Granulometric Studies Research Articles

Rock magnetic methods in the study of the loess-soil series of Eastern Siberia

Rock magnetic methods complement geological and granulometric studies of subaerial deposits, allowing to solve relevant and interesting problems in terms of paleogeography. The magnetic characteristics are numerical and provide a reasonable basis for a correct comparison of subaerial deposits among themselves, for a more detailed stratigraphic dissection of sediments and specifying their genesis, for the identification of marker horizons, and for the correlation of the data of different methods. The paper discusses the main mechanisms of formation of the magnetic properties of loess-soil series in different regions (“Chinese” and “Alaskan”) and peculiarities in the interpretation of rock magnetic parameters within the framework of different mechanisms. The paleoclimatic informativity of rock magnetic parameters in different physical-geographic settings is analyzed. The fundamental differences in the formation of the magnetic properties of the loess-soil series of Siberia (“Siberian” mechanism) are shown and the principles of paleoclimatic interpretation of rock magnetic data on the basis of more than 40 sections of subaerial complexes of southern Western, Preenisei and Eastern Siberia are developed. Based on changes in rock magnetic parameters, the trend of climatic changes during the quaternary period, which consists in the change from the “pedogenic” mechanism to the “Siberian” one and then to the “Alaskan” one, was revealed using the example of subaerial sediments of Eastern Siberia. This difference in mechanisms may serve as a criterion for diagnosing subaerial deposits of Eopleistocene age.

LOW-COST AND EASY ACCESS MATERIALS FOR A LABORATORY CLASS: A PROPOSAL OF LIQUID CHROMATOGRAPHY FOR FOOD COLORING SEPARATION AS AN EXPERIENCE OF MEANINGFUL LEARNING

The experimental activities for undergraduate chemistry students play an important role to develop skills and expertise in that science thus, the practice-experimental classes are so important to achieve this purpose. This work deals with a demonstrative experience for dye separation from food coloring sample using liquid column chromatography. Beyond the experimental practice and the facility in visualizing the separation, this demonstration shows how a simple experiment involving alternative and easy access materials can promote a meaningful learning once it is possible to handle the acquired data, trace and analyze the results themselves, thus developing skills rather than the operational procedure. This proposal could be implemented in initial chemistry classes in Brazilian universities. Sea and river sands were used as stationary phases and aqueous ethanolic solutions were used as mobile phases. A food coloring (a mixture of 3 dyes) was chosen as sample to be studied. Chromatographic separation was followed by spectrophotometric measurements. A set of analyses were carried out to discuss the solubility of the food coloring, granulometric studies of the stationary phases used and electronic microscopy images of the sands studied here. As alternative materials were used in this work, a chromatographic column was also constructed with low-cost materials.

LITHOLOGY AND SEDIMENTOGENESIS OF THE EARLY OLIGOCENE LOWER PLANORBELLIAN DEPOSITS IN THE NORTHWESTERN PART OF THE INDOLO-KUBAN DEPRESSION

On the basis of lithological, lithmological, mineralogical-petrographic, and granulometric studies of the Lower Planorbellian deposits of the northwestern side of the Indolo-Kuban depression, in combination with the data of facies interpretation of logging results (radioactive methods), the environments of Early Planorbellian sedimentation were reconstructed. It has been established that the lithological structure of the Lower Planorbellian sequence of the Maikop of the northwestern side of the Indolo-Kuban depression is characterized by an almost uniform distribution of mudstones (34–71%, average 49%) and siltstones (27–57%, average 41%) with a subordinate development of sandstones (3–27%, average 10%). According to the features of the spatial distribution of these components within the studied region, four lithological complexes of three series were distinguished: psammite-siltstone-argillite (sandstones 0–25%, siltstones 50–75%, mudstones 25–50%) complex of the siltstone series; predominantly mudstonesiltstone (sandstones 0–25%, siltstones 25–50%, mudstones 25–50%) and mixed terrigenous (sandstones 25–50%, siltstones 25–50%, mudstones 25–50%) complexes of mixed psammitic-siltstone-argillite series and argillite with interlayers of sandstones and siltstones (sandstones 0–25%, siltstones 0–25%, mudstones 50–75%) complex of the argillite series. The genetic interpretation of the results of granulometric analyzes of terrigenous rocks showed the dominance within the region of formations of shelf basins with a directed system of watercourses. A cyclic (transgressive-regressive) character of the Early Planorbellian sedimentation was revealed, which manifested itself in the upsection replacement of sandy formations of the initial stages of the development of the basin by siltstoneargillaceous silts in the middle and again by the accumulation of clastogenic deposits at the final stage. On the whole, the sedimentation basin was a sublittoral shoal with local directed watercourses, within which formations of estuarine and alongshore bars, alluvial fans, and shelf plains are distinguished.

Characterization of the Physicochemical, Functional, Granulometric and Mineral Properties of Néré (Parkia Biglobosa) FN, FW and FK Flours From Korhogo in Côte d'Ivoire

The néré fruit is known in the north of Côte d’Ivoire for its seeds, which are used to prepare soumbara, and for its pulp, which is also consumed. Unfortunately, the nutritional value of the pulp is not known by the population and it is not processed by local industries. This study contributes to the valorization of néré fruits. After hulling, the pulp is dried in the sun, crushed, and sieved to produce three types of flour, depending on its origin. The flours from Niofoin, Waragniéré, and Kanoroba have been coded FN, FW, and FK respectively. The study of the physicochemical properties of the flours showed, depending on their origin, a moisture content of 5.4 to 7.6%, the average fibre content of 15.27%, high total carbohydrate content (81.05 to 84%), high energy value (360.4 to 369.13 Kcal/100g). The study showed the presence of antioxidants such as polyphenols (319.15 to 400.09mg/100g). Anti-nutrients like oxalates (7.42 to 10.81mg/100g) were found in low amounts. The study of functional properties showed a water absorption capacity of 199.54 to 207.55%, and an oil absorption capacity of 105.46 to 109.35%. The mineral study showed the presence of magnesium (0.05 to 0.076ppm), potassium (0.01 to 0.054ppm), calcium (0, 094 to 0.131ppm), iron (0.025ppm), copper (0.02 to 0.129ppm). The granulometric studies showed that the vast majority of the particles of the flours FN, FW, and FK, are smaller than 250 µm. The flours FN, FW, and FK contain macronutrients, high energy value, fibre, interesting functional properties, antioxidants, and minerals that are beneficial for the local populations and can be used by the food industries.

Sedimentary facies and textural characteristics of Cretaceous sandstones in the southern Bida Basin, Nigeria: Implication for reservoir potential and depositional environment

A study of sedimentary facies, mineral and textural characteristics of sections of conglomerates/pebbles and sandstone facies found within the Lokoja and Patti Formations in southern Bida Basin, Nigeria, is carried out to evaluate the paleo-environment and reservoir quality of the sandstones of the formations through field observations and textural and mineralogical (using X-Ray Diffractogram) analyses. Nine lithofacies are identified and grouped into three main facies associations. These sedimentary facies suggest deposition in both foreshore and estuaries. The mineral analysis (XRD) shows that the quartz content in sandstone facies of the Lokoja Formation ranges between 49% and 67%, and that of the Patti Sandstone between 43% and 56%, indicating a quartz dominance. The granulometric studies reveal that the Lokoja Formation comprises coarse-to medium-grained (−0.63 to 1.30 φ) sandstone with moderate-poor sorting of 0.72–1.82 φ. On the other hand, medium to fine-grained sandstones dominate the Patti Formation, which is averagely poorly sorted (1.29–1.54 φ). The sandstones are coarsely skewed to finely skewed, with the kurtosis ranging from very platykurtic to leptokurtic. Morphological results of the pebbles from both Lokoja and Patti Formations indicate that the study areas are mainly characterized by the interplay of both wave and fluvial processes, which suggests that the environment of deposition of sandstone facies is predominantly of the fluvial to the shallow marine environment with the indication of tidal influence.Integrating sedimentary facies and textural results suggests subtidal sand ridge/foreshore, estuarine mudflat, and estuarine delta environments with fluvial influences. Evidence from the textural and mineral characteristics indicate that the sandstone facies of the Lokoja and Patti Formations are fairly matured and can act as potential hydrocarbon reservoirs in the formations. The facies, XRD mineral, and textural results have revealed potential hydrocarbon reservoir areas and paleo-depositional features of the Lokoja and Patti Formations.

ANALYSIS OF POROUS NANOSILICON BY RAMAN SPECTROSCOPY

The technologies of obtaining nanostructured silicon, including porous nanosilicon are presented. The method for the synthesis of porous nanosilicon using electrochemical etching is described. The main parameters of the generation of porous silicon with specified characteristics are given. The results of the study of nanostructured porous silicon samples using a Renishaw InVia Raman Spectrometer are described in detail. This spectrometer permits to register and identify both amorphous and crystalline phase components in the samples. According to the results of granulometric studies, the crystal structure of the samples is established. The approximation of the Raman spectra confirms the absence of amorphous silicon in the samples under study. In the Raman spectra of the samples, a shift of lines towards lower energies is observed, which is characteristic of nanoparticles with a decrease in their size. The photoluminescence spectra of the synthesized samples of porous silicon exhibit a stable intense band in the range 700—900 nm, which confirms the nanocrystalline nature of the samples. We demonstrate the efficiency and sensitivity of Raman spectroscopy, which makes it possible to register even insignificant changes in the crystalline and amorphous fractions of silicon structures.

MODULATORY EFFECT OF POLYMER TYPE AND CONCENTRATION ON DRUG RELEASE FROM SUSTAINED RELEASE MATRIX TABLETS OF RANOLAZINE: A COMPARATIVE RELEASE KINETIC STUDY

Objective: Ranolazine (RZ), antianginal drug indicated for the treatment of chronic stable angina pectoris, was formulated into sustained-release matrix tablets and optimized to improve patient compliance and achieve controlled release over a certain period.
 Methods: Different formulations were prepared by wet- and melt-granulation techniques. Excipients at different ratios as Eudragit® L100-55, Methocel™ E5, Avicel® PH-101, and carnauba wax powder were used to develop a ternary polymeric matrix system for the controlled delivery of RZ. The prepared formulations were subjected to granulometric and characteristic studies. Comparative dissolution and release kinetic studies of the selected formulation and the reference product, Ranexa® extended-release film-coated tablets, Gilead Sciences, Inc., USA, were further carried out to ensure product similarity.
 Results: The optimum pH-dependent to pH-independent polymers ratio was 1:1.3 (w/w). Extragranular carnauba wax in a concentration of 32.50 mg/tablet (2.50 gm% w/w) was the key excipient in controlling drug release kinetics by forming waxy matrix granules which prevent rapid dissolution. Modulation of the microenvironmental pH using a potent alkalinizing agent was very effective for controlling drug release patterns in different dissolution media from pH 1.2–6.8.
 Conclusion: The release of RZ from the matrix tablets was controlled for a period of 24 h, and thereby expected to provide patient compliance with minimal side effects.

Fluvial facies and petrography of Late Pleistocene Baneta sediments, Central Narmada Basin, Madhya Pradesh, India

Baneta Formation, comprising of fining upward sequences of pebbly conglomerate, sandstone and siltstone, exhibits development of five distinct lithofacies, viz., massive pebbly conglomerate, large scale tabular cross bedded sandstone, horizontal parallel bedded coarse-grained sandstone, parallel laminated fine-grained yellowish sandstone and siltstone; representing channel lag, point bar and overbank flood plain deposits of mixed load meandering river. In these sediments, development of nodular, buckled bedded calcrete, rhizoliths and tepee is noticed. Granulometric studies of these sediments revealed presence of wide range of grain size classes, polymodal grain size distribution, moderate to very poor sorting, positive skewness and leptokurtic nature, supporting fluvial environment of deposition. Lithic arenitic nature, heavy mineral assemblage with dominance of augite and low ZTR index of these sediments indicate mineralogical immaturity and presence of illite, kaolinite and montmorllionite together with geochemical composition indicate their derivation from mixed provenance of Precambrian granite, metapelites, Vindhyan Supergroup, Gondwana Supergroup, Deccan trap basalt, and laterite. The thin sections studies reveal signatures of meteoric phreatic and vadose zone diagenesis related with semi-arid climate and subaerial exposure. The δ13C and δ18O content of calcretes indicate their pedogenic and/or shallow groundwater origin under semi-arid climatic conditions, and C3–C4 mixed vegetation with dominance of C4 vegetation. OSL and 14C dates of the samples from Baneta Formation suggest deposition of these sediments in Late Pleistocene.

Applications of synthetic and semisynthetic polymers (Kollidon K25, Kollidon K90 and Hydroksyethylocellulose) as carriers of ketoprofen in solid oral prolonged release dosage forms. The impact of selected non-ionic surfactants (Tween 80 and Rofam 70) on the release kinetics

Hydrophilic matrices used as oral forms of sustained release drugs are a suitable application medium for short-acting nonsteroidal anti-inflammatory drugs (NSAID) - ketoprofen. A properly selected hydrophilic matrix in oral preparations may significantly increase efficacy and application safety of ketoprofen. The aim of the research was to analyze the usefulness of polymers (synthetic Kollidon K25 and K90, semi-synthetic hydroxyethylcellulose) and calcium hydrogen phosphate dihydrate (as an inorganic filler) in manufacturing solid oral matrix forms of ketoprofen and to study of the effect of non-ionic surfactants (Tween 80, Rofam 70) on release kinetics. Ketoprofen, HEC, Kollidon K25, and K90, calcium hydrogen phosphate, magnesium stearate. Incorporation. Studies on the tablet mass. Direct tableting. Studies on the pharmacopoeial parameters and pharmaceutical availability. Approximation of the results. The results of the granulometric studies on tablet mass were in accordance with pharmacopoeial standards. The results of morphological and biopharmaceutical studies of the obtained matrices (tablets) were consistent with the pharmacopoeial standards for formulations with HEC, K25 and K90. The release results most closely related to row 0 kinetics were obtained for the matrix containing HEC and K25. Tween 80 added to 0.1N HCl accelerated the release of ketoprofen, while Rofam 70 decelerated it. Tween 80 and Rofam 70 added to the pH 7.4 buffer accelerated the release of ketoprofen. The presented model system of preformulation studies showed the usefulness of HEC and Kolidon K25 in the technology of hydrophilic matrices with ketoprofen. Surfactants added to the medium do not affect the release rate of ketoprofen.

Туфопесчаники перекатнинской свиты: состав, происхождение, источники сноса (Усть-Бельские горы, Корякское нагорье)

Research subject . In this work, we set out to investigate the petrographic, mineralogical and granulometric composition of tuff-sandstones in the Perekatnaya formation (Albian-Turonian). Materials and methods . The work was based on the materials obtained during the course of fieldwork in the Ust-Belsky Mountains (Koryak Highlands) undertaken in 2011 and 2016 by researchers from the Geological Institute of the Russian Academy of Sciences. The collected samples of sedimentary rocks were comprehensively studied using granulometric and mineralogical analysis based on the petrographic method. Results . The tuff-sandstones under study were represented by quartz-feldspar, feldspar and proper greywacke. The lithoclast composition was dominated by acidic and intermediate rock fragments. Specimens with a high lithoclast content value were characterized by a lower amount of quartz and feldspars, as well as by a larger grain size. An increase in the proportion of lithoclasts and the coarsening of grains are shown to occur from the southeast to the northwest. This fact has allowed us to establish the direction of material migration from the source area, which was located in the northwestern part of the region. According to the results of granulometric and mineralogical studies, the sediments appear to have been formed by high-speed turbidity currents under moderately deep marine conditions and at a relatively little distance from the coast, where the rivers (their deltas) provided sufficient amount of clastic material. Conclusion . The obtained data confirm the assumptions about the evolution of the Perekatnaya formation under marine conditions on a continental margin (slope). The conditions for the sedimentation of the tuff-sandstones under study can be compared with those typical of areas in the vicinity of river deltas and/or prodelts. The sedimentation occurred concurrently with volcanism, which was associated with the existence of an active continental margin (Okhotsk-Chukotka volcanoplutonic belt).

Granulometric Studies, Rate of Sedimentation and Ostracod Distribution from a Short Core off Ongole Coast, Andhra Pradesh, Bay of Bengal

Granulometric Studies, Rate of Sedimentation and Ostracod Distribution from a Short Core off Ongole Coast, Andhra Pradesh, Bay of Bengal

La metafora de la piel en el proceso poyectual de la vestimenta

Este trabajo considera al cuerpo desde su vitalidad de intercambio con el mundo ( respirar , comer percibir ) La piel emerge como borde de interacción, contenedor y permeable, entre un cuerpo vivo y un mundo siempre cambiante. En lugar de entender el diseño de la vestimenta, desde una visión fragmentada entre el sujeto y el objeto (el vestido) que involucra una clasi - cación que ya está pautado. Se explora desde la vitalidad de las interacciones (múltiples y variadas). La metáfora emerge como lenguaje proyectual que habilita al diseñador a aproximarse a aquello que aun no tiene forma. El proceso proyectual desde “la metáfora de la piel” , alude a una metáfora vincular que valida al cuerpo , a la percepción y al universo poético como experiencia para soñar, imaginar y proyectar forma, materialidad, mundo.

Sedimentary characteristics of palaeolake deposits along the Indus River valley, Ladakh, Trans‐Himalaya: Implications for the depositional environment

ABSTRACTThis study is an attempt to contribute to the data set of granulometric studies of sediments by measuring the sedimentary structure and texture, along with statistical parameters, of cold and arid lake systems. The palaeolake sequence along the River Indus on the western fringe of the Tibetan Plateau in Ladakh sector was selected in order to shed light on depositional environmental changes within the lake from post‐last glacial maximum to 5 ka. The River Indus was blocked by Lamayuru dam burst during the deglaciation, after the Last Glacial Maximum (LGM) and the subsequent increase in water level led to the formation of the Saspol–Khalsi palaeolake. This lake was ca 55 km in length, extending from Nimo to Khalsi, had a surface area of 370 km2 and was in existence until 5 ka. Two sections (Saspol and Khalsi) separated by an aerial distance of 35 km show a similar trend in sediment character due to their deposition in the same lake system. Grain‐size studies show a polymodal nature of sediments for both of the sections. However, sediments of the lower/downstream section (Khalsi) show a poorer degree of sorting, and coarser grain size and high energy depositional condition as compared with the sediments of Saspol section (positioned upstream) due to the location of the sections within the lake system. It was noted that, in high‐altitude arid regions, the sedimentological characteristics of large‐sized valley lakes may vary greatly, horizontally as well as vertically, owing to local stream input, inflow intensity from the catchment, outflow velocity of water channels, lithology and valley widths at the different sites.

Características mineralógicas e granulométricas das fontes de poeiras no Polo Cerâmico de Santa Gertrudes - SP

Resumo Estudos recentes relativos à presença de fluxos de poeiras que entram na atmosfera atestam que eles podem ser até oito vezes maiores do que as estimativas até então consolidadas. Com origem atribuída principalmente às novas demandas de usos dos solos, combustíveis e rochas, essa concentração pode modificar globalmente os principais componentes do Geossistema Climático e colocar em risco os limites ecossistêmicos que suportam a vida no planeta. Em que pese a relevância do Brasil como produtor de commodities minerais e agrícolas e, portanto, um grande produtor de poeiras minerais, poucos estudos dessa natureza têm sido realizados. O presente estudo aborda esse tema em uma região conhecida como Polo Cerâmico de Santa Gertrudes que, além de abrigar as maiores indústrias cerâmicas do Brasil, destaca-se pela sua grande produção agrícola. Técnicas de difração de raios X e difração a laser foram utilizadas para caracterizar a composição mineralógica e granulométrica relativamente dos solos (fonte pedológica), minério de argila (fonte litológica) e seus produtos de transformação (fonte terrígena e industrial), considerados como principais fontes emissoras de poeiras dessa região. A presença de uma assembleia de minerais silicatados ricos em alumínio e ferro que predominam nessas fontes de poeiras explica os altos teores de SiO2, Al2O3 e Fe2O3 encontrados no minério, solos e na atmosfera da região. O predomínio de argilas cauliníticas pode ser considerado como diagnóstico de fonte pedológica, enquanto que o predomínio de argilas ilíticas caracteriza a fonte litológica. Os estudos granulométricos revelaram que, entre as diferentes fontes, a pedológica é a que possui maior volume de materiais argilosos na fração MP10 e, portanto, a que mais tem condição de contribuir com os processos de ressuspensão que são eficientes na transferência de poeiras minerais da superfície para a atmosfera.

Geotechnical Investigation for Resort Construction Using Resistivity and Granulometric Studies in Pattinamaruthur Coast, Southern India

The aim of this article is to find out the soil strength, depth of hard rock, boundary of Archean and Quaternary stages, and aquifer conditions for resort construction in Pattinamaruthur coast, Southern India. Thus geotechnical studies using the electrical resistivity method and grain size analysis were carried out in marine environs using the CRM-500 equipment and microscope. In the field 20 profiles were covered using the square array configuration and the data were interpreted using the curve matching technique. The contour maps of soil thickness and depth to the basement were prepared using the GIS software package (ArcGIS 9.3). The results indicate that the top layer has a resistivity value ranging from 20 to 100 Ω-m showing clayey, sand and sandy clay with maximum a layer thickness of 1.5 m. It is also able to distinguish the soil and rock boundaries. The electrical resistivity values are obtained that range from 1 to 5 Ω-m for saltwater, 5–50 Ω-m for sandstone and >400 Ω-m for weathered genesis rock in the study area. The grain size analysis has identified the depositional environment such as coastal and inland dunes, and freshwater deposits; and also recommended for wood house foundation in the coastal area for disaster management.

Erratum to: Refining landscape contexts for open-air, Lower and Middle Paleolithic sites: a case study from Muthanna Province, Southern Iraq

Open-air Paleolithic sites in desert and semiarid landscapes provide interpretive quandaries because of the absence of depositional matrices and stratigraphic controls. This paper argues that datable and stratified vertical contexts may be preserved in the vicinity of open-air artifact scatters. These, in turn, may account for paleo-environmental conditions that would have attracted Paleolithic groups. The site in question is in the Southern Iraqi desert, a locale heretofore terra incognita for early hominin activity. Optically stimulated luminescence (OSL) dates were taken from ancient spring and dune deposits in a depression flanking the hamada surfaces on which the artifact distributions were found. Geochemical and granulometric studies were used to reconstruct the depositional histories of the spring locale, and the dates were projected onto contemporary oxygen isotope curves that serve as proxies for the climatic cycles operational across the greater Near East. The advent of OSL dating provides a new window for dating events and environments linked to Paleolithic chronologies. The locations of surface scatters may signify preservation of nearby micro-environments which could be proxies for structuring landscape and occupational chronologies.

Physical weathering and modification of a rhyolitic hyaloclastite in Iceland

Fragmental volcanic glass or ‘hyaloclastite’ is a common glaciovolcanic eruption product that is formed in large abundance during basaltic, andesitic and rhyolitic subglacial eruptions. The physical weathering of rhyolitic hyaloclastites differs notably from basaltic hyaloclastites due to differences in cementation and edifice consolidation. As rhyolitic glasses are also much rarer, comparatively little is known about their physical weathering and fracturing characteristics. In the presented study, we provide a process-oriented analysis of the physical modification of subglacially erupted rhyolitic hyaloclastites from the Blahnukur edifice in Torfajokull (Iceland). Frost weathering experiments were performed to determine how vesicular glass particles fragment to finer particle sizes. The surficial porosity of the glass drives such frost weathering through the process of pore pressurisation and was quantified using high-pressure mercury intrusion. Uniaxial compression experiments were carried out to understand how the glass structure responds to the application of external stress. The observed fracturing in both experimental treatments was found to adhere to fractal statistics, which allowed the compression experiments to be used in conjunction with the frost weathering experiments for inferring the fracturing characteristics of rhyolitic volcanic glasses. Transport processes by wind and gravity were simulated by long-duration abrasion experiments in rock tumblers (through granular avalanching), but these low-energy particle interactions were not found to significantly abrade particles. A notable result from our fragmentation experiments was the production of <10 μm particles. This size range is considered respirable and illustrates how physical weathering can continuously create potentially harmful ash textures; a process which is often overlooked in health hazard assessments after volcanic eruptions. Fragmentation by post-eruptive weathering can lead to overestimations of the fine ash fraction produced by syneruptive fragmentation and granulometric studies therefore need to be appreciative of the effects of such secondary fracturing processes.

CdS Powders Obtained by Chemical Bath Deposition

We studied the influence of the mixing on the properties of CdS powders obtained by Chemical Bath Deposition. The powders were obtained from baths containing cadmium chloride, thiourea, and ammonia. The obtained powders were characterized using FT-IR, in order to evaluate the purity of the obtained powder. Granulometric studies were made in order to establish the grain size distribution of the particles, and X ray diffraction in order to determine the structure of nanostructured CdS.

Sediment characterisation of the 26 December 2004 Indian ocean tsunami in Andaman group of islands, bay of Bengal, India

The large tsunami, which was generated by an earthquake on 26 December 2004, affected most of the countries around the Indian Ocean. A total of 48 tsunamigenic surface sediments have been collected from various coastal geomorphological features such as beaches, estuaries/creeks and mangrove areas in the Andaman group of islands. These samples were analysed for sediment characteristics such as sediment texture, granulometric studies. The studied tsunamigenic sediments, deposited by the 26 December 2004 tsunami in the Andaman group of islands consist of poorly sorted, coarse sand to medium sands, and are similar to depositional effects of previously reported earthquake-generated tsunami waves. The tsunamigenic sediment consists of a coarse sand layer with abundant reworked shell and other carbonate fragments. The tsunami sediments were mainly composed of boulders of corals and sand which determines the high-energy environment throughout the study area. The variation in Ф mean size, therefore, reveals the differential energy conditions that lead to the deposition of these kinds of sediments in different locations. The tsunamigenic sediments were mainly poorly sorted, moderately well sorted and well sorted during the post-tsunami (2005) and whereas they were mainly moderately well sorted to well sorted during the post-monsoon (2008). The symmetry of the samples varies from strongly fine skewed to strongly very coarse skewed in the post-tsunami (2005) and post-monsoon (2008). The Kurtosis of the tsunami sediments were mainly Platykurtic, Mesokurtic and Lepokurtic during the post-tsunami (2005) and mainly Mesokurtic and Lepokurtic in post-monsoon (2008).

Characterisation of elastomer prepared from ground tyre rubber: morphological and granulometric study

The characterisation of an elastomer prepared from ground tyre rubber has been carried out in terms of both morphological and granulometric studies. A large number of waste tyres are discarded every year. These residuals represent a crucial environmental problem. Thus, the redemption and recycling of waste tyres constitute a research field of great interest nowadays. In this connection, the study of the size distribution of particulates is of the utmost importance. In the present work, the morphological study of a ground tyre rubber previously prepared has been carried out. The use of SEM techniques indicates that the powder is not completely uniform. The granulometric study of the powder was carried out by applying the Rosin–Rammler and Gates–Gaudin–Schuhmann models. The particle size distribution of the sample here studied satisfactorily fits the Rosin–Rammler model, especially for mesh sizes above 0·250 mm. According to the results of this study, a homogeneous behaviour of the sinterised product during the thermocompression process is expected.