High-energy Compounds Research Articles

A New Method for Evaluating the Energy Characteristics of CHNO Energetic Compounds

AbstractFrom the law of conversation of energy, the release energy from the initiation to the Chapman–Jouguet point during the detonation of an energetic compound has been deduced as a function of initial density, detonation velocity, and detonation pressure. For CHNO energetic compounds the relative release energy per unit volume (Iv) approaches the relative specific wall kinetic energy (Ecyl/EHMX) at 19 mm wall displacement from the cylinder test with HMX as reference. A good linear relationship between Iv and Ecyl/EHMX has been regressed, implying that Ecyl/EHMX is also a function of initial density, detonation velocity, and detonation pressure. It has been concluded that Iv can reflect the driving force of detonation products of energetic compounds and is appropriate to be used for the evaluation of energy characteristics. The assessment of the energy for a series of synthesized and theoretically designed high‐energy compounds reveals that the future of CHNO energetic compounds is promising after CL‐20 and ONC.

4,10-Diformyl-2,6,8,12-tetra-nitro-2,4,6,8,10,12-hexa-azatetra-cyclo-[5.5.0.0.0]dodeca-ne.

The title compound TNDFIW, C8H8N10O10, is a caged heterocycle substituted with four nitro and two formyl groups. It is related to the hexa­azaisowurtzitane family of high-density high-energy polycyclic cage compounds. Four nitro groups are appended to the four N atoms of the two five-membered rings, while the other two formyl groups are attached to the two N atoms of the six-membered ring, which adopts a boat conformation. The compound has a cage structure which is constructed from one six-membered and two five-membered rings which are closed by a C—C bond, thus creating two seven-membered rings. There are a number of close intermolecular contacts [O⋯O = 2.827 (5), 2.853 (4) and 2.891 (5) Å; O⋯N = 2.746 (2) and 2.895 (2) Å] The calculated density of TNDFIW is 1.891 Mg m−3.

The ratio of foliar nitrogen to foliar phosphorus: a determinant of leaf attributes and height in life-forms of subtropical and tropical plant communities

In the species-rich overstorey of tropical and subtropical closed-forests (rainforests), a series of life-forms (emergent trees, canopy trees, subcanopy trees, mid-stratum trees and shrubs, interlaced with lianes) of increasing basal area, height and foliage attributes (leaf area, leaf specific weight and internode length) develop in equilibrium with aerodynamic fluxes (frictional, thermal, evaporative ± atmospheric salinity) in the atmosphere as it flows turbulently over and through a plant community. In both closed-forest and open-forest communities in eastern Australia, the translocation of high-energy nitrogen and phosphorus compounds into developing leaves – during the driest season of the year – increases as soil water becomes more available in the climatic gradient from the subhumid to the per-humid zone. Foliage attributes (leaf area and leaf specific weight) of vertical shoots are determined by the rate of input of high-energy compounds into developing shoot apices. Increasing nutrient input in the transpiration stream results in a greater number of leaves (with similar leaf specific weights) on vertical foliage shoots. The leaf area index of the tree is thus enhanced and leads to increased biomass, basal area and height at maturity. In each life-form within a closed-forest, the size of the root system is allometrically related to aboveground attributes. The ability of the root system to explore available nitrogen and phosphorus stored in the surface soil thus determines the attributes of developing foliage shoots in each of these life-forms. Both leaf areas and leaf specific weights decrease from maxima in canopy trees to leaves of subcanopy and mid-stratum trees in the milder climate under the dense structure of per-humid rainforests. In contrast, in the open-structured, subhumid rainforests, although leaf areas decrease in the gradient from canopy to mid-stratum trees – all exposed to direct solar radiation – leaf specific weights increase as temperatures in the boundary layer around growth-apices increase. The production of nitrate ions in soil, exposed to solar radiation in gaps, increases the uptake of nitrogen into leaves of pioneer trees. Larger and thinner leaves, with higher foliar N : P ratios and nitrate reductase activity, result in and enable rapid regeneration of the rainforest.

Forisomes: calcium-powered protein complexes with potential as ‘smart’ biomaterials

Sieve tubes in legumes contain forisomes, which are spindle-like bodies that are composed of ATP-independent, mechanically active proteins. Upon injury, forisomes occlude sieve tubes by dispersion and thus, help to prevent loss of nutrient-rich transport sap. Forisome enlargement by dispersion is brought about by Ca2+-induced conformational changes that confer radial expansion and longitudinal contraction. Forisomes recontract upon Ca2+ removal. In vitro, forisomes reversibly disperse and contract in the presence or absence of Ca2+, respectively, and at distinct pHs. Recently, forisomes have received renewed attention because of their unique capacity to convert chemical into mechanical energy independent of high-energy organic compounds. Forisome-based 'smart' materials can be used to produce self-powered monitoring and diagnostic systems. Here, we focus on physiological, chemical and physical aspects of forisomes and discuss their potential as biomimetic devices.

10-Formyl-2,4,6,8,12-pentanitro-2,4,6,8,10,12-hexaazatetracyclo[5.5.0.03,11.05,9]dodecane

The title compound, C7H7N11O11 (PNMFIW), is a caged heterocycle substituted with five nitro and one formyl groups. It is related to the hexa­azaisowurtzitane family of high-density high-energy polycyclic cage compounds. Four nitro groups are appended to the four N atoms of the two five-membered rings, while a nitro group and a formyl are attached to the two N atoms of the six-membered ring.

Oxidative modification and aggregation of creatine kinase from aged mouse skeletal muscle

Creatine kinase catalyzes the reversible transfer of the gamma phosphate from ATP to creatine forming the high energy compound creatine phosphate. Muscle creatine kinase (CKm) activity maintains energetic homeostasis as variations in energy requirements dictate that ATP be readily available. Recent studies suggest that CKm activity is altered during aging. Proteomic analyses have shown that CKm is 3-nitrotyrosine (3-NT) modified and carbonylated in aged rodent skeletal muscle. However, it remains unknown if these modifications affect its structure and activity. To address this we characterized oxidatively modified CKm from the quadriceps of young, middle-aged, and aged mice. Our data indicate that 3-NT modified and carbonylated CKm are found predominantly in aged muscle and that it exists in high molecular weight oligomers and insoluble protein aggregates. CKm from middle-aged and aged mouse quadriceps also exhibits structural instability that may account for its reduction in function. These structural and functional changes correlate with the differential protein modifications. Interestingly, the majority of the age-related changes in enzyme activity and protein stability occurred by middle age. Our studies indicate that the age-associated oxidative and nitrative modification of CKm results in a decrease in its activity and may cause structural changes that promote oligomerization and aggregation.

Metabolic biomarkers related to energy metabolism in Saudi autistic children

Objectives Energy metabolism is usually manipulated in many neurodegenerative diseases. Autism is considered a definable systemic disorder resulting in a number of diverse factors that may affect the brain development and functions both pre and post natal. The increased prevalence of autism will have enormous future public implications and has stimulated intense research into potential etiologic factors. This study aims to establish a connection between autism and the deterioration accompanied it, especially in the brain cognitive areas through a postulation of energy manipulation. Materials and methods The biochemical changes in activities of enzymes and pathways that participate in the production of ATP as the most important high-energy compound needed by the human brain were measured in Saudi autistic children. Na +/K +ATPase, ectonucleotidases (NTPDases) (ADPase and ATPase) and creatine kinase (CK), were assessed in plasma of 30 Saudi autistic patients and compared to 30 age-matching control samples. In addition, adenosine mono, di and trinucleotides (ATP, ADP, and AMP) were measured calorimetrically in the red blood cells of both groups and the adenylate energy charge (AEC) was calculated. Moreover, lactate concentration in plasma of both groups was monitored. Results The obtained data recorded 148.77% and 72.35% higher activities of Na +/K +ATPase and CK respectively in autistic patients which prove the impairment of energy metabolism in these children compared to age and sex matching healthy controls. While ADPase was significantly higher in autistic patients, ATPase were non-significantly elevated compared to control. In spite of the significant increase of Na +/K +ATPase activity in autistic patients, there was no significant difference in the levels of ATP, ADP, and AMP in both groups and the calculated AEC values were 0.814 ± 0.094 and 0.806 ± 0.081 for autistic and control groups respectively. The unchanged AEC value in autistic patients was easily correlated with the induced activity of CK and ADPase as two enzymes playing a critical role in the stabilization of AEC. Lactate as an important energy metabolite for the brain was significantly higher in autistic patients compared to control showing about 40% increase. Conclusion The present study confirmed the impairment of energy metabolism in Saudi autistic patients which could be correlated to the oxidative stress previously recorded in the same investigated samples. The identification of biochemical markers related to autism would be advantageous for earlier clinical diagnosis and intervention.

Metabolic Profiles in Urine Reflect Nephrotoxicity of Sirolimus and Cyclosporine following Rat Kidney Transplantation

Background: Cyclosporine and/or sirolimus impair recovery of renal transplants. This study examines the changes in urine metabolite profiles as surrogate markers of renal cell metabolism and function after cyclosporine and/or sirolimus treatment employing a rat kidney transplantation model. Methods: Using inbred Lewis rats, kidneys were transplanted into bilaterally nephrectomized recipients followed by treatment with either CsA (cyclosporine) 10, Rapa (sirolimus) 1, CsA10/Rapa1 or CsA25/Rapa1 mg/kg/day for 7 days. On day 7, urine was analyzed by ¹H-NMR spectroscopy. Blood and kidney tissue drug concentrations, tissue high-energy compounds (including ATP, ADP) and oxidative stress markers (15-F_2t-isoprostanes) in urine were measured by HPLC mass spectrometry. Results: Changes in urine metabolites followed the order Rapa1 < CsA10 < CsA10/Rapa1 < CsA25/Rapa1. Compared with controls, CsA25/Rapa1 showed the greatest changes (creatinine –36%, succinate –57%, citrate –89%, α-ketoglutarate –75%, creatine +498%, trimethylamine +210% and taurine +370%). 15-F_2t-isoprostane concentrations in urine increased in the combined immunosuppressant-treated animals ([CsA25/Rapa1]: 795 ± 222, [CsA10/Rapa1]: 475 ± 233 pg/mg/creatinine) as compared with controls (165 ± 78 pg/mg creatinine). Rapa concentration in blood and tissues increased in the combined treatment (blood: 31 ± 8 ng/ml, tissue: 1.3 ± 0.4 ng/mg) as compared with monotherapy (blood: 14 ± 8 ng/ml, tissue: 0.35 ± 0.15 ng/mg). Drug blood concentrations correlated with isoprostane urine concentrations, which correlated negatively with citrate, α-ketoglutarate and creatinine concentrations in urine. Only CsA25/Rapa1 significantly reduced high-energy metabolite concentrations in transplant kidney tissue (ATP –55%, ADP –24%). Conclusion: Immunosuppressant drugs induce changes in urine metabolite patterns, suggesting that immunosuppressant-induced oxidative stress is an early event in the development of nephrotoxicity. Urine 15-F_2t-isoprostane concentrations and metabolite profiles may be sensitive markers of immunosuppressant-induced nephrotoxicity.

Theoretical Investigation on Structures, Densities, Detonation Properties, and the Pyrolysis Mechanism of the Derivatives of HNS

The derivatives of 2,2',4,4',6,6'-hexanitrostilbene (HNS) are optimized to obtain their molecular geometries and electronic structures at the DFT-B3LYP/6-31G* level. Detonation properties are evaluated using the modified Kamlet-Jacobs equations based on the calculated densities and heats of formation. It is found that there are good linear relationships between the density, detonation velocity, detonation pressure, and number of nitro, amino, and hydroxy groups. The thermal stability and pyrolysis mechanism of the title compounds are investigated by calculating the bond dissociation energies at the unrestricted B3LYP/6-31G* level. For the nitro and amino derivatives of HNS, the C-NO(2) bond is a trigger bond during the thermolysis initiation process, while for hydroxy derivatives, it is started from the isomerization reaction of the hydrogen transfer in the O-H bond. According to the quantitative standard of energetics and stability, as high-energy density compounds, 2,2',3,3',4,4',5,6,6'-nonanitrostilbene and 2,2',3,3',4,4',5,5',6,6'-decanitrostilbene essentially satisfy this requirement. In addition, we have discussed the effect of the nitro, amino, and hydroxy groups on the structure and properties.

Silane coupling di-carbazoles with high triplet energy as host materials for highly efficient blue phosphorescent devices

We report the synthesis and characterization of two high triplet energy compounds bis(4-(9-carbazolyl)phenyl)dimethylsilane (DMSiCBP) and bis(4-(9-carbazolyl)phenyl)diphenylsilane (DPSiCBP), which can be used as the host materials for blue phosphorescent devices. Triplet energy of both DMSiCBP and DPSiCBP arrive at a level of 3.0 eV, which is significantly higher than the commonly used host materials for blue phosphorescence, such as CBP(2.6 eV) and mCP(2.9 eV). The DPSiCBP is fully-amorphous with a higher glass transition temperature of 120 °C, and excellent morphologically stability based on DSC analysis and annealing atomic force microscopy (AFM) investigation. The phosphorescent EL devices, employing DPSiCBP doped with blue iridium complex Firpic as the emitting layer, show the maximum brightness of 12130 cd/m2 and maximum luminous efficiency of 6.5 cd/A, which is superior to those of CBP-based devices.

Mitochondrial function in vivo: Spectroscopy provides window on cellular energetics

Mitochondria integrate the key metabolic fluxes in the cell. This role places this organelle at the center of cellular energetics and, hence, mitochondrial dysfunction underlies a growing number of human disorders and age-related degenerative diseases. Here we present novel analytical and technical methods for evaluating mitochondrial metabolism and (dys)function in human muscle in vivo. Three innovations involving advances in optical spectroscopy (OS) and magnetic resonance spectroscopy (MRS) permit quantifying key compounds in energy metabolism to yield mitochondrial oxidation and phosphorylation fluxes. The first of these uses analytical methods applied to optical spectra to measure hemoglobin (Hb) and myoglobin (Mb) oxygenation states and relative contents ([Hb]/[Mb]) to determine mitochondrial respiration (O 2 uptake) in vivo. The second uses MRS methods to quantify key high-energy compounds (creatine phosphate, PCr, and adenosine triphosphate, ATP) to determine mitochondrial phosphorylation (ATP flux) in vivo. The third involves a functional test that combines these spectroscopic approaches to determine mitochondrial energy coupling (ATP/O 2), phosphorylation capacity (ATP max) and oxidative capacity (O 2max) of muscle. These new developments in optical and MR tools allow us to determine the function and capacity of mitochondria noninvasively in order to identify specific defects in vivo that are associated with disease in human and animal muscle. The clinical implication of this unique diagnostic probe is the insight into the nature and extent of dysfunction in metabolic and degenerative disorders, as well as the ability to follow the impact of interventions designed to reverse these disorders.

A Theoretical Study of Highly Nitrated Azacubanes

The geometries of highly nitrated azacubanes have been fully optimized at the B3LYP/6-31 ++ G** theory level, and the gas phase enthalpies of formation have been obtained by designing the isodesmic reaction in which the azacubane cage skeleton is not destroyed. An efficient procedure for judging the driving force of detonation products of energetic compounds has been developed from the conservation of energy condition. The MP2/6-31 ++ G**//B3LYP/6-31 ++ G** atom-atom overlap-weighted NAO bond order shows that after the full nitration of 1,4-diazacubane and 1,3,5,7-tetraazacubane the weakest C–N bond on the 1,3,5,7-tetraazacubane cage skeleton strengthens slightly, but on the 1,4-diazacubane cage skeleton it weakens. For highly nitrated azacubanes, the introduction of –NH2 group results in the destabilization of the neighboring C–N bond on the cage skeleton. The shock stability of 2,4,6,8-tetranitro-1,3,5,7-tetraazacubane (TNTAzC) is superior to that of 2,3,5,6,7,8-hexanitro-1,4-diazacubane (HNDAzC). The detonation velocity and pressure for TNTAzC are predicted to reach 11.10 km/s and 101.7 GPa, respectively. The driving force of detonation products of HNDAzC is close to that of octanitrocubane, and the driving force of TNTAzC is about 4.0 times as large as that of the widely used high explosive HMX, showing that TNTAzC is a potential candidate of super high-energy compound.

Marine fish spermatozoa: racing ephemeral swimmers

After a long period of spermatogenesis (several weeks to months), marine fish spermatozoa are delivered at male spawning in seawater (SW) at the same time as ova. In some fish species, as the ova micropyle closes quickly after release, these minute unicells, the spermatozoa, have to accomplish their task of reaching the micropyle within a very brief period (several seconds to minutes), for delivery of the haploid male genetic information to the ova. To achieve this goal, their high-performance motile equipment, the flagellum, must fully activate immediately on contact with the SW and then propel the sperm cell at an unusually high initial velocity. The cost of such 'hyperactivity' is a very rapid consumption of intracellular ATP that outstrips the supply. The spermatozoa become rapidly exhausted because mitochondria cannot compensate for this very fast flagellar energy consumption. Therefore, any spermatozoon ends up with two possibilities: either becoming exhausted and immotile or reaching the egg micropyle within its very short period of forward motility (in the range of tens of seconds) before micropyle closure in relation to both contact of SW and cortical reaction. The aim of the present review is to present step by step the successive events occurring in marine fish spermatozoa from activation until their full arrest of motility. The present knowledge of activation mechanisms is summarized, as well as a description of the motility parameters characterizing the motility period. As a complement, in vitro results on axonemal motility obtained after demembranation of flagella bring further understanding. The description of the sperm energetic content (ATP and other high energy compounds) and its evolution during the swimming period is also discussed. A general model aiming to explain all the successive cellular events occurring immediately after the activation is presented. This model is proposed as a guideline for understanding the events governing the sperm lifespan in the marine fish species that reproduce through external fertilization.

Harnessing plant biomass for biofuels and biomaterials

Harnessing plant biomass for biofuels and biomaterials

Endotoxemia does not limit energy supply in exercising rat skeletal muscle

Although depletion in high-energy phosphorylated compounds and mitochondrial impairment have been reported in septic skeletal muscle at rest, their impact on energy metabolism has not been documented during exercise. In this study we aimed to investigate strictly gastrocnemius muscle function non-invasively, using magnetic resonance techniques in endotoxemic rats. Endotoxemia was induced by injecting animals intraperitoneally at t(0) and t(0) + 24 h with Klebsiella pneumoniae lipopolysaccharides (at 3 mg kg(-1)). Investigations were performed at t(0) + 48 h during a transcutaneous electrical stimulation protocol consisting of 5.7 min of repeated isometric contractions at a frequency of 3.3 HZ. Endotoxin treatment produced a depletion in basal phosphocreatine content and a pronounced reduction in oxidative adenosine triphosphate (ATP) synthesis capacity, whereas the resting ATP concentration remained unchanged. During the stimulation period, endotoxemia caused a decrease in force-generating capacity that was fully accounted for by the loss of muscle mass. It further induced an acceleration of glycolytic ATP production and an increased accumulation of adenosine diphosphate (ADP, an important mitochondrial regulator) that allowed a near-normal rate of oxidative ATP synthesis. Finally, endotoxemia did not affect the total rate of ATP production or the ATP cost of contraction throughout the whole stimulation period. These data demonstrate that, in an acute septic phase, metabolic alterations in resting muscle do not impact energy supply in exercising muscle, likely as a result of adaptive mechanisms.

A novel mode of dimerization via formation of a glutamate anhydride crosslink in a protein crystal structure

Acid anhydrides are formed by removal of water, are very active, and can react with water to form the original binary components.

Conformations and charge distributions of diazocyclopropanes

AbstractThree diazo‐substituted cyclopropane compounds, which have been suggested as new potential high energy compounds, were studied employing the B3LYP‐DFT/6‐31G(d,p) method. Geometries were optimized. Distributed multipole analysis, computed from the B3LYP‐DFT/6‐31G(d,p) density matrix, was used to describe the details of the molecular charge distribution of the three molecules. It was verified that electron withdrawing from the C ring atoms and charge build‐up on the N atoms bonded to the ring increased with the number of diazo groups. These effects were related to increased sensitivity to impact and easiness of CN bond breaking in the three compounds. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008

The structure and functionality of contractile forisome protein aggregates

Although they have been discovered decades ago, only in the last years forisome protein aggregates received broader attention due to their ability to convert chemical into mechanical energy. In contrast to most other motor proteins, these proteins from Fabaceae plants are independent of high-energy chemical compounds, like e.g. ATP, but undergo an anisotropic shape transition (longitudinally expanded to contracted) in response to ion concentration changes (Ca 2+, H +, etc.), instead. We present morphological and functional data on forisomes obtained using atomic force microscopy (AFM). High-aspect ratio AFM tips allow the detailed elucidation of structural characteristics that are inaccessible with standard AFM tips. Microindentation measurements were employed to calculate the elasticity of the forisome material. Young's moduli were found to be ∼32.7 kPa in the expanded state and ∼2.748 kPa in the contracted state of the polymer. These results are compared to investigations where a tipless AFM cantilever was utilized to exert a load against the shape transition. In the latter experiments, an energy conversion of ∼2.29 pJ per stroke was detected. Energetical considerations support the hypothesis that the switching process is accompanied by a change in cross-linking of the constituent subunits and allow estimating the extent of cooperativity during the pH-induced transition. Finally, useful parameters were identified and characterized that are crucial for the application of forisomes as functional elements in microfluidic chips.

One-step isolation of adenosine triphosphate from crude fermentation broth of Saccharomyces cerevisiae by anion-exchange chromatography using supermacroporous cryogel

Adenosine triphosphate (ATP) is an important high-energy compound widely used in biological and therapeutic fields. It can be produced by phosphorylation of adenosine monophosphate (AMP) with microbial cells in industrial scale and the effective isolation of ATP from microbial fermentation broth is a challenging work. In this work, we develop a novel one-step method to directly separate ATP from fermentation broth of Saccharomyces cerevisiae by anion-exchange chromatography using supermacroporous cryogel. The cryogel bed with tertiary amine groups was prepared by grafting N, N-dimethylaminoethyl methacrylate (DMAEMA) monomer chains onto the matrix of a polyacrylamide-based cryogel in a glass column and its properties of liquid dispersion, water permeability, porosity as well as the ligand density were measured. Chromatographic separation of ATP from the fermentation broth by the cryogel was carried out using deionised water and 0.01 M HCl as running buffer, respectively. The breakthrough characteristics and elution performance in the cryogel bed were revealed and analyzed. The purities of the obtained ATP were analyzed quantitatively by high performance liquid chromatography (HPLC). The maximal purity of ATP by the one-step separation method was 95.5% using 0.01 M HCl as running buffer in this work. The corresponding chromatographic behaviors were investigated and analyzed.

Intense exercise increases adenosine concentrations in rat brain: Implications for a homeostatic sleep drive

Intense exercise and sleep deprivation affect the amount of homeostatically regulated slow wave sleep in the subsequent sleep period. Since brain energy metabolism plays a decisive role in the regulation of behavioral states, we determined the concentrations of nucleotides and nucleosides: phosphocreatine, creatine, ATP, ADP, AMP, adenosine, and inosine after moderate and exhaustive treadmill exercise as well as 3 and 5 h of sleep deprivation and sleep in the rat brain using the freeze-clamp technique. High intensity exercise resulted in a significant increase of the sleep-promoting substance adenosine. In contrast, following sleep, inosine and adenosine levels declined considerably, with an accompanied increase of ADP after 3 h and ATP after 5 h. Following 3 h and 5 h sleep deprivation, ADP and ATP did not differ significantly, whereas inosine increased during the 3 and 5-h period. The concentrations of AMP, creatine and phosphocreatine remained unchanged between experimental conditions. The present results are in agreement with findings from other authors and suggest that depletion of cerebral energy stores and accumulation of the sleep promoting substance adenosine after high intensity exercise may play a key role in homeostatic sleep regulation, and that sleep may play an essential role in replenishment of high-energy compounds.