Vanadium of petroleum asphaltenes and source kerogens (La Luna Formation, Venezuela): isotopic study and origin

High-resolution mass spectrometry indicates that the isotopic abundance of ⁵⁰vanadium (V) of the Late Cretaceous La Luna petroleum asphaltenes and related source kerogens of marine origin (both highly enriched with V>2000 ppm) is higher by about 3.5% than that of inorganic source (VOSO₄·5H₂O, Merck). Similar results are obtained with the isotopic analysis of the asphaltenes (containing high V) extracted from the floating asphalts (Dead Sea, Israel). We propose that the difference in the ⁵⁰V/⁵¹V values between the La Luna petroleum asphaltenes/source kerogens and inorganic source can be best ascribed to the biological processing of the seawater V. The fact that the isotopic composition of V of the vary over a very narrow range (2.46-2.52) suggests an essentially same (or similar) and fixed (micro)biological source of V. Isotopic analysis was also extended to the methanol-soluble fractions of the La Luna asphaltic petroleums (DM-119/-120/-124) highly enriched with extractable (alkyl) vanadyl-porphyrins (VO²⁺-P). This analysis shows that the isotopic abundance of ⁵⁰V for the methanol-soluble fractions agrees (within the limits of experimental error) with those of the asphaltenes/kerogens.     

Portland cement clinker mineralogical and chemical investigations: Part II electron microprobe analysis

The chemistry of the clinker minerals was studied with the electron microprobe; the alites and belites could be easily determined but the aluminates and ferrites were difficult or impossible to determine separately. In addition to the absolute contents of the major and minor components, some quotients were also investigated. In coexisting alites and belites S, Na, K and Fe are incorporated mainly in belites and Mg in alites. Al can be incorporated both in alites and in belites. The alkali contents of alites and belites show no relation to those of the corresponding clinkers. A relationship is indicated between the Al₂O₃ contents of belites and those of the clinker; the Fe₂O₃ contents are correlated with the Fe₂O₃ contents of the corresponding clinkers for the alites and for the belites. The MgO contents of the alites and belites correlate very well with those of the clinkers.     

Processing of electron microprobe data from the analysis of altered cementitious materials

The purpose of this paper is to present a method for processing electron microprobe data coming from the analysis of degraded cementitious materials. The application domain is that of cement matrices exposed to attack by aggressive media inducing the leaching of one or more chemical elements from the cement paste — typically attacked by neutral or acid aqueous environments. As raw data obtained from electron probe microanalysis (EPMA) come in the form of relative quantities of elements, the aim of the processing is to obtain the absolute variation of the specimen's chemical composition in the degraded zone and consequently to allow a better understanding of the degradation mechanisms by the aggressive environment under consideration. This method was designed for degraded specimens in which the porosity was not filled with resin before the EPMA. The method uses the titanium content of the cement matrix as a control, this element being stable during attack by neutral or acidic media. The method is described in detail using the example of the attack of cement pastes by a mix of several organic acids (notably acetic acid) at pH 4. The use of EPMA for sound and altered cement pastes is also validated. The application domain of the correction method is discussed.     

Examination of coal surfaces by microscopy and the electron microprobe

Coal surfaces were examined by means of the optical microscope, the electron microscope and the electron microprobe. While qualitative optical microscopy gave no conclusive information, the electron microscope and microprobe provided much useful information, especially with regard to sulphur and iron distribution.     

An X-ray,EPMA, and oxygen isotope study of vermiculitized micas in the ultramafic rocks at Askos,Macedonia, Greece

Extensive metasomatic zones of vermiculite-, tremolite-, chlorite-, and talc-rich rocks have been developed at the contacts of serpentinized ultramafic bodies and surrounding two-mica gneisses in the Askos area, Macedonia, Greece. These zones are probably related to the intrusion of acid magmatic bodies in the area. X-ray and EPMA studies confirmed the formation of vermiculite through a layer-by-layer transformation of original micas. In decreasing abundance, the following mixed-layer and discrete phases were identified: biotite/trioctahedral vermiculite (hydrobiotite), biotite/smectite, trioctahedral chlorite/trioctahedral vermiculite (corrensite), vermiculite/smectite and discrete biotite, vermiculite, chlorite and talc. The 2–20 μm fraction of the vermiculitic samples consists mostly of biotite/vermiculite (>40%) with the biotite percentage dominating in the mixed phase. Lower abundances (20–40%) of biotite/smectite and chlorite/vermiculite occur in both finer fractions (2–20 and <2 μm) of all vermiculitic samples. Vermiculite/smectite is very abundant in the <2 μm fractions of most vermiculitic samples. The DTA curves of the samples analyzed are characteristic of Mg-vermiculites. The electron microprobe analyses show a gradual K leaching from precursor mica with increasing degree of weathering. Oxygen isotope results confirm this assumption. Initially, hydrothermal fluids derived from the neighboring granitic intrusions, were responsible for the micatization of the primary minerals of the ultramafic bodies. Hydrothermal activity was also responsible for the partial formation of corrensite. Consequently, water moving downwards was very important for the formation of the vermiculite and other clay mineral mixed-layer phases through the alteration of micas and chlorite. The low relief and the long-lasting tectonic stability of the area were essential for the development of a significant thickness of the vermiculite zones. These vermiculites have properties desirable in certain building, agriculture, and horticulture products.     

La (III) polychelates of phenolic resin: synthesis,characterization and ion-exchange study

The polymeric ligand, specially resins are proved very effective, active and satisfy specific requirements. The formation of polychelates with polymeric resin behave as an excellent catalysts, ion-exchanger, heat resistant surface coatings, antifouling paints and antimicrobial agents. This is due to the presence of organic and inorganic materials because these two are the prime factors to establish the effective and desire change in their physical and chemical properties. Therefore, an attempt has been made to synthesis and characterizes polymeric ligand (resin) and its polychelates, to study ion-exchange property of resin. The polymeric ligand [(2-hydroxy-4-methoxy benzophenone)1,4-butylene (HMBP-1,4-BD)] was synthesized by polycondensation of 2-hydroxy-4 -methoxy benzophenone with 1,4-butane diol in presence of polyphosphoric acid as a catalyst at 160 °C for 13 h. La(III), Pr(III), Nd(III), Sm(III), Gd(III), Tb(III) and Dy(III) metal ions were selected for the synthesis of polychelates. HMBP-1,4-BD possess good selectivity for the lanthanides (III). The use of resin, as an ion-exchanger has been studies, and it has been found that resin can be used as an ion-exchanger.     

辽东湾地区古近系烃源岩有机地球化学特征

辽东湾地区古近系主要发育三套烃源岩,烃源岩的非均质性以及热演化生烃的不均衡性制约着大中型油气田的形成与分布。本文从有机质丰度、类型、成熟度等有机地球化学方面研究辽东湾地区主力烃源岩的有机地球化学特征;采用IES盆地模拟技术,模拟平面展布特征,得出烃源岩非均质性较强,古近系烃源岩对该地区油气成藏有着重要的作用。     

Fe Mössbauer spectroscopic study of organic-rich sediments (source rocks) from test wells CTP-1 and MDP-1 located in Eastern Krishna-Godavari basin, India

A large number of sub-surface sedimentary samples using Mössbauer spectroscopy were obtained from various depths of wells CTP-1 and MDP-1 drilled in Eastern Krishna-Godavari basin (KG basin) of India. Results indicate that iron is distributed in pyrite, siderite and in clay minerals, apart from these minerals an anomalously large presence of sulfate minerals was also found. Their presence indicates oxidizing conditions in sediments. Significance of presence of minerals, which show oxidizing conditions in context of source rock characterization, is discussed.     

Electrometric study of La(III), Ce(III), Pr(III) and Sm(III) complexes of n-glycylglycine

Saxena and co-workers have made extensive study on the complexing tendencies of several thiols and some of the aminoacids with various metals[1–4]. This paper reports the determination of composition and stabilities of La(III), Ce(III), Pr(III) and Sm(III) complexes of N-Glycylglycine at 30° C and 40° C by applying potentiometric and conductometric titration techniques and also the values of ΔG, ΔH and ΔS at 30° C accompanying the complexation reactions. There is however, no reference in the literature on the study of the present system.     

Structural analysis of electron beam irradiated ethylene-vinyl acetate copolymer (EVA) film (II)

The crosslinked structure of irradiated ethylene-vinyl acetate copolymer (EVA) film was examined by means of ESR, IR and pyrolysis-gas chromatography. The ESR spectrum of 35 Mrad irradiated EVA film with 95g kg^?1 vinyl acetate content consisted of a three-line component with an intensity ratio of 1:2:1, a hyperfine structure coupling of 22.4 G and g factor of 2.0049. Therefore, the spectrum was assigned to the methylene radical with two α protons on the same plane; this radical is formed by loss of a hydrogen atom from the acetoxymethyl group. In pyrolysing EVA films at 500°C, the yield of acetic acid from 10 Mrad-150 g kg^?1 film significantly decreased compared with that of unirradiated film, and it decreased with increasing crosslinking density. By measuring the IR spectra of methanolysed EVA films, the following results were obtained: the absorbances at 1740, 1250 and 1050cm^?1, attributed to the C?O, O?C? O? R and C? O? C groups, respectively, had a marked decrease, whereas the three peaks for 20Mrad film were much stronger than those of unirradiated film. On the basis of these findings, it is suggested that the crosslinking reaction in electron beam irradiated EVA film with lower doses takes place between the acetoxy groups and the main chains.     

Poly (α-methylstyrene) and α-methylstyrene-maleic anhydride copolymer: an electron beam lithographic study

The electron beam sensitivity and contrast are reported for syndiotactic poly(α-methylstyrene), and random, and alternating copolymers of α-methylstyrene-maleic anhydride. Once again it has been observed that tacticity has a marked effect on the sensitivity of a homopolymer. Comparison of the properties of a random and alternating copolymer, indicate that the sensitivity and contrast are higher, for the alternating copolymer. Similar behaviour has been reported in another copolymer system, supporting this observation.     

Raman microprobe spectra of spin-oriented and drawn filaments of poly(ethylene terephthalate)

Polarized Raman spectra of single filaments of spin-oriented and drawn fibres of poly(ethylene terephthalate) were recorded. Various Raman bands and their intensities correlated with (1) conformation of the glycol linkage, (2) orientation of the chains, and (3) crystallinity. Because the degrees of crystallinity and orientation were known from X-ray diffraction, density and optical birefringence, it became possible to identify features of the Raman spectra which correlated with each of the effects noted above. The degree of orientation, as a function of take-up speed or draw ratio, was correlated with the intensity ratios of the various polarization components. The appearance and increases in intensity of bands due to trans glycol conformations and the disappearance of the gauche bands with increasing orientation could be followed readily. It appears that many of the Raman bands earlier assigned to crystallinity in PET actually represent the trans conformation of the glycol group as is also observed in i.r. spectra. This conclusion is based on the observation that in spinoriented amorphous materials the trans conformation bands increase in intensity with increasing birefringence. Also an amorphous highly oriented fibre shows these same transconformation bands with high intensity. On the other hand, the width of the carbonyl band, which is the classical indicator of the amorphous or crystalline character of PET, confirmed the amorphous nature of this sample. In conclusion, by monitoring appropriate features of the Raman spectra of spin-oriented and drawn fibres, we have been able to confirm that orientation can occur independently of crystallization in PET.     

Comparative electron diffraction study of the diamond nucleation layer on Ir(001)

The carbon layer formed during the bias enhanced nucleation (BEN) procedure on iridium has been studied by different electron diffraction techniques. In reflection high energy electron diffraction (RHEED) and low energy electron diffraction (LEED) the carbon nucleation layer does not give any indication of crystalline diamond even if the presence of domains proves successful nucleation. In contrast, X-ray photoelectron diffraction (XPD) shows a clear C 1s pattern when domains are present after BEN. The anisotropy in the Ir XPD patterns is reduced after BEN while the fine structure is essentially identical compared to a single crystal Ir film. The change in the Ir XPD patterns after BEN can be explained by the carbon layer on top of a crystallographically unmodified Ir film. The loss and change in the fine structure of the C 1s patterns as compared to a single crystal diamond film are discussed in terms of mosaicity and a defective structure of the ordered fraction within the carbon layer. The present results suggest that the real structure of the BEN layer is more complex than a pure composition of small but perfect diamond crystallites embedded in an amorphous matrix.     

A comparative study of elastic recoil detection analysis (ERDA), electron energy loss spectroscopy (EELS) and X-ray photoelectron spectroscopy (XPS) for structural analysis of amorphous carbon nitride films

A set of carbon and carbon nitride films has been prepared by ion-beam-assisted filtered cathodic vacuum arc deposition. The films were examined by elastic recoil detection analysis (ERDA), electron energy loss spectroscopy (EELS) and X-ray photoelectron spectroscopy (XPS). ERDA provides the stoichiometry and mass density of the samples. This study covers the range of 0 up to 29 at.% N and 2.9 g cm⁻³ down to 2.0 g cm⁻³ respectively. The carbon K-edge and the plasmon loss were examined by EELS. The C 1s and N 1s core level spectra were recorded by XPS. The main result is that for significant nitrogen contents the mass density, and hence the plasmon energy and very likely the sp³-fraction, is reduced considerably. The C 1s signals of the carbon nitride layers show a multi-peak structure but the peaks are rather broad and an accurate determination of peak positions is not possible. The splitting of the N 1s signal in four contributions at about 398, 400, 400.6 and 402 eV is observed only for the low density carbon nitrides. A CN_x sample with a density of 2.6 g cm⁻³ and equal amounts of sp²- and sp³-bonded carbon shows only a single peak. We show that the components in the N 1s multi-peak structure can be related to atomic arrangements in a fully sp²-bonded network. In particular, the component at 398 eV does not necessarily indicate the presence of a material similar to β-C₃N₄.     

Kinetic analysis of biological sulphate reduction using lactate as carbon source and electron donor: Effect of sulphate concentration

This study investigated the effect of feed sulphate concentration on the kinetics of anaerobic sulphate reduction by a mixed SRB culture, using lactate as the sole carbon source and electron donor. Chemostat cultures were operated across a range of residence times (0.5–5 d) and feed sulphate concentrations (1.0–10.0 g l^?1). Similar phenomena were observed at feed sulphate concentrations of 1.0 and 10.0 g l^?1 with the volumetric sulphate reduction rate increasing linearly with increasing volumetric sulphate loading rate. These reactors were characterised by higher specific volumetric sulphate reduction rates with maximum values of 0.24 and 0.20 g h^?1 g^?1. Contrastingly, the reactors fed with sulphate concentrations of 2.5 and 5.0 g l^?1 showed distinctly different trends in which the volumetric sulphate reduction rate passed through a maximum at the dilution rates of 0.014 and 0.021 h^?1, respectively, followed by a decline with further increase in sulphate loading rate. The maximum specific volumetric sulphate reduction rates observed were 2–6-fold lower than those observed at 1.0 and 10.0 g l^?1 feed sulphate concentrations. Profiles of specific volumetric sulphate reduction rate and biomass concentration suggested a shift in lactate utilisation from oxidation to fermentation at high dilution rates, implying a change in the dominant components of the microbial consortium. The data suggest that population structure was influenced by lactate affinity and dissolved sulphide concentration. The trends observed were attributed to the greater ability of lactate oxidisers to scavenge lactate under limiting concentrations of the substrate and their greater resilience to dissolved sulphide species in comparison to lactate fermenters.