Inorganic Grains Research Articles

The seismic dispersion and attenuation characteristics of organic shales

SUMMARY To improve our understanding of wave dispersion and adsorption signature of organic shales, we select a set of vertical shale samples cored from different formations and conduct the forced-oscillation measurements in seismic frequencies of 2–800 Hz at the oven-dried conditions. The results demonstrated that both Young's modulus and Poisson's ratio of immature Barnett and Eagle Ford shales and mature Mancos shale remain roughly constant and the extensional attenuations are also insignificant at the entire frequency band. However, the mature Jungar shale exhibits strong dispersions with the magnitude of 23.4 per cent for Young's modulus at the confining pressure of 3.4 MPa. The dispersion and magnitude of Jungar shale overall exhibit a decreasing trend with increasing pressure, but still maintain strong attenuation at the confining pressure of 20.8 MPa. It is found that the single parameter of TOC, thermal maturity and clay content are not the controlling factors of wave dispersion and adsorption signatures. Instead, the geochemical index ${\rm{TOC}} \times {S_1}/({S_1}{\rm{ + }}{S_2})$ is positively correlated with dispersion and attenuation magnitude, suggesting that organic richness and maturity level jointly control the wave adsorption characteristics. Geochemical analysis and phenomenological modelling imply that such kinds of energy dissipation in organic shales are possibly caused by the viscous friction at interfaces between inorganic grains and the surface of liquefied or bitumen-filled organic matter. Besides, a modified standard linear solid model containing multiple sets of a characteristic frequency is proposed and well captures the continuous dispersion signatures considering that the Jungar shale contains various maturity-induced viscous organic matter.

Stable and Highly Flexible Perovskite Solar Cells with Power Conversion Efficiency Approaching 20% by Elastic Grain Boundary Encapsulation

Here, we show that flexible perovskite solar cells (PSCs) with high operational stability and power conversion efficiency (PCE) approaching 20% were achieved by elastic grain boundary (GB) encapsul...

A Comparison between the Grain Quality Parameters of Rice Grown under Organic and Inorganic Production System

India contributes about one-third of the world acreage under rice. Rice is available in over 5000 varieties, of which Basmati rice occupies a prime position on account of its extra long superfine slender grains, pleasant, exquisite aroma, fine cooking quality, sweet taste, soft texture, length-wise elongation with least breadth-wise swelling on cooking and tenderness of cooked rice. The present work was undertaken to compare the effect of an organic and inorganic method of cultivation on the quality of rice. The results revealed higher hardness, true density and percent porosity in inorganic grains of rice. Inorganic rice had better milling quality but cooking quality was found better of organic rice as evident from higher elongation ratio and swelling rate. Organically grown foods were found to be tastier in comparison to inorganic foods as organic samples scored higher for all the parameters of sensory. Moisture content was found higher in inorganic rice. The quantity of protein was less, but the quality was better in organic crops as measured by in-vitro protein digestibility. No definite trend was seen for effect of inorganic and organic mode of cultivation on total ash, crude fiber and carbohydrate content on rice crops. Iron was found to be significantly higher in organic rice (1.32 mg/100 g); phosphorus was significantly higher in inorganic rice (112.80 mg/100 g). No significant difference was observed in manganese, cobalt, zink and copper content of the produced from an organic and inorganic mode of cultivation.

Pore characterization and shale facies analysis of the Ordovician-Silurian transition of northern Guizhou, South China: The controls of shale facies on pore distribution

The Ordovician-Silurian Wufeng-Longmaxi Formations in the Upper Yangtze Platform have been considered as the most promising shale play in China. However, few studies of detailed shale facies and their influence on pore distribution have been conducted. Therefore, it is important to describe the heterogeneity of shale facies in detail and elucidate their relationship to pore networks and development. Seven distinct facies were identified on the basis of their characteristic physical, biological, and chemical attributes. Ion-milled samples from all facies were examined with SEM for identification of pore types. Point-counting was used to quantify porosity. Four major pore types appear dominant: framework pores, phyllosilicate framework (PF) pores, intrapores within inorganic grains, and organic matter (OM) pores. Due to variability in composition and depositional setting of the different facies, pore networks are not uniform. Framework pores between detrital grains and PF pores are widespread in bioturbated claystones, Pores in black siliceous shales are dominated by framework pores supported by authigenic silica. Most of these are filled with kerogen/bitumen that is host to “foam” and “bubble” type OM pores. Intrapores within calcite or dolomite grains are common in fossiliferous mudstones and black dolomitic siltstones, but are isolated and do not contribute to productive porosity. In muddy siltstones, PF pores are well developed within silty bands. Initial framework pores within silty beds or laminae, however, were subsequently cemented by calcite or destroyed by compaction. As most of primary PF pores and primary frameworks pores are lost during compaction, porosity is highly dependent on the population of framework pores between authigenic quartz grains. Secondary cracking of amorphous organic matter added porosity after initial infilling of porosity by oil and bitumen migration. Therefore, porosity is mainly controlled by abundance of authigenic silica and TOC, in spite of differences of burial diagenesis among various facies. Understanding these main controls on porosity should be helpful to predict and find and more porous facies and have a significant impact on future gas exploration in the Wufeng-Longmaxi Formations.

Physicochemical characterization of mineral deposits in human ligamenta flava.

The aim of our study was the detailed characterization of calcium deposits in ligamenta flava. The use of microcomputed tomography allowed extending the routine medical investigations to characterize mineral grains in the microscopic scale. A possible connection between spinal stenosis and ligament mineralization was investigated. The studies were carried out on 24 surgically removed ligamentum flavum samples divided into control and stenosis groups. Physicochemical characterization of the inorganic material was performed using X-ray fluorescence, X-ray diffraction, and Fourier transform infrared spectroscopy. The minerals were present in 14 of 24 ligament samples, both in stenosis and control groups. The inorganic substance constitutes on average ~0.1% of the sample volume. The minerals are scattered in the soft tissue matrix without any regular pattern. It was confirmed that minerals possess an internal structure and consist of the organic material and small inorganic grains mixture. The physicochemical analyses show that the predominant crystalline phase was hydroxyapatite (HAP). In the stenosis group calcium pyrophosphate dehydrate (CPPD) was identified. Both structures were never present in a single sample. Two different crystal structures suggest two independent processes of mineralization. The formation of CPPD may be treated as a more intense process since CPPD minerals are characterized by bigger values of the structural parameters and higher density than HAP deposits. The formation of HAP minerals is a soft tissue degeneration process that begins, in some cases, at early age or may not occur at all. Various density and volume of mineral grains indicate that the mineralization process does not occur in a constant environment and proceeds with various speeds. The formation of minerals in ligamenta flava is not directly associated with diagnosed spinal canal stenosis.

Spatial variation of salt-marsh organic and inorganic deposition and organic carbon accumulation: Inferences from the Venice lagoon, Italy

Salt marshes are ubiquitous features of the tidal landscape governed by mutual feedbacks among processes of physical and biological nature. Improving our understanding of these feedbacks and of their effects on tidal geomorphological and ecological dynamics is a critical step to address issues related to salt-marsh conservation and response to changes in the environmental forcing. In particular, the spatial variation of organic and inorganic soil production processes at the marsh scale, a key piece of information to understand marsh responses to a changing climate, remains virtually unexplored. In order to characterize the relative importance of organic vs. inorganic deposition as a function of space, we collected 33 shallow soil sediment samples along three transects in the San Felice and Rigà salt marshes located in the Venice lagoon, Italy. The amount of organic matter in each sample was evaluated using Loss On Ignition (LOI), a hydrogen peroxide (H2O2) treatment, and a sodium hypochlorite (NaClO) treatment following the H2O2 treatment. The grain size distribution of the inorganic fraction was determined using laser diffraction techniques. Our study marshes exhibit a weakly concave-up profile, with maximum elevations and coarser inorganic grains along their edges. The amount of organic and inorganic matter content in the samples varies with the distance from the marsh edge and is very sensitive to the specific analysis method adopted. The use of a H2O2+NaClO treatment yields an organic matter density value which is more than double the value obtained from LOI. Overall, inorganic contributions to soil formation are greatest near the marsh edges, whereas organic soil production is the main contributor to soil accretion in the inner marsh. We interpret this pattern by considering that while plant biomass productivity is generally lower in the inner part of the marsh, organic soil decomposition rates are highest in the better aerated edge soils. Hence the higher inorganic soil content near the edge is due to the preferential deposition of inorganic sediment from the adjacent creek, and to the rapid decomposition of the relatively large biomass production. The higher organic matter content in the inner part of the marsh results from the small amounts of suspended sediment that makes it to the inner marsh, and to the low decomposition rate which more than compensates for the lower biomass productivity in the low-lying inner zones. Finally, the average soil organic carbon density from the LOI measurements is estimated to be 0.044 g C cm−3. The corresponding average carbon accumulation rate for the San Felice and Rigà salt marshes, 132 g C m−2 yr−1, highlights the considerable carbon stock and sequestration rate associated with coastal salt marshes.

SEM-EDX analysis and TOF-SIMS 3D imaging of a textile/rubber interface undergoing fatigue loading

Unidirectional textile⿿rubber composites must exhibit a strong interface to reach admissible lifetime expectancy. Usually, this is achieved by coating the textile with Resorcinol-Formaldehyde-Latex (RFL). Nevertheless, former SEM observations of our composite revealed microcracks at the RFL/rubber interface. They appeared to propagate through fatigue loading, in correlation with hardening of RFL and interfacial rubber, both highlighted by nanoindentation tests. This mechanical damage was not correlated to chemical structure degradation which limited the development of more reliable interfacial materials⿿ formulations. In this perspective, EDX and ToF-SIMS are used in the present study to characterize RFL coated textile and composite's textile/rubber interface compositions, before and after different numbers of cycles of fatigue loading. Those analyses allow the identification of textile contaminants, potentially responsible for composite's initial interfacial microcracks: inorganic grains, polysiloxanes, fatty acids, latex surfactants and esters contaminants, attributed to diffusion from the RFL layer or from textile sizing. Concerning RFL hardening, four potential mechanisms can be raised: VP-latex complexation with metallic ions coming from rubber formulation, RF post-condensation or disproportion, migration of latex surfactants and thermo-oxidative degradations. This last mechanism seems to be the main one responsible for the hardening of interfacial rubber.

The distribution of Cd and Cu in sediments covered with algal mat

In coastal marine environments, with shallow, warm and calm waters, it is sometimes possible to observe the presence of organosedimentary structures that are commonly flat and laminar in shape. These structures are called algal mats or recent stromatolites due to their remarkable similarities to fossil stromatolites. The aim of this work was the study of the distribution of the various forms of Cu and Cd in the main layers of coastal algal mats in a closed bay at Anavissos, on the coast of Saronikos Gulf. Small sediment cores were collected from one point inside the cove on a seasonal basis and the trace metals extracted according to the BCR sequential extraction method. The main results of the study were: Most of the labile Cd was associated with small inorganic grains or lime particles. The contribution of the fraction associated with Mn and Fe oxides, was similar to that adsorbed to organic compounds and sulfides. The high contribution of the labile Cd to the total element (over 85%) was a strong indication of anthropogenic origin. On the other hand, most of the Cu in the sediment was associated with the crystal lattice (74%). Cu showed increased seasonal fluctuation; most of its labile forms were associated with organic compounds and sulfides whereas the less abundant form was that associated with Mn and Fe oxides. On the whole, the sediments were slightly enriched in Cd, while the concentrations of Cu were normal for the region.

Microstructural investigation of gas shales in two and three dimensions using nanometer-scale resolution imaging

The microstructure of gas shale samples from nine different formations has been investigated using a combination of focused ion beam (FIB) milling and scanning electron microscopy (SEM). Backscattered electron (BSE) images of FIB cross sectioned shale surfaces show a complex microstructure with variations observed among the formations. Energy dispersive spectroscopy of the shale cross sections indicates that clay, carbonate, quartz, pyrite, and kerogen are the most prevalent components. In the BSE images, areas of kerogen are observed interspersed with the inorganic grains. Pores are observed in both the kerogen and inorganic matrix with the size, shape, and number of pores varying among the shale samples. By using FIB milling and SEM imaging sequentially and repetitively, three-dimensional (3-D) data sets of SEM images have been generated for each of the shale samples. Three-dimensional volumes of the shales are reconstructed from these images. By setting thresholds on the gray scale, the kerogen and pore networks are segmented out and visualized in the reconstructed shale volumes. Estimates of kerogen and pore volume percentages of the reconstructed shale volumes have been made and range from 0 to 90.0% for the kerogen and 0.2 to 2.3% for pores. Estimates of pore-size distributions suggest that although pores with radii of approximately 3 nm dominate in number, they do not necessarily dominate in total volumetric contribution. Scanning electron microscopy images and 3-D reconstructions reinforce the facts that shales are quite different and that their microstructures are highly variable and complex.

Particle selection by the sea lily Metacrinus rotundus Carpenter 1884 (Echinodermata, Crinoidea)

Crinoids feed on particles less than 1 mm in diameter and are regarded as passive suspension feeders. Previous studies on crinoid gut contents have revealed that crinoids catch a variety of particles, including biotic crusts (e.g. algal filament, sponge spiracle, crustacean appendage), unicellular organisms, detritus, and inorganic grains, and transport them to their intestines, suggesting that feeding is a nonselective process. In this study, we quantitatively examined the gut contents of the stalked crinoid Metacrinus rotundus and assessed whether preferential particle selection was occurring. Crinoid individuals were held in an aquarium and provided with a model food consisting of a mixture of glass beads (to mimic sand particles) in two different sizes, phytoplankton cells (approximately 30 μm), and copepods (approximately 300 μm to 2 mm). M. rotundus took both organic and inorganic particles, but phytoplankton cells were taken in larger numbers than other particles. Our results showed that crinoids selectively took phytoplankton, followed by copepods and glass beads. The ancestor of echinoderms is presumed to have been a sessile filter feeder, and therefore the crinoid food selection process has most likely been maintained since its early Paleozoic ancestors. Because passive suspension feeders filter a smaller volume of seawater per unit time compared to active suspension feeders and because organic matter generally decreases with depth, food selectivity is a key function for passive suspension feeders living in deeper water.

Expression of the Early Toarcian negative carbon-isotope excursion in separated carbonate microfractions (Jurassic, Paris Basin)

The causes of the pronounced negative excursion in carbon-isotope values that was recorded during the Early Toarcian Oceanic Anoxic Event (T-OAE) are still under debate, particularly with regard to the local versus global pattern of the excursion, and the extent to which recorded signals are under a diagenetic control. In this study we employ a novel microseparation technique in order to investigate the isotopic and mineralogical characteristics of different size fractions of the carbonate content from a Toarcian section recovered from the Sancerre–Couy borehole, southern Paris Basin. Beyond the recognition of a − 6‰ δ 13C excursion in the bulk carbonate content, our data also demonstrate that biogenic particles (such as coccoliths) and inorganic grains precipitated as early diagenetic phases (including dolomite) both record the excursion with the same magnitude. Although several black shales occur through the Paris Basin Toarcian section, it is only that associated with the onset of the OAE that coincides with a large negative carbon-isotope excursion. Taken together these observations indicate that during this event, the entire water column was characterized by homogeneous carbon-isotope values; such a pattern is incompatible with the idea that the negative excursion was generated simply through the upwelling of bottom waters enriched in re-mineralized organic carbon (cf. “the Küspert model”), since this would have required a strong vertical gradient in the water column. Additionally, the Paris Basin data show that the decrease in carbonate δ 13C values during the OAE occurred in several discrete steps (each of some − 2‰), as has previously been found for organic carbon substrates in other European sections. The stepped nature of the isotopic profile, which is part of a stratigraphic signature previously ascribed to Milankovitch forcing, is compatible with regular pulsed input of light carbon into the whole atmosphere–ocean system from a climatically sensitive source such as gas hydrate, or from thermal methanogenesis of organic-rich sediments in the Karoo–Ferrar large igneous province. Contrasts in the amplitude of the negative carbon-isotope excursion on a regional scale remain an important unexplained aspect of the Toarcian record.

Development and Structure of Eukaryotic Biofilms in an Extreme Acidic Environment, Río Tinto (SW, Spain)

An in situ colonization assay was performed to study the early stages of biofilm formation in Rio Tinto (SW, Spain), an extremely acidic environment (pH ca. 2). Eukaryotic assemblages were monitored at monthly intervals for 1 year. Diversity, colonization rates, and seasonal variations were analyzed. Structural features of naturally grown biofilms were explored by light and scanning electron microscopy in backscattered electron mode. A total of 14 taxa were recognized as constituents of the eukaryotic assemblages. The eukaryotic communities were dissimilar at the different sampling sites. The lowest diversity was found at the most extreme locations, in terms of pH and heavy metal concentrations. The biofilms were mainly formed by species from the genera Dunaliella and Cyanidium. Two genera of filamentous algae, Zygnemopsis and Klebsormidium, were principally responsible for the variability in the cell number throughout the year. These species appear in June to decrease almost completely between October and November. In contrast, the number of heterotrophic flagellates and ciliates remained constant throughout the year. The microcolonization sequence showed an initial accumulation of amorphous particles composed of bacteria and inorganic grains of minerals. By the end of the second month, the organic matrix was also populated by fungi, bacteria, and a few eukaryotic heterotrophs such as amoebae and small flagellates. Diatoms only showed significant colonization in regions where mycelial matrices were first established. Flagellated green algae such as Dunaliella or Chlamydomonas as well as Euglena were also present at the very beginning of the biofilm development, although in low numbers (<100 cells cm(-2)). After the flagellated cells, sessile species of algae such Chlorella or Cyanidium appeared. Filamentous algae were the last species to colonize the biofilms. Most of the naturally grown biofilms were found to be structures composed of different species organized in different layers separated, probably by extracellular polymeric substances, although more analysis should be done in this regard. The possible implications of the biofilm structure in the adaptation to this extreme habitat are discussed.

The synthesis of organic and inorganic compounds in evolved stars.

Recent isotopic analysis of meteorites and interplanetary dust has identified solid-state materials of pre-solar origin. We can now trace the origin of these inorganic grains to the circumstellar envelopes of evolved stars. Moreover, organic (aromatic and aliphatic) compounds have been detected in proto-planetary nebulae and planetary nebulae, which are the descendants of carbon stars. This implies that molecular synthesis is actively happening in the circumstellar environment on timescales as short as several hundred years. The detection of stellar grains in the Solar System suggests that they can survive their journey through the interstellar medium and that they are a major contributor of interstellar grains.

From Stardust to Meteorites: The Synthesis of Inorganic and Organic Grains in AGB and Post-AGB Stars

Infrared spectroscopic observations of the circumstellar envelopes of AGB and post-AGB stars have identified a variety of inorganic grains including amorphous silicates, crystalline silicates, silicon carbide, carbonates, corundum, spinels and possibly rutiles. Isotopic studies of meteorites have also identified similar species of presolar origin. The existence of aromatic and aliphatic features in the spectra of post-AGB stars suggests that organic compounds in solid-state form are made during the post-AGB phase of stellar evolution. These features show similarity with the IR spectra of kerogen, which is also found in meteorites. These grains therefore represent an important link between stars and the solar system.

Effect of the addition of ZrO 2 to polysulfone based UF membranes

Flat sheet Zirfon ® membranes composed of organic (polysulfone; PSf) and inorganic (zirconium oxide; ZrO 2) constituents were prepared by the phase-inversion process. The casting solutions consist of 18 wt% polymer solutions of PSf in N-methyl-pyrrolidone to which different amounts of ZrO 2 were added. The membranes were evaluated by measurements of their permeability, porosity and dextran retention. High resolution scanning electron microscopy was applied to obtain direct information on the skin morphology. The membrane permeability was found to increase for growting amounts of inorganic grains added to the casting solution. However, image analysis of the surface micrographs did not reveal corresponding changes in the surface porosity and pore dimensions of the skin. The observed flux behaviour is atributed to the disturbance of the normal phase-inversion process by the presence of the inorganic grains. From 40 wt% ZrO 2, the hindrance by the inorganic grains is sufficiently high to cause the formation of a highly porous surface layer. A further increase in wt% ZrO 2 influences the formation of the total skin layer, enhancing a higher throughput to the porous sub layer.

Thermoluminescence analysis for testing the irradiation of spices

Thermoluminescence signals of irradiated and unirradiated spices and herbs are due to inorganic matter grains adhering to the surfaces. This study reports the mineral composition of this dust being, mainly quartz, calcite and philosilicates; it shows the differences between samples exposed and non-exposed to γ-radiation on the basis of TL signals after long storage periods (1–16 months). A saturation process in the TL signal is found when the samples absorb doses higher than 5 kGy. Finally, the TL glow curve intensities do not suffer significant changes with the dose rate of the γ-source used in the radiation process.

Mineral and organic particles in astronomy

A mixture of inorganic mineral grains comprised mainly of silica with linked SiO4 tetrahedra together with organic grains characterised by the spectrum of an ‘average’ bacterium provides excellent agreement with astronomical data relating to broad 10 and 20μm emission and absorption features. Mineral clay-like particles of radii ∼0.01 μm are most likely to condense in the atmospheres of Mira-type stars and be expelled by radiation pressure into interstellar space. These particles would tend to stick onto the surfaces of bacterial grains in conditions of high density associated with regions of star formation.

Statistical Analysis of Calcisiltites from Bird Spring Group, Mountain Springs, Nevada: ABSTRACT

Seventeen petrographic variables observed in duplicate thin sections for each of 62 calcarenites and calcisiltites collected from the Monte Cristo Limestone and the Bird Spring Group are the basis for this study. The samples are assigned to 6 microfacies, of which 31 and 17 belong to microfacies 0 and 1, respectively. R-mode cluster analysis grouped the variables into 7 clusters; 5 are composed of various organic and inorganic grains and associated alteration products, 1 is composed of acid insolubles, and 1 of sparite and micrite. Interclass and intraclass variation was tested by means of the Mahalanobis D2 and associated F statistics. The null hypothesis was accepted for all diagonal elements and rejected for all nondiagonal elements. Initial clustering of ra - and transformed-data sets by means of Q-mode factor analysis--first using 17 primary variables, and then using 2 derived variables--indicated that the 2-variable case provided the best separation between microfacies 0 and 1. Null hypotheses concerning group dispersion and the equality of sample centroids were rejected for both the raw and transformed 2-variable case; consequently, an appropriate form of the T2 statistic was employed to test for a significant difference between these two microfacies. Associated F values indicate a statistically significant difference between these microfacies for both raw- and transformed-data sets. Computed discriminant functions are approximately 98 and 79% efficient for the raw and transformed cases, respectively. The upper Monte Cristo Li estone was deposited under relatively stable environmental conditions that produced massive, low-energy micrites with very few biogenic grains. After an interval of erosion, the alternate quartzose sandstones and biomicrites of the lower Bird Spring Group were deposited under relatively unstable conditions. Environmental stability increased during the deposition of the upper Bird Spring Group, which consists of an almost unbroken sequence of micrites and biomicrites. End_of_Article - Last_Page 556------------