High Energy Charge Research Articles

High-energy pion-induced double charge exchange and isovector renormalization

The (${\mathrm{\ensuremath{\pi}}}^{+}$,${\mathrm{\ensuremath{\pi}}}^{\mathrm{\ensuremath{-}}}$) double-charge-exchange reaction for pion energies of 200 to 1400 MeV is calculated with a zero-parameter Glauber theory that includes spin flip and pion absorption. Differential cross sections and excitation functions are obtained for $^{14}\mathrm{C}$ and $^{18}\mathrm{O}$ targets. Results for ${\mathit{T}}_{\mathrm{\ensuremath{\pi}}}$=300--525 MeV are compared with recent experimental results and suggest a new quenching process. We have calculated effects of medium polarization on the isovector pion operator and find a strong reduction in good agreement with data. A pronounced dip in the cross section near ${\mathit{T}}_{\mathrm{\ensuremath{\pi}}}$=1300 MeV offers a unique testing ground for unconventional mechanisms.

Charge transfer and tree initiation in polyethylene subjected to AC voltage stress

An electrical tree is grown in the region of a dielectric subjected to an intensified local electric field. It can be artificially generated in a specimen by using a needle-to-plane electrode configuration. It is characterized by an incubation period which usually tends to decrease with applied voltage. During this period, charge carriers (electrons and positive holes) move back and forth repeatedly between the electrode and the dielectric. This repeated charge transfer is believed to be mainly responsible for tree initiation. Two main contributions can be conceived: the space charge buildup and the attack on the polymer chains by high-energy charge carriers. A space-charge distortion model is proposed for the initiation of an electric tree in polyethylene. This model can also include material aging processes initiated by injected carriers. It can explain ultraviolet light emission and morphological effects which are experimentally observed in association with tree initiation.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Adenine compounds in the male reproductive tract and the spermatophore of the silkmoth, Bombyx mori

1. 1. Studies were made on the levels of six adenine compounds in various glands of the male reproductive tract before and after ejaculation and their changes with time in the spermatophore of the silkworm, Bombyx mori. 2. 2. The ductus (d.) deferens, ampulla d. deferentis and vesicular seminalis contain high concentrations of cAMP. The total amount of cAMP transferred from the male reproductive tract corresponds to its content in the spermatophore, and is sufficient to induce motility of apyrene spermatozoa. 3. 3. The ATP content of the g. pellucida is much higher than those of the two other adenine nucleotides, indicating a high energy charge. But, in the other male glands, the AMP content is very much higher than that of ATP, indicating low energy charges.

Isomer differentiation by charge inversion tandem mass spectrometry: an investigation into the structure of the ionic products from an S N(ANRORC) reaction

Negative ion fast atom bombardment and negative ion chemical ionization tandem mass spectrometry combined with charge inversion reactions are used to confirm that 2-chloro-5-nitropyridine reacts with the hydroxide ion by an S N(ANRORC) mechanism in solution to form a ring-opened C 5H 3N 2O − 3 anion that has the structure of the (M-H) − anion of 2-nitro-4-cyano-2-butenal. The addition of excess hydroxide ion forms the expected 2-oxy-5-nitropyridine anion. In the gas phase the same reaction forms only the 2-oxy-5-nitropyridine anion. High energy charge inversion is shown to be an excellent means of differentiating between these isomeric negative ions.

Genetic Effects of Cosmic Radiation

In space environment, radiation dose due to high charge and high energy particles (HZE) and other cosmic radiation is, in general, 2 to 3 orders of magnitude greater than the dose from cosmic rays which are falling on the surface of the Earth. Although radiation dose during 7 to 8 day Shuttle mission is so small as to cause any harmful effect on astronauts, this will change with the advent of Space Station and manned Mars Mission. The purpose of our experiment is to examine possible effects of space radiation on living organisms, particularly the genetic effects. For this, we are analyzing mutations induced in fruit flies of the species Drosophila melanogaster during the space flight.

Mass dependence of high-energy pion double charge exchange.

The mass dependence of cross sections for double-isobaric-analog states from pion-induced double-charge-exchange reactions is examined with small-angle data taken at 450 and 500 MeV incident pion energies for several targets. New ({pi}{sup +},{pi}{sup {minus}}) cross sections are reported for {sup 26}Mg, {sup 46,50}Ti, {sup 54,56}Fe, {sup 52}Cr, {sup 80}Se, {sup 90}Zr, {sup 197}Au, and {sup 208}Pb. The ({ital f}{sub 7/2}){sup {ital n}} data are fitted to a two-amplitude model which contains expressions for cross sections for transitions to the DIAS and to nonanalog ground states in the residual nucleus.

Energetics and Power Output of Isolated Fish Fast Muscle Fibres Performing Oscillatory Work

Fast myotomal muscle fibres were isolated from the cod (Gadus morhua L.) and the energy cost of contraction was measured under conditions simulating swimming. Fibre bundles were subjected to sinusoidal cycles of shortening and lengthening about their in situ fibre length, and stimulated at selected phases in each cycle. The preparations were poisoned with iodoacetic acid and bubbled with nitrogen to block the synthesis of ATP. After an initial rapid decline over the first 10 cycles, force and net work remained steady in some cases for up to 64 oscillatory length cycles, but more commonly declined slowly after about 30 cycles. The total mechanical work performed increased largely in proportion to the number of work cycles. At the end of each experiment fibres were frozen in isopentane cooled in liquid nitrogen and metabolite concentrations determined by high performance liquid chromatography (HPLC) and enzymatic analysis. Concentrations of adenylates did not differ significantly from control values, although a significant increase in IMP concentrations at 64 cycles accounted for the maintenance of relatively high energy charge values. Creatine (C) concentrations increased and creatine phosphate (CP) concentrations decreased, implying a tight coupling of the ATP/ADP reaction to the CP/C reaction. Muscle economy was calculated as the positive work performed during a work cycle divided by the total chemical energy expended. These values (approx. 7 mJ mumol-1) were found to be independent of the number of work cycles performed, although a trend to increase was observed. Muscle efficiency values, calculated assuming a Gibb's force free energy change for CP splitting in vivo of 55 kJ mol-1, were in the range 12-23%.

Regulation of Electron Transport in Plant Mitochondria under State 4 Conditions

The regulation of electron transport in pea (Pisum sativum L.) leaf mitochondria under state 4 conditions has been investigated by simultaneously monitoring oxygen uptake, the steady-state reduction level of ubiquinone, and membrane potential. Membrane potentials were measured using a methyltriphenylphosphonium electrode while a voltametric technique was used to monitor changes in the steady-state reduction levels of quinone. It was found that the addition of glycine to mitochondria oxidising malate in state 4 led to a marked increase in the rate of O(2) uptake and increased both the membrane potential and reduction level of the quinone pool. Increases in the state 4 respiratory rate were attributed to both an increase in driving flux, due to increased Q-pool reduction, and in membrane potential. Due to the nonohmic behavior of the inner membrane, under these conditions, an increase in potential would result in a considerable rise in proton conductance. Measurement of dual substrate oxidation, in the presence of n-propylgallate, revealed that the increase in respiratory activity was not mediated by the alternative oxidase. Similar increases in membrane potential and the level of Q-pool reduction were observed even in the presence of rotenone suggesting that the rotenone-insensitive pathway is a constitutive feature of plant mitochondria and may play a role in facilitating rapid state 4 rates even in the presence of a high energy charge.

A comment on satellites in nickel

The satellites in Ni can be described with a basis of itinerant electron states and that the satellite is a precursor of the Mott-Hubbard band splitting expected for localized electronic states. In general, satellites can be related to the presence of large amplitude collective high energy charge fluctuations, similar to damped plasmon modes. The energy scale associated with these collective charge excitations is significantly reduced by the large degeneracy N of the d bands. The satellites, when resolved into its various k components does show some dispersion in its peak position, indicating the persistence of itinerant character in the satellite states, this is in contrast with the Davis-Feldkamp model of Ni in which the satellite is completely localized. The satellites have energies which are above and below the range of energies associated with the non-interacting d band. This is in agreement with precepts of the Davis-Feldkamp model, in which the satellite is related to a bound state splitting off from the edge of the d band due to the screening of a localized hole.

Photochemical reactivity of the cluster tetradecachlorohexamolybdate(2-): photosubstitution and photoredox processes

Photoreversible ligand substitution and ligand oxidation reactions have been observed in UV photolyses of Mo 6 Cl 14 2− in acetonitrile. The photosubstitution of the ligand detected in λ excit >300 nm takes place in competition with population of the low-lying states associated with Mo 6 Cl 14 2− phosphorescence and leads to the formation of intermediates that can be scavenged by excess cluster, Br − , or I − . The photoredox reaction, investigated by continuous and flash photolyses, has been detected for irradiation at wavelengths of the high energy charge transfer bands, λ excit <300 nm

Corn phosphoglycolate phosphatase: Modulation of activity by pyridine nucleotides and adenylate energy charge

The activity of corn phosphoglycolate phosphatase (EC 3.1.3.18), a bundle sheath chloroplastic enzyme, is modulated, in vitro, both by NADP(H) and adenylate energy charge. The Vmax of the enzyme is increased by NADP (25%) and NADPH (16%) whatever the pH used, 7.0 or 7.9 respective pH of the stroma in the dark and in the light. At both pH, the adenylate energy charge alone has a positive effect with two peaks of activation, characteristics for this enzyme, at 0.2 and a maximum at 0.8 accentuated under nonsaturating concentration of phosphoglycolate. At low energy charge, NADP(H) increased the activation with an additive effect most particularly observed at pH 7.9 under saturating phosphoglycolate concentration; at high energy charge, NADP(H) had a positive or negative effect on the activation, depending on the pH value and the concentrations of substrate and NADP(H).The ferredoxin-thioredoxin system does not regulate the activity since i) DTT addition do not have any effect, ii) the light-reconstituted system containing ferredoxin, ferredoxin-thioredoxin reductase, thioredoxins and thylakoids is not effective either. However, light-dark experiments indicate that phosphophycolate phosphatase can be subjected to a fine tuning of its activity.All these data suggest that light cannot induce a modification of the protein but could exert a tight control of its activity by the intermediate of Mg(2+) and substrate concentrations and the levels of metabolites such as NADP(H), ATP, ADP, AMP. So, the regulation of the activity shown, in vitro, by energy charge and NADP(H) might be of physiological significance.

Primary blast injury after a bomb explosion in a civilian bus.

A 6-kg explosive charge detonated under a seat in the center of a crowded city bus in Jerusalem, killing three passengers immediately. Of the 55 survivors, all of whom were transferred to two major medical centers, 29 were hospitalized. Among those admitted, a high rate of primary blast injuries was found, including perforated ear drums (76%), blast lung (38%), and abdominal blast injuries (14%). Two of the latter patients suffered bowel perforations, which were diagnosed with considerable delay. Eight patients (31%) had sustained life-threatening trauma, consisting of a combination of primary, secondary, and tertiary blast injuries. The overall mortality rate was 10.3%. The large number of primary blast injuries, including the unexpected finding of bowel perforations, is explained by the high amplitude of the air pressure wave (3.8-5.2 atm) and its relatively long duration (2-3 msec) resulting from the detonation of the high-energy explosive charge in the small, enclosed space of the bus. Besides the usual wounds sustained by victims of an explosion that occurs in a confined space, the possibility of primary blast injury to the abdomen and to the lungs should be taken into account by the treating surgeon.

Adenylate energy charge during the life cycle ofMyxococcus coralloidesD

The adenylate energy charge of cells of Myoococcus coralloides D has been measured during the different stages of its life cycle. The energy charge of the vegetative cells (0.8) did not change significantly either during glycerol-induced myxospore formation, or during germination of these myxospores. Fruiting body myxospores had a relatively high energy charge (0.65). The adenylate energy charge decreased slightly (from 0.82 to 0.65) throughout fruiting body development and returned to values of vegetative cells in the early hours of germination of fruiting body myxospores. The levels of adenine nucleotide in myxospores in desiccation conditions were similar to those before desiccation.

Effects of naloxone on cardiac energy metabolism in hypovolemic shock in rats

It has been reported that naloxone may be useful in the treatment of hypovolemic shock. However, the effects of naloxone on cardiac energy metabolism in hemorrhagic shock have not been investigated. The effects of naloxone on myocardial metabolism were evaluated in the rats which were bled to a systolic pressure of 40 mmHg and maintained at that pressure for 30 min. Naloxone (10 mg/kg) was administered intravenously 5 min before the heart was removed. Then the intramyocardial high energy phosphates, pyruvate, lactate, and glycogen were measured. Naloxone increased systolic blood pressure and decreased heart rate significantly. However, there were no significant differences in high energy phosphates, energy charge, pyruvate, lactate and glycogen between the control and naloxone groups. These data suggest that naloxone may have no direct effect on the cardiac energy metabolism in a 30-min hypovolemic shock.

Metabolic consequences of rapid cycles of temperature change for freeze-avoiding vs freeze-tolerant insects

The metabolic responses to repeated cycles of temperature change, alternating 24 h at −16 and +3°C, were compared for a freeze-tolerant ( Eurosta solidaginis) vs a freeze-avoiding ( Epiblema scudderiana) insect. The two species differed most strongly in the response by cellular energetics. ATP content and energy charge were depressed in E. scudderiana larvae with each −16°C exposure but rebounded with each return to +3°C; after 12 such cycles, final energy status at +3°C was not significantly different than control values. By contrast, E. solidaginis larvae maintained a high energy charge (at the expense of a decrease in the total adenylate pool) over the first two cycles of freeze/thaw only. Subsequently energy stress was cumulative, with no recovery in the +3°C half of each cycle, and energy charge fell to 0.70–0.75. Both species showed a rise in glucose-6- P with each cold exposure, indicative of cold shock activation of glycogen phosphorylase. E. scudderiana showed no net increase in cryoprotectant content over the experimental course but sorbitol levels rose 4-fold in E. solidaginis. Alanine content increased significantly in E. solidaginis over the 12 cycles but no glycolytic end products accumulated in E. scudderiana. The data indicate that the freeze-avoiding specie is better able to maintain cellular homeostasis in the face of rapid and wide variations in environmental temperature than is the freeze-tolerant specie and that this may represent a worthwhile advantage of the freeze-avoidance strategy of cold hardiness for some species.

SYNTHESIS AND CHARACTERIZATION OF A CHROMIUM(III) PHTHALATE

Abstract A chromium(III) phthalate (CP) of composition [Cr(pht)1–x(Hpht)x(OH)1+x(H2O)1–x] (x < 0.5; pht = phthalate ion. C8H4O4 2-; Hpht = hydrogen phthalate ion) has been prepared by aerial oxidation of a chromium(II) phthalate. TG analysis shows that CP loses its water content at 110°C in an essentially reversible manner, while the bulk of the organic component is lost in the 300–520°C range. A least-squares analysis of the electronic spectrum of CP reveals three d[sbnd]d transitions consistent with an octahedral environment around the Cr(III) sites, together with a high energy charge transfer band.

Regulation of Nonphosphorylating Electron Transport Pathways in Soybean Cotyledon Mitochondria and Its Implications for Fat Metabolism

The respiration of mitochondria isolated from germinating soybean cotyledons was strongly resistant to antimycin and KCN. This oxygen uptake was not related to lipoxygenase which was not detectable in purified mitochondria. The antimycin-resistant rate of O(2) uptake was greatest with succinate as substrate and least with exogenous NADH. Succinate was the only single substrate whose oxidation was inhibited by salicyl hydroxamic acid alone, indicating engagement of the alternative oxidase. Concurrent oxidation of two or three substrates led to greater involvement of the alternative oxidase. Despite substantial rotenone-resistant O(2) uptake with NAD-linked substrates, respiratory control was observed in the presence of antimycin, indicating restriction of electron flow through complex I. Addition of succinate to mitochondria oxidizing NAD-linked substrates in state four stimulated O(2) uptake substantially, largely by engaging the alternative oxidase. We suggest that these properties of soybean cotyledon mitochondria would enable succinate received from the glyoxysome during lipid metabolism to be rapidly oxidized, even under a high cytosolic energy charge.

Degradation and resynthesis of adenine nucleotides in adult rat heart myocytes.

The degradation and short-term resynthesis of adenine nucleotides have been examined in a preparation of isolated rat heart myocytes. These myocyte preparations are essentially free of vascular and endothelial cells, contain levels of adenine nucleotides quite comparable to those of intact heart tissue, and retain these components remarkably well for up to 2 h of aerobic incubation in the presence of 1 mM Ca2+. When the cells are rapidly and synchronously de-energized by addition of uncoupler, an inhibitor of respiration and iodoacetate, cellular ATP is degraded almost quantitatively to AMP. The AMP is then converted to either intracellular adenosine, which accumulates to high concentrations before release to the cell exterior, or to IMP. The relative contribution of these two pathways depends on the metabolic state of the cells just prior to de-energization, with IMP production favored when respiring cells are de-energized and adenosine formation predominant when glycolyzing myocytes are subjected to this treatment. Cells de-energized by anaerobiosis in the absence of glucose lose ATP and adenine nucleotides with the production of IMP and adenosine. Upon reoxygenation, these cells restore a high adenylate energy charge and about 60% of control levels of GTP. There is a net resynthesis of 5-7 nmol of adenine nucleotides.mg-1 protein with a corresponding decline in IMP. Added [14C]adenosine labels the adenine nucleotide pool, but little net resynthesis of adenine nucleotides via adenosine kinase can be detected. It therefore appears that a rapid regeneration of adenine nucleotides can occur via the enzymes of the purine nucleotide cycle in heart myocytes and is limited by the size of the IMP pool retained.

Trapping and annihilation in the antenna system of Photosystem I

The primary charge separation in Photosystem I of pea chloroplasts was measured as a photovoltage in the pico- and nanosecond time range by applying laser flashes at 532 nm of variable energy and different duration (12 ns and 30 ps, respectively). Contributions to the photovoltage from Photosystem II was eliminated by addition of 3-(3,4-dichlorophenyl)-1,1-dimethylurea and preillumination. The dependence of the photovoltage amplitude on the excitation energy could be described by an exponential saturation law when the excitation flash had a duration of 12 ns. Nearly the same dependence was found when the excitation source was the train of a mode-locked laser (approx. ten 30-ps flashes spaced by 7 ns; highest energy of a single flash, 80 μJ / cm −2). Even with single 30-ps flashes the photovoltage was only slightly smaller than the one elicited by 12-ns flashes of the same energy. These findings demonstrate that trapping of excitation energy by the reaction center of Photosystem I is much more effective than losses by annihilation and other loss processes. The photovoltage yield was nearly independent of the fraction of closed traps, thus demonstrating that the absorption cross section of Photosystem I is not altered by the closing of its reaction centers. By recording the rise time of the photovoltage with our highest time resolution we found that the trapping rate of the excitation energy in Photosystem I depended on the energy of the 30-ps flashes: at low excitation energies (less than 10 14 photons / cm 2 per pulse) trapping occurred within 90 ± 15 ps and at high excitation energy (10 15 photons / cm 2 per pulse) trapping and charge stabilization occurred within the time resolution of the apparatus, i.e., up to 50 ps. The trapping rate at low energies is in agreement with the one determined by fluorescence decay kinetics. Up to 50 ns there was no further detectable electrogenic phase (neither forward nor backward reactions). This demonstrates that all the electrogenicity, produced by the charge separation, takes place in less than 50 ps.

CHANGES IN LACTATE PRODUCTION IN ENTEROCYTES UNDER AEROBIC AND ANAEROBIC CONDITIONS

The aerobic production of lactate from glucose by the intestine has been proposed as an important source of carbon substrate for liver glycogen synthesis. In order to determine the significance of aerobic and anaerobic lactate production by jejunal villus cells, we determined lactate production and energy charge (EC), an indicator of intracellular oxygen availability and oxidative phosphorylation activity, in jejunal villus cells under aerobic and anaerobic conditions. Adult rat villus cells were incubated in a polarographic chamber containing Krebs Ringer Phosphate Buffer, 5 mM glutamine, 5 mM glucose and 5 mg/ml BSA. The rate of O2 consumption was determined using a Clark electrode. Aliquots of assay mixture were removed and analyzed for lactate, ATP, ADP and AMP conc, after 5 periods (5 min (aerobic), 4 min (anaerobic-O2 sat<3%), 4 min anaerobic, 4 min recovery in which the cells were placed in an aerobic medium and a 4 min aerobic period). Lactate production was calculated by substracting lactate concentration of successive samples and dividing by the time interval. EC=(ATP+0.5*ADP)/(ATP+ADP+AMP). The results are means±SD (n=4). The rate of O2 consumption, initially 0.66±.05(μmol/mg/min) was not affected by 8 min of hypoxia(0.7±.23). The EC during the aerobic period was 0.60±.07. The EC decreased to 0.52±.08 and 0.46±.05 (p<.03) at the end of 4 and 8 min of hypoxia, indicating that the hypoxic conditions altered the enterocyte oxidative phosphorylation activity. After the recovery and subsequent aerobic period, the EC increased to 0.67±.07 and 0.65±.09 respectively, Indicating aerobic metabolism of undamaged enterocytes. Lactate production remained constant during the initial aerobic and anaerobic periods (45.8±2.0 nmol/mg/min, 30.8±9 and 37.0±0). During the recovery period when the EC was initially .46, lactate production increased to 77.8±20.1 (p<.01). In the subsequent aerobic period, lactate production decreased to its original rate (42.3± 13.1). In summary, under aerobic conditions with a high EC, enterocytes can metabolize glucose to lactate and is a possible source of portal venous lactate. Furthermore, enterocyte lactate production can increase two fold during hypoxic conditions.