Suppressed ion-scale turbulence in a hot high-ß plasma.

An economic magnetic fusion reactor favours a high ratio of plasma kinetic pressure to magnetic pressure in a well-confined, hot plasma with low thermal losses across the confining magnetic field. Field-reversed configuration (FRC) plasmas are potentially attractive as a reactor concept, achieving high plasma pressure in a simple axisymmetric geometry. Here, we show that FRC plasmas have unique, beneficial microstability properties that differ from typical regimes in toroidal confinement devices. Ion-scale fluctuations are found to be absent or strongly suppressed in the plasma core, mainly due to the large FRC ion orbits, resulting in near-classical thermal ion confinement. In the surrounding boundary layer plasma, ion- and electron-scale turbulence is observed once a critical pressure gradient is exceeded. The critical gradient increases in the presence of sheared plasma flow induced via electrostatic biasing, opening the prospect of active boundary and transport control in view of reactor requirements.

Achieving a long-lived high-beta plasma state by energetic beam injection.

Developing a stable plasma state with high-beta (ratio of plasma to magnetic pressures) is of critical importance for an economic magnetic fusion reactor. At the forefront of this endeavour is the field-reversed configuration. Here we demonstrate the kinetic stabilizing effect of fast ions on a disruptive magneto-hydrodynamic instability, known as a tilt mode, which poses a central obstacle to further field-reversed configuration development, by energetic beam injection. This technique, combined with the synergistic effect of active plasma boundary control, enables a fully stable ultra-high-beta (approaching 100%) plasma with a long lifetime.

Inverse free electron lasers and laser wakefield acceleration driven by CO2 lasers.

The staged electron laser acceleration (STELLA) experiment demonstrated staging between two laser-driven devices, high trapping efficiency of microbunches within the accelerating field and narrow energy spread during laser acceleration. These are important for practical laser-driven accelerators. STELLA used inverse free electron lasers, which were chosen primarily for convenience. Nevertheless, the STELLA approach can be applied to other laser acceleration methods, in particular, laser-driven plasma accelerators. STELLA is now conducting experiments on laser wakefield acceleration (LWFA). Two novel LWFA approaches are being investigated. In the first one, called pseudo-resonant LWFA, a laser pulse enters a low-density plasma where nonlinear laser/plasma interactions cause the laser pulse shape to steepen, thereby creating strong wakefields. A witness e-beam pulse probes the wakefields. The second one, called seeded self-modulated LWFA, involves sending a seed e-beam pulse into the plasma to initiate wakefield formation. These wakefields are amplified by a laser pulse following shortly after the seed pulse. A second e-beam pulse (witness) follows the seed pulse to probe the wakefields. These LWFA experiments will also be the first ones driven by a CO(2) laser beam.

Evidence of relaxation and spontaneous transition to a high-confinement state in high-beta steady-state plasmas sustained by rotating magnetic fields.

Evidence of relaxation has appeared, for the first time, in the extremely high-beta, steady-state field-reversed configuration plasma states driven by rotating magnetic fields (RMF) in the translation, confinement, and sustainment experiment. The plasma self-organizes into a near-force-free state in the vicinity of the magnetic axis, with significant improvement in confinement. Associated with this change in magnetic topology is the appearance of an axial RMF component; this would, in turn, generate a current drive in the poloidal direction, thus sustaining the magnetic helicity. A newly developed two-dimensional "equilibrium-lite" model is employed to analyze the magnetic properties of the final high-confinement state, and shows a large q and a significant magnetic shear in the core.

Observations of improved stability and confinement in a high-beta self-organized spherical-torus-like field-reversed configuration.

An extremely high-beta (over 85%) self-organized field-reversed configuration (FRC) with a spherical-torus- (ST-)like core is produced in the translation, confinement, and sustainment experiment by highly super-Alfvénic translation of a spheromaklike plasmoid. Substantial flux conversion from toroidal into poloidal occurs during the capture process, resulting in the ST-like core. This plasma state exhibits a remarkable stabilizing property for the ubiquitous centrifugally driven interchange modes present in theta-pinch formed FRCs. This is explained, for the first time, by a simple model taking into account magnetic shear and centrifugal effects. The FRC-ST configuration has up to 4 times improvement in flux confinement times over the scaling of conventional theta-pinch formed FRCs and, thus, a significant improvement in the resistivity and transport.

Flux conversion and evidence of relaxation in a high-beta plasma formed by high-speed injection into a mirror confinement structure.

High-beta plasmoids can survive the violent dynamics of supersonic reflection off mirror structures, producing a stable high-beta field-reversed configuration (FRC). This shows both the robustness of FRCs and their tendency to assume a preferred plasma state, possibly conforming to a relaxation principle. The key observations are (1) approximate preservation of the magnetic helicity, (2) substantial conversion from toroidal to poloidal magnetic flux, (3) substantial toroidal flow, and (4) a high-beta quiescent final state. These results are from the Translation, Confinement, and Sustainment experiment where a disorganized plasmoid is injected at super-Alfvenic speed into a confinement chamber. After successive reflections from end mirrors, the plasmoid settled into a near-FRC state with high beta and low toroidal magnetic field. The flux conversion and helicity preservation are inferred by an interpretive model.

Demonstration of high-trapping efficiency and narrow energy spread in a laser-driven accelerator.

Laser-driven electron accelerators (laser linacs) offer the potential for enabling much more economical and compact devices. However, the development of practical and efficient laser linacs requires accelerating a large ensemble of electrons together ("trapping") while keeping their energy spread small. This has never been realized before for any laser acceleration system. We present here the first demonstration of high-trapping efficiency and narrow energy spread via laser acceleration. Trapping efficiencies of up to 80% and energy spreads down to 0.36% (1 sigma) were demonstrated.

Decision support systems for chemical structure representation, reaction modeling, and spectra simulation.

The choice of an appropriate structure coding scheme is the secret to success in QSAR studies. Depending on the problem at hand, 2D or 3D descriptors have to be chosen; the consideration of electronic effects might be crucial, conformational flexibility has to be of special concern. Artificial neural networks, both with unsupervised and with supervised learning schemes, are powerful tools for establishing relationships between structure and physical, chemical, or biological properties. The EROS system for the simulation of chemical reactions is briefly presented and its application to the degradation of s-triazine herbicides is shown. It is further shown how the simulation of chemical reactions can be combined with the simulation of infrared spectra for the efficient identification of the structure of degradation products.

First staging of two laser accelerators.

Staging of two laser-driven, relativistic electron accelerators has been demonstrated for the first time in a proof-of-principle experiment, whereby two distinct and serial laser accelerators acted on an electron beam in a coherently cumulative manner. Output from a CO2 laser was split into two beams to drive two inverse free electron lasers (IFEL) separated by 2.3 m. The first IFEL served to bunch the electrons into approximately 3 fs microbunches, which were rephased with the laser wave in the second IFEL. This represents a crucial step towards the development of practical laser-driven electron accelerators.

Simulation of organic reactions: from the degradation of chemicals to combinatorial synthesis

Organic reactions can be run under a variety of conditions, from laboratory experiments, through technical processes, to combinatorial chemistry. The scope is further extended when the metabolism of compounds and the reactions in the mass spectrometer are included. We present here several concepts: reactors, phases, and modes, which, together with a kinetic modeling, allow the treatment of such a broad scope of organic reactions. These concepts have been implemented in a knowledge-based system, EROS. Several applications of this system to the wide world of organic reactions are given.

The plastidic phosphoglucomutase from Arabidopsis. A reversible enzyme reaction with an important role in metabolic control.

An Arabidopsis cDNA (AtPGMp) encoding the plastidic phosphoglucomutase (PGM) predicted a 623-amino acid protein with an N-terminal sequence typical of a plastid signal peptide. Expression of a recombinant protein in Escherichia coli confirmed its enzyme activity. The recombinant enzyme had an apparent K(m) value of 98.5 microM and a V(max) of 4.48 micromol min(-1) (mg protein)(-1). The Calvin cycle intermediates fructose-1,6-bisphosphate and ribulose-1, 5-bisphosphate exerted an inhibitory effect on PGM activity, supporting its proposed involvement in controlling photosynthetic carbon flow. A point mutation was identified in the AtPGMp gene of the Arabidopsis pgm-1 mutant. The mutation in the mutant transcript generated a stop codon at about one third of the wild-type open reading frame, and thus rendered the polypeptide nonfunctional. Storage lipid analysis of the pgm-1 mutant seeds showed a 40% reduction in oil content compared with that of wild type. Our results indicate that plastidic PGM is an important factor affecting carbon flux in triacylglycerol accumulation in oilseed plants, most likely through its essential role in starch synthesis.

The effect of different promoter-sequences on transient expression of gus reporter gene in cultured barley (Hordeum vulgare L.) cells.

The cauliflower mosaic virus 35S (35S) and the enhanced 35S (E35S) promoters fused with maize alcohol dehydrogenase (Adh1) intron1 or maize shrunken locus (sh1) intronl along with maize Adh1 and rice actin (Act1) promoters fused to their respective first introns were tested for transient expression of the E.coli ß-glucuronidase (gus) reporter gene in cultured barley (Hordeum vulgare L) cells. The plasmids, carrying the respective promoterintron combinations to drive the gus fused to nopaline synthase (nos) terminator, were introduced into cultured barley cells using a particle gun. The rice Act1 promoter with its first intron gave the highest expression of all promoter intron combinations studied. This was followed by the E35S promoter and no significant differences were observed between the other two promoters tested. The rice actin promoter is now being used to drive selectable marker genes to obtain stably transformed cereal cells.

Inhibition of carbon tetrachloride induced hepatotoxicity by dantrolene sodium.

A 50 mg/kg dose of dantrolene sodium decreased the hepatotoxicity of carbon tetrachloride in fed and fasted rats, as indicated by lower levels of SGPT following a toxic dose of carbon tetrachloride; however, the dantrolene sodium pretreatment did not inhibit the induction of lipid peroxidation by carbon tetrachloride. The dantrolene sodium did inhibit superoxide production by the hepatic endoplasmic reticulum in fasted rats. Also, the dantrolene sodium inhibited covalent binding of [14C] carbon tetrachloride to the hepatic endoplasmic reticulum in fasted rats, but not in fed rats.

Alteration of chemically induced hepatotoxicity by copper (II) (3,5-diisopropylsalicylate)2.

The effects of copper (II) (3,5-diisopropylsalicylate)2 (CuDIPS), which is a synthetic superoxide dismutase, on the hepatotoxicity of carbon tetrachloride and acetaminophen in fed and fasted animals were investigated. CuDIPS did not alter the covalent binding of metabolites of either of these chemicals to the hepatic endoplasmic reticulum. However, CuDIPS did inhibit the hepatotoxicity of carbon tetrachloride by inhibiting the induction of lipid peroxidation by carbon tetrachloride. CuDIPS had only a slight, and histologically insignificant, ability to decrease acetaminophen hepatotoxicity which is related to the inability of CuDIPS to prevent depletion of reduced glutathione by acetaminophen. The observation that fasting potentiates the hepatotoxicity of acetaminophen is emphasized, and the mechanism of this potentiation is suggested to be related to the depletion of reduced glutathione.

Radiorespirometry of Candida utilis in phased culture under nitrogen-, carbon-, and phosphorus-limited growth.

The release of 14CO2 from specifically labelled glucose ([G-1-14C],[G-2-14C],[G-3,4-14C], and [G-6-14C]) by phased cells of C. utilis was examined at intervals during 6-h cycles under conditions of N-,P-, and C-limited growth. On the basis that the release of 14CO2 from [G-1-C14] could serve as a measure of hexose monophosphate pathway (HMP) activity, of 14CO2 from [G-3,4-14C] as a measure of Embden-Meyerhof-Parnas (EMP) activity, and 14CO2 from [G-6-14C] as indicative of tricarboxylic acid (TCA) cycle activity, it was concluded that a relatively uniform operation of EMP occurred throughout the cycle in N-, P-, and C-limited cells, and of HMP and TCA in C-limited cells, but considerable variations took place in HMP and TCA cycle activities in N- and P-limited cells. The patterns of 14CO2 released from [G-2-14C] were more closely related to those observed from [G-1-14C] and [G-3,4-14C] than from [G-6-14C]. Changes in the rate of 14CO2 evolution during the cycle were sometimes abrupt and likely coincided with 'critical points' of metabolic activity in the cycle.

Some comparative observations on the relative contributions of alternate pathways in the metabolism of glucose by Candida utilis.

Candida utilis was grown in batch, chemostat, and continuously synchronised (phased) culture on a nitrogen-limited glucose mineral salts medium: phosphorus- and carbon-limited phased cultures were also used. The 14CO2 evolved from [G-1-14c]and [G-6-14c] was used, as a simple C1/C6 ratio, to observe the relative changes in EMP and HMP contributions during growth of the cultures. The ratio varied during the cell cycle, and changed with growth rate, and with nutrient limitation. The changes generally indicated that the HMP predominated, most notably in the early part of the batch-growth sequence and early in the cell cycle. The overall results reflected the relative merits of the different cultivation techniques for examining microbial metabolism: the advantage of a greater resolution by the synchronised method, based upon the unit performance rather than the randomised mean performance of the cell population...