Kinetics of copper electrodeposition in citrate electrolytes

The kinetics of copper electrocrystallization in citrate electrolytes (0.5M CuSO₄, 0.01 to 2M sodium citrate) and citrate ammonia electrolytes (up to pH 10.5) were investigated. The addition of citrate strongly inhibits the copper reduction. For citrate concentrations ranging from 0.6 to 0.8 M, the impedance plots exhibit two separate capacitive features. The low frequency loop has a characteristic frequency which depends mainly on the electrode rotation speed. Its size increases with increasing current density or citrate concentration and decreases with increasing electrode rotation speed. A reaction path is proposed to account for the main features of the reduction kinetics (polarization curves, current dependence of the current efficiency and impedance plots) observed in the range 0.5 to 0.8 M citrate concentrations. This involves the reduction of cupric complex species into a compound that can be either included as a whole into the deposit or decomplexed to produce the metal deposit. The resulting excess free complexing ions at the interface would adsorb and inhibit the reduction of complexed species. With a charge transfer reaction occurring in two steps coupled by the soluble Cu(I) intermediate which is able to diffuse into the solution, this model can also account for the low current efficiencies observed in citrate ammonia electrolytes and their dependencies upon the current density and electrode rotation speed.Nomenclature b, b ₁, b ₁ ^* Tafel coefficients (V^–1) - bulk concentration of complexed species (mol cm^–3) - (si*) concentration of intermediate C^* atx=0 (mol cm^–3) - C concentration of (Cu Cit H)^2– atx=0 (mol cm^–3) - C C variation due to E - C concentration of complexing agent (Cit)^3- at the distancex (mol cm^–3) - C _o concentrationC atx=0 (mol cm^–3) - C _o C _o variation due to E - Cv _s bulk concentrationC (mol cm^–3) - (Cit H), (Cu), (Compl) molecular weights (g) - C _dl double layer capacitance (F cm^–2) - D diffusion coefficient of (Cit)^3- (cm²s^–1) - D ₁ diffusion coefficient of C^* (cm²s^–1) - E electrode potential (V) - f ₁ frequency in Equation 25 (s^–1) - F Faraday's constant (96 500 A smol^–1) - i, i ₁, i ₁ ^* current densities (A cm^–2) - i i variation due to E - Im(Z) imaginary part ofZ - j - k ₁, k ₁ ^* , K₁, K ₁ ^* , K₂, K rate constants (cms^–1) - K rate constant (s^–1) - K ₃ rate constant (cm³ A^–1s^–1) - R _t transfer resistance (cm²) - R _p polarization resistance (cm²) - Re(Z) real part ofZ - t time (s) - x distance from the electrode (cm) - Z _f faradaic impedance (cm²) - Z electrode impedance (cm²) Greek symbols maximal surface concentration of complexing species (molcm^–2) - thickness of Nernst diffusion layer (cm) - , ₁, ₂ current efficiencies - angular frequency (rads^–1) - electrode rotation speed (revmin^–1) - =K ^–1(s) - _d diffusion time constant (s) - electrode coverage by adsorbed complexing species - (in0) electrode coverage due toC _s - variation due to E     

A study of factors that control biosynthesis of the compounds which comprise the boll weevil pheromone

Biosynthesis of the four monoterpene compounds that comprise the pheromone of the male boll weevil,Anthonomus grandis Boheman, [1, (+)-cis-2-isopropenyl-1-methylcyclobutaneethanol; II, (Z)-3,3-dimethyl-^1,-cyclohexaneethanol; III, (Z)-3,3-dimethyl-^1,-cyclohexaneacetaldehyde; and IV, (E)-3,3-dimethyl-^1,-cyclohexane-acetaldehyde] was studied. More pheromone was biosynthesized in the summer months, somewhat less was produced by males in the presence of females than by isolated males, and the pheromone was concentrated in the gut and surrounding tissue of the abdomen of the males. Incubation of abdomens with the pheromone alcohols yielded related hydrocarbons, aldehydes, and alcohols, which suggested the presence of several enzyme systems. Boll weevils were able to allylically oxidize myrcene and limonene to alcohols, a capability that suggests pheromone precursors may be at least in part inhaled rather than ingested. The hemolymph may then transport the precursor to the gut or some alternative site where allylic oxidation to the pheromone occurs.Coleoptera: Curculionidae.In cooperation with the Mississippi Agricultural and Forestry Experiment Station, Mississippi State, Mississippi 39762. Received for publication.     

Analysis of irreversible oxidation wave of adsorbed CO at Pt(1 1 1), Pt(1 0 0) and Pt(1 1 0) electrodes

The oxidation wave of CO preadsorbed at 50 mV on Pt(1 1 1), (1 0 0) and (1 1 0) electrodes in phosphate buffer solution of pH 3 was observed as a function of the sweep rate. The sweep rate dependence of the peak current and peak potential, as well as the form of the wave, were examined on the basis of the Gilman mechanism that the electron transfer from a complex consisting of CO and oxygen containing species is the rate-determining step. An electron transfer step from CO itself was excluded. The peak current and peak potential analyses and the wave simulation gave the same value for f, the change in the interaction energy during the formation of the activated complex from the reactants. f was sweep-rate and surface-structure dependent. The nature of f was discussed.Nomenclature symmetry factor - reversible work required to bring an adsorbed species from its standard state - µ electrochemical potential - electrode potential referred to the reversible hydrogen electrode - _p peak potential - _1/2 width at half height of the oxidation wave - (a) adsorbed state - f() mutual interaction energy of the activated complex inRT units - f(R) mutual interaction energy of the reactants in RT units - f f() –f(R) - i oxidation current density, mA cm^–2 - i _p peak current, mA CM^–2 - k rate constant - Q ₀ electric charge, mCcm^–2 - v sweep rate, m Vs^–1 This paper is dedicated to Professor Brian E. Conway on the occasion of his 65th birthday, and in recognition of his outstanding contribuion to electrochemistry.     

Pheromone biosynthesis in lepidoptera

Pheromone components for many lepidopteran species are produced by the use of unique chain-shortening and 9, 10, and 11 desaturase systems. Correlations in the Tortricidae indicate that the pheromone components derived from 9 and 01 desaturases are found in the more primitive species (those possessing morphological plesiomorphies). The precise blend ofZ andE acetates in a number of species is regulated in the final reduction sequence from acyl intermediates. Preliminary research has been conducted on the characterization of the various desaturase enzymes used and on the important blend regulating sequence. Initial purification work on the 11 desaturase enzyme found in the cabbage looper moth is reported.     

Effects of gas bubbles on the current and potential profiles within porous flow-through electrodes

This paper presents a mathematical model to calculate the distributions of currenti(x), potentialE(x), gas void fraction (x) and pore electrolyte resistivity (x) within porous flow-through electrodes producing hydrogen. It takes into consideration the following effects: (i) the kinetics of the interfacial charge transfer step, (ii) the effect of the non-uniformly generated gas bubbles on the resistivity of the gas-electrolyte dispersion within the pores of the electrode (x) and (iii) the convective transport of the electrolyte through the pores. These effects appear in the form of three dimensional groups i.e.K=i _o L where i_o is the exchange current density, is the specific surface area of the electrode andL its thickness.= ⁰ L where ⁰ is the pore electrolyte resistivity and =/Q where is a constant, =tortuosity/porosity of the porous electrode andQ is the superficial electrolyte volume flow rate within it. Two more dimensionless groups appear: i.e. the parameter of the ohmic effect =K/b and the kinetic-transport parameterI=K. The model equations were solved fori(x),E(x), (x) and (x) for various values of the above groups.Nomenclature specific surface area of the bed, area per unit volume (cm^–1) - b RT/F in volts, whereR is the gas constant,T is the absolute temperature (K) - B =[1–(I ² Z/4)], Equation 9a - C =(1–B ²), Equation 9b - E(L) potential at the exit face (V) - E(0) potential at the entry face (V) - E(x) potential at distancex within the electrode (V) - E _rev reversible potential of the electrochemical reaction (V) - F Faraday's constant, 96500 C eq^–1 - i _o exchange current density of the electrode reaction (A cm^–2 of true surface area) - i(L) current density at the exit face (A cm^–2 of geometrical cross-sectional area of the packed bed) - I K =i _oL(/Q) (dimensionless group), Equation 7d - K =i _oL, effective exchange current density of the packed bed (A cm^–2) Equation 7a - L bed thickness (cm) - q tortuosity factor (dimensionless) - Q superficial electrolyte volume flow rate (cm³ s^–1) - x =position in the electrode (cm) - Z =exp [(0)], Equation 7f - transfer coefficient, =0.5 - =K/b=(i ₀ L ⁰ L)/b (dimensionless group) Equation 7e - (x) gas void fraction atx (dimensionless) - = ⁰ L, effective resistivity of the bubble-free pore electrolyte for the entire thickness of the electrode ( cm²) - (0) polarization at the entry face (V) - (L) polarization at the exit face (V) - =q/, labyrinth factor - constant (cm³ C^–1), Equation 3a - =/Q (A ^–1) conversion factor, Equation 3b - porosity of the bed - (x) effective resistivity of the gas-electrolyte dispersion within the pores ( cm) - ⁰ effective resistivity of the bubble-free pore electrolyte ( cm)     

The role of soil pH in the dissolution of phosphate rock fertilizers

The influence of soil pH on the dissolution of phosphate rock fertilizers was investigated in laboratory experiments with reactive North Carolina phosphate rock (PR) in a lateritic soil adjusted to several pH values. Increased soil pH resulted in decreased dissolution as estimated by the increase in exchangeable calcium (Ca) method. The extent of PR dissolution was related to soil pH by an equation of the form Log Ca = a–b pH, and it increased with contact period and rate of PR application. Increased plant available P, as estimated by NaHCO₃ soluble-P (BicP) was about one third of the P dissolved from PR. BicP was related to soil pH by an equation of the form Log Bic P = c–d pH. Dissolution of PR in soil can be considered as a simple chemical reaction between apatite and hydrogen ions supplied by soil constituents.     

On the possibility of estimating weak interactions of macromolecules in solutions from the experimental viscous flow activation energies data

Summary The initial viscosity and activation energy in viscous flow of the systems: water(W)-casein(C)-polysaccharide(PS) (gum arabic(G),de-xtran(D), extran sulfat (DS)) have been determined for various ionic strengths corresponding to total or limited thermodynamic compatibility of macrocomponents. Excess activation energy H ^E due to the protein-polysaccharide interactions has been calculated. It is positive for systems with total compatibility and negative for systems with limited compatibility. Moreover, it yields information on type of the protein-polysaccharide interactions. Negative H ^E means that repulsive forces are dominant, while positive H ^E means that attractive forces are dominant. Since the properties of the systems W-C-D and W-C-DS are similar, it is believed that C-D complexes can possibly be formed with an energy 2 kT(10 mJ/g).The authors express their sincere graditude to Konstantinov A.A., Kondratev V.P., Chernysh M.M. (Special Design Bureau of the Institute of Petroleum Chemical Synthesis, The USSR Academy of Sciences) and Dmitrienko A.P. (Institute of Organoelement compounds, The USSR Academy of Sciences) for their invaluable help.     

Mandibular gland secretions of the male beewolvesPhilanthus crabroniformis,P. barbatus,andP. pulcher (Hymenoptera: Sphecidae)

The composition of the territorial marking pheromones from mandibular glands of males of the beewolvesPhilanthus crabroniformis, P. barbatus, andP. pulcher have been determined. The structures of the components were elucidated by gas chromatography-mass spectrometry and gas chromatography-Fourier transform infrared spectroscopy. The major compound ofP. crabroniformis is isopropyl tetradecanoate, with somewhat lesser amounts of 2-tridecanone, 3-methyl-3-butenyl tetradecanoate, and 928 (Z)(E)-11-eicosen-1-ol. The major compounds ofP. barbatus are ethyl tetradecanoate and hexadecanal, which are present in approximately a 6040 ratio. These two compounds comprise over 95% of the neutral lipids. Also present in lesser amounts are ethyl dodecanoate, tetradecanal, hexadecan-1-ol, a ^x -octadecen-1-ol, and octadecan-1-ol. The major compounds ofP. pulcher are ethyl (Z)-7-hexadecenoate and geranylgeraniol acetate, which comprise nearly 90% of the neutral lipid fraction, with smaller amounts of tetradecanal, pentadecanal, and ethyl hexadecanoate; trace amounts of ^x hexadecenal, hexadecanal, and octadecanal are also present.     

Birefringence of polyamide fibres of nonround cross-sectional from

Conclusions A method of determining the birefringence n of fibres having an uncomplicated profile (pentagonal, trilobal, or double rhombus) consists of the following: Over sections of the fibre one determines the ratio of the outer-contour dimensions — the diameterl of the fibre to its thickness d — the path over which the beam acquires the difference in speed ; the values of ,l, andl/d are averaged; and the calculation of n is carried out from the equation n = .This method has been tested on specimens of polyamide fibre prepared under identical melt flow rate conditions.Translated from Khimicheskie Volokna, No. 3, pp. 42–43, May–June, 1983.     

Solubilization of soil organic N by alkaline-hydrolysing N fertilizers

Interactions between¹⁵N-labelled fertilizers applied at concentrations representative of the fertilizer microsite and the solubility of the nitrogenous component of soil organic matter were investigated in laboratory experiments. Soil organic N was solubilized in a-irradiated soil due to addition of NH_3(aq), and the fertilizer-induced loss of unlabelled total N in the extracted soil (TU_s) increased with increasing N fertilizer concentration and soil pH. TU_s was linearly correlated with ammoniacal-N concentration and the pH of the fertilized soil within the range of 7.5-10 (r = 0.94).Total organic N in the soil extract (OT_e) increased rapidly up to day 14 following addition of 2000 mg urea-N kg^–1 soil, but was then stable up to day 28. OT_e of a range of soils increased from between 5 and 148 to between 15 and 368 mg N kg^–1 soil after application of 1045 mg NH₃-N kg^–1 soil. While up to 25% of the organic N was solubilized by the fertilizer in nine soils, the change in total organic N in the extracts (OT_e) of three soils was not significant. The highest OT_e of 399 mg N kg^–1 soil (35.4% of soil organic N) was measured after application of 2000 mg NH₃-N kg^–1 soil.pH and OT_e decreased in the order of NH_3(aq) > urea > di-ammonium phosphate > ammonium sulphate at equivalent rates of N addition. A negative OT_e was measured following application of ammonium sulphate. OT_e was correlated with the pH of the fertilized soil but not ammoniacal-N concentration for different N fertilizer sources.     

Musk deer (Moschus moschiferus): Reinvestigation of main lipid components from preputial gland secretion

The qualitative and quantitative composition of the principal lipid constituents of Siberian musk deer (Moschus moschiferus) preputial gland secretion, main odor carriers and potential precursors of odorous substances, was investigated by means of high-performance liquid chromatography. Free fatty acids and phenols (10%), waxes (38%), and steroids (38%) were found to be the main groups of the secretion lipids. Cholestanol (I), cholesterol (II), androsterone (III), ⁴-3-hydroxy-17-ketoandrostene (IV), 5, 3-hydroxy-17-ketoandrostane (V), 5, 3, 17-dihydroxyandrostane (VI), 5, 3, 17-dihydroxyandrostane (VII), and 5, 3, 17-dihydroxyandrostane (VIII) were isolated from the steroid fraction and their structures confirmed by IR, PMR, and mass spectra. 3-Methylpentadecanone (muscone) was not identified among the secretion lipids. Preputial gland secretion stimulated sex behavior of musk deer females.     

Tissue-Specific Fatty Acid Composition of Glandular Trichomes of Mite-Resistant and -Susceptible Pelargonium xhortorum

Anacardic acids, alkyl phenolic acids excreted by tall glandular trichomes of the garden geranium, Pelargonium xhortorum, confer small-pest resistance. Up to 90% of the trichome exudate from mite-resistant P. xhortorum inbreds consists of an unusual anacardic acid with an unsaturated omega-5 (⁵) alkyl chain. As fatty acids are biochemical precursors to anacardic acids, we examined by GC the fatty acid composition of leaves, pedicels, petals, sepals, mature seeds, and glandular trichomes from pest-resistant and pest-susceptible Pelargonium inbred lines to determine the localization of ⁵-fatty acids within plant tissues. The fatty acid composition of lipid classes (galactolipids, phospholipids, and neutral lipids) extracted from glandular trichomes from mite-resistant pedicels were also examined. ⁵-Fatty acids (16:111 and 18:113) were found only in the glandular trichomes from pest-resistant geraniums (27.2% in trichomes of pedicels) and were localized predominantly in the phospho- and galactolipids (phosphatidylinositol, 25.9%; phosphatidylcholine, 18.2%; monogalactosyldiglyceride, 15.5%; and diglactosyldiglyceride, 14.0%).     

Transcrystallization of maleated polypropylene in the presence of various carbon fibers

Summary In this paper, the influence of the fiber surface sizing on development of transcrystallization, TCR, as well as the fiber-matrix interactions were analysed. Sized (CT) and unsized (CU) high-strength carbon fibers and maleated polypropylene, mPP, were used in model systems. Transcrystallization was followed by polarizing optical microscopy, in isothermal regime (Tc=124–130 °C). Besides the radius, distribution of the thickness and growth rate of the transcrystalline layer and the surface energetic parameters have been also determined. Lower value for was obtained for the system with surface treated C fibers ( ^CT =1,145x10 ^-7 J/cm ² ) which also contribute for their higher nucleation activity. Using FTIR microscopy and model reaction, an attempt was made to analyse the chemical interactions at fibedmatrix interface.     

Unsteady mass transfer in turbulent flow close to a rotating cylinder

Electrodiffusional methods of studying unsteady turbulent mass transfer involved measurement of a transient current characteristicI() after step polarization of a rotating annular cylindrical 46 mm dia electrode at a fixed rotational velocity atRe=(2–9)×10⁴ andSc=2.4×10³. The potassium ferri-ferrocyanide system with NaOH background electrolyte was used. An initial asymptote at 0 served as a test. The similarity of the normalized transfer coefficientK ₊=/u _* with respect to the Reynolds number demonstrated turbulent flow development. Tests were aimed at determining the powern in the approximate law of attenuation of turbulent diffusionD _t in they-direction normal to the wallD _t/v=by ₊ ⁿ .A numerical solution of the unsteady turbulent diffusion equation obtained as a set of lg ()=f() curves for 3n4 with an interval 0.2, where ()=I/I()_#x2212;1 has been achieved.Notation I diffusion current - C C ₀ andC _p concentration, concentration in the bulk liquid and polymer concentration, respectively - C _f drag of a Newtonian fluid - time - U linear velocity - v kinematic viscosity - angular velocity - j flow - y ₊ yu _*/v, ₊ = u _* ² and =(1-C/C ₀), dimensionless quantities This paper was presented at the Workshop on Electrodiffusion Flow Diagnostics, CHISA, Prague, August 1990.     

Impedance of a porous electrode with an axial gradient of concentration

When the impedance is measured on a battery, an inductive impedance is often observed in a high frequency range. This inductance is frequently related to the cell geometry and electrical leads. However, certain authors claimed that this inductance is due to the concentration distribution of reacting species through the pores of battery electrodes. Their argument is based on a paper in which a fundamental error was committed. Hence, the impedance is re-calculated on the basis of the same principle. The model shows that though the diffusion process plays an outstanding role, the overall reaction rate is never completely limited by this process. The faradaic impedance due to the concentration distribution is capacitive. Therefore, the inductive impedance observed on battery systems cannot be, by any means, attributed to the concentration distribution inside the pores. Little frequency distribution is found and the impedance is close to a semi-circle. Therefore depressed impedance diagrams in porous electrodes without forced convection cannot be ascribed to either a Warburg nor a Warburg-de Levie behaviour.Nomenclature A D¦C¦ (mole cm s^–1) - B j+K¦C¦ (mole cm s^–1) - b Tafel coefficient (V^–1) - C(x) Concentration ofS in a pore at depthx (mole cm^–3) - C ₀ Concentration ofS in the solution bulk (mole cm^–3) - C C(x) change under a voltage perturbation (mole cm^–3) - ¦C¦ Amplitude of C (mole cm^–3) - D Diffusion coefficient (cm² s^–1) - E Electrode potential (V) - E Small perturbation inE namely a sine-wave signal (V) - ¦E¦ Amplitude of E(V) - F Faraday constant (96500 A s mol^–1) - F(x) Space separate variable forC - f Frequency in Hz (s^–1) - g(x) KC(x)¦E¦(mole cm s^–1) - I Apparent current density (A cm^–2) - I _st Steady-state current per unit surface of pore aperture (A cm^–2) - j Imaginary unit [(–1)^1/2] - K Pseudo-homogeneous rate constant (s^–1) - K Potential derivative ofK, dK/dE (s^–1 V^–1) - K ^* Heterogeneous reaction rate constant (cm s^–1) - L Pore depth (cm) - n Reaction order - P Reaction product - p Parameter forF(x), see Equation 13 - q Parameter forF(x), see Equation 13 - R _e Electrolyte resistance (ohm cm) - R _p Polarization resistance per unit surface of pore aperture (ohm cm²) - R _t Charge transfer resistance per unit surface of pore aperture (ohm cm²) - S Reacting species - S _a Total surface of pore apertures (cm²) - S ₀ Geometrical surface area - S _p Developed surface area of porous electrode per unit volume (cm² cm^–3) - s Concentration gradient (mole cm^–3 cm^–1) - t Time - U Ohmic drop - x Distance from pore aperture (cm) - Z Faradaic impedance per unit surface of pore aperture (ohm cm²) - Z _x Local impedance per unit pore length (ohm cm³) - z Charge transfer number - Porosity - Thickness of Nernst diffusion layer - Penetration depth of reacting species (cm) - Penetration depth of a.c. signal determined by the potential distribution (cm) - Electrolyte (solution) resistivity (ohm cm) - ₀ Flow of S at the pore aperture (mole cm² s^–1) - Angular freqeuncy of a.c. signal, 2f(s^–1) - Integration constant     

Calorimetric,X-ray and infra-red investigations on poly(hexamethylene adipamide)

Summary In dependence on crystallization conditions three ranges with different crystal structure and heat of fusion were found by DSC,WAXS,and IR for unoriented PA 6.6 samples of densities between 1.10 and 1.17gcm^–3: Range I:_I triclinic, _c ^I =1.225 gcm^–3,H _M ^I = 235 Jg^–1. Range II:_II triclinic, _c ^II =1.165 gcm^–3, H _M ^II =185 Jg^–1. Range III:Continuous variation from _c ^I ,H _M ^I to _c ^II , H _M ^II . _a=1.095 gcm^–3 is independent of crystallization. conditions. The transition between _I and _II is probably due to changes of the chain conformation.     

Chemical determination of microstructure of diene units in 1-chloro-1,3-butadiene copolymers

A comparative study has been carried out on the electrical conductivity of PS, PMMA, and PVC before and after irradiation with -rays up to a dose of 100 MR, The obtained results are explained on the basis of electron trapping theory by making use of a formula suitable for calculating the characteristic parameter . The conclusion that the average value of is near to the theoretical value =0.5 indicates that these polymers possess long decay times and have a large number of exponentially distributed traps.     

Aggregation pheromone characterization and comparison inDrosophila ananassae andDrosophila bipectinata

(Z)-11-Octadecenyl acetate (Z11–18Ac) and (Z)-11-eicosenyl acetate (Z11–20Ac) were identified as the aggregation pheromones ofDrosophila ananassae, andZ11–20Ac was identified as the aggregation pheromone ofDrosophila bipectinata. Z11–18Ac andZ11–20Ac were not attractive alone; however, in combination with fermenting food odors, the acetates attracted flies of both sexes in a wind-tunnel olfactometer. The pheromones were present in the ejaculatory bulb of sexually mature male flies and transferred to the female during mating. MaleD. bipectinata released little if anyZ11–20Ac to the food; however, recently mated females releasedZ11–20Ac to the surrounding surfaces in just a few hours after mating.D. ananassae males, on the other hand, appeared to release moreZ11–18Ac andZ11–20Ac to the surroundings than mated females. AlthoughD. bipectinata males had noZ11–18Ac, flies were as attracted toZ11–18Ac as to an equal quantity ofZ11–20Ac.D. ananassae were attracted toZ11–18Ac but not toZ11–16Ac orZ11–20Ac. However,Z11–20Ac in combination withZ11–18Ac was significantly more attractive thanZ11–18Ac alone.     

Soldier defense secretions of malaysian free-ranging termite of the genusLacessititermes (Isoptera,Nasutitermitinae)

Soldiers of free-ranging termites of the genusLacessititermes (Isoptera, Nasutitermitinae) secrete from their frontal glands a mixture of monoterpenes, sesquiterpenes, and diterpenes.Lacessititermes ransoneti, L. laborator, andL. species A produce species-specific secretions, the composition being most complex forL. laborator. Apart from known mono- and dihydroxytrinervitadienes, the following new diterpenes were isolated and tentatively assigned as trinervita-1(15),8(19)-dien-2,3,9,14-tetraol 2,3,14-O-triacetate, trinervita-1(15),8(19)-dien-2,3,9,14-tetraol 2,3,14-O-triacetate, 2,3,9, 14-tetraacetoxy-1 (15), 8(19)-trinervitadiene, and 2,3,11,13-tetraacetoxy-1(15),8(19)-trinervitadiene. Data on intragenus chemical variations were subjected to canonical discriminant analysis and genetic distances among the species were calculated to depict intragenus identities and affinities.     

Interrelation between the Glass Transition Temperature, Thermal Expansion Coefficient, and Poisson Ratio for Some Glasses in the AV–BVI–CVIISystems

In the framework of the free volume concept, the dependences of _g T _gand T _gon and are considered and the interrelation between the fraction of the fluctuation free volume f _g, Poisson ratio , and Grüneisen lattice parameter for chalcogenide, oxogenide, and oxohalide glasses is discussed. The fluctuation free volume model and the model of soft atomic configurations are compared in terms of anharmonicity of the glasses under investigation.