Fusion Conditions Research Articles

Design and synthesis of new potential ligands of μ- and δ-opiate receptors in the series of decahydro-4a-hydroxy-6-isoquinolone

A new approach has been proposed for simplification of the morphine molecule in order to obtain new potential μ- and δ-opiate receptor ligands. The reaction of 1,2,5-trimethyl-4-piperidone and 2,2-di-methyl-4-tetrahydropyrone with substituted benzalacetones under Robinson ring fusion conditions gave decahydroisoquinoline and decahydroisochromene derivatives. A thorough conformational analysis of these products was carried out. The effect of the products on the functional activity of opiate receptors on the mouse vas deferens isolated organ (MVD) model was studied. Prior screening showed that 8-(p-dimethylaminophenyl)-4a-hydroxy-2,3,8a-trimethyldecahydro-6-isoquinolone displays opiate activity and has agonist properties.

Hole Boring in a DT Pellet and Fast-Ion Ignition with Ultraintense Laser Pulses

Recently achieved high intensities of short laser pulses open new prospects in their application to hole boring in inhomogeneous overdense plasmas and for ignition in precompressed DT fusion targets. A simple analytical model and numerical simulations demonstrate that pulses with intensities exceeding 10;{22} W/cm;{2} may penetrate deeply into the plasma as a result of efficient ponderomotive acceleration of ions in the forward direction. The penetration depth as big as hundreds of microns depends on the laser fluence, which has to exceed a few tens of GJ/cm;{2}. The fast ions, accelerated at the bottom of the channel with an efficiency of more than 20%, show a high directionality and may heat the precompressed target core to fusion conditions.

Glycosidase-induced fusion of isoprenoid gentiobiosyl lipid membranes at acidic pH

A difficulty in explaining the mechanism whereby archaeal lipid membrane vesicles (archaeosomes) deliver entrapped protein antigens to the MHC class I cytosolic pathway from phagolysosomes of antigen-presenting cells has been the observation that they tend not to fuse. Here, we determine that archaeosomes, composed of archaeal isoprenoid mixtures of glyco and phospholipids, can be highly fusogenic when exposed to the pH and enzymes found in late phagolysosomes. Fusions were strictly dependent on acidic pH and the presence of alpha- or beta-glucosidase. Resonance energy transfer (RET) assays demonstrated that fusion conditions induced lipid mixing of archaeosome lipids with self-unlabeled archaeosomes. Because PC/PG/cholesterol liposomes by themselves did not fuse, it was possible to unequivocally show a fusion of rhodamine-labeled liposomes with archaeosomes by fluorescence microscopy and to demonstrate lipid mixing between labeled liposomes and archaeosomes by the RET assay. Radiotracer and (1)H NMR studies revealed that glycolipids in fused archaeosomes were not degraded significantly by glucosidase treatment during fusion. Rather, the glucosidases dramatically induced small archaeosomes to rapidly and visually aggregate at pH 4.8, but not 6.8, thus bringing membranes together appropriately as a first step in the fusion process. (1)H NMR was used to demonstrate that conditions causing aggregation correlated with binding of glucosidase to the archaeosomes. Binding at acidic pH occurred by the electrostatic interaction of positively charged glucosidase with the anionic phospholipids, although the interaction also occurred with the gentiobiosyl lipids. The data indicate a mechanism of membrane-membrane fusion for archaeal glycolipid membranes induced by glycosidase and illustrate the importance for inclusion of glycolipids in compositions of vesicles designed to deliver protein antigens to the cytosol for MHC class I presentation.

A measurable Lawson criterion and hydro-equivalent curves for inertial confinement fusion

It is shown that the ignition condition (Lawson criterion) for inertial confinement fusion (ICF) can be cast in a form dependent on the only two parameters of the compressed fuel assembly that can be measured with existing techniques: the hot spot ion temperature (Tih) and the total areal density (ρRtot), which includes the cold shell contribution. A marginal ignition curve is derived in the ρRtot, Tih plane and current implosion experiments are compared with the ignition curve. On this plane, hydrodynamic equivalent curves show how a given implosion would perform with respect to the ignition condition when scaled up in the laser-driver energy. For 3<⟨Tih⟩n<6keV, an approximate form of the ignition condition (typical of laser-driven ICF) is ⟨Tih⟩n2.6⋅⟨ρRtot⟩n>50keV2.6⋅g∕cm2, where ⟨ρRtot⟩n and ⟨Tih⟩n are the burn-averaged total areal density and hot spot ion temperature, respectively. Both quantities are calculated without accounting for the alpha-particle energy deposition. Such a criterion can be used to determine how surrogate D2 and subignited DT target implosions perform with respect to the one-dimensional ignition threshold.

ADULT DEGENERATIVE SCOLIOSIS

To review and define principles and features of treatment for adult degenerative scoliosis, the most common cause of adult spinal deformities. We conducted a comprehensive review of the literature and our clinical experience. A systematic review of Medline was conducted, including journal articles published in March 2007 and before. We searched for articles related to adult spinal deformities (scoliosis) and treatments. Degenerative scoliosis is a complex disorder. The primary surgical aims are to decompress the neural elements, normalize both sagittal balance and coronal and rotational deformity, fixate to the sacrum/ilium when appropriate, and optimize conditions for osteogenesis and fusion.

HANDLING RESOURCE SHARING PROBLEM USING PROPERTY-PRESERVING PLACE FUSIONS OF PETRI NETS

Resource sharing is a very complex task in system design because it may induce undesirable properties such as deadlocks and overflows. This paper proposes a method for handling this task. Resource sharing is formulated as a place fusion on a Petri net specification that satisfies a designated set of properties and includes some duplicated places representing accesses to the resources. If this fusion satisfies some conditions, the obtained net will preserve the original properties after the incorporation of resource sharing. This paper considers two classes of property-preserving place fusions. Each class specifies the Petri net type to be used, the structural relationship among the resource places and possibly some additional conditions for the place fusion to preserve a designated set of properties. As an illustration, these place fusion approaches are applied to solve a resource sharing problem in the design of manufacturing systems.

On the efficacy of imploding plasma liners for magnetized fusion target compression

A new theoretical model is formulated to study the idea of merging a spherical array of converging plasma jets to form a “plasma liner” that further converges to compress a magnetized plasma target to fusion conditions [Y. C. F. Thio et al., “Magnetized target fusion in a spheroidal geometry with standoff drivers,” Current Trends in International Fusion Research II, edited by E. Panarella (National Research Council Canada, Ottawa, Canada, 1999)]. For a spherically imploding plasma liner shell with high initial Mach number (M=liner speed/sound speed) the rise in liner density with decreasing radius r goes as ρ∼1∕r2, for any constant adiabatic index γ=dlnp∕dlnρ. Accordingly, spherical convergence amplifies the ram pressure of the liner on target by the factor A∼C2, indicating strong coupling to its radial convergence C=rm∕R, where rm(R)=jet merging radius (compressed target radius), and A=compressed target pressure/initial liner ram pressure. Deuterium-tritium (DT) plasma liners with initial velocity ∼100km∕s and γ=5∕3, need to be hypersonic M∼60 and thus cold in order to realize values of A∼104 necessary for target ignition. For optically thick DT liners, T<2eV, n>1019–1020cm−3, blackbody radiative cooling is appreciable and may counteract compressional heating during the later stages of the implosion. The fluid then behaves as if the adiabatic index were depressed below 5∕3, which in turn means that the same amplification A=1.6×104 can be accomplished with a reduced initial Mach number M≈12.7(γ−0.3)4.86, valid in the range (10<M<60). Analytical calculations indicate that the hydrodynamic efficiency for plasma liners assembled by current and anticipated plasma jets is <4%. A new similarity model for fusion α-particle heating of the collapsed liner indicates that “spark” ignition of the DT liner fuel does not appear to be possible for magnetized fusion targets with typical threshold values of areal density ρR<0.02gcm−2.

Particle deposition and optical response of ITER motional Stark effect diagnostic first mirrors

Particle deposition and erosion can affect mirrors used in plasma diagnostics and this is a major concern for future fusion reactors. This subject is analysed for the first and second mirrors of the proposed motional Stark effect edge plasma current diagnostic for ITER. Particle fluxes to the diagnostic module aperture are given by edge plasma/impurity-transport solutions for convective plasma flow for full-power fusion conditions. The MC-Mirror code with input of TRIM-SP results is used to compute in-module direct, reflected and sputtered particle transport. Particles analysed are D–T and He atoms/ions from the plasma, and Fe, Be and W from first wall sputtering and/or in-module sputtering. Many of the results are encouraging for optical diagnostic use in ITER and possibly for post-ITER high duty-factor reactors. The LLNL-4B module design analysed works well in minimizing particle flux to the mirrors, with a factor of ∼200–400 reduction in aperture-to-first-mirror flux. Sputtering erosion/degradation of Mo or Rh coated mirrors by incident D, T and He is negligible. IMD optical effects code analysis shows probably tolerable changes in light reflection and polarization due to mirror beryllium deposition. Tungsten flux to the mirrors is very low. Based on available but limited data, however, there is major concern about the effect of the predicted helium flux on mirror optical properties.

Building three‐dimensional objects by deposition of molten metal droplets

PurposeThe purpose of this paper is to determine conditions under which good metallurgical bonding was achieved in 3D objects formed by depositing tin droplets layer by layer.Design/methodology/approachMolten tin droplets (0.18‐0.75 mm diameter) were deposited using a pneumatic droplet generator on an aluminum substrate. The primary parameters varied in experiments were those found to most affect bonding between droplets on different layers: droplet temperature (varied from 250 to 325°C) and substrate temperature (varied from 100 to 190°C). Droplet generation frequency was kept low enough (1‐10 Hz) that each layer of droplets solidified and cooled down before another molten droplet impinged on it.FindingsIn this paper, a one dimensional heat transfer model was used to predict the minimum droplet and substrate temperatures required to remelt a thin layer of the substrate and ensure good bonding of impinging droplets. Cross‐sections through samples confirmed that increasing either the droplet temperature or the substrate temperature to the predicted remelting region produces good bonding between deposition layers.Originality/valueThis paper used a practical model to provide reasonable prediction of conditions for droplet fusion which is essential to droplet‐based manufacturing. The feasibility of fabricating 3D metal objects by deposition of molten metal droplets has been well demonstrated.

Preparation and Liner Compression of Plasma From an Ultrahigh Speed Flow

Preparation of the target plasma represents a critical issue in liner compression techniques to achieve fusion conditions. We consider the use of an ultrahigh speed plasma flow from a special coaxial-gun arrangement known as the plasma flow switch. Experiments have demonstrated that this arrangement can provide plasma flows with speeds in excess of 2000 km/s. Stagnation of such a plasma flow results in fully stripped aluminum plasma with electron temperatures of 30 keV. Substitution of deuterium or a deuterium-tritium mixture could provide target plasma at kilovolt temperatures within an imploding liner. Such temperatures suggest that, even if substantial heat loss occurred during liner compression, fusion-level temperatures would be possible. The concatenation of events to generate the ultrahigh speed flow, to direct it into the implosion chamber, and to arrange liner dynamics for effective compression demands numerical simulation, which is based on initial analytical estimates. Both types of calculation for exploring this concept are discussed.

Experimental and Computational Progress on Liner Implosions for Compression of FRCs

Magnetized target fusion (MTF) is a means to compress plasmas to fusion conditions that uses magnetic fields to greatly reduce electron thermal conduction, thereby greatly reducing compression power density requirements. The compression is achieved by imploding the boundary, a metal shell. This effort pursues formation of the field-reversed configuration (FRC) type of magnetized plasma, and implosion of the metal shell by means of magnetic pressure from a high current flowing through the shell. We reported previously on experiments demonstrating that we can use magnetic pressure from high current capacitor discharges to implode long cylindrical metal shells (liners) with size, symmetry, implosion velocity, and overall performance suitable for compression of FRCs. We also presented considerations of using deformable liner-electrode contacts of Z-pinch geometry liners or theta pinch-driven liners, in order to have axial access to inject FRCs and to have axial diagnostic access. Since then, we have experimentally implemented the Z-pinch discharge driven deformable liner-electrode contact, obtained full axial coverage radiography of such a liner implosion, and obtained 2frac12 dimensional MHD simulations for a variety of profiled thickness long cylindrical liners. The radiographic results indicate that at least 16 times radial compression of the inner surface of a 0.11-cm-thick Al liner was achieved, with a symmetric implosion, free of instability growth in the plane of the symmetry axis. We have also made progress in combining 2frac12-D MHD simulations of FRC formation with imploding liner compression of FRCs. These indicate that capture of the injected FRC by the imploding liner can be achieved with suitable relative timing of the FRC formation and liner implosion discharges.

Biological Control Agent for Rice Weeds from Protoplast Fusion betweenCurvularia lunataandHelminthosporium gramineum

The advancement of biological weed control is limited by the slow development of effective, broader-spectrum biological control agents. Protoplast fusion was carried out between theHelminthosporium gramineumsubsp.echinochloae(HGE) strain, HM1, andCurvularia lunata(CL) to breed new strains with improved biocontrol efficiency. The HM1 strain was derived from HGE by ultraviolet (UV) treatment. Conditions for protoplast fusion were optimized, including lytic enzyme mixtures and incubation time. The efficacy of lytic enzyme mixtures on cell wall digestion was also compared. The most effective lytic enzyme mixture for CL was 2% lywallzyme plus 2% snailase and for HM1, 2% cellulase plus 2% snailase. The optimum incubation time was 16 h for CL and 24 h for HM1. All fusant strains exhibited similar morphological and conidial properties to the HM1 parent. A total of 1,360 fusant strains were produced, 136 of which were randomly selected for characterization. Seven fusant strains showed improved spore productivity and four fusant strains had increased production of the phytotoxin ophiobolin A, compared with HM1. Random amplified polymorphic DNA (RAPD) analysis of the fusant strains showed that the seven phytoactive fusant strains had a high similarity index (95 to 99%) to the parent HM1, but low similarity (22 to 26%) to the parent CL. Ethyl acetate extract of the culture broth and mycelia effectively controlled major weeds in rice production.

Numerical investigation of non-local electron transport in laser-produced plasmas

Non-local electron transport in laser-produced plasmas under inertial confinement fusion (ICF) conditions is studied based on Fokker–Planck (FP) and hydrodynamic simulations. A comparison between the classical Spitzer–Härm (SH) transport model and non-local transport models has been made. The result shows that among those non-local models the Epperlein and Short (ES) model of heat flux is in reasonable agreement with the FP simulation in overdense region. However, the non-local models are invalid in the hot underdense plasmas. Hydrodynamic simulation is performed with the flux limiting model and the non-local model, separately. The simulation results show that in the underdense region of the laser-produced plasmas the temperature given by the flux limiting model is significantly higher than that given with the non-local model.

Production and Evaluation of Somatic Hybrids Derived from Monoploid Potato

Biotechnological approaches to hasten hybrid plant breeding are available, including anther culture to halve the genome and protoplast fusion to create hybrids between incompatible partners. We applied these techniques to potato to evaluate their potential for breeding a highly heterozygous, cross-pollinating species. Four families of monoploids (2n=1x=12), developed from diploid hybrids with various genomic constitutions favoringSolarium phureja, an ancestral cultivated potato subsequently selected for tuberization under long photoperiod, were used in electrofusion experiments to create intermonoploid somatic hybrids. The “monoploid sieve” results in the survival of only those gametes free of lethal and deleterious genes, but it generates sterile sporophytes, necessitating protoplast fusion for developing hybrids from differentially derived monoploids. From six intermonoploid electrofusion combinations, 178 plants, including both somaclones and somatic hybrids confirmed by microsatellite analysis, were regenerated over six to nine months. Fusion conditions of 8 V for 45 sec with two pulses and 12 V for 30 sec and one pulse were optimum. Ploidy of the fusion products as determined by flow cytometry ranged from 2x to 8x with only somaclones at the 2x level and both 4x and 6x somatic hybrids. Field evaluations over three years revealed that intermonoploid somatic hybrids were inferior toSolarium tuberosum cultivars. Dihaploids derived by anther culture of a tetraploid intermonoploid somatic hybrid were reduced in vigor with the increase in homozygosity, while 2x X 2x sexually derived populations were similar in yield to the somatic hybrids. The biotechnological breeding scheme to reduce generation time will require selection for horticultural traits during inbreeding in order to produce potatoes more similar to cultivars. The elimination of epistatic and/or intra-allelic interactions through reduc-tion of ploidy may underlie the poor performance of monoploids, doubled monoploids and dihaploids as well as most somatic hybrids compared to conventionally bred potato germplasm.

Adiabatic Compression of a Doublet Field Reversed Configuration (FRC)

The adiabatic compression of magnetized plasmas has come to the fore in recent times as an interesting hybrid of both inertial and magnetic fusion energy schemes, possibly allowing a means to reach fusion conditions in a compact pulsed system (R.P. Drake et al. Fusion Tech. 30, 310, (1996)). It is possible to compress a range of different magnetic configurations (D.D. Ryutov, R.E. Siemon, Com. Mod. Phys. 2, 185, (2001)), here we consider the compression of a FRC: a favorable target due to high s. The literature relating to the adiabatic compression of magnetic concepts is reviewed. We present analytic modeling and MHD simulations of the reconnection and compression of a doublet FRC configuration that might serve as a target for compression.

Heavy-ion-fusion-science: summary of US progress

Over the past two years noteworthy experimental and theoretical progress has been made towards the top-level scientific question for the US programme on heavy-ion-fusion-science and high energy density physics: ‘How can heavy-ion beams be compressed to the high intensity required to create high energy density matter and fusion conditions?’ New results in transverse and longitudinal beam compression, high-brightness transport and beam acceleration will be reported. Central to this campaign is final beam compression. With a neutralizing plasma, we demonstrated transverse beam compression by an areal factor of over 100 and longitudinal compression by a factor of > 50. We also report on the first demonstration of simultaneous transverse and longitudinal beam compression in plasma. High beam brightness is key to high intensity on target, and detailed experimental and theoretical studies on the effect of secondary electrons on beam brightness degradation are reported. A new accelerator concept for near-term low-cost target heating experiments was invented, and the predicted beam dynamics validated experimentally. We show how these scientific campaigns have created new opportunities for interesting target experiments in the warm dense matter regime. Finally, we summarize progress towards heavy-ion fusion, including the demonstration of a compact driver-size high-brightness ion injector. For all components of our high intensity campaign, the new results have been obtained via tightly coupled efforts in experiments, simulations and theory.

Rapid Membrane Fusion of Individual Virus Particles with Supported Lipid Bilayers

Many enveloped viruses employ low-pH-triggered membrane fusion during cell penetration. Solution-based in vitro assays in which viruses fuse with liposomes have provided much of our current biochemical understanding of low-pH-triggered viral membrane fusion. Here, we extend this in vitro approach by introducing a fluorescence assay using single particle tracking to observe lipid mixing between individual virus particles (influenza or Sindbis) and supported lipid bilayers. Our single-particle experiments reproduce many of the observations of the solution assays. The single-particle approach naturally separates the processes of membrane binding and membrane fusion and therefore allows measurement of details that are not available in the bulk assays. We find that the dynamics of lipid mixing during individual Sindbis fusion events is faster than 30ms. Although neither virus binds membranes at neutral pH, under acidic conditions, the delay between membrane binding and lipid mixing is less than half a second for nearly all virus-membrane combinations. The delay between binding and lipid mixing lengthened only for Sindbis virus at the lowest pH in a cholesterol-dependent manner, highlighting the complex interaction between lipids, virus proteins, and buffer conditions in membrane fusion.

Material irradiation conditions for the IFMIF medium flux test module

The International Fusion Materials Irradiation Facility (IFMIF) is an accelerator driven neutron source, which is designed to perform material irradiations at conditions very close to that of future fusion reactors up to the anticipated lifetime of structural materials. Besides irradiation of material samples in the high flux test module, in situ creep-fatigue tests for structural materials in the creep-fatigue test module (CFTM) and tritium release experiments for breeder blanket materials in the tritium release module (TRM) are foreseen in the medium flux test module (MFTM) of IFMIF. The present study is devoted to the evaluation of the creep-fatigue specimens and beryllium irradiation conditions in the MFTM of IFMIF. It is demonstrated that maximum displacement damage rate in the CFTM is about 13 dpa/fpy. The analysis shows that the TRM can closely meet fusion-typical He and dpa production rates in Be, while the T-production is somewhat above fusion conditions for the present test module design. Removing the CFTM and shifting of the whole TRM upstream increases the damage rate to about 60% of that for a fusion reactor and provides tritium and helium production rates comparable with fusion. In addition, the important He/T ratio nicely fits the fusion relevant value after one year of irradiation in the IFMIF TRM.

Studies of reactor irradiation effect on hydrogen isotope release from vanadium alloy V4Cr4Ti

Vanadium alloys are most promising materials being considered for lithium blanket-breeder in future fusion reactors. The primary reason for these stems from good combination of physical–mechanical and radiation properties of vanadium alloys. In operational conditions of fusion reactors the very important issue is behavior of vanadium alloy with respect to hydrogen isotopes under neutron and gamma irradiation. This paper shows results of the experimental studies of reactor irradiation influence on parameters of hydrogen release from vanadium alloys. Experiments were carried out for various levels of reactor irradiation and showed the effect of irradiation on parameters of hydrogen release from vanadium alloy V4Cr4Ti.

Neutralized drift compression experiments with a high-intensity ion beam

To create high-energy density matter and fusion conditions, high-power drivers, such as lasers, ion beams, and X-ray drivers, may be employed to heat targets with short pulses compared to hydro-motion. Both high-energy density physics and ion-driven inertial fusion require the simultaneous transverse and longitudinal compression of an ion beam to achieve high intensities. We have previously studied the effects of plasma neutralization for transverse beam compression. The scaled experiment, the Neutralized Transport Experiment (NTX), demonstrated that an initially un-neutralized beam can be compressed transversely to ∼1 mm radius when charge neutralization by background plasma electrons is provided. Here, we report longitudinal compression of a velocity-tailored, intense, neutralized 25 mA K + beam at 300 keV. The compression takes place in a 1–2 m drift section filled with plasma to provide space-charge neutralization. An induction cell produces a head-to-tail velocity ramp that longitudinally compresses the neutralized beam, enhances the beam peak current by a factor of 50 and produces a pulse duration of about 3 ns. The physics of longitudinal compression, experimental procedure, and the results of the compression experiments are presented.