Synthesis of ultrafine diamonds from alloys of TNT with polycyclic nitramines

The synthesis of ultrafine diamonds from alloys of TNT with new polycyclic nitramines was studied experimentally. The use of nitramines with an oxygen balance smaller than that of RDX increases the yield of ultrafine diamonds. An increase in the particle size of the sensitizer in the TNT alloys was shown to result in a higher yield of diamonds. __________ Translated from Fizika Goreniya i Vzryva, Vol. 42, No. 4, pp. 131–134, July–August, 2006.     

Soil and vegetation carbon pools in a mountainous watershed of Nepal

Assessment of carbon stocks in vegetation and soil is a basic step in evaluating the carbon sequestration potential of an ecosystem. We collected soil (core and composite) samples from 0–10, 10–20, 20–40, and 40–70 cm depths, or down to the bed rock, in the soil profile of four types of forest (managed dense Shorea (DS), degraded forest (DF), pine mixed (PS), and Schima–Castanopsis (SC) forest) and two types of cultivated land (irrigated low land (Khet) and rain-fed upland (Bari)) in the Pokhare Khola watershed of Nepal. In addition to other essential properties, soil bulk density and carbon concentration were assessed. Fine roots were also collected from each sampling site. The biomass of standing trees and shrubs was estimated by using allometric relationships after measuring their diameter and height, while the biomass of grasses was estimated by a direct measurement of grass from a defined area. The carbon stocks in all forest vegetation (trees, shrubs, and ground grass) and in the soil profiles under different land uses were estimated. The vegetation carbon pool was largest in DS forest (219 ± 34 Mg ha⁻¹) and least in SC forest (36 ± 5 Mg ha⁻¹), while its order among forest types was DS > DF > PS > SC. The soil organic carbon (SOC) pool was largest in Bari land (15.7 ± 1.5 kg C m⁻²) and least in PS forest (6.2 ± 0.5 kg C m⁻²) but the overall order among land uses was Bari > DF > Khet > SC > DS > PS. The total SOC stock in the whole watershed was 59 815 Mg, of which 36, 32, and 32% were in the 0–20, 20–40, and >40 cm soil depths, respectively. In the surface layer (0–10 cm), SOC stock was highest in Bari (36%) followed by DS (31%), and least was in PS forest (3%). This distribution pattern can primarily be assigned to SOC concentration and area covered by these land uses.     

Direct Measurement of Aircraft Engine Soot Emissions Using a Cavity-Attenuated Phase Shift (CAPS)-Based Extinction Monitor

The optical properties of soot particles in plumes emanating from a high bypass turbofan aircraft engine (V2527) were measured at distances of 40–80 m behind the engine with a cavity-enhanced phase shift (CAPS)-based extinction monitor (known as the CAPS PM_ex) and a multi-angle absorption photometer, both operating at wavelength ～630 nm. Integrated plume measurements from the two instruments were highly correlated with each other (r ² > 0.99, N = 12) and with measured carbon dioxide emission concentrations. Ancillary measurements indicated that the soot particle volume-weighted mobility diameter distribution peaked at 60 nm with a full width at half maximum of ～60 nm. The soot single scattering albedo determined using the absorption and extinction measurements under engine idle conditions was 0.05 ± 0.02 (where the uncertainty represents 2σ precision), in agreement with previous measurements of aircraft exhaust. The engine soot emission index (mass soot per mass fuel burned) for this particular engine, derived from these measurements and a wavelength-specific mass absorption coefficient and the measured in-plume carbon dioxide concentrations, was 225 ± 35 mg kg^?1 at engine idle conditions. These results plus more limited data collected from in-use aircraft on the runway indicate that the CAPS extinction monitor can provide (with an appropriate albedo correction) a credible measurement of the engine soot emission index in situations where the time response and sensitivity of particle absorption monitors are not otherwise sufficient.     

Detonation of mixtures of bistrinitroethylnitramine with carbon

The dependence of detonation rate on charge density is determined for bistrinitroethylnitramine and stoichiometric mixtures of it with carbon (soot, graphite with different particle sizes). A characteristic feature of dependences for mixtures of BTNENA with carbon is a discontinuity whose position corresponds to the following charge densities, g/cm³: 1.43 for a mixture with soot, 1.15 and <0.4 g/cm³ for a mixture with graphite (particle size 10⁻³cm) and 5.6·10⁻³ cm respectively). The treatment of experimental results is provided. Institute of Chemical Physics, Russian Academy of Sciences, Chernogolovka 142432. Translated from Fizika Goreniya i Vzryva, Vol. 30, No. 5, pp. 97–99, September–October, 1994.     

Composite WSi<Subscript>2</Subscript>–<Emphasis Type="Italic">Me</Emphasis><Superscript>V</Superscript>B<Subscript>2</Subscript> materials in W–Si–<Emphasis Type="Italic">Me</Emphasis><Superscript>V</Superscript>–B systems

Sections are constructed for WSi₂–Me ^VB₂ of the quaternary systems W–Si–(V, Nb, Ta)–B described by eutectic diagrams of state with T _eut (1940 ± 20), (1980 ± 20) and (2020 ± 30)°C and a boride content in the eutectics of 35, 20 and 15 mol.% respectively. Translated from Novye Ogneupory, No. 3, pp. 41 – 44, March 2009.     

Oxidation of a coal particle in flow of a supercritical aqueous fluid

A study was made of the conversion of single spherical coal particles of diameter 1–5 mm in a supercritical H₂O/O₂ fluid with an oxygen mass fraction of 0–6.6% in a semibatch reactor at a pressure of 30 MPa and a temperature of 673–1023 K. A decrease in the particle mass was observed in two parallel processes: gasification of coal with water and oxidation of coal with oxygen. An activation energy 19 ± 7 kJ/mole and a pre-exponential factor 10^−2±0.4 sec⁻¹ were obtained under the assumption of zero order for the concentration H₂O and an Arrhenius dependence for the rate of gasification with water. The oxidation with oxygen at a temperature above 780 K was found to be limited by the rate of O₂ diffusion to the coal organic matter. Below 780 K, the rate of heterogeneous oxidation with oxygen is described by a first-order reaction for the concentration of O₂ and a zero-order reaction for the concentration of H₂O with an activation energy of 150 ± 27 kJ/mole and a pre-exponential factor of 10^7.6±1.9 cm³/(g · sec). __________ Translated from Fizika Goreniya i Vzryva, Vol. 44, No. 2, pp. 23–31, March–April, 2008.     

Relative contribution of trees and crops to soil carbon content in a parkland system in Burkina Faso using variations in natural 13C abundance

The origin of organic matter was studied in the soils of a parkland of karité (Vitallaria paradoxa C.F. Gaertn) and néré (Parkia biglobosa (Jacq.) Benth.), which is extensively cultivated without the use of fertilisers. In such systems, fertility (physical, chemical and biological) gradients around trees have been attributed by some authors to a priori differences in fertility, allowing for better tree establishment on richer sites. In reverse, other workers believed that these gradients are due to the contribution of trees to the formation of soil organic matter through litter and decay of roots. Measurements of the variations in the ¹³C isotopic composition allowed for a distinction between tree (C₃) derived C and crop and grass (C₄) derived C in the total soil organic C content. The organic carbon contents of the soils were recorded under the two species at two soil depths and at five distances going from tree trunk to the open area and their C isotopic signatures were analysed. The results showed that soil carbon contents under karité (6.43 ± 0.45 g kg⁻¹) and néré (5.65 ± 0.27 g kg⁻¹) were significantly higher (p<0.01) than in the open area (4.09 ± 0.26 g kg⁻¹). The δ¹³C of soil C was significantly higher (p<0.001) in the open area (−17.5 ± 0.3‰) compared with the values obtained on average with depth and distance from tree under karité (−20.2 ± 0.4‰) and néré (−20.1 ± 0.4‰). The C₄-derived soil C was approximately constant, and the differences in total soil C were fully explained by the C₃ (tree) contributions to soil carbon of 4.01 ± 0.71, 3.02 ± 0.53, 1.53 ± 0.10 g kg⁻¹, respectively under karité, néré and in the open area. These results show that trees in parklands have a directly positive contribution to soil carbon content, justifying the need to encourage the maintenance of trees in these systems in semi-arid environments where the carbon content of soil appears to be the first limiting factor for crop growth.     

Bidirectional Selection for Novel Pheromone Blend Ratios in the Almond Moth, <Emphasis Type="Italic">Cadra cautella</Emphasis>

The sex pheromone of the almond moth, Cadra cautella, is a blend of (Z,E)-9,12-tetradecadienyl acetate (Z9,E12–14:Ac, the major component capable of inducing attraction alone) and (Z)-9-tetradecenyl acetate (Z9–14:Ac, the minor component, which is unattractive alone but augments attraction of the major component). In this study, the ratio of the two components responded to artificial directional selection in five of six selected lines, whereas no change was observed in the three control lines. The mean ratio (±SE) of Z9,E12–14:Ac to Z9–14:Ac went from 13.72 ± 1.02:1 to 20.13 ± 0.68:1 in high line 1, an increase of 47%. In the second high-selected line, the mean ratio (±SE) increased from 9.87 ± 0.54:1 to 15.89 ± 0.85:1, an increase of 61%. In low line 1, the mean ratio (±SE) in the parental generation was 10.74 ± 0.78:1 and 7.35 ± 0.41:1 in the last selected generation, a decrease of 32%. The response to selection was greater in low line 2, as the mean ratio (±SE) decreased from 10.11 ± 0.66:1 to 5.65 ± 0.55:1 in the last generation, a decrease of 44%. In low line 3, the mean ratio (±SE) in the parental generation was 13.63 ± 0.82:1 and 6.47 ± 0.26:1 in the last generation, a decrease of 53%. The response to selection was approximately symmetrical with a mean increase of 54% and a mean decrease of 43%. The increases in ratio observed in the high lines were caused by an increase in the titer of the Z9,E12–14:Ac component with no concurrent change in the titer of the component Z9–14:Ac. Among the low selected lines, the titers of both components increased; however, there was a greater relative increase in the titer of the component Z9–14:Ac. The absolute and relative titers of the sex pheromone components had decreased significantly in the F10 generation in some of the selected lines, five generations after the discontinuation of selection.     

A study of the interaction between the components of heterogeneous explosives by the electrical-conductivity method

The detonation of TNT/RDX alloys is studied by the electrical-conductivity method. The measurement technique is developed with correction for the deformation of electrodes in the explosion. The maximum electrical conductivity of pure TNT was ≈25 Ω⁻¹·cm⁻¹. The addition of RDX decreases the electrical conductivity and width of the conducting zone, which, is, apparently, connected with the formation of diamond. It is shown that the RDX particle size plays an important role. With equal mass fraction, the conductivity of the sample is several times smaller for micron particles than for millimeter particles. This fact is explained by the different degree of mixing of the detonation products of the heterogeneous-explosive components. Translated fromFizika Goreniya i Vzryva, Vol. 36, No. 5, pp. 97–108, September–October, 2000. This work was supported by the Russian Foundation for Fundamental Research (Grant Nos. 99-03-32336 and 96-15-96264).     

Formation and growth of dispersed carbon particles during pyrolysis of ethylene,benzene, and naphthalene in a reflected shock wave

The formation and growth rates of dispersed carbon particles were determined experimentally for pyrolysis of ethylene, benzene, and naphthalene in a reflected shock wave at temperatures of 1920–2560 K and hydrocarbon concentrations in argon of 1.8–20%. The diameter of the particles formed was estimated (30–600 Å). The maximum rate of particle formation at various temperatures [(0.7–96) · 10¹⁶ cm⁻³·sec⁻¹] and the particle growth rate (0.002–0.036 cm · sec⁻¹) were determined from results of measurements of reaction (residence) times. For pyrolysis of benzene, the activation energy of the overall process of particle formation is 410 kJ/mole, and for all hydrocarbons studied, the activation energy of the overall process of particle growth is 5–50 kJ/mole. The surface average particle diameter increases with increasing concentration of the initial hydrocarbon at a constant temperature. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 4, pp. 82–89, July–August, 2007.     

Investigation of the reaction zone in heterogeneous explosives substances using an electrical conductivity method

A technique for measuring the electrical conductivity profile behind a detonation wave front with a resolution of about 0.1 mm was used to analyze the reaction zone in heterogeneous explosives. TNT-RDX mixtures, RDX with additives of water, NaCl, and a saturated aqueous solution of NaCl, and pure RDX of low density were studied. It was shown that the particle size of the explosive can have a significant effect on the structure of the reaction zone. The most narrow conducting zone (0.22 mm) was observed in fine RDX of density 1.2 g/cm³. __________ Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 2, pp. 109–115, March–April, 2008.     

Measurement of Light Absorption Extinction in Denver

Simultaneous measurements of b _ext (teleradiometer), b _sp (integrating nephelometer), and b _ag (N0₂ monitor) were used to obtain particle absorption extinction coefficients b _ap for the Denver atmosphere during January 1982. The average of the ratio b _ap/b _sp was measured to be 0.185 ± 0.015 at 530 nm, which is 2–3 times smaller than previous measurements. Supplementary data included b _ap measurements by the integrating plate method, which yielded values systematically higher by about 35%, and elemental carbon (black soot) aerosol concentration, from which a value of 8.0±0.6 m² g^?1 was obtained for the mass-specific absorption coefficient of elemental carbon.     

Highly selective and sensitive Th<Superscript>4+</Superscript>-PVC-based membrane sensor based on 2-(diphenylphosphorothioyl)-<Emphasis Type="Italic">N</Emphasis>′,<Emphasis Type="Italic">N</Emphasis>′-diphenylacetamide

A Th⁴⁺ ion-selective membrane sensor was fabricated from poly (vinyl chloride) (PVC) matrix membrane containing 2-(diphenylphosphorothioyl)-N′,N′-diphenyl acetamide (DPTD) as a neutral carrier, potassium tetrakis (p-chlorophenyl) borate (KTpClPB) as anionic excluder and o-nitrophenyloctyl ether (NPOE) as a plasticizing solvent mediator. The effects of the membrane composition, pH and additive anionic influence on the response properties were investigated. The sensor, comprising 30% PVC, 63% solvent mediator, 4% ionophore and 3% anionic additive demonstrates the best potentiometric response characteristics. It displays Nernstian behavior (15.2 ± 0.5 mV per decade) over the concentration range 1.0 × 10⁻²–1.0 × 10⁻⁶ M. The detection limit of the electrode is 6.3 × 10⁻⁷ M (∼140 ng/ml). The response time of the electrode is 30 s .The sensor can be used in the pH range 3.0–9.0 for about 6 weeks. The membrane sensor was used as an indicator electrode in the potentiometric titration of Th⁴⁺ ions with EDTA. It was successfully applied to the determination of thorium ions in binary mixture.     

A Study of Optical Properties of Soot Aggregates Composed of Poly-Disperse Monomers Using the Superposition T-Matrix Method

The diameters of soot monomers may not be constant in the single fractal aggregated soot particle. The optical properties of light absorbing soot particles aggregated with poly-disperse monomers were studied using the superposition T-matrix method. Soot aggregates were generated with different log-normal probability distribution functions (PDF) of soot monomer diameter, according to the same soot volumes and monomer numbers. The single scattering properties of soot particles were calculated at a wavelength of 550 nm, assuming a soot refractive index of 1.95 + 0.79i and a mass density of 1.8 g/cm³. The random-orientation averaging results indicated that the optical properties of soot aggregates were fairly varied for the different distributions of the monomer diameters. In these simulations, the extinction and absorption of soot aggregates were slightly (<10%) affected by the monomer poly-dispersity. The simulated mass absorption cross-sections (MAC) of fresh dry soot particles aggregated with poly-disperse monomers reached up to 6.62 ± 0.07 m²/g, which was closer to the measurement (7.5 ± 1.2 m²/g) than the assumption of volume-equivalent mono-disperse monomer (6.36 ± 0.06 m²/g). Moreover, the optical properties of soot coated with an organic shell were calculated, and the optical results showed that the absorption cross-sections of the internally mixed soot particles were also slightly (<8%) influenced by the monomer poly-dispersity. We found that the effect of the monomer poly-dispersity on the light scattering and the single scattering albedo may be considerably large (up to ?50% in extreme cases) for fresh dry soot aggregates. This effect on light scattering should be taken into account for those aggregates composed of monomers with widely distributed diameters.

Copyright 2015 American Association for Aerosol Research     

Variation in fatty acid content and seed weight in some lauric acid richCuphea species

Significant genetic variation for lauric acid (12∶0) and capric acid (10∶0) composition and seed weight was measured within lauric acid-rich, self-pollinating germplasm accessions ofCuphea wrightii, C. tolucana, andC. lutea. Means and ranges of individual plant progenies for 12∶0 content ofC. wrightii accessions was 60.5±.63% (49.8±65.8%), 10∶0 content was 23.7±.54% (18.6±33.0%), and 1000-seed weight was 1.50±.03 g (1.20–2.47 g). Progenies of single plant selections carried to the S₂ generation exhibited reduced variability within selections, but significant variation among selections for 12∶0, 10∶0 and 1000-seed weight. Variation among single plant selections ofC. tolucana was less than that ofC. wrightii and attributed to a restricted germplasm base. Means and ranges for 12∶0 content were 61.6±.47% (59.2–69.9%), 10∶0 was 22.3±.62% (11.7–25.3%), and 1000-seed weight was 1.40±.05 g (0.90–1.69 g).Cuphea lutea has a significantly different 12∶0−10∶0 profile than the other lauric acid-rich species. Means and ranges for 12∶0 were 36.8±.14% (33.7–40.8%), 10∶0 was 21.8±.08% (16.4–23.9%), 1000-seed weight was 2.26±.02 g (1.82–272 g). The 1000-seed weight was highly positively correlated with 8∶0, 10∶0, 18∶1 and 18∶2 contents and highly negatively correlated with 12∶0, 14∶0 and 16∶0 in bothC. wrightii andC. tolucana. No such relationship was found forC. lutea. A highly significant negative correlation was also measured for 12∶0 and 10∶0 contents inC. wrightii andC. tolucana.     

Vitamin E. Deficiency increases the synthesis of platelet-activating factor (PAF) in rat polymorphonuclear leucocytes

Vitamin E deficiency was found to stimulate FMLP (N-formyl-L-methionyl-L-leucyl-L-phenylalanine)-induced biosynthesis of PAF (1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine) in polymorphonuclear leucocytes (PMN) from rat peritoneum. In three separate experiments each, the amounts of PAF synthesized during 6min and 12 min incubation of PMN cells from control, vitamin E-supplemented, and vitamin E-deficient rats were 129–240, 131–227 and 248–354 pmol/10⁶ cells, respectively. The activity of the acetyl-transferase, which transfers the acetyl moiety of [³H]acetyl-CoA to 2-lysoPAF (1-O-alkyl-sn-glycero-3-phosphocholine) to form [³H]PAF, was higher in PMN homogenates from vitamin E-deficient rats (2.28±0.07 nmol/min/mg protein) than in those from E-supplemented rats (1.06±0.10 nmol/min/mg protein). However, there was no difference between the two groups in the activity of acetylhydrolase (4.26±0.71 and 4.26±0.06 nmol/min/mg protein, respectively), measured as degradation of [³H]PAF to [³H]lysoPAF.In vitro addition of α-tocopherol did not inhibit the increased activity of acetyl-transferase in vitamin E-deficient rats, in-dicating that the enzyme in vitamin E-supplemented rats was not directly inhibited by α-tocopherol. The acetyltransferases of the two groups showed similar Km values for acetyl-CoA, but different Vmax values (225 μM and 6.4 nmol/min/mg protein in vitamin E-deficient rats, and 216 μM and 3.6 nmol/min/mg protein in vitamin E-supplemented rats), suggesting that the enzyme was not activated but increased in amount in vitamin E deficiency.     

Root exudates of a legume tree as a nitrogen source for a tropical fodder grass

Exudation of nitrogenous compounds from the roots of dinitrogen-fixing plants is a potential source of nitrogen for adjacent plants in intercropping systems. We studied (1) the extent of N exudation from the roots of a tropical legume tree Gliricidia sepium (Jacq.) Kunth ex Walp., and (2) the ability of a C4 fodder grass Dichantium aristatum (Poir) C.E. Hubbard and its mycorrhizal symbionts to absorb N from tree exudates in a glasshouse experiment. Root exudates of ¹⁵N-labelled trees were collected in hydroponic culture and applied with irrigation water on grass grown in separate pots. During the 10-week experiment, the trees exuded 34.1 ± 5.0 mg of N, which represented 1.7 ± 0.2% of their total N by the end of the experiment. The total amount exuded would have been enough to supply 16% of grass N content by the end of the experiment. The grass, however, absorbed only 3.8–7.5% of ¹⁵N in exudates and gained 0.8–1.1% of its N from exudates. The low absorption of exudate N by grass was explained by probable soil microbial immobilisation and by the dilution of exuded N in the substantially larger pool of soil mineral N. A close contact between the root systems of N donor and recipient plants directly or via their mycorrhizal symbionts seems to be a precondition of the apparently direct N transfer earlier observed in field studies of the same soil-plant system.     

A spectroscopic study of the interaction of nigerloxin,a fungal metabolite,with serum albumin

Nigerloxin [2-amido-3-hydroxy-6-methoxy-5-methyl-4-(prop-1′-enyl) benzoic acid], a fungal metabolite, is an inhibitor of lipoxygenase and aldose reductase with free radical-scavenging properties. The interaction of nigerloxin with bovine serum albumin (BSA) was investigated using fluorescence spectroscopy and circular dichroic measurements. The fluorescence of BSA was quenched following interaction with nigerloxin, and this property was used to generate a binding constant. The estimated association constant was 1.01±0.2×10⁶ M⁻¹. Job's method of continuous variation indicated that nigerloxin formed a 1∶1±0.1 complex with BSA. To understand the nature of the interaction, the variance in the association constant as a function of temperature in the range of 14–45°C was used to calculate the thermodynamic parameters. The thermodynamic parameters at 27°C derived from the mass action plot and van't Hoff's plot were as follows: ΔG=−8.2±0.1 kcal/mol, ΔH≈0 kcal/mol, and ΔS=27.5±0.4 cal/mol/K (where ΔG is free energy, ΔH is enthalpy, and ΔS is entropy). Increasing ionic strength did not favor interaction. Circular dichroic measurements revealed that the interaction of nigerloxin with BSA did not lead to changes in the secondary structure of the protein. The reversibility of the interaction verified by the dilution method was found to be reversible. These measurements suggest that partial hydrophobic and partial ionic bonding play a role in the interaction of nigerloxin with BSA.     

Soot formation in isothermal pyrolysis of carbon tetrachloride and its mixture with methane

The formation of soot during pyrolysis of tetrachloride carbon in the temperature interval 1423–1623 K and its mixtures with methane at 1573 K is studied under conditions close to the isothermal ones. The induction periods of soot formation from CCl₄ are measured. The equations to calculate the induction period of soot formation, the concentration of soot particles, and its specific surface as a function of the temperature and concentration of CCl₄ are derived. The inhibition of soot formation is observed in the isothermal pyrolysis of a CCl₄−CH₄ mixture. It is shown that the particle nuclei are formed only from Cl₄, and the CH₄ molecules are spent only for the heterogeneous growth of the formed particles. Translated fromFizika Goreniya i Vzryva, Vol. 35, No. 4, pp. 41–47, July–August 1999.     

Structure and properties of Dalan detonation diamonds

This paper presents the results of an investigation of the fine crystal structure of Dalan diamonds synthesized from graphite and carbon black by detonation. The phase composition of the diamond powders was found to vary widely; the structural and structural-morphological states of diamond particles were studied. The main types and subtypes of detonation diamonds are characterized according to transmission electron microscopy data. Assumptions are made concerning diamond formation during detonation synthesis. __________ Translated from Fizika Goreniya i Vzryva, Vol. 45, No. 1, pp. 108–116, January–February, 2009.