probe for the electrochemical sensing of lymphoma cells. • The peptide probe consists of cell-penetrating/apoptosis-inducing/electron-transfer peptides. • The electrode response of the peptide probe changes due to selective uptake into the cells.

  14. Impact of Solid Electrolyte Interphase lithium salts on cycling ability of Li-ion battery: Beneficial effect of glymes additives

    Science.gov (United States)

    Chrétien, Fabien; Jones, Jennifer; Damas, Christine; Lemordant, Daniel; Willmann, Patrick; Anouti, Mérièm

    2014-02-01

    The Solid Electrolyte Interphase (SEI), formed during the first cycles of life in lithium-ion batteries, contains a variety of lithium salts, with direct effect on the aging performance of the battery. In this work, we investigate the impact of addition of SEI lithium salts (LiF, Li2CO3, LiOH, Li2O, LiOCH3 and LiOC2H5) in the electrolyte on the cycling ability of graphite and LiNi1/3Mn1/3Co1/3O2 (NMC) electrodes. Results show that NMC is more sensitive to salt addition than graphite material. Furthermore, results demonstrate that both LiOH and Li2O have a negative effect on the SEI formation. Conversely, Li2CO3, LiOCH3 and LiOC2H5 are beneficial and promote the formation of a polymeric coating on the SEI. Finally, the impact of the presence of LiF on the SEI depends mainly on its concentration. The effect of the presence of additives capable of complexing lithium salts such as the glyme series, CH3O[CH2CH2O]nCH3 (Gn, with n = 2, 3 or 4), is investigated by cyclic voltammetry, galvanostatic charge-discharge tests and electrochemical impedance spectroscopy (EIS). Results show that the glymes chain length is a determining factor in their complexation mechanism, which depends on both the nature and the concentration of the lithium salt.

  15. Diagnosis of CMT1A duplications and HNPP deletions by interphase FISH: Implications for testing in the cytogenetics laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Shaffer, L.G.; Kennedy, G.M.; Spikes, A.S. [Baylor College of Medicine, Houston, TX (United States)] [and others

    1997-03-31

    Charcot-Marie-Tooth (CMT) disease type 1A is an inherited peripheral neuropathy characterized by slowly progressive distal muscle wasting and weakness, decreased nerve conduction velocities, and genetic linkage to 17p12. Most (>98%) CMT1A cases are caused by a DNA duplication of a 1.5-Mb region in 17p12 containing the PMP22 gene. The reciprocal product of the CMT1A duplication is a 1.5-Mb deletion which causes hereditary neuropathy with liability to pressure palsies (HNPP). The most informative current diagnostic testing requires pulsed-field gel electrophoresis to detect DNA rearrangement-specific junction fragments. We investigated the use of interphase FISH for the detection of duplications and deletions for these disorders in the clinical molecular cytogenetics laboratory. Established cell lines or blood specimens from 23 individuals with known molecular diagnoses and 10 controls were obtained and scored using a two-color FISH assay. At least 70%, of CMT1A cells displayed three signals consistent with duplications. Using this minimum expected percentile to make a CMT1A duplication diagnosis, all patients with CMT1A showed a range of 71-92% of cells displaying at least three signals. Of the HNPP cases, 88% of cells displayed only one hybridization signal, consistent with deletions. The PMP22 locus from normal control individuals displayed a duplication pattern in {approximately}9% of cells, interpreted as replication of this locus. The percentage of cells showing replication was significantly lower than in those cells displaying true duplications. We conclude that FISH can be reliably used to diagnose CMT1A and HNPP in the clinical cytogenetics laboratory and to readily distinguish the DNA rearrangements associated with these disorders from individuals without duplication or deletion of the PMP22 locus. 43 refs., 4 figs., 2 tabs.

  16. The clustering of CpG islands may constitute an important determinant of the 3D organization of interphase chromosomes.

    Science.gov (United States)

    Gushchanskaya, Ekaterina S; Artemov, Artem V; Ulyanov, Sergey V; Logacheva, Maria D; Penin, Aleksey A; Kotova, Elena S; Akopov, Sergey B; Nikolaev, Lev G; Iarovaia, Olga V; Sverdlov, Eugene D; Gavrilov, Alexey A; Razin, Sergey V

    2014-07-01

    We used the 4C-Seq technique to characterize the genome-wide patterns of spatial contacts of several CpG islands located on chromosome 14 in cultured chicken lymphoid and erythroid cells. We observed a clear tendency for the spatial clustering of CpG islands present on the same and different chromosomes, regardless of the presence or absence of promoters within these CpG islands. Accordingly, we observed preferential spatial contacts between Sp1 binding motifs and other GC-rich genomic elements, including the DNA sequence motifs capable of forming G-quadruplexes. However, an anchor placed in a gene/CpG island-poor area formed spatial contacts with other gene/CpG island-poor areas on chromosome 14 and other chromosomes. These results corroborate the two-compartment model of the spatial organization of interphase chromosomes and suggest that the clustering of CpG islands constitutes an important determinant of the 3D organization of the eukaryotic genome in the cell nucleus. Using the ChIP-Seq technique, we mapped the genome-wide CTCF deposition sites in the chicken lymphoid and erythroid cells that were used for the 4C analysis. We observed a good correlation between the density of CTCF deposition sites and the level of 4C signals for the anchors located in CpG islands but not for an anchor located in a gene desert. It is thus possible that CTCF contributes to the clustering of CpG islands observed in our experiments.

  17. A Miniature Probe for Ultrasonic Penetration of a Single Cell

    Directory of Open Access Journals (Sweden)

    Mingfei Xiao

    2009-05-01

    Full Text Available Although ultrasound cavitation must be avoided for safe diagnostic applications, the ability of ultrasound to disrupt cell membranes has taken on increasing significance as a method to facilitate drug and gene delivery. A new ultrasonic resonance driving method is introduced to penetrate rigid wall plant cells or oocytes with springy cell membranes. When a reasonable design is created, ultrasound can gather energy and increase the amplitude factor. Ultrasonic penetration enables exogenous materials to enter cells without damaging them by utilizing instant acceleration. This paper seeks to develop a miniature ultrasonic probe experiment system for cell penetration. A miniature ultrasonic probe is designed and optimized using the Precise Four Terminal Network Method and Finite Element Method (FEM and an ultrasonic generator to drive the probe is designed. The system was able to successfully puncture a single fish cell.

  18. Kinetic viability assays using DRAQ7 probe.

    Science.gov (United States)

    Wlodkowic, Donald; Akagi, Jin; Dobrucki, Jurek; Errington, Rachel; Smith, Paul J; Takeda, Kazuo; Darzynkiewicz, Zbigniew

    2013-07-01

    Cell death within cell populations is a stochastic process where cell-to-cell variation in temporal progression through the various stages of cell death arises from asynchrony of subtle fluctuations in the signaling pathways. Most cell death assays rely on detection of the specific marker of cell demise at the end-point of cell culturing. Such an approach cannot account for the asynchrony and the stochastic nature of cell response to the death-inducing signal. There is a need therefore for rapid and high-throughput bioassays capable of continuously tracking viability of individual cells from the time of encountering a stress signal up to final stages of their demise. In this context, a new anthracycline derivative, DRAQ7, is gaining increasing interest as an easy-to-use marker capable of long-term monitoring of cell death in real-time. This novel probe neither penetrates the plasma membrane of living cells nor does it affect the cells' susceptibility to the death-inducing agents. However, when the membrane integrity is compromised, DRAQ7 enters cells undergoing demise and binds readily to nuclear DNA to report cell death. Here, we provide three sets of protocols for viability assays using DRAQ7 probe. The first protocol describes the innovative use of single-color DRAQ7 real-time assay to dynamically track cell viability. The second protocol outlines a simplified end-point DRAQ7 staining approach. The final protocol highlights the real-time and multiparametric apoptosis assay utilizing DRAQ7 dye concurrently with tetramethylrhodamine methyl ester (TMRM), the mitochondrial trans-membrane electrochemical potential (ΔΨm) sensing probe.

  19. Direct quantification of negatively charged functional groups on membrane surfaces

    KAUST Repository

    Tiraferri, Alberto

    2012-02-01

    Surface charge plays an important role in membrane-based separations of particulates, macromolecules, and dissolved ionic species. In this study, we present two experimental methods to determine the concentration of negatively charged functional groups at the surface of dense polymeric membranes. Both techniques consist of associating the membrane surface moieties with chemical probes, followed by quantification of the bound probes. Uranyl acetate and toluidine blue O dye, which interact with the membrane functional groups via complexation and electrostatic interaction, respectively, were used as probes. The amount of associated probes was quantified using liquid scintillation counting for uranium atoms and visible light spectroscopy for the toluidine blue dye. The techniques were validated using self-assembled monolayers of alkanethiols with known amounts of charged moieties. The surface density of negatively charged functional groups of hand-cast thin-film composite polyamide membranes, as well as commercial cellulose triacetate and polyamide membranes, was quantified under various conditions. Using both techniques, we measured a negatively charged functional group density of 20-30nm -2 for the hand-cast thin-film composite membranes. The ionization behavior of the membrane functional groups, determined from measurements with toluidine blue at varying pH, was consistent with published data for thin-film composite polyamide membranes. Similarly, the measured charge densities on commercial membranes were in general agreement with previous investigations. The relative simplicity of the two methods makes them a useful tool for quantifying the surface charge concentration of a variety of surfaces, including separation membranes. © 2011 Elsevier B.V.

  20. Membrane Insertion Profiles of Peptides Probed by Molecular Dynamics Simulations

    Science.gov (United States)

    2008-07-17

    Medical Research and Materiel Command, Fort Detrick, Maryland #Department of Cell Biology and Biochemistry , U.S. Army Medical Research Institute of...Molecular dynamics of n- alkanes ," J. Comput. Phys., vol. 23, pp. 327-341, 1977. [24] S. Kumar, D. Bouzida, R. H. Swendsen, P. A. Kollman, and J. M

  1. Histone H1 phosphorylation occurs site-specifically during interphase and mitosis: identification of a novel phosphorylation site on histone H1.

    Science.gov (United States)

    Sarg, Bettina; Helliger, Wilfried; Talasz, Heribert; Förg, Barbara; Lindner, Herbert H

    2006-03-10

    H1 histones, isolated from logarithmically growing and mitotically enriched human lymphoblastic T-cells (CCRF-CEM), were fractionated by reversed phase and hydrophilic interaction liquid chromatography, subjected to enzymatic digestion, and analyzed by amino acid sequencing and mass spectrometry. During interphase the four H1 subtypes present in these cells differ in their maximum phosphorylation levels: histone H1.5 is tri-, H1.4 di-, and H1.3 and H1.2, only monophosphorylated. The phosphorylation is site-specific and occurs exclusively on serine residues of SP(K/A)K motifs. The phosphorylation sites of histone H1.5 from mitotically enriched cells were also examined. In contrast to the situation in interphase, at mitosis there were additional phosphorylations, exclusively at threonine residues. Whereas the tetraphosphorylated H1.5 arises from the triphosphosphorylated form by phosphorylation of one of two TPKK motifs in the C-terminal domain, namely Thr137 and Thr154, the pentaphosphorylated H1.5 was the result of phosphorylation of one of the tetraphosphorylated forms at a novel nonconsensus motif at Thr10 in the N-terminal tail. Despite the fact that histone H1.5 has five (S/T)P(K/A)K motifs, all of these motifs were never found to be phosphorylated simultaneously. Our data suggest that phosphorylation of human H1 variants occurs nonrandomly during both interphase and mitosis and that distinct serine- or threonine-specific kinases are involved in different cell cycle phases. The order of increased phosphorylation and the position of modification might be necessary for regulated chromatin decondensation, thus facilitating processes of replication and transcription as well as of mitotic chromosome condensation.

  2. cAMP-dependent protein kinase and c-Jun N-terminal kinase mediate stathmin phosphorylation for the maintenance of interphase microtubules during osmotic stress.

    Science.gov (United States)

    Yip, Yan Y; Yeap, Yvonne Y C; Bogoyevitch, Marie A; Ng, Dominic C H

    2014-01-24

    Dynamic microtubule changes after a cell stress challenge are required for cell survival and adaptation. Stathmin (STMN), a cytoplasmic microtubule-destabilizing phosphoprotein, regulates interphase microtubules during cell stress, but the signaling mechanisms involved are poorly defined. In this study ectopic expression of single alanine-substituted phospho-resistant mutants demonstrated that STMN Ser-38 and Ser-63 phosphorylation were specifically required to maintain interphase microtubules during hyperosmotic stress. STMN was phosphorylated on Ser-38 and Ser-63 in response to hyperosmolarity, heat shock, and arsenite treatment but rapidly dephosphorylated after oxidative stress treatment. Two-dimensional PAGE and Phos-tag gel analysis of stress-stimulated STMN phospho-isoforms revealed rapid STMN Ser-38 phosphorylation followed by subsequent Ser-25 and Ser-63 phosphorylation. Previously, we delineated stress-stimulated JNK targeting of STMN. Here, we identified cAMP-dependent protein kinase (PKA) signaling as responsible for stress-induced STMN Ser-63 phosphorylation. Increased cAMP levels induced by cholera toxin triggered potent STMN Ser-63 phosphorylation. Osmotic stress stimulated an increase in PKA activity and elevated STMN Ser-63 and CREB (cAMP-response element-binding protein) Ser-133 phosphorylation that was substantially attenuated by pretreatment with H-89, a PKA inhibitor. Interestingly, PKA activity and subsequent phosphorylation of STMN were augmented in the absence of JNK activation, indicating JNK and PKA pathway cross-talk during stress regulation of STMN. Taken together our study indicates that JNK- and PKA-mediated STMN Ser-38 and Ser-63 phosphorylation are required to preserve interphase microtubules in response to hyperosmotic stress.

  3. 低碳钛、钒微合金钢中的相间析出%Interphase precipitation in low carbon Ti-V microalloyed steels

    Institute of Scientific and Technical Information of China (English)

    贾涛; 魏娇; 冯洁; 张维娜; 刘振宇; 王国栋

    2014-01-01

    The present study focuses on the Ti-V microalloying system which draws less attention. By using the Formaster-FII dilatometer,the sample was held at austenite/ferrite dual-phase temperature region and the Ti-V complex interphase precipitates were obtained during the austenite to ferrite transformation. Optical Microscopy (OM) and transmission electron microscopy (TEM) were employed to analyze the microstructure , especially the morphology of the interphase precipitate and its crystallographic orientation relationship with ferrite matrix. Studies show that 650℃is the nose temperature for static isothermal transforma-tion. The interphase precipitates exhibit sheet-like distribution,including flat and curved sheets and adopt Baker-Nutting orientation relationships with the ferrite matrix.%针对目前较少关注的Ti-V微合金体系,在Formaster-FII膨胀仪上进行奥氏体/铁素体两相区等温,在铁素体相变同时获得Ti、V复合相间析出。采用金相、透射电子显微镜对显微组织、尤其是相间析出形貌、及其与铁素体基体的位向关系进行了观察与分析。研究表明,650℃为静态等温相变的鼻温点,相间析出呈层状分布,具有平面和曲面两种形貌,相间析出碳化物与铁素体基体之间存在Baker-Nutting取向关系。

  4. Noninvasive probes of mitochondrial molecular motors

    Science.gov (United States)

    Nawarathna, Dharmakeerthna; Claycomb, James

    2005-03-01

    We report on a noninvasive method of probing mitochondrial molecular motors using nonlinear dielectric spectroscopy. It has been found previously that enzymes in the plasma membrane, particularly H+ ATPase, result in a strong low frequency (less than 100 Hz) nonlinear harmonic response. In this study, we find evidence that molecular motors located in the inner membranes of mitochondria cause the generation of harmonics at relatively high frequencies (1 - 30 kHz). In particular, we find that potassium cyanide (KCN), a respiratory inhibitor that binds to cytochrome c oxidase and thus prevents transport of protons across the mitochondrial inner membrane, suppresses the harmonic response. We observe this behavior in yeast (S. cerevisiae), a eucaryote that typically contains about 300 mitochondria, and B. indicas, a procaryote believed to be related to the ancient ancestor of mitochondria. Our current modeling efforts are focusing on a Brownian ratchet model of the F0 unit of ATP synthase, a remarkable molecular turbine driven by the proton gradient across the mitochondrial inner membrane.

  5. Sensing Phosphatidylserine in Cellular Membranes

    Directory of Open Access Journals (Sweden)

    Jason G. Kay

    2011-01-01

    Full Text Available Phosphatidylserine, a phospholipid with a negatively charged head-group, is an important constituent of eukaryotic cellular membranes. On the plasma membrane, rather than being evenly distributed, phosphatidylserine is found preferentially in the inner leaflet. Disruption of this asymmetry, leading to the appearance of phosphatidylserine on the surface of the cell, is known to play a central role in both apoptosis and blood clotting. Despite its importance, comparatively little is known about phosphatidylserine in cells: its precise subcellular localization, transmembrane topology and intracellular dynamics are poorly characterized. The recent development of new, genetically-encoded probes able to detect phosphatidylserine within live cells, however, is leading to a more in-depth understanding of the biology of this phospholipid. This review aims to give an overview of the current methods for phosphatidylserine detection within cells, and some of the recent realizations derived from their use.

  6. Interphase fluorescence in situ hybridization in multiple myeloma and monoclonal gammopathy of undetermined significance without and with positive plasma cell identification

    DEFF Research Database (Denmark)

    Christensen, Jacob H; Abildgaard, Niels; Plesner, Torben

    2007-01-01

    Interphase fluorescence in-situ hybridization (i-FISH) was used to investigate 192 patients with multiple myeloma (MM; n = 182) and benign monoclonal gammopathy of undetermined significance (MGUS; n = 10). Of the 182 MM cases, 132 were investigated without and 50 with positive plasma cell......32. Of these, translocations t(4;14) constituted 9% and t(11;14), 20%. Finally, based on the small number of cytogenetically abnormal cases, it is recommended to include cytogenetics (and, for example, the DNA index) in the prognostic armamentarium....

  7. Numerical simulation of Marangoni effects of single drops induced by interphase mass transfer in liquid-liquid extraction systems by the level set method

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The mathematical model of mass transfer-induced Marangoni effect is formulated. The drop surface evolution is captured by the level set method, in which the interface is represented by the embedded set of zero level of a scalar distance function defined in the whole computational domain. Numerical simulation of the Marangoni effect induced by interphase mass transfer to/from deformable single drops in unsteady motion in liquid-liquid extraction systems is performed in a Eulerian axisymmetric reference frame. The occurrence and development of the Marangoni effect are simulated, and the re- sults are in good agreement with the classical theoretical analysis and previous simulation.

  8. Numerical simulation of Marangoni effects of single drops induced by interphase mass transfer in liquid-liquid extraction systems by the level set method

    Institute of Scientific and Technical Information of China (English)

    WANG JianFeng; YANG Chao; MAO ZaiSha

    2008-01-01

    The mathematical model of mass transfer-induced Marangoni effect is formulated. The drop surface evolution is captured by the level set method, in which the interface is represented by the embedded set of zero level of a scalar distance function defined in the whole computational domain. Numerical simulation of the Marangoni effect induced by interphase mass transfer to/from deformable single drops in unsteady motion in liquid-liquid extraction systems is performed in a Eulerian axisymmetric reference frame. The occurrence and development of the Marangoni effect are simulated, and the re-sults are in good agreement with the classical theoretical analysis and previous simulation.

  9. Function of nuclear membrane proteins in shaping the nuclear envelope integrity during closed mitosis.

    Science.gov (United States)

    Yang, Hui-Ju; Iwamoto, Masaaki; Hiraoka, Yasushi; Haraguchi, Tokuko

    2017-06-01

    The nuclear envelope (NE) not only protects the genome from being directly accessed by detrimental agents but also regulates genome organization. Breaches in NE integrity threaten genome stability and impede cellular function. Nonetheless, the NE constantly remodels, and NE integrity is endangered in dividing or differentiating cells. Specifically, in unicellular eukaryotes undergoing closed mitosis, the NE expands instead of breaking down during chromosome segregation. The newly assembling nuclear pore complexes (NPCs) penetrate the existing NE in interphase. A peculiar example of NE remodelling during nuclear differentiation in Tetrahymena involves formation of the redundant NE and clustered NPCs. Even under these conditions, the NE remains intact. Many recent studies on unicellular organisms have revealed that nuclear membrane proteins, such as LEM-domain proteins, play a role in maintaining NE integrity. This review summarizes and discusses how nuclear membrane proteins participate in NE integrity. © The Authors 2017. Published by Oxford University Press on behalf of the Japanese Biochemical Society. All rights reserved.

  10. Rapid detection of chromosome 18 copy number in buccal smears using DNA probes and FISH

    Energy Technology Data Exchange (ETDEWEB)

    Harris, C.; Nunez, M. [Univ. of Wisconsin, WI (United States); Giraldez, R. [ONCOR, Inc., Gaithersburg, MD (United States)

    1994-09-01

    Rapid diagnosis of trisomy 18 in newborns is often critical to clinical management decisions that must be made in a minimum of time. DNA probes combined with FISH can be used to accurately to determine the copy number of chromosome 18 in interphase cells. We have used the D18Z1 alpha satellite DNA probe to determine signal frequency in normal, previously karyotyped subjects, 12 females and 6 males. We also present one clinical case of trisomy 18, confirmed by karyotype, for comparison to the results obtained from normal subjects. Buccal smears, unlike cytogenetic preparations from peripheral blood, are quite resistant to penetration of probes and detection reagents resulting in higher levels of false monosomy. We have studied 19 individuals and have obtained consistent FISH results, ranging from 64 to 90% disomy. False monosomy rates ranged from 10 to 36%, while false trisomy or tetrasomy was less than 1% in all samples. High rates of false monosomy make this test questionable for detection of low order mosaicism for monosomy, but the extremely low false hyperploidy rate suggests that this is a dependable procedure for detection of trisomy 18, enabling the use of buccal epithelium which can be collected easily from even premature and tiny infants.

  11. Hard Probes at ATLAS

    CERN Document Server

    Citron, Z; The ATLAS collaboration

    2014-01-01

    The ATLAS collaboration has measured several hard probe observables in Pb+Pb and p+Pb collisions at the LHC. These measurements include jets which show modification in the hot dense medium of heavy ion collisions as well as color neutral electro-weak bosons. Together, they elucidate the nature of heavy ion collisions.

  12. Endocavity Ultrasound Probe Manipulators.

    Science.gov (United States)

    Stoianovici, Dan; Kim, Chunwoo; Schäfer, Felix; Huang, Chien-Ming; Zuo, Yihe; Petrisor, Doru; Han, Misop

    2013-06-01

    We developed two similar structure manipulators for medical endocavity ultrasound probes with 3 and 4 degrees of freedom (DoF). These robots allow scanning with ultrasound for 3-D imaging and enable robot-assisted image-guided procedures. Both robots use remote center of motion kinematics, characteristic of medical robots. The 4-DoF robot provides unrestricted manipulation of the endocavity probe. With the 3-DoF robot the insertion motion of the probe must be adjusted manually, but the device is simpler and may also be used to manipulate external-body probes. The robots enabled a novel surgical approach of using intraoperative image-based navigation during robot-assisted laparoscopic prostatectomy (RALP), performed with concurrent use of two robotic systems (Tandem, T-RALP). Thus far, a clinical trial for evaluation of safety and feasibility has been performed successfully on 46 patients. This paper describes the architecture and design of the robots, the two prototypes, control features related to safety, preclinical experiments, and the T-RALP procedure.

  13. One-Probe Search

    DEFF Research Database (Denmark)

    Östlin, Anna; Pagh, Rasmus

    2002-01-01

    We consider dictionaries that perform lookups by probing a single word of memory, knowing only the size of the data structure. We describe a randomized dictionary where a lookup returns the correct answer with probability 1 - e, and otherwise returns don't know. The lookup procedure uses an expan...

  14. Probing the Solar System

    Science.gov (United States)

    Wilkinson, John

    2013-01-01

    Humans have always had the vision to one day live on other planets. This vision existed even before the first person was put into orbit. Since the early space missions of putting humans into orbit around Earth, many advances have been made in space technology. We have now sent many space probes deep into the Solar system to explore the planets and…

  15. One-Probe Search

    DEFF Research Database (Denmark)

    Östlin, Anna; Pagh, Rasmus

    2002-01-01

    We consider dictionaries that perform lookups by probing a single word of memory, knowing only the size of the data structure. We describe a randomized dictionary where a lookup returns the correct answer with probability 1 - e, and otherwise returns don't know. The lookup procedure uses an expan...

  16. Probing the Solar System

    Science.gov (United States)

    Wilkinson, John

    2013-01-01

    Humans have always had the vision to one day live on other planets. This vision existed even before the first person was put into orbit. Since the early space missions of putting humans into orbit around Earth, many advances have been made in space technology. We have now sent many space probes deep into the Solar system to explore the planets and…

  17. A Mechanistic Study of Chemically Modified Inorganic Membranes for Gas and Liquid Separations

    Energy Technology Data Exchange (ETDEWEB)

    Way, J Douglas

    2011-01-21

    This final report will summarize the progress made during the period August 1, 1993 - October 31, 2010 with support from DOE grant number DE-FG03-93ER14363. The objectives of the research have been to investigate the transport mechanisms in micro- and mesoporous, metal oxide membranes and to examine the relationship between the microstructure of the membrane, the membrane surface chemistry, and the separation performance of the membrane. Examples of the membrane materials under investigation are the microporous silica hollow fiber membrane manufactured by PPG Industries, chemically modified mesoporous oxide membranes, and polymer membranes containing microporous oxides (mixed matrix membranes). Analytical techniques such as NMR, FTIR and Raman spectroscopy, thermal analysis, and gas adsorption were used to investigate membrane microstructure and to probe the chemical interactions occurring at the gas-membrane interface.

  18. Pressure effects on lipids and bio-membrane assemblies

    Directory of Open Access Journals (Sweden)

    Nicholas J. Brooks

    2014-11-01

    Full Text Available Membranes are amongst the most important biological structures; they maintain the fundamental integrity of cells, compartmentalize regions within them and play an active role in a wide range of cellular processes. Pressure can play a key role in probing the structure and dynamics of membrane assemblies, and is also critical to the biology and adaptation of deep-sea organisms. This article presents an overview of the effect of pressure on the mesostructure of lipid membranes, bilayer organization and lipid–protein assemblies. It also summarizes recent developments in high-pressure structural instrumentation suitable for experiments on membranes.

  19. The histone H4 lysine 20 monomethyl mark, set by PR-Set7 and stabilized by L(3mbt, is necessary for proper interphase chromatin organization.

    Directory of Open Access Journals (Sweden)

    Ayako Sakaguchi

    Full Text Available Drosophila PR-Set7 or SET8 is a histone methyltransferase that specifically monomethylates histone H4 lysine 20 (H4K20. L(3MBT has been identified as a reader of methylated H4K20. It contains several conserved domains including three MBT repeats binding mono- and dimethylated H4K20 peptides. We find that the depletion of PR-Set7 blocks de novo H4K20me1 resulting in the immediate activation of the DNA damage checkpoint, an increase in the size of interphase nuclei, and drastic reduction of cell viability. L(3mbt on the other hand stabilizes the monomethyl mark, as L(3mbt-depleted S2 cells show a reduction of more than 60% of bulk monomethylated H4K20 (H4K20me1 while viability is barely affected. Ploidy and basic chromatin structure show only small changes in PR-Set7-depleted cells, but higher order interphase chromatin organization is significantly affected presumably resulting in the activation of the DNA damage checkpoint. In the absence of any other known functions of PR-Set7, the setting of the de novo monomethyl mark appears essential for cell viability in the presence or absence of the DNA damage checkpoint, but once newly assembled chromatin is established the monomethyl mark, protected by L(3mbt, is dispensable.

  20. The biphasic interphase-mitotic polarity of cell nuclei induced under DNA replication stress seems to be correlated with Pin2 localization in root meristems of Allium cepa.

    Science.gov (United States)

    Żabka, Aneta; Trzaskoma, Paweł; Winnicki, Konrad; Polit, Justyna Teresa; Chmielnicka, Agnieszka; Maszewski, Janusz

    2015-02-01

    Long-term treatment of Allium cepa seedlings with low concentration of hydroxyurea (HU) results in a disruption of cell cycle checkpoints, leading root apex meristem (RAM) cells to an abnormal organization of nuclear structures forming interphase (I) and mitotic (M) domains of chromatin at opposite poles of the nucleus. Thus far, both critical cell length and an uneven distribution of cyclin B-like proteins along the nuclear axis have been recognized as essential factors needed to facilitate the formation of biphasic interphase-mitotic (IM) cells. Two new aspects with respect to their emergence are investigated in this study. The first concerns a relationship between the polarity of increasing chromatin condensation (IM orientation) and the acropetal (base→apex) alignment of RAM cell files. The second problem involves the effects of auxin (IAA), on the frequency of IM cells. We provide evidence that there is an association between the advanced M-poles of the IM cell nuclei and the polarized accumulation sites of auxin efflux carriers (PIN2 proteins) and IAA. Furthermore, our observations reveal exclusion regions for PIN2 proteins in the microtubule-rich structures, such as preprophase bands (PPBs) and phragmoplast. The current and previous studies have prompted us to formulate a hypothetical mechanism linking PIN2-mediated unilateral localization of IAA and the induction of bipolar IM cells in HU-treated RAMs of A. cepa.

  1. Position of chromosomes 18, 19, 21 and 22 in 3D-preserved interphase nuclei of human and gorilla and white hand gibbon

    Directory of Open Access Journals (Sweden)

    Bhatt Samarth

    2008-04-01

    Full Text Available Abstract Background Even though comparative nuclear architecture studies in hominoids are sparse, nuclear chromosome architecture was shown to be conserved during hominoid evolution. Thus, it is suspected that yet unknown biological mechanisms must underlie this observation. Results Here for the first time a combination of multicolor banding (MCB and three-dimensional analysis of interphase cells was used to characterize the position and orientation of human chromosomes #18, #19, #21 and #22 and their homologues in primate B-lymphocytic cells. In general, our data is in concordance with previous studies. The position of the four studied human chromosomes and their homologues were conserved during primate evolution. However, comparison of interphase architecture in human B-lymphocytic cells and sperm revealed differences of localization of acrocentric chromosomes. The latter might be related to the fact that the nucleolus organizing region is not active in sperm. Conclusion Studies in different tissue types may characterize more – potentially biologically relevant differences in nuclear architecture.

  2. CFD Simulation of Effect of Interphase Forces and Turbulence Models on Gas-Liquid Two-Phase Flows in Non-Industrial Aluminum Electrolysis Cells

    Science.gov (United States)

    Zhan, Shuiqing; Yang, Jianhong; Wang, Zhentao; Zhao, Ruijie; Zheng, Jun; Wang, Junfeng

    2017-09-01

    Numerical simulations of gas-liquid two-phase flows in aluminum electrolysis cells using the Euler-Euler approach were presented. The attempt was made to assess the performance and applicability of different interphase forces (drag, lift, wall lubrication, and turbulent dispersion forces) and turbulence models (standard k- ɛ, renormalization group k- ɛ, standard k- ω, shear stress transport k- ω, and Reynolds stress models). Moreover, three different bubble-induced turbulence models have been also analyzed. The simulated electrolyte velocity profiles were discussed by comparing with each other and against published experimental data. Based on the results of the validation of different interphase forces and turbulence models, a set consisting of the dispersed standard k- ɛ model, Grace drag coefficient model, Simonin turbulent dispersion force model, and Sato et al.'s bubble-induced effective viscosity model was found to provide the best agreement with the experimental data. The prediction results showed that the contributions of the lift force and the wall lubrication force can be neglected for the present bubbly flows.

  3. Fission yeast Mog1p homologue, which interacts with the small GTPase Ran, is required for mitosis-to-interphase transition and poly(A)(+) RNA metabolism.

    Science.gov (United States)

    Tatebayashi, K; Tani, T; Ikeda, H

    2001-04-01

    We have cloned and characterized the Schizosaccharomyces pombe gene mog1(+), which encodes a protein with homology to the Saccharomyces cerevisiae Mog1p participating in the Ran-GTPase system. The S. pombe Mog1p is predominantly localized in the nucleus. In contrast to the S. cerevisiae MOG1 gene, the S. pombe mog1(+) gene is essential for cell viability. mog1(+) is required for the mitosis-to-interphase transition, as the mog1-1 mutant arrests at restrictive temperatures as septated, binucleated cells with highly condensed chromosomes and an aberrant nuclear envelope. FACS analysis showed that these cells do not undergo a subsequent round of DNA replication. Surprisingly, also unlike the Delta mog1 mutation in S. cerevisiae, the mog1-1 mutation causes nucleolar accumulation of poly(A)(+) RNA at the restrictive temperature in S. pombe, but the signals do not overlap with the fibrillarin-rich region of the nucleolus. Thus, we found that mog1(+) is required for the mitosis-to-interphase transition and a class of RNA metabolism. In our attempt to identify suppressors of mog1-1, we isolated the spi1(+) gene, which encodes the fission yeast homologue of Ran. We found that overexpression of Spi1p rescues the S. pombe Delta mog1 cells from death. On the basis of these results, we conclude that mog1(+) is involved in the Ran-GTPase system.

  4. CFD Simulation of Effect of Interphase Forces and Turbulence Models on Gas-Liquid Two-Phase Flows in Non-Industrial Aluminum Electrolysis Cells

    Science.gov (United States)

    Zhan, Shuiqing; Yang, Jianhong; Wang, Zhentao; Zhao, Ruijie; Zheng, Jun; Wang, Junfeng

    2017-03-01

    Numerical simulations of gas-liquid two-phase flows in aluminum electrolysis cells using the Euler-Euler approach were presented. The attempt was made to assess the performance and applicability of different interphase forces (drag, lift, wall lubrication, and turbulent dispersion forces) and turbulence models (standard k-ɛ, renormalization group k-ɛ, standard k-ω, shear stress transport k-ω, and Reynolds stress models). Moreover, three different bubble-induced turbulence models have been also analyzed. The simulated electrolyte velocity profiles were discussed by comparing with each other and against published experimental data. Based on the results of the validation of different interphase forces and turbulence models, a set consisting of the dispersed standard k-ɛ model, Grace drag coefficient model, Simonin turbulent dispersion force model, and Sato et al.'s bubble-induced effective viscosity model was found to provide the best agreement with the experimental data. The prediction results showed that the contributions of the lift force and the wall lubrication force can be neglected for the present bubbly flows.

  5. Comparative study of interphase cell death and severity of bone marrow aplasia in bank voles of the Moscow suburbs and C57B1 mice under the influence of ionizing radiation. [Whole-body x irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Samokhvalova, N.S.; Popova, M.F.; Domareva, O.P.; Suvorova, E.A.

    1978-01-01

    Interphase of bone marrow cells, which may reach significant dimensions according to some researchers, is one of the criteria of radiation lesion to the marrow. The method of estimating the total number of nuclear cells in animal bone marrow also makes it possible to gain an idea about the severity of tissue destruction. The objective of this work was to study interphase cell death and severity of aplasia in the bone marrow of bank voles of the Moscow suburbs and C57B1 mice after exposing these animals to x rays.

  6. From biological membranes to biomimetic model membranes

    Directory of Open Access Journals (Sweden)

    Eeman, M.

    2010-01-01

    Full Text Available Biological membranes play an essential role in the cellular protection as well as in the control and the transport of nutrients. Many mechanisms such as molecular recognition, enzymatic catalysis, cellular adhesion and membrane fusion take place into the biological membranes. In 1972, Singer et al. provided a membrane model, called fluid mosaic model, in which each leaflet of the bilayer is formed by a homogeneous environment of lipids in a fluid state including globular assembling of proteins and glycoproteins. Since its conception in 1972, many developments were brought to this model in terms of composition and molecular organization. The main development of the fluid mosaic model was made by Simons et al. (1997 and Brown et al. (1997 who suggested that membrane lipids are organized into lateral microdomains (or lipid rafts with a specific composition and a molecular dynamic that are different to the composition and the dynamic of the surrounding liquid crystalline phase. The discovery of a phase separation in the plane of the membrane has induced an explosion in the research efforts related to the biology of cell membranes but also in the development of new technologies for the study of these biological systems. Due to the high complexity of biological membranes and in order to investigate the biological processes that occur on the membrane surface or within the membrane lipid bilayer, a large number of studies are performed using biomimicking model membranes. This paper aims at revisiting the fundamental properties of biological membranes in terms of membrane composition, membrane dynamic and molecular organization, as well as at describing the most common biomimicking models that are frequently used for investigating biological processes such as membrane fusion, membrane trafficking, pore formation as well as membrane interactions at a molecular level.

  7. Calibration Fixture For Anemometer Probes

    Science.gov (United States)

    Lewis, Charles R.; Nagel, Robert T.

    1993-01-01

    Fixture facilitates calibration of three-dimensional sideflow thermal anemometer probes. With fixture, probe oriented at number of angles throughout its design range. Readings calibrated as function of orientation in airflow. Calibration repeatable and verifiable.

  8. Perspectives in enzymology of membrane proteins by solid-state NMR.

    Science.gov (United States)

    Ullrich, Sandra J; Glaubitz, Clemens

    2013-09-17

    Membrane proteins catalyze reactions at the cell membrane and facilitate thetransport of molecules or signals across the membrane. Recently researchers have made great progress in understanding the structural biology of membrane proteins, mainly based on X-ray crystallography. In addition, the application of complementary spectroscopic techniques has allowed researchers to develop a functional understanding of these proteins. Solid-state NMR has become an indispensable tool for the structure-function analysis of insoluble proteins and protein complexes. It offers the possibility of investigating membrane proteins directly in their environment, which provides essential information about the intrinsic coupling of protein structure and functional dynamics within the lipid bilayer. However, to date, researchers have hardly explored the enzymology of mem-brane proteins. In this Account, we review the perspectives for investigating membrane-bound enzymes by solid-state NMR. Understanding enzyme mechanisms requires access to kinetic parameters, structural analysis of the catalytic center, knowledge of the 3D structure and methods to follow the structural dynamics of the enzyme during the catalytic cycle. In principle, solid-state NMR can address all of these issues. Researchers can characterize the enzyme kinetics by observing substrate turnover within the membrane or at the membrane interphase in a time-resolved fashion as shown for diacylglycerol kinase. Solid-state NMR has also provided a mechanistic understanding of soluble enzymes including triosephosphate isomerase (TIM) and different metal-binding proteins, which demonstrates a promising perspective also for membrane proteins. The increasing availability of high magnetic fields and the development of new experimental schemes and computational protocols have made it easier to determine 3D structure using solid-state NMR. Dynamic nuclear polarization, a key technique to boost sensitivity of solid-state NMR at low

  9. Microporous Inorganic Membranes as Proton Exchange Membranes

    Energy Technology Data Exchange (ETDEWEB)

    Vichi, F.M. Tejedor-Tejedor, M.I. Anderson, Marc A

    2002-08-28

    Porous oxide electrolyte membranes provide an alternative approach to fabricating proton exchange membrane fuel cells based on inorganic materials. This study focused on elucidating the properties of these inorganic membranes that make them good electrolyte materials in membrane electrode assemblies; in particular, we investigated several properties that affect the nature of proton conductivity in these membranes. This report discusses our findings on the effect of variables such as site density, amount of surface protonation and surface modification on the proton conductivity of membranes with a fixed pore structure under selected conditions. Proton conductivities of these inorganic membranes are similar to conductivities of nafion, the polymeric membrane most commonly used in low temperature fuel cells.

  10. Probing properties of cold radiofrequency plasma with polymer probe

    Science.gov (United States)

    Bormashenko, E.; Chaniel, G.; Multanen, V.

    2015-01-01

    The probe intended for the characterization of cold plasma is introduced. The probe allows the estimation of Debye length of cold plasma. The probe is based on the pronounced modification of surface properties (wettability) of polymer films by cold plasmas. The probe was tested with the cold radiofrequency inductive air plasma discharge. The Debye length and the concentration of charge carriers were estimated for various gas pressures. The reported results coincide reasonably with the corresponding values established by other methods. The probe makes possible measurement of characteristics of cold plasmas in closed chambers.

  11. Probing Properties of Cold Radiofrequency Plasma with Polymer Probe

    CERN Document Server

    Bormashenko, Edward; Multanen, Victor

    2014-01-01

    The probe intended for the characterization of cold plasma is introduced. The probe allows estimation of the Debye length of the cold plasma. The probe is based on the pronounced modification of surface properties (wettability) of polymer films by cold plasmas. The probe was tested with the cold radiofrequency inductive air plasma discharge. The Debye length and the concentration of charge carriers were estimated for various gas pressures. The reported results coincide reasonably with the corresponding values established by other methods. The probe makes possible measurement of characteristics of cold plasmas in closed chambers.

  12. Phoenix Conductivity Probe

    Science.gov (United States)

    2008-01-01

    This image taken by the Surface Stereo Imager on Sol 49, or the 49th Martian day of the mission (July 14, 2008), shows thermal and electrical conductivity probe on NASA's Phoenix Mars Lander's Robotic Arm. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is led by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  13. Atom probe tomography today

    OpenAIRE

    Alfred Cerezo; Peter H. Clifton; Mark J. Galtrey; Humphreys, Colin J.; Kelly, Thomas. F.; David J. Larson; Sergio Lozano-Perez; Marquis, Emmanuelle A.; Oliver, Rachel A.; Gang Sha; Keith Thompson; Mathijs Zandbergen; Roger L. Alvis

    2007-01-01

    This review aims to describe and illustrate the advances in the application of atom probe tomography that have been made possible by recent developments, particularly in specimen preparation techniques (using dual-beam focused-ion beam instruments) but also of the more routine use of laser pulsing. The combination of these two developments now permits atomic-scale investigation of site-specific regions within engineering alloys (e.g. at grain boundaries and in the vicinity of cracks) and also...

  14. Einstein Inflationary Probe (EIP)

    Science.gov (United States)

    Hinshaw, Gary

    2004-01-01

    I will discuss plans to develop a concept for the Einstein Inflation Probe: a mission to detect gravity waves from inflation via the unique signature they impart to the cosmic microwave background (CMB) polarization. A sensitive CMB polarization satellite may be the only way to probe physics at the grand-unified theory (GUT) scale, exceeding by 12 orders of magnitude the energies studied at the Large Hadron Collider. A detection of gravity waves would represent a remarkable confirmation of the inflationary paradigm and set the energy scale at which inflation occurred when the universe was a fraction of a second old. Even a strong upper limit to the gravity wave amplitude would be significant, ruling out many common models of inflation, and pointing to inflation occurring at much lower energy, if at all. Measuring gravity waves via the CMB polarization will be challenging. We will undertake a comprehensive study to identify the critical scientific requirements for the mission and their derived instrumental performance requirements. At the core of the study will be an assessment of what is scientifically and experimentally optimal within the scope and purpose of the Einstein Inflation Probe.

  15. Nanoscale thermal probing

    Directory of Open Access Journals (Sweden)

    Yanan Yue

    2012-03-01

    Full Text Available Nanoscale novel devices have raised the demand for nanoscale thermal characterization that is critical for evaluating the device performance and durability. Achieving nanoscale spatial resolution and high accuracy in temperature measurement is very challenging due to the limitation of measurement pathways. In this review, we discuss four methodologies currently developed in nanoscale surface imaging and temperature measurement. To overcome the restriction of the conventional methods, the scanning thermal microscopy technique is widely used. From the perspective of measuring target, the optical feature size method can be applied by using either Raman or fluorescence thermometry. The near-field optical method that measures nanoscale temperature by focusing the optical field to a nano-sized region provides a non-contact and non-destructive way for nanoscale thermal probing. Although the resistance thermometry based on nano-sized thermal sensors is possible for nanoscale thermal probing, significant effort is still needed to reduce the size of the current sensors by using advanced fabrication techniques. At the same time, the development of nanoscale imaging techniques, such as fluorescence imaging, provides a great potential solution to resolve the nanoscale thermal probing problem.

  16. Anaerobic membrane bioreactors: Are membranes really necessary?

    NARCIS (Netherlands)

    Davila, M.; Kassab, G.; Klapwijk, A.; Lier, van J.B.

    2008-01-01

    Membranes themselves represent a significant cost for the full scale application of anaerobic membrane bioreactors (AnMBR). The possibility of operating an AnMBR with a self-forming dynamic membrane generated by the substances present in the reactor liquor would translate into an important saving. A

  17. DMSO Induces Dehydration near Lipid Membrane Surfaces

    Science.gov (United States)

    Cheng, Chi-Yuan; Song, Jinsuk; Pas, Jolien; Meijer, Lenny H.H.; Han, Songi

    2015-01-01

    Dimethyl sulfoxide (DMSO) has been broadly used in biology as a cosolvent, a cryoprotectant, and an enhancer of membrane permeability, leading to the general assumption that DMSO-induced structural changes in cell membranes and their hydration water play important functional roles. Although the effects of DMSO on the membrane structure and the headgroup dehydration have been extensively studied, the mechanism by which DMSO invokes its effect on lipid membranes and the direct role of water in this process are unresolved. By directly probing the translational water diffusivity near unconfined lipid vesicle surfaces, the lipid headgroup mobility, and the repeat distances in multilamellar vesicles, we found that DMSO exclusively weakens the surface water network near the lipid membrane at a bulk DMSO mole fraction (XDMSO) of DMSO was found to effectively destabilize the hydration water structure at the lipid membrane surface at XDMSO 0.1, DMSO enters the lipid interface and restricts the lipid headgroup motion. We postulate that DMSO acts as an efficient cryoprotectant even at low concentrations by exclusively disrupting the water network near the lipid membrane surface, weakening the cohesion between water and adhesion of water to the lipid headgroups, and so mitigating the stress induced by the volume change of water during freeze-thaw. PMID:26200868

  18. Viscoelastic properties of actin-coated membranes

    Science.gov (United States)

    Helfer, E.; Harlepp, S.; Bourdieu, L.; Robert, J.; Mackintosh, F. C.; Chatenay, D.

    2001-02-01

    In living cells, cytoskeletal filaments interact with the plasma membrane to form structures that play a key role in cell shape and mechanical properties. To study the interaction between these basic components, we designed an in vitro self-assembled network of actin filaments attached to the outer surface of giant unilamellar vesicles. Optical tweezers and single-particle tracking experiments are used to study the rich dynamics of these actin-coated membranes (ACM). We show that microrheology studies can be carried out on such an individual microscopic object. The principle of the experiment consists in measuring the thermally excited position fluctuations of a probe bead attached biochemically to the membrane. We propose a model that relates the power spectrum of these thermal fluctuations to the viscoelastic properties of the membrane. The presence of the actin network modifies strongly the membrane dynamics with respect to a fluid, lipid bilayer one. It induces first a finite (ω=0) two-dimensional (2D) shear modulus G02D~0.5 to 5 μN/m in the membrane plane. Moreover, the frequency dependence at high frequency of the shear modulus [G'2D(f )~f0.85+/-0.07] and of the bending modulus (κACM(f)~f0.55+/-0.21) demonstrate the viscoelastic behavior of the composite membrane. These results are consistent with a common exponent of 0.75 for both moduli as expected from our model and from prior measurements on actin solutions.

  19. Model cell membranes

    DEFF Research Database (Denmark)

    Günther-Pomorski, Thomas; Nylander, Tommy; Cardenas Gomez, Marite

    2014-01-01

    The high complexity of biological membranes has motivated the development and application of a wide range of model membrane systems to study biochemical and biophysical aspects of membranes in situ under well defined conditions. The aim is to provide fundamental understanding of processes...... controlled by membrane structure, permeability and curvature as well as membrane proteins by using a wide range of biochemical, biophysical and microscopic techniques. This review gives an overview of some currently used model biomembrane systems. We will also discuss some key membrane protein properties...... that are relevant for protein-membrane interactions in terms of protein structure and how it is affected by membrane composition, phase behavior and curvature....

  20. Nine New Fluorescent Probes

    Science.gov (United States)

    Lin, Tsung-I.; Jovanovic, Misa V.; Dowben, Robert M.

    1989-06-01

    Absorption and fluorescence spectroscopic studies are reported here for nine new fluorescent probes recently synthesized in our laboratories: four pyrene derivatives with substituents of (i) 1,3-diacetoxy-6,8-dichlorosulfonyl, (ii) 1,3-dihydroxy-6,8-disodiumsulfonate, (iii) 1,3-disodiumsulfonate, and (iv) l-ethoxy-3,6,8-trisodiumsulfonate groups, and five [7-julolidino] coumarin derivatives with substituents of (v) 3-carboxylate-4-methyl, (vi) 3- methylcarboxylate, (vii) 3-acetate-4-methyl, (viii) 3-propionate-4-methyl, and (ix) 3-sulfonate-4-methyl groups. Pyrene compounds i and ii and coumarin compounds v and vi exhibit interesting absorbance and fluorescence properties: their absorption maxima are red shifted compared to the parent compound to the blue-green region, and the band width broadens considerably. All four blue-absorbing dyes fluoresce intensely in the green region, and the two pyrene compounds emit at such long wavelengths without formation of excimers. The fluorescence properties of these compounds are quite environment-sensitive: considerable spectral shifts and fluorescence intensity changes have been observed in the pH range from 3 to 10 and in a wide variety of polar and hydrophobic solvents with vastly different dielectric constants. The high extinction and fluorescence quantum yield of these probes make them ideal fluorescent labeling reagents for proteins, antibodies, nucleic acids, and cellular organelles. The pH and hydrophobicity-dependent fluorescence changes can be utilized as optical pH and/or hydrophobicity indicators for mapping environmental difference in various cellular components in a single cell. Since all nine probes absorb in the UV, but emit at different wavelengths in the visible, these two groups of compounds offer an advantage of utilizing a single monochromatic light source (e.g., a nitrogen laser) to achieve multi-wavelength detection for flow cytometry application. As a first step to explore potential application in

  1. Membrane protein structure determination in membrana.

    Science.gov (United States)

    Ding, Yi; Yao, Yong; Marassi, Francesca M

    2013-09-17

    The two principal components of biological membranes, the lipid bilayer and the proteins integrated within it, have coevolved for specific functions that mediate the interactions of cells with their environment. Molecular structures can provide very significant insights about protein function. In the case of membrane proteins, the physical and chemical properties of lipids and proteins are highly interdependent; therefore structure determination should include the membrane environment. Considering the membrane alongside the protein eliminates the possibility that crystal contacts or detergent molecules could distort protein structure, dynamics, and function and enables ligand binding studies to be performed in a natural setting. Solid-state NMR spectroscopy is compatible with three-dimensional structure determination of membrane proteins in phospholipid bilayer membranes under physiological conditions and has played an important role in elucidating the physical and chemical properties of biological membranes, providing key information about the structure and dynamics of the phospholipid components. Recently, developments in the recombinant expression of membrane proteins, sample preparation, pulse sequences for high-resolution spectroscopy, radio frequency probes, high-field magnets, and computational methods have enabled a number of membrane protein structures to be determined in lipid bilayer membranes. In this Account, we illustrate solid-state NMR methods with examples from two bacterial outer membrane proteins (OmpX and Ail) that form integral membrane β-barrels. The ability to measure orientation-dependent frequencies in the solid-state NMR spectra of membrane-embedded proteins provides the foundation for a powerful approach to structure determination based primarily on orientation restraints. Orientation restraints are particularly useful for NMR structural studies of membrane proteins because they provide information about both three-dimensional structure

  2. Evaluation of the lymphocyte interphase nuclei phenotype by quantitative phase imaging (QPI in patients with endometrial ovarian cysts

    Directory of Open Access Journals (Sweden)

    S. A. Gasparyan

    2017-01-01

    dienogest, respectively. Relative distance between the centers of the nuclear segments (ΔL demonstrated a trend towards an increase by 0.6 and 0.9, 4.2 and 2.1%. The numbers of nuclear segments increased by 18.3 and 13.4, 27.4 and 16.9%, whereas the nuclear perimeter decreased by 13.9 and 12.6, 11.9 and 7.8%, respectively. In the patients treated with dienogest, the rate of non-relapse at 6 and 12 months of the follow-up was 100%, whereas in the patients without dienogest therapy, 97.5 and 93.5%, respectively. Discussion: Interphase chromatin is a unique biosensor of the early abnormalities in a lymphoid cell. Modification of its structure and packaging density not only indicate changes of the morphofunctional status of the lymphocyte, but can be projected to the body as a whole and used for early pre-clinical diagnosis, assessment of severity of the pathological process and prediction of the outcome in various critic states. Conclusion: Practical implementation of QPI for clinical monitoring of patients with ovarian endometrial cysts makes it possible to obtain important information on the cell immunity in real time. It opens new opportunities to assess the efficacy of treatment and rehabilitation activities, as well as for early pre-clinical diagnosis of relapsing disease. 

  3. Pulsed EPR in the method of spin labels and probes

    Energy Technology Data Exchange (ETDEWEB)

    Dzuba, Sergei A [Institute of Chemical Kinetics and Combustion, Siberian Branch of the Russian Academy of Sciences, Novosibirsk (Russian Federation)

    2007-08-31

    Various pulsed EPR in the method of spin labels and probes based on electron spin echo spectroscopy (spin echo envelope modulation through electron-nuclear interactions, electron-electron double resonance, echo detected EPR, etc.) are considered. These methods provide information on the conformations of complex biomolecules, nanostructure of matter, depth of water penetration into biological membranes, supramolecular structure of multicomponent systems (membrane-peptide, etc.), co-operative orientational dynamics of molecules and dynamic low-temperature transitions in disordered molecular media and biosystems.

  4. Pulsed EPR in the method of spin labels and probes

    Science.gov (United States)

    Dzuba, Sergei A.

    2007-08-01

    Various pulsed EPR in the method of spin labels and probes based on electron spin echo spectroscopy (spin echo envelope modulation through electron-nuclear interactions, electron-electron double resonance, echo detected EPR, etc.) are considered. These methods provide information on the conformations of complex biomolecules, nanostructure of matter, depth of water penetration into biological membranes, supramolecular structure of multicomponent systems (membrane-peptide, etc.), co-operative orientational dynamics of molecules and dynamic low-temperature transitions in disordered molecular media and biosystems.

  5. Erythrocyte membrane proteins and membrane skeleton

    Institute of Scientific and Technical Information of China (English)

    LU Yiqin; LIU Junfan

    2007-01-01

    Considerable advances in the research field of erythrocyte membrane were achieved in the recent two decades.New findings in the structure-function correlation and interactions of erythrocyte membrane proteins have attracted extensive attention.Interesting progress was also made in the molecular pathogenesis of erythrocyte membrane disorders.Advances in the composition,function and interaction of erythrocyte membrane proteins,erythrocyte membrane skeleton,and relevant diseases are briefly described and summarized here on the basis of domestic and world literatures.

  6. Nanobits, Nembranes and Micro Four-Point Probes: Customizable Tools for insitu Manipulation and Characterisation of Nanostructures

    DEFF Research Database (Denmark)

    Bøggild, Peter; Petersen, Dirch Hjorth; Sardan Sukas, Özlem;

    2010-01-01

    on a cantilever; (ii) scanning micro four point probes allow fast, non- destructive mapping of local electrical properties (sheet resistance and Hall mobility) and hysteresis effects of graphene sheets; (iii) sub 100 nm freestanding devices with wires, heaters, actuators, sensors, resonators and probes were...... defined in a 100 nm thin membrane with focused ion beam milling. By patterning generic membrane templates (Nembranes) the fabrication time of a TEM compatible NEMS device is effectively reduced to less around 20 minutes....

  7. Development of Mackintosh Probe Extractor

    Science.gov (United States)

    Rahman, Noor Khazanah A.; Kaamin, Masiri; Suwandi, Amir Khan; Sahat, Suhaila; Jahaya Kesot, Mohd

    2016-11-01

    Dynamic probing is a continuous soil investigation technique, which is one of the simplest soil penetration test. It basically consist of repeatedly driving a metal tipped probe into the ground using a drop weight of fixed mass and travel. Testing was carried out continuously from ground level to the final penetration depth. Once the soil investigation work done, it is difficult to pull out the probe rod from the ground, due to strong soil structure grip against probe cone and prevent the probe rod out from the ground. Thus, in this case, a tool named Extracting Probe was created to assist in the process of retracting the probe rod from the ground. In addition, Extracting Probe also can reduce the time to extract the probe rod from the ground compare with the conventional method. At the same time, it also can reduce manpower cost because only one worker involve to handle this tool compare with conventional method used two or more workers. From experiment that have been done we found that the time difference between conventional tools and extracting probe is significant, average time difference is 155 minutes. In addition the extracting probe can reduce manpower usage, and also labour cost for operating the tool. With all these advantages makes this tool has the potential to be marketed.

  8. Probe-based data storage

    CERN Document Server

    Koelmans, Wabe W; Abelmann, L

    2015-01-01

    Probe-based data storage attracted many researchers from academia and industry, resulting in unprecendeted high data-density demonstrations. This topical review gives a comprehensive overview of the main contributions that led to the major accomplishments in probe-based data storage. The most investigated technologies are reviewed: topographic, phase-change, magnetic, ferroelectric and atomic and molecular storage. Also, the positioning of probes and recording media, the cantilever arrays and parallel readout of the arrays of cantilevers are discussed. This overview serves two purposes. First, it provides an overview for new researchers entering the field of probe storage, as probe storage seems to be the only way to achieve data storage at atomic densities. Secondly, there is an enormous wealth of invaluable findings that can also be applied to many other fields of nanoscale research such as probe-based nanolithography, 3D nanopatterning, solid-state memory technologies and ultrafast probe microscopy.

  9. Optical probes in biology

    CERN Document Server

    Zhang, Jin; Schultz, Carsten

    2015-01-01

    Introduction and BasicsEngineering of Optimized Fluorescent Proteins: An Overview from a Cyan and FRET Perspective Lindsay Haarbosch, Joachim Goedhart, Mark A. Hink, Laura van Weeren, Daphne S. Bindels, and Theodorus W.J. GadellaFluorescent Imaging Techniques: FRET and Complementary Methods Stefan Terjung and Yury BelyaevTracking: Sensors for Tracking BiomoleculesProtein-Based Calcium Sensors Thomas Thestrup and Oliver GriesbeckMonitoring Membrane Lipids with Protein Domains Expressed in Living Cells Peter Varnai

  10. High frequency, cell type-specific visualization of fluorescent-tagged genomic sites in interphase and mitotic cells of living Arabidopsis plants

    Directory of Open Access Journals (Sweden)

    van der Winden Johannes

    2010-01-01

    Full Text Available Abstract Background Interphase chromosome organization and dynamics can be studied in living cells using fluorescent tagging techniques that exploit bacterial operator/repressor systems and auto-fluorescent proteins. A nuclear-localized Repressor Protein-Fluorescent Protein (RP-FP fusion protein binds to operator repeats integrated as transgene arrays at defined locations in the genome. Under a fluorescence microscope, the tagged sites appear as bright fluorescent dots in living cells. This technique has been used successfully in plants, but is often hampered by low expression of genes encoding RP-FP fusion proteins, perhaps owing to one or more gene silencing mechanisms that are prevalent in plant cells. Results We used two approaches to overcome this problem. First, we tested mutations in four factors involved in different types of gene silencing and/or epigenetic modifications for their effects on nuclear fluorescence. Only mutations in DDM1, a chromatin remodelling ATPase involved in repeat-induced heterochromatin formation and DNA methylation, released silencing of the RP-FP fusion protein. This result suggested that the operator repeats can trigger silencing of the adjacent gene encoding the RP-FP fusion protein. In the second approach, we transformed the tagged lines with a second T-DNA encoding the RP-FP fusion protein but lacking operator repeats. This strategy avoided operator repeat-induced gene silencing and increased the number of interphase nuclei displaying fluorescent dots. In a further extension of the technique, we show that green fluorescent-tagged sites can be visualized on moving mitotic chromosomes stained with red fluorescent-labelled histone H2B. Conclusions The results illustrate the propensity of operator repeat arrays to form heterochromatin that can silence the neighbouring gene encoding the RP-FP fusion protein. Supplying the RP-FP fusion protein in trans from a second T-DNA largely alleviates this problem. Depending

  11. PROcess Based Diagnostics PROBE

    Science.gov (United States)

    Clune, T.; Schmidt, G.; Kuo, K.; Bauer, M.; Oloso, H.

    2013-01-01

    Many of the aspects of the climate system that are of the greatest interest (e.g., the sensitivity of the system to external forcings) are emergent properties that arise via the complex interplay between disparate processes. This is also true for climate models most diagnostics are not a function of an isolated portion of source code, but rather are affected by multiple components and procedures. Thus any model-observation mismatch is hard to attribute to any specific piece of code or imperfection in a specific model assumption. An alternative approach is to identify diagnostics that are more closely tied to specific processes -- implying that if a mismatch is found, it should be much easier to identify and address specific algorithmic choices that will improve the simulation. However, this approach requires looking at model output and observational data in a more sophisticated way than the more traditional production of monthly or annual mean quantities. The data must instead be filtered in time and space for examples of the specific process being targeted.We are developing a data analysis environment called PROcess-Based Explorer (PROBE) that seeks to enable efficient and systematic computation of process-based diagnostics on very large sets of data. In this environment, investigators can define arbitrarily complex filters and then seamlessly perform computations in parallel on the filtered output from their model. The same analysis can be performed on additional related data sets (e.g., reanalyses) thereby enabling routine comparisons between model and observational data. PROBE also incorporates workflow technology to automatically update computed diagnostics for subsequent executions of a model. In this presentation, we will discuss the design and current status of PROBE as well as share results from some preliminary use cases.

  12. A novel cassette method for probe evaluation in the designed biochips.

    Directory of Open Access Journals (Sweden)

    Vitaly Zinkevich

    Full Text Available A critical step in biochip design is the selection of probes with identical hybridisation characteristics. In this article we describe a novel method for evaluating DNA hybridisation probes, allowing the fine-tuning of biochips, that uses cassettes with multiple probes. Each cassette contains probes in equimolar proportions so that their hybridisation performance can be assessed in a single reaction. The model used to demonstrate this method was a series of probes developed to detect TORCH pathogens. DNA probes were designed for Toxoplasma gondii, Chlamidia trachomatis, Rubella, Cytomegalovirus, and Herpes virus and these were used to construct the DNA cassettes. Five cassettes were constructed to detect TORCH pathogens using a variety of genes coding for membrane proteins, viral matrix protein, an early expressed viral protein, viral DNA polymerase and the repetitive gene B1 of Toxoplasma gondii. All of these probes, except that for the B1 gene, exhibited similar profiles under the same hybridisation conditions. The failure of the B1 gene probe to hybridise was not due to a position effect, and this indicated that the probe was unsuitable for inclusion in the biochip. The redesigned probe for the B1 gene exhibited identical hybridisation properties to the other probes, suitable for inclusion in a biochip.

  13. Nanopillar arrays on semiconductor membranes as electron emission amplifiers

    Energy Technology Data Exchange (ETDEWEB)

    Qin Hua; Kim, Hyun-Seok; Blick, Robert H [Department of Electrical and Computer Engineering, University of Wisconsin-Madison, 1415 Engineering Drive, Madison, WI 53706 (United States)], E-mail: QIN1@WISC.EDU, E-mail: hqin2007@sinano.ac.cn

    2008-03-05

    A new transmission-type electron multiplier was fabricated from silicon-on-insulator (SOI) material by integrating an array of one-dimensional (1D) silicon nanopillars onto a two-dimensional (2D) silicon membrane. Primary electrons are injected into the nanopillar-membrane (NPM) system from the flat surface of the membrane, while electron emission from the nanopillars is probed by an anode. The secondary electron yield (SEY) from the nanopillars in the current device is found to be about 1.8 times that of the plain silicon membrane. This gain in electron number is slightly enhanced by the electric field applied from the anode. Further optimization of the dimensions of the NPM and an application of field emission promise an even higher gain for detector applications and allow for probing of electronic/mechanical excitations in an NPM system stimulated by incident particles or radiation.

  14. Atom probe tomography today

    Directory of Open Access Journals (Sweden)

    Alfred Cerezo

    2007-12-01

    Full Text Available This review aims to describe and illustrate the advances in the application of atom probe tomography that have been made possible by recent developments, particularly in specimen preparation techniques (using dual-beam focused-ion beam instruments but also of the more routine use of laser pulsing. The combination of these two developments now permits atomic-scale investigation of site-specific regions within engineering alloys (e.g. at grain boundaries and in the vicinity of cracks and also the atomic-level characterization of interfaces in multilayers, oxide films, and semiconductor materials and devices.

  15. Experimental probes of axions

    Energy Technology Data Exchange (ETDEWEB)

    Chou, Aaron S.; /Fermilab

    2009-10-01

    Experimental searches for axions or axion-like particles rely on semiclassical phenomena resulting from the postulated coupling of the axion to two photons. Sensitive probes of the extremely small coupling constant can be made by exploiting familiar, coherent electromagnetic laboratory techniques, including resonant enhancement of transitions using microwave and optical cavities, Bragg scattering, and coherent photon-axion oscillations. The axion beam may either be astrophysical in origin as in the case of dark matter axion searches and solar axion searches, or created in the laboratory from laser interactions with magnetic fields. This note is meant to be a sampling of recent experimental results.

  16. Atom Probe Tomography 2012

    Science.gov (United States)

    Kelly, Thomas F.; Larson, David J.

    2012-08-01

    In the world of tomographic imaging, atom probe tomography (APT) occupies the high-spatial-resolution end of the spectrum. It is highly complementary to electron tomography and is applicable to a wide range of materials. The current state of APT is reviewed. Emphasis is placed on applications and data analysis as they apply to many fields of research and development including metals, semiconductors, ceramics, and organic materials. We also provide a brief review of the history and the instrumentation associated with APT and an assessment of the existing challenges in the field.

  17. Mobile Probing Kit

    DEFF Research Database (Denmark)

    Larsen, Jakob Eg; Sørensen, Lene Tolstrup; Sørensen, J.K.

    2007-01-01

    characterized as being highly nomadic and thus potential users of mobile and ubiquitous technologies. The methodology has been applied in the 1ST MAGNET Beyond project in order to obtain user needs and requirements in the process of developing pilot services. We report on the initial findings from applying......Mobile Probing Kit is a low tech and low cost methodology for obtaining inspiration and insights into user needs, requirements and ideas in the early phases of a system's development process. The methodology is developed to identify user needs, requirements and ideas among knowledge workers...

  18. BODIPY-Coumarin Conjugate as an Endoplasmic Reticulum Membrane Fluidity Sensor and Its Application to ER Stress Models.

    Science.gov (United States)

    Lee, Hoyeon; Yang, Zhigang; Wi, Youngjin; Kim, Tae Woo; Verwilst, Peter; Lee, Yun Hak; Han, Ga-In; Kang, Chulhun; Kim, Jong Seung

    2015-12-16

    An endoplasmic reticulum (ER) membrane-selective chemosensor composed of BODIPY and coumarin moieties and a long alkyl chain (n-C18) was synthesized. The emission ratio of BODIPY to coumarin depends on the solution viscosity. The probe is localized to the ER membrane and was applied to reveal the reduced ER membrane fluidity under ER stress conditions.

  19. Magnetically controlled permeability membranes

    KAUST Repository

    Kosel, Jurgen

    2013-10-31

    A bioactive material delivery system can include a thermoresponsive polymer membrane and nanowires distributed within the thermoresponsive polymer membrane. Magnetic activation of a thermoresponsive polymer membrane can take place via altering the magnetization or dimensions of nanowires dispersed or ordered within the membrane matrix.

  20. Compositional asynchronous membrane systems

    Institute of Scientific and Technical Information of China (English)

    Cosmin Bonchis; Cornel Izbasa; Gabriel Ciobanu

    2007-01-01

    This paper presents an algorithmic way of building complex membrane systems by coupling elementary membranes. Its application seems particularly valuable in the case of asynchronous membrane systems, since the resulting membrane system remains asynchronous. The composition method is based on a handshake mechanism implemented by using antiport rules and promoters.

  1. Rapid and reliable diagnosis of murine myeloid leukemia (ML by FISH of peripheral blood smear using probe of PU. 1, a candidate ML tumor suppressor

    Directory of Open Access Journals (Sweden)

    Ban Nobuhiko

    2008-10-01

    Full Text Available Abstract Background Murine myeloid leukemia (ML provides a good animal model to study the mechanisms of radiation-induced leukemia in humans. This disease has been cytogenetically characterized by a partial deletion of chromosome 2 with G-banding. For the rapid diagnosis of ML, this study reports a FISH method using spleen cells and peripheral blood smears from ML mice exposed to gamma rays and neutrons with PU.1, a candidate ML tumor suppressor, as a probe. Results Among mice that were tentatively diagnosed with ML by clinical findings and blood smear examination, 85% carried spleen cells showing the loss of PU.1 although the frequency of these abnormal cells varied among individuals. Mice with very low frequencies of cells showing the loss of one copy of PU.1 (one-PU.1 frequency were later diagnosed pathologically not with ML but with blastic or eosinophilic leukemia. Some neutron-irradiated mice had cells showing translocated PU.1, although no pathological features differentiated these ML mice from ML mice expressing the simple loss of PU.1. The one-PU.1 frequency can be detected from spleen metaphase cells, spleen interphase cells, and blood smears. There was a good correlation between the one-PU.1 frequency in spleen metaphase cells and that in spleen interphase cells (r = 0.96 and between one-PU.1 frequency in spleen interphase cells and that in blood cells (r = 0.83. Conclusion The FISH method was capable of detecting aberration of copy number of the PU.1 gene on murine chromosome 2, and using a peripheral blood smear is more practical and less invasive than conventional pathological diagnosis or the cytogenetic examination of spleen cells.

  2. "a" interfacial parameter in Nicolais-Narkis model for yield strength of polymer particulate nanocomposites as a function of material and interphase properties.

    Science.gov (United States)

    Zare, Yasser

    2016-05-15

    In this paper, "a" interfacial parameter in Nicolais-Narkis model is expressed by thickness "ri" and strength "σi" of interphase between polymer and nanoparticles as well as material properties. "a" parameter is connected to "B1" interfacial parameter in modified Pukanszky model and the effects of "ri" and "σi" on "a" are explained. The negligible difference between "a" values calculated by fitting the experimental results to Nicolais-Narkis model and also, by "B1" results confirms the accurateness of the suggested relation between "a" and "B1" parameters. Additionally, an inverse relation is found between "a" and "B1" parameters for nanocomposites containing spherical nanoparticles. The results demonstrate that the slight levels of "ri" and "σi" data give a large value of "a" which indicates the poor interfacial adhesion.

  3. Molecular cytogenetic interphase analysis of Phosphoinositide-specific Phospholipase C β1 gene in paraffin-embedded brain samples of major depression patients.

    Science.gov (United States)

    Lo Vasco, Vincenza Rita; Polonia, Patrizia

    2012-01-01

    Mood disorders represent a major medical need, as their chronic treatments are not effective in all patients. Literature data suggested that phosphoinositides (PI) signal transduction pathway and related molecules such as the Phosphoinositide-specific Phospholipase C (PI-PLC) enzymes, might be involved in the pathophysiology of mood disorders, including major depression. By using interphase fluorescent in situ hybridization methodology, we analyzed PLCB1 gene, which codifies for the PI-PLC β1 enzyme, in paraffin embedded samples of orbito-frontal cortex of 15 patients affected with major depression and in 15 normal controls. No deletions of PLCB1 were identified with the methodology used, which allows to exclude wide gene deletions. The results, the technical aspects of the FISH methodology, and its limitations are discussed.

  4. Facilitated alkali ion transfer at the water 1,2-dichloroethane interphase Ab-initio calculations concerning alkaline metal cation - 1,10-phenanthroline complexes

    CERN Document Server

    Sánchez, C; Baruzzi, A M; Leiva, E P M

    1997-01-01

    A series of calculations on the energetics of complexation of alkaline metals with 1,10-phenanthroline are presented. It is an experimental fact that the ordering of the free energy of transfer across the water - 1,2-dichloroethane interphase is governed by the charge / size ratio of the diferent cations; the larger cations showing the lower free energy of transfer. This ordering of the free energies of transfer is reverted in the presence of 1,10-phenanthroline in the organic phase. We have devised a thermodynamic cycle for the transfer process and by means of ab-initio calculations have drawn the conclusion that in the presence of phen the free energy of transfer is governed by the stability of the PHEN/M $^{+}$complex, which explains the observed tendency from a theoretical point of view.

  5. Study of the influence of morphology and strength of interphase boundaries on the integral mechanical properties of NiCr-TiC composite

    Science.gov (United States)

    Eremina, Galina M.; Smolin, Alexey Yu.; Shilko, Evgeny V.; Psakhie, Sergey G.

    2016-11-01

    Sintered metal-ceramic materials are characterized by high mechanical and tribological properties. A key element of the internal structure of the metal-ceramic composites which have an important, and in many cases, a decisive influence on the integral mechanical properties of these materials is the interphase boundary. In this paper, based on numerical simulation we show the influence of morphology and strength properties of interfaces for integral mechanical properties of the dispersion-reinforced composite NiCr-TiC (50 : 50). Computer simulation results indicate that the phase boundary significantly contributes to the integral mechanical characteristics of a composite material and to the nature of the initiation and development of cracks.

  6. Potential control of Aedes aegypti (Diptera: Culicidae) with Piper aduncum L. (Piperaceae) extracts demonstrated by chromosomal biomarkers and toxic effects on interphase nuclei.

    Science.gov (United States)

    Rafael, M S; Hereira-Rojas, W J; Roper, J J; Nunomura, S M; Tadei, W P

    2008-01-01

    Dillapiol, a phenylpropanoid isolate from essential oils of leaves of Piper aduncum (Piperaceae), has insecticidal, fungicidal and antimicrobial activities. The insecticidal activity of dillapiol was tested in vivo on the larvae and pupae of Aedes aegypti, the mosquito vector of dengue. Specifically, the effect of dillapiol on the formation of micronuclei and chromosome aberrations was analyzed. Dillapiol treatments comprised two concentrations of 200 and 400 micro dissolved in well water, and a pure well water control used to rear four generations of mosquitoes. Micronuclei occurred in mitotic diploid and tetraploid chromosomes of larvae; nuclear abnormalities also occurred in interphase, metaphase, telophase, and single nucleus cells of pupae. Mortality, oviposition, chromosome breakage, and anaphase bridges were significantly greater in the extract treatments than in controls. The genotoxic effects of dillapiol described here suggest that this natural product may be a useful alternative for the control of A. aegypti.

  7. Detection of the deletion of chromosome 13 and the translocation of immunoglobulin heavy chain gene by interphase fluorescence in situ hybridization in patients with multiple myeloma%荧光原位杂交检测多发性骨髓瘤患者13号染色体缺失和IgH基因易位

    Institute of Scientific and Technical Information of China (English)

    赵文杰; 岑岭

    2011-01-01

    Objective To investigate the relationship of the deletion of the long arm of chromosome 13 [ del( 13q) ] and the translocation of immunoglobulin heavy chain ( IgH) gene [t(14q)]in multiple myeloma ( MM) patients with related clinical factors. Methods The interphase fluorescence in situ hybridization ( FISH) was performed in 25 primarily-diagnosed MM patients to detect del(13q)and t(14q) with probe D13S319 and IgH. Results The positive rates of del ( 13q) and t ( 14q) were 32. 0% and 16. 0% in 25 MM patients. Two patients ( 8. 0% ) had both 2 abnormalities of them. The patients with the 2 abnormalities had higher beta2 -microglobin ( β2 -MG) level and bone marrow plasma cell percentage. Conclusions Interphase FISH is a sensitive method to detect the mutation of MM. The del( 13q) and t( 14q) can be used to predict treatment response and prognosis.%目的 分析多发性骨髓瘤(MM)患者13号染色体长臂缺失[ del(13q)]和免疫球蛋白重链(IgH)基因易位[t(14q)]与临床相关因素的关系.方法 采用间期荧光原位杂交(FISH)技术对25例初诊MM患者应用探针D13S319、IgH分别进行del(13q)和t(14q)的检测.结果 25例患者中del( 13 q)8例(32.0%)、IgH易位4例(16.0%),同时存在上述2种异常2例(8.0%).伴del( 13 q)及IgH易位的患者具有较高的血清B2-微球蛋白(β2-MG)水平及较高的骨髓浆细胞百分比.结论 间期FISH是一种检测MM患者骨髓瘤细胞突变的敏感方法,具有临床应用价值.del(13q)、t(14q)对判断临床疗效和预后具有指导作用.

  8. DISTANCE ESTIMATION TO THE INTERPHASE-FAULT LOCATION IN THE DISTRIBUTIVE AIR-LINE GRIDS BASED ON ANALYSIS OF THE HARMONIC COMPONENT PARAMETERS OF THE OPERATING EMERGENCY CONDITIONS

    Directory of Open Access Journals (Sweden)

    E. V. Kalentionok

    2015-01-01

    Full Text Available Most techniques of the fault location based on the one-side measurement of the emergency mode characteristics use the short-circuit steady-regime parameters in the fundamental mode frequency. This approach compels to seek additional devices for tuning out the loadings of transformer-substations. Besides, it is susceptible to the nonlinearity effect of closed-circuit arc in the fault location which significantly reduces the accuracy of the remote location of the failure.For estimating the distance to the location of interphase failure on the aerial distributive transmission lines the article proposes a new technique employing the harmonic components of the operating emergency parameters. The algorithm of the present method realization includes: taking down oscillograms of the emergency-mode parameter values (e. g. in doublephase failure – the short-circuit current, the linear voltage between the faulty phases with necessary discretization interval; expansion of the operating emergency parameters in a Fourier series (realized with a quick Fourier expansion algorithm; estimating the distance to the fault location by the analytical expression; performing the statistical analysis of a row of distance values and finding the most probable distance to the fault location.For effectiveness investigation of the proposed method of trapping harmonic components the paper considers a 10 kV distributive electrical grid feeding nine transformer substations. The authors performed calculation of normal and emergency modes utilizing computer program MatLab in dynamic simulating environment Simulink. The arc is represented by a block describing the linearized dynamic volt-ampere characteristic of the arc. The built characteristic curves demonstrate dependence of the fault-location distance value from the frequency at which this value is obtained and the number if its reiterations. Based on the calculations, the authors establish that the accuracy of the distance

  9. Next-generation repeat-free FISH probes for DNA amplification in glioblastoma in vivo: Improving patient selection to MDM2-targeted inhibitors.

    Science.gov (United States)

    Brunelli, Matteo; Eccher, Albino; Cima, Luca; Trippini, Tobia; Pedron, Serena; Chilosi, Marco; Barbareschi, Mattia; Scarpa, Aldo; Pinna, Giampietro; Cabrini, Giulio; Pilotto, Sara; Carbognin, Luisa; Bria, Emilio; Tortora, Giampaolo; Fioravanzo, Adele; Schiavo, Nicola; Meglio, Mario; Sava, Teodoro; Belli, Laura; Martignoni, Guido; Ghimenton, Claudio

    2017-01-01

    A next-generation FISH probe mapping to the MDM2 locus-specific region has recently been designed. The level of MDM2 gene amplification (high versus low) may allow selection of patients for cancer treatment with MDM2 inhibitors and may predict their responsiveness. We investigated the spectrum of MDM2 gene alterations using the new probes in vivo after visualizing single neoplastic cells in situ from a series of glioblastomas. Signals from next-generation repeat-free FISH interphase probes were identified in tissue microarrays that included 3 spots for each of the 48 cases. The murine double minutes (MDM2)-specific DNA probe and the satellite enumeration probe for chromosome 12 were used. Three cases (6%) showed more than 25 signals (high gene amplification), and 7 (15%) showed 3-10 signals (gains); among these, 4 cases (8%) had an equal number of MDM2 and centromeric signals on chromosome 12 (polyploidy). Genomic heterogeneity was observed only in 3 cases with low gene amplification. In our series, 6% of glioblastomas exhibited high MDM2 amplification (in vivo) with a pattern related to the known double minutes/chromothripsis phenomenon (in situ), and only cases with low amplification showed genomic heterogeneity. We concluded that the rate of MDM2 gene amplification can be a useful predictive biomarker to improve patient selection.

  10. In-situ Mass Spectrometric Determination of Molecular Structural Evolution at the Solid Electrolyte Interphase in Lithium-Ion Batteries

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Zihua; Zhou, Yufan; Yan, Pengfei; Vemuri, Venkata Rama Ses; Xu, Wu; Zhao, Rui; Wang, Xuelin; Thevuthasan, Suntharampillai; Baer, Donald R.; Wang, Chong M.

    2015-08-19

    Dynamic molecular evolution at solid/liquid electrolyte interface is always a mystery for a rechargeable battery due to the challenge to directly probe/observe the solid/liquid interface under reaction conditions, which in essence appears to be similarly true for all the fields involving solid/liquid phases, such as electrocatalysis, electrodeposition, biofuel conversion, biofilm, and biomineralization, We use in-situ liquid secondary ion mass spectroscopy (SIMS) for the first time to directly observe the molecular structural evolution at the solid electrode/liquid electrolyte interface for a lithium (Li)-ion battery under dynamic operating conditions. We have discovered that the deposition of Li metal on copper electrode leads to the condensation of solvent molecules around the electrode. Chemically, this layer of solvent condensate tends to deplete the salt anion and with low concentration of Li+ ions, which essentially leads to the formation of a lean electrolyte layer adjacent to the electrode and therefore contributes to the overpotential of the cell. This unprecedented molecular level dynamic observation at the solid electrode/liquid electrolyte interface provides vital chemical information that is needed for designing of better battery chemistry for enhanced performance, and ultimately opens new avenues for using liquid SIMS to probe molecular evolution at solid/liquid interface in general.

  11. 几种植物生殖细胞质膜表面的凝集素受体荧光标记%Probing Lectin Receptors on the Plasma Membrane of Isolated Viable Generative Cells in Angiosperms by Means of Single Cell Manipulation

    Institute of Scientific and Technical Information of China (English)

    房克凤; 孙蒙祥; 周嫦

    2003-01-01

    为进一步探讨从生殖细胞到精子的发育过程中细胞质膜表面凝集素受体的可能变化,及其与两类对凝集素标记有不同结果的精子的关系,用异硫氰酸荧光素标记的伴刀豆凝集素(Con A)、麦芽凝集素(WGA)和大豆凝集素(SBA)对蚕豆(Vicia faba L.)、鸢尾(Iris tectorium Maxim.)和朱顶红(Hippeastrum vittatum Herb.)的生殖细胞质膜表面的凝集素受体进行标记.结果显示:在不同植物中均有部分生殖细胞不能被凝集素探针标记,且在保持尾状形态的生殖细胞的表面发现有凝集素受体的极性分布.这可能是导致部分精子表面不能被同种凝集素标记的重要原因.此外,同一种凝集素受体在不同物种的生殖细胞上分布不一致,不同的凝集素受体在同一种植物的生殖细胞上的分布模式亦有不同.在蚕豆和鸢尾的生殖细胞表面均有这三种凝集素的受体.在朱顶红生殖细胞的表面有前两种凝集素的受体,分布比较均一,但是没有大豆凝集素的受体.此外,在具尾生殖细胞表面发现有凝集素受体极性分布的现象,为探讨精细胞功能及其表面糖蛋白分布的可能差异提供了重要启示.%Fluorescein isothiocyanate (FITC) conjugated concanavalin agglutinin (Con A), wheat germ agglutinin (WGA) and soybean agglutinin (SBA) were used as probes to localize their specific receptors on the plasma membrane of generative cells (GCs) isolated from Vicia faba L., Iris tectorium Maxim. and Hippeastrum vittatum Herb. It is a further investigation on possible distributive dynamic of lectin receptors during the developmental process from generative cells to sperm cells. In the present study, all the three lectin receptors were found on the surface of generative cells of V. faba and l. tectorium. However, on generative cells of H. vittaturn only Con A and WGA, but not SBA receptors were observed. The same lectin receptors on the generative cells from different species

  12. The Antartic Ice Borehole Probe

    Science.gov (United States)

    Behar, A.; Carsey, F.; Lane, A.; Engelhardt, H.

    2000-01-01

    The Antartic Ice Borehole Probe mission is a glaciological investigation, scheduled for November 2000-2001, that will place a probe in a hot-water drilled hole in the West Antartic ice sheet. The objectives of the probe are to observe ice-bed interactions with a downward looking camera, and ice inclusions and structure, including hypothesized ice accretion, with a side-looking camera.

  13. Lipid-Bilayer Dynamics Probed by a Carbon Dot-Phospholipid Conjugate.

    Science.gov (United States)

    Nandi, Sukhendu; Malishev, Ravit; Bhunia, Susanta Kumar; Kolusheva, Sofiya; Jopp, Jürgen; Jelinek, Raz

    2016-05-10

    Elucidating the dynamic properties of membranes is important for understanding fundamental cellular processes and for shedding light on the interactions of proteins, drugs, and viruses with the cell surface. Dynamic studies of lipid bilayers have been constrained, however, by the relatively small number of pertinent molecular probes and the limited physicochemical properties of the probes. We show that a lipid conjugate comprised of a fluorescent carbon dot (C-dot) covalently attached to a phospholipid constitutes a versatile and effective vehicle for studying bilayer dynamics. The C-dot-modified phospholipids readily incorporated within biomimetic membranes, including solid-supported bilayers and small and giant vesicles, and inserted into actual cellular membranes. We employed the C-dot-phospholipid probe to elucidate the effects of polymyxin-B (a cytolytic peptide), valproic acid (a lipophilic drug), and amyloid-β (a peptide associated with Alzheimer's disease) upon bilayer fluidity and lipid dynamics through the application of various biophysical techniques.

  14. Sheet Membrane Spacesuit Water Membrane Evaporator

    Science.gov (United States)

    Bue, Grant; Trevino, Luis; Zapata, Felipe; Dillion, Paul; Castillo, Juan; Vonau, Walter; Wilkes, Robert; Vogel, Matthew; Frodge, Curtis

    2013-01-01

    A document describes a sheet membrane spacesuit water membrane evaporator (SWME), which allows for the use of one common water tank that can supply cooling water to the astronaut and to the evaporator. Test data showed that heat rejection performance dropped only 6 percent after being subjected to highly contaminated water. It also exhibited robustness with respect to freezing and Martian atmospheric simulation testing. Water was allowed to freeze in the water channels during testing that simulated a water loop failure and vapor backpressure valve failure. Upon closing the backpressure valve and energizing the pump, the ice eventually thawed and water began to flow with no apparent damage to the sheet membrane. The membrane evaporator also serves to de-gas the water loop from entrained gases, thereby eliminating the need for special degassing equipment such as is needed by the current spacesuit system. As water flows through the three annular water channels, water evaporates with the vapor flowing across the hydrophobic, porous sheet membrane to the vacuum side of the membrane. The rate at which water evaporates, and therefore, the rate at which the flowing water is cooled, is a function of the difference between the water saturation pressure on the water side of the membrane, and the pressure on the vacuum side of the membrane. The primary theory is that the hydrophobic sheet membrane retains water, but permits vapor pass-through when the vapor side pressure is less than the water saturation pressure. This results in evaporative cooling of the remaining water.

  15. Probing Cellular Dynamics with Mesoscopic Simulations

    DEFF Research Database (Denmark)

    Shillcock, Julian C.

    2010-01-01

    Cellular processes span a huge range of length and time scales from the molecular to the near-macroscopic. Understanding how effects on one scale influence, and are themselves influenced by, those on lower and higher scales is a critical issue for the construction of models in Systems Biology....... Advances in computing hardware and software now allow explicit simulation of some aspects of cellular dynamics close to the molecular scale. Vesicle fusion is one example of such a process. Experiments, however, typically probe cellular behavior from the molecular scale up to microns. Standard particle...... soon be coupled to Mass Action models allowing the parameters in such models to be continuously tuned according to the finer resolution simulation. This will help realize the goal of a computational cellular simulation that is able to capture the dynamics of membrane-associated processes...

  16. Micro scanning probes

    CERN Document Server

    Niblock, T

    2001-01-01

    This thesis covers the design methodology, theory, modelling, fabrication and evaluation of a Micro-Scanning-Probe. The device is a thermally actuated bimorph quadrapod fabricated using Micro Electro Mechanical Systems technology. A quadrapod is a structure with four arms, in this case a planar structure with the four arms forming a cross which is dry etched out of a silicon diaphragm. Each arm has a layer of aluminium deposited on it forming a bimorph. Through heating each arm actuation is achieved in the plane of the quadrapod and the direction normal to it. Fabrication of the device has required the development of bulk micromachining techniques to handle post CMOS fabricated wafers and the patterning of thickly sputtered aluminium in bulk micro machined cavities. CMOS fabrication techniques were used to incorporate diodes onto the quadrapod arms for temperature measurement of the arms. Fine tungsten and silicon tips have also been fabricated to allow tunnelling between the tip and the platform at the centr...

  17. Cosmological Probes for Supersymmetry

    Directory of Open Access Journals (Sweden)

    Maxim Khlopov

    2015-05-01

    Full Text Available The multi-parameter character of supersymmetric dark-matter models implies the combination of their experimental studies with astrophysical and cosmological probes. The physics of the early Universe provides nontrivial effects of non-equilibrium particles and primordial cosmological structures. Primordial black holes (PBHs are a profound signature of such structures that may arise as a cosmological consequence of supersymmetric (SUSY models. SUSY-based mechanisms of baryosynthesis can lead to the possibility of antimatter domains in a baryon asymmetric Universe. In the context of cosmoparticle physics, which studies the fundamental relationship of the micro- and macro-worlds, the development of SUSY illustrates the main principles of this approach, as the physical basis of the modern cosmology provides cross-disciplinary tests in physical and astronomical studies.

  18. Cosmological Probes for Supersymmetry

    CERN Document Server

    Khlopov, Maxim

    2015-01-01

    The multi-parameter character of supersymmetric dark-matter models implies the combination of their experimental studies with astrophysical and cosmological probes. The physics of the early Universe provides nontrivial effects of non-equilibrium particles and primordial cosmological structures. Primordial black holes (PBHs) are a profound signature of such structures that may arise as a cosmological consequence of supersymmetric (SUSY) models. SUSY-based mechanisms of baryosynthesis can lead to the possibility of antimatter domains in a baryon asymmetric Universe. In the context of cosmoparticle physics, which studies the fundamental relationship of the micro- and macro-worlds, the development of SUSY illustrates the main principles of this approach, as the physical basis of the modern cosmology provides cross-disciplinary tests in physical and astronomical studies.

  19. Spontaneous Symmetry Probing

    CERN Document Server

    Nicolis, Alberto

    2011-01-01

    For relativistic quantum field theories, we consider Lorentz breaking, spatially homogeneous field configurations or states that evolve in time along a symmetry direction. We dub this situation "spontaneous symmetry probing" (SSP). We mainly focus on internal symmetries, i.e. on symmetries that commute with the Poincare group. We prove that the fluctuations around SSP states have a Lagrangian that is explicitly time independent, and we provide the field space parameterization that makes this manifest. We show that there is always a gapless Goldstone excitation that perturbs the system in the direction of motion in field space. Perhaps more interestingly, we show that if such a direction is part of a non-Abelian group of symmetries, the Goldstone bosons associated with spontaneously broken generators that do not commute with the SSP one acquire a gap, proportional to the SSP state's "speed". We outline possible applications of this formalism to inflationary cosmology.

  20. New probe of naturalness.

    Science.gov (United States)

    Craig, Nathaniel; Englert, Christoph; McCullough, Matthew

    2013-09-20

    Any new scalar fields that perturbatively solve the hierarchy problem by stabilizing the Higgs boson mass also generate new contributions to the Higgs boson field-strength renormalization, irrespective of their gauge representation. These new contributions are physical, and in explicit models their magnitude can be inferred from the requirement of quadratic divergence cancellation; hence, they are directly related to the resolution of the hierarchy problem. Upon canonically normalizing the Higgs field, these new contributions lead to modifications of Higgs couplings that are typically great enough that the hierarchy problem and the concept of electroweak naturalness can be probed thoroughly within a precision Higgs boson program. Specifically, at a lepton collider this can be achieved through precision measurements of the Higgs boson associated production cross section. This would lead to indirect constraints on perturbative solutions to the hierarchy problem in the broadest sense, even if the relevant new fields are gauge singlets.

  1. Advanced Langmuir Probe (LP)

    Science.gov (United States)

    Voronka, N. R.; Block, B. P.; Carignan, G. R.

    1991-01-01

    The dynamic response of the MK-2 version of the Langmuir probe amplifier was studied. The settling time of the step response is increased by: (1) stray node-to-ground capacitance at series connections between high value feedback resistors; and (2) input capacitance due to the input cable, FET switches, and input source follower. The stray node-to-ground capacitances can be reduced to tolerable levels by elevating the string of feedback resistors above the printing board. A new feedback network was considered, with promising results. The design uses resistances having much lower nominal values, thereby minimizing the effect of stray capacitances. Faster settling times can be achieved by using an operational amplifier having a higher gain-bandwidth product.

  2. The detection of HBV DNA with gold nanoparticle gene probes

    Institute of Scientific and Technical Information of China (English)

    Dong Xi; Xiaoping Luo; Qin Ning; Qianghua Lu; Kailun Yao; Zuli Liu

    2007-01-01

    Objective:Gold nanoparticle Hepatitis B virus (HBV) DNA probes were prepared, and their application for HBV DNA measurement was studied. Methods:Alkanethiol modified oligonucleotide was bound with self-made Au nanoparticles to form nanoparticle HBV DNA gene probes, through covalent binding of Au-S. By using a fluorescence-based method, the number of thiol-derivatized, single-stranded oligonucleotides and their hybridization efficiency with complementary oligonucleotides in solution was determined. With the aid of Au nanoparticle-supported mercapto-modified oligonucleotides serving as detection probes, and oligonucleotides immobilized on a nylon membrane surface acting as capturing probes,HBV DNA was detected visually by sandwich hybridization based on highly sensitive aggregation and silver staining. The modified nanoparticle HBV DNA gene probes were also used to detect the HBV DNA extracted from serum in patients with hepatitis B. Results:Compared with bare Au nanoparticles, oligonucleotide modified nanoparticles had a higher stability in NaCl solution or under high temperature environment and the absorbance peak of modified Au nanoparticles shifted from 520nm to 524nm. For Au nanoparticles, the maximal oligonucleotide surface coverage of hexaethiol 30-mer oligonucleotide was (132 ± 10) oligonucleotides per nanoparticle, and the percentage of hybridization strands on nanoparticles was (22 ± 3% ). Based on a two-probe sandwich hybridization/nanoparticle amplification/silver staining enhancement method, Au nanoparticle gene probes could detect as low as 10-11 mol/L composite HBV DNA molecules on a nylon membrane and the PCR products of HBV DNA visually. As made evident by transmission electron microscopy, the nanoparticles assembled into large network aggregates when nanoparticle HBV DNA gene probes were applied to detect HBV DNA molecules in liquid. Conclusion:Our results showed that successfully prepared Au nanoparticle HBV DNA gene probes could be used to

  3. Detection of molecular interactions at membrane surfaces through colloid phase transitions

    Science.gov (United States)

    Baksh, Michael M.; Jaros, Michal; Groves, Jay T.

    2004-01-01

    The molecular architecture of-and biochemical processes within-cell membranes play important roles in all living organisms, with many drugs and infectious disease agents targeting membranes. Experimental studies of biochemical reactions on membrane surfaces are challenging, as they require a membrane environment that is fluid (like cell membranes) but nevertheless allows for the efficient detection and characterization of molecular interactions. One approach uses lipid membranes supported on solid substrates such as silica or polymers: although the membrane is trapped near the solid interface, it retains natural fluidity and biological functionality and can be implanted with membrane proteins for functional studies. But the detection of molecular interactions involving membrane-bound species generally requires elaborate techniques, such as surface plasmon resonance or total internal reflection fluorescence microscopy. Here we demonstrate that colloidal phase transitions of membrane-coated silica beads provide a simple and label-free method for monitoring molecular interactions on lipid membrane surfaces. By adjusting the lipid membrane composition and hence the pair interaction potential between the membrane-supporting silica beads, we poise our system near a phase transition so that small perturbations on the membrane surface induce dramatic changes in the macroscopic organization of the colloid. We expect that this approach, used here to probe with high sensitivity protein binding events at membrane surfaces, can be applied to study a broad range of cell membrane processes.

  4. Membrane Automata with Priorities

    Institute of Scientific and Technical Information of China (English)

    Luděk Cienciala; Lucie Ciencialová

    2004-01-01

    In this paper the one-way P automata with priorities are introduced. Such automata are P systemshere the membranes are only allowed to consume objects from parent membranes, under the given conditions. The result of computation of these systems is the set of multiset sequences consumed by skin membrane intc the system. The rules associated in some order with each membrane cannot modify any objects, they can only move them through membrane. We show that P automata with priorities and two membranes can accept every recursively enumerated language.

  5. Cellular Precipitation at a 17-7 PH Stainless Steel Interphase Interface During Low-Temperature Nitridation

    Science.gov (United States)

    Wang, Danqi; Ernst, Frank; Kahn, Harold; Heuer, Arthur H.

    2014-07-01

    Cellular precipitation of Cr-rich nitrides was observed at an austenite-ferrite interface in 17-7 PH stainless steel after low-temperature nitridation. Fine-scale lamellar rocksalt-structured nitride (MN1- x , M: randomly distributed Fe, Cr, and Al) was identified at the interfaces between austenite and ferrite by local-electrode atom-probe tomography and transmission electron microscopy. The small size and spacing of the nitride lamellae reflect the low mobility of substitutional atoms under the conditions of low-temperature nitridation. Nitrides of the same structure were formed within the ferrite grain as extremely small particles. The face-centered cubic nitride precipitates in the Bain orientation relationship with the ferrite.

  6. Membrane-Protein Crystallography and Potentiality for Drug Design

    Science.gov (United States)

    Yamashita, Atsuko

    Structure-based drug design for membrane proteins is far behind that for soluble proteins due to difficulty in crystallographic structure determination, despite the fact that about 60% of FDA-approved drugs target membrane proteins located at the cell surface. Stable homologs for a membrane protein of interest, such as prokaryotic neurotransmitter transporter homolog LeuT, might enable cooperative analyses by crystallography and functional assays, provide useful information for functional mechanisms, and thus serve as important probes for drug design based on mechanisms as well as structures.

  7. Graphene as a prototype crystalline membrane.

    Science.gov (United States)

    Katsnelson, Mikhail I; Fasolino, Annalisa

    2013-01-15

    The understanding of the structural and thermal properties of membranes, low-dimensional flexible systems in a space of higher dimension, is pursued in many fields from string theory to chemistry and biology. The case of a two-dimensional (2D) membrane in three dimensions is the relevant one for dealing with real materials. Traditionally, membranes are primarily discussed in the context of biological membranes and soft matter in general. The complexity of these systems hindered a realistic description of their interatomic structures based on a truly microscopic approach. Therefore, theories of membranes were developed mostly within phenomenological models. From the point of view of statistical mechanics, membranes at finite temperature are systems governed by interacting long-range fluctuations. Graphene, the first truly two-dimensional system consisting of just one layer of carbon atoms, provides a model system for the development of a microscopic description of membranes. In the same way that geneticists have used Drosophila as a gateway to probe more complex questions, theoretical chemists and physicists can use graphene as a simple model membrane to study both phenomenological theories and experiments. In this Account, we review key results in the microscopic theory of structural and thermal properties of graphene and compare them with the predictions of phenomenological theories. The two approaches are in good agreement for the various scaling properties of correlation functions of atomic displacements. However, some other properties, such as the temperature dependence of the bending rigidity, cannot be understood based on phenomenological approaches. We also consider graphene at very high temperature and compare the results with existing models for two-dimensional melting. The melting of graphene presents a different scenario, and we describe that process as the decomposition of the graphene layer into entangled carbon chains.

  8. Coexistence of probe conformations in lipid phases-a polarized fluorescence microspectroscopy study.

    Science.gov (United States)

    Urbančič, Iztok; Ljubetič, Ajasja; Arsov, Zoran; Strancar, Janez

    2013-08-20

    Several well-established fluorescence methods depend on environment-sensitive probes that report about molecular properties of their local environment. For reliable interpretation of experiments, careful characterization of probes' behavior is required. In this study, bleaching-corrected polarized fluorescence microspectroscopy with nanometer spectral peak position resolution was applied to characterize conformations of two alkyl chain-labeled 7-nitro-2-1,3-benzoxadiazol-4-yl phospholipids in three model membranes, representing the three main lipid phases. The combination of polarized and spectral detection revealed two main probe conformations with their preferential fluorophore dipole orientations roughly parallel and perpendicular to membrane normal. Their peak positions were separated by 2-6 nm because of different local polarities and depended on lipid environment. The relative populations of conformations, estimated by a numerical model, indicated a specific sensitivity of the two probes to molecular packing with cholesterol. The coexistence of probe conformations could be further exploited to investigate membrane organization below microscopy spatial resolution, such as lipid rafts. With the addition of polarized excitation or detection to any environment-sensitive fluorescence imaging technique, the conformational analysis can be directly applied to explore local membrane complexity.

  9. Transport properties of zeolite Na-X-Nafion membranes: effect of zeolite loadings and particle size

    Energy Technology Data Exchange (ETDEWEB)

    Lavorgna, M. [Institute of Composite and Biomedical Materials, National Research Council, Portici (Italy); Sansone, L.; Scherillo, G. [Department of Materials and Production, University of Napoli Federico II, Napoli (Italy); Gu, R.; Baker, A.P. [Department of Materials Science and Engineering, HIT Graduate School, Xili, Shenzhen (China)

    2011-12-15

    Na-X zeolites particles, synthesized in two size ranges, namely 200-300 nm and 30-100 nm, were used to prepare Nafion/Na-X zeolite composite membranes by recast method. The physical, chemical, and morphological properties of the zeolite powders and composite membranes were examined by XRD, N{sub 2} adsorption isotherms, FTIR, SEM, and SAXS analysis. Furthermore, the effect of zeolite particles size and loadings (i.e., 5 and 10% w/w) on the water, methanol, and proton transport properties was investigated. It has been found that the size of the Na-X zeolite particles plays a key role in the proton and methanol transport behavior since it rules the zeolite hydrophilic behavior, the morphology of polymer-filler interphase, and also the nature of water established in the composite membrane. The results show that the membranes loaded with a 5% w/w of submicron-sized Na-X zeolite exhibit a proton conductivity and selectivity significantly higher than Nafion. In particular the proton conductivity at 120 C is around eight times and the selectivity at 25 C is around 40% higher than those exhibited by recast Nafion. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  10. Non-inductive current probe

    DEFF Research Database (Denmark)

    Bak, Christen Kjeldahl

    1977-01-01

    The current probe described is a low-cost, shunt resistor for monitoring current pulses in e.g., pulsed lasers. Rise time is......The current probe described is a low-cost, shunt resistor for monitoring current pulses in e.g., pulsed lasers. Rise time is...

  11. Fluorogenic probes reveal a role of GLUT4 N-glycosylation in intracellular trafficking.

    Science.gov (United States)

    Hirayama, Shinya; Hori, Yuichiro; Benedek, Zsolt; Suzuki, Tadashi; Kikuchi, Kazuya

    2016-10-01

    Glucose transporter 4 (GLUT4) is an N-glycosylated protein that maintains glucose homeostasis by regulating the protein translocation. To date, it has been unclear whether the N-glycan of GLUT4 contributes to its intracellular trafficking. Here, to clarify the role of the N-glycan, we developed fluorogenic probes that label cytoplasmic and plasma-membrane proteins for multicolor imaging of GLUT4 translocation. One of the probes, which is cell impermeant, selectively detected exocytosed GLUT4. Using this probe, we verified the 'log' of the trafficking, in which N-glycan-deficient GLUT4 was transiently translocated to the cell membrane upon insulin stimulation and was rapidly internalized without retention on the cell membrane. The results strongly suggest that the N-glycan functions in the retention of GLUT4 on the cell membrane. This study showed the utility of the fluorogenic probes and indicated that this imaging tool will be applicable for research on various membrane proteins that show dynamic changes in localization.

  12. Lateral mobility of plasma membrane lipids in dividing Xenopus eggs

    NARCIS (Netherlands)

    Laat, S.W. de; Tetteroo, P.A.T.; Bluemink, J.G.; Dictus, W.J.A.G.; Zoelen, E.J.J. van

    1984-01-01

    The lateral mobility of plasma membrane lipids was analyzed during first cleavage of Xaopus Levis eggs by fluorescence photobleaching recovery (FPR) measurements, using the lipid analogs 5-(N-hexadecanoyl)aminofluorescein (“HEDAF”) and 5-(N-tetradecanoyl)aminofluorescein (“TEDAF”) as probes. The pre

  13. Desipramine induces disorder in cholesterol-rich membranes

    DEFF Research Database (Denmark)

    Pakkanen, Kirsi; Salonen, Emppu; Mäkelä, Anna R

    2009-01-01

    canine parvovirus (CPV), a virus known to interact with endosomal membranes and sphingomyelin, as an intracellular probe. DMI was found to cause retention of the virus in intracellular vesicular structures leading to the inhibition of viral proliferation. This implies that DMI has a deleterious effect...

  14. Lateral mobility of plasma membrane lipids in dividing Xenopus eggs

    NARCIS (Netherlands)

    Laat, S.W. de; Tetteroo, P.A.T.; Bluemink, J.G.; Dictus, W.J.A.G.; Zoelen, E.J.J. van

    1984-01-01

    The lateral mobility of plasma membrane lipids was analyzed during first cleavage of Xaopus Levis eggs by fluorescence photobleaching recovery (FPR) measurements, using the lipid analogs 5-(N-hexadecanoyl)aminofluorescein (“HEDAF”) and 5-(N-tetradecanoyl)aminofluorescein (“TEDAF”) as probes. The

  15. Bioorthogonal probes for imaging sterols in cells.

    Science.gov (United States)

    Jao, Cindy Y; Nedelcu, Daniel; Lopez, Lyle V; Samarakoon, Thilani N; Welti, Ruth; Salic, Adrian

    2015-03-01

    Cholesterol is a fundamental lipid component of eukaryotic membranes and a precursor of potent signaling molecules, such as oxysterols and steroid hormones. Cholesterol and oxysterols are also essential for Hedgehog signaling, a pathway critical in embryogenesis and cancer. Despite their importance, the use of imaging sterols in cells is currently very limited. We introduce a robust and versatile method for sterol microscopy based on C19 alkyne cholesterol and oxysterol analogues. These sterol analogues are fully functional; they rescue growth of cholesterol auxotrophic cells and faithfully recapitulate the multiple roles that sterols play in Hedgehog signal transduction. Alkyne sterol analogues incorporate efficiently into cellular membranes and can be imaged with high resolution after copper(I)-catalyzed azide-alkyne cycloaddition reaction with fluorescent azides. We demonstrate the use of alkyne sterol probes for visualizing the subcellular distribution of cholesterol and for two-color imaging of sterols and choline phospholipids. Our imaging strategy should be broadly applicable to studying the role of sterols in normal physiology and disease.

  16. Red emitting neutral fluorescent glycoconjugates for membrane optical imaging.

    Science.gov (United States)

    Redon, Sébastien; Massin, Julien; Pouvreau, Sandrine; De Meulenaere, Evelien; Clays, Koen; Queneau, Yves; Andraud, Chantal; Girard-Egrot, Agnès; Bretonnière, Yann; Chambert, Stéphane

    2014-04-16

    A family of neutral fluorescent probes was developed, mimicking the overall structure of natural glycolipids in order to optimize their membrane affinity. Nonreducing commercially available di- or trisaccharidic structures were connected to a push-pull chromophore based on dicyanoisophorone electron-accepting group, which proved to fluoresce in the red region with a very large Stokes shift. This straightforward synthetic strategy brought structural variations to a series of probes, which were studied for their optical, biophysical, and biological properties. The insertion properties of the different probes into membranes were evaluated on a model system using the Langmuir monolayer balance technique. Confocal fluorescence microscopy performed on muscle cells showed completely different localizations and loading efficiencies depending on the structure of the probes. When compared to the commercially available ANEPPS, a family of commonly used membrane imaging dyes, the most efficient probes showed a similar brightness, but a sharper pattern was observed. According to this study, compounds bearing one chromophore, a limited size of the carbohydrate moiety, and an overall rod-like shape gave the best results.

  17. Cobra Probes Containing Replaceable Thermocouples

    Science.gov (United States)

    Jones, John; Redding, Adam

    2007-01-01

    A modification of the basic design of cobra probes provides for relatively easy replacement of broken thermocouples. Cobra probes are standard tube-type pressure probes that may also contain thermocouples and that are routinely used in wind tunnels and aeronautical hardware. They are so named because in side views, they resemble a cobra poised to attack. Heretofore, there has been no easy way to replace a broken thermocouple in a cobra probe: instead, it has been necessary to break the probe apart and then rebuild it, typically at a cost between $2,000 and $4,000 (2004 prices). The modified design makes it possible to replace the thermocouple, in minimal time and at relatively low cost, by inserting new thermocouple wire in a tube.

  18. Nanobits: customizable scanning probe tips

    DEFF Research Database (Denmark)

    Kumar, Rajendra; Shaik, Hassan Uddin; Sardan Sukas, Özlem

    2009-01-01

    silicon processing. Using a microgripper they were detached from an array and fixed to a standard pyramidal AFM probe or alternatively inserted into a tipless cantilever equipped with a narrow slit. The nanobit-enhanced probes were used for imaging of deep trenches, without visible deformation, wear......We present here a proof-of-principle study of scanning probe tips defined by planar nanolithography and integrated with AFM probes using nanomanipulation. The so-called 'nanobits' are 2-4 mu m long and 120-150 nm thin flakes of Si3N4 or SiO2, fabricated by electron beam lithography and standard...... or dislocation of the tips of the nanobit after several scans. This approach allows an unprecedented freedom in adapting the shape and size of scanning probe tips to the surface topology or to the specific application....

  19. Wearable probes for service design

    DEFF Research Database (Denmark)

    Mullane, Aaron; Laaksolahti, Jarmo Matti; Svanæs, Dag

    2014-01-01

    by service employees in reflecting on the delivery of a service. In this paper, we present the ‘wearable probe’, a probe concept that captures sensor data without distracting service employees. Data captured by the probe can be used by the service employees to reflect and co-reflect on the service journey......Probes are used as a design method in user-centred design to allow end-users to inform design by collecting data from their lives. Probes are potentially useful in service innovation, but current probing methods require users to interrupt their activity and are consequently not ideal for use......, helping to identify opportunities for service evolution and innovation....

  20. Electrophoresis-mass spectrometry probe

    Science.gov (United States)

    Andresen, Brian D.; Fought, Eric R.

    1987-01-01

    The invention involves a new technique for the separation of complex mixtures of chemicals, which utilizes a unique interface probe for conventional mass spectrometers which allows the electrophoretically separated compounds to be analyzed in real-time by a mass spectrometer. This new chemical analysis interface, which couples electrophoresis with mass spectrometry, allows complex mixtures to be analyzed very rapidly, with much greater specificity, and with greater sensitivity. The interface or probe provides a means whereby large and/or polar molecules in complex mixtures to be completely characterized. The preferred embodiment of the probe utilizes a double capillary tip which allows the probe tip to be continually wetted by the buffer, which provides for increased heat dissipation, and results in a continually operating interface which is more durable and electronically stable than the illustrated single capillary tip probe interface.