It is well known the remarkable optical properties of both graphene and left handed materials, for which we study the optical properties of a multilayer system building by graphene-dielectric-left hand material. In this work, we show the transmission, reflection and absorption spectra for a different set of parameters of the left-handed material structure. It is important to highlight that the inclusion of graphene remarkably modifies the transmission and absorption spectra. The optical properties of the graphene-LHM can be modulated via the different parameters of system. We showed that the fill function do not change the line form of the spectra, however, modify their amplitudes. With respect to light polarization, it’s possible to observe that the spectra are widen for TM respect to TE polarization.

Development of biomaterials with primary amine surfaces is very important for the study of some cells of the immune systemuch as macrophages. Currently, the modification can be carried out by physical or chemical methods with several disadvantages due to the presence of additives or subproducts in the system. To overcome this problem, modified polypropylene (PP) films were synthesized by gamma radiation. In this work, radiation grafting of acryloyl chloride onto PP has been employed to form an acyl chloride. Then, the radiation-grafted films were reacted with ethylenediamine in several solvents to obtain the different concentration of the primary amine. The surface amine concentration was determined by derivatization with 4-trifluoromethyl benzaldehyde and characterized by x-ray photoelectron spectroscopy (N/C ratios), Fourier transform infrared spectroscopy with attenuated total reflection, contact angle, scanning electron microscopy, atomic force microscopy, and elementary analysis. The stability of the amines was measured up to 90 days, without the occurrence of aging as was found by plasma modification.

New speleothem records from northeastern Iberian caves provide data to explore the climatic patterns during the Holocene. We present δ13C and Mg/Ca from three speleothems from two different caves located in the Iberian Range allowing replication of the climatic signal for several millennia. Through the integration of those stalagmites covering since the Holocene onset to 2 ka, the early Holocene (11.7–8.5 ka) appears as the wettest interval. A marked change towards aridity is observed during the middle Holocene (8.5–4.8 ka) and an increase of humidity afterwards (4.8–2 ka). This three-part pattern, contrasting with other Iberian sequences, seems to be associated with the different role that seasonality has played in the response of different proxies (or records) to changes in water availability. Interpreting our speleothem records as changes in winter-spring precipitation along the Holocene allows reconciling previous data on hydrological variability from the western Mediterranean borderlands.

Knowledge of habitat segregation of mosasaurs has been based on lithology and faunal assemblages associated with fossil remains of mosasaurs and stable isotopes (δ13C). These approaches have sometimes provided equivocal or insufficient information and, therefore, the preference of habitat by different mosasaur taxa is still suboptimally constrained. The present study is focused on the analysis of rare earth element (REE) ratios of mosasaur fossils from the Upper Cretaceous formations of western Alabama, USA. Results of the REE analysis are used to infer the relative paleobathymetry associated with the mosasaur specimens and then to determine if certain taxonomic groups showed a preference for a particular water depth. Comparisons are then made with mosasaur specimens reported in the literature from other regions of North America from different depositional environments. Results indicate that Mosasaurus, Platecarpus and Plioplatecarpus may have preferred more restricted habitats based on water depth whereas Tylosaurus and Clidastes favoured a wider range of environments. Results also suggest that Plioplatecarpus lived in a shallower environment than its Platecarpus predecessor. Although the results of this study are encouraging, caution must be exercised before drawing any final conclusions due to the small sample size of most of the taxa analysed.

This study evaluates the behavior of the adherence layers - sawn flat iron boride formed on the surface of steels used in manufacturing industry in Mexico. In steels AISI 1018, AISI 8620 and AISI 316 was characterized this behavior, boriding thermochemical treatment with box technique, with a processing temperature of 1273 °K, with an exposure time of 8 hours. Furthermore the adherence is assessed by the Rockwell C hardness technique prescribed by the German standard VDI 3198 of traction, this impact test qualitatively determine the type of adherence formed three thermochemical steels treated by the technique of boriding. Moreover optical microscopy determines the type of film morphology FeB/ Fe2B of each of the materials exposed to a boriding, also shows the thicknesses of the phases generated in the surface type in all three steels boriding. Phase presence boride FeB/Fe2B was determined by X -ray diffraction (XRD). Technique for scanning electron microscopy (EDS) was evaluated qualitatively the presence of FeB/Fe2B of boronizing. Otherwise determines the hardness and elastic modulus by nanoindentation technique of the phases present in the three steels. Lastly, AISI 1018 and AISI 8620 are bounding scale H1 to H3, the AISI 316 steel has an adherence of H3 to H6 under German standard VDI 3198.

A comprehensive palaeoenvironmental reconstruction of the last 219 ka has been carried out by determining the isotopic signatures (δ18O and δ13C) in 766 samples of a thermogene travertine formation in the Guadix-Baza Tertiary basin (Granada, SE Spain). This travertine formation was dated from ≈ 220 to ≈ 5 ka by means of the alpha-spectrometry technique. Initially, the study of the δ18O values of the travertine formation was carried out because they are excellent indicators of the overall palaeoclimatic condition of a particular site. Likewise, the evolution of δ13C values, which can be directly related to the biomass development of the site, has also been studied. Finally, an integrated study of both isotopic records has been performed, identifying a total of 12 climatic periods based on their palaeoclimatic and palaeoenvironmental conditions. These periods are grouped into four climatic scenarios: scenario A, characterized by warm and dry periods; scenario B, characterized by cold and humid periods; scenario C, constituted by warm and humid periods; and scenario D, which is characterized by cold and dry periods. Palaeoclimatic scenarios A and B mainly characterized the palaeoclimatic evolution of the site, while in northern Europe the palaeoclimatic evolution is mainly characterized by scenarios C and D. Therefore, it is suggested that the palaeoenvironmental evolution at lower latitudes on the Iberian Peninsula is the opposite of that identified in northern Europe. However, the main climatic events identified at higher latitudes are also reflected in the studied area.

The processes involved in vital effects, defined as biological processes overriding environmental signals, are not well understood and this hampers the interpretation of environmental parameters such as seawater temperature. Insufficient knowledge is available about changes in physico-chemical parameters, in particular those related to crystallography, associated with biomineral formation and emplacement. This paper assesses the influence of crystallography on Mg2+ concentration and distribution in calcite biominerals of bivalved marine organisms, mussels and rhynchonelliform brachiopods, and considers the implications for Mg/Ca thermometry. In the mussel Mytilus edulis, changes in Mg2+ are not associated with crystallography; but in the brachiopod Terebratulina retusa, increases in Mg2+ concentrations (∼0·5–0·6 wt. ) are associated with the {0001 planes of calcite biominerals. A comparison between mussels and brachiopods with avian eggshells, which form at constant ambient temperature, also reveals that there is at least a common 0·1 wt. variation in magnesium concentration in these calcite biomineral systems unrelated to temperature or crystallography. Results demonstrate that the integration of contextual crystallographic, biological and chemical information may be important to extract accurate environmental information from biominerals.

Electron backscatter diffraction (EBSD) is becoming a widely used technique to determine crystallographic orientation in biogenic carbonates. Despite this use, there is little information available on preparation for the analysis of biogenic carbonates. EBSD data are compared for biogenic aragonite and calcite in the common blue mussel, Mytilus edulis, using different types of resin and thicknesses of carbon coating. Results indicate that carbonate biomineral samples provide better EBSD results if they are embedded in resin, particularly epoxy resin. A uniform layer of carbon of 2.5 nm thickness provides sufficient conductivity for EBSD analyses of such insulators to avoid charging without masking the diffracted signal. Diffraction intensity decreases with carbon coating thickness of 5 nm or more. This study demonstrates the importance of optimizing sample preparation for EBSD analyses of insulators such as carbonate biominerals.

A series of Polynesian pearls has been investigated with particular attention to the structural and compositional patterns of the early developmental stages of the pearl layer. These initial steps in pearl formation bear witness of the metabolic changes that have occurred during the pearl-sac formation. The resulting structurally and biochemically complex structures have been investigated using a variety of techniques that provide us with information concerning both mineral phases and the organic components. Results are discussed with respect to our understanding of the biomineralization mechanisms, as well as for the grafting process.

Calcium carbonate biominerals are frequently analysed in materials science due to their abundance, diversity and unique material properties. Aragonite nacre is intensively studied, but less information is available about the material properties of biogenic calcite, despite its occurrence in a wide range of structures in different organisms. In particular, there is insufficient knowledge about how preferential crystallographic orientations influence these material properties. Here, we study the influence of crystallography on material properties in calcite semi-nacre and fibres of brachiopod shells using nanoindentation and electron backscatter diffraction (EBSD). The nano-indentation results show that calcite semi-nacre is a harder and stiffer (H ≈ 3—5 GPa; E = 50–85 GPa) biomineral structure than calcite fibres (H = 0.4—3 GPa; E = 30—60 GPa). The integration of EBSD to these studies has revealed a relationship between the crystallography and material properties at high spatial resolution for calcite semi-nacre. The presence of crystals with the c-axis perpendicular to the plane-of-view in longitudinal section increases hardness and stiffness. The present study determines how nano-indentation and EBSD can be combined to provide a detailed understanding of biomineral structures and their analysis for application in materials science.

Living systems exert exquisite control on all aspects of biomineral production and organic components, including proteins, are essential to this biological control. The protein-rich extrapallial (EP) fluid of bivalve molluscs is a strong candidate for the source of such proteins. Differences in calcium carbonate polymorphs between Modiolus modiolus and Mytilus edulis are concurrent with differences in EP fluid protein profiles. In conjunction with this biological control is the environmental influence which is interpreted using proxies such as δ18O to determine the history of ambient seawater temperature. In the horse mussel, Modiolus modiolus, the difference in oxygen isotope fractionation in the nacreous aragonite and the prismatic aragonite layer results in respective δ18O values of 2.1±0.2% and 2.5±0.2%. These δ18O values result in estimates of ambient seawater of 12.1±0.6°C and 10.2±0.6°C for nacreous and prismatic aragonite, respectively. Electron backscatter diffraction is used here to determine the crystallographic orientation at high spatial resolution, allowing the measurements of stable isotopes to be accurately mapped in terms of shell architecture. These preliminary data suggest that it is essential to account for both polymorph and crystal habit when deciphering ambient seawater temperature using δ18O as a proxy.

With their long geological history and stable low-Mg calcite shells, Rhynchonelliform brachiopods are attractive sources of environmental data such as past seawater temperature (Buening and Spero, 1996; Auclair et al., 2003; Brand et al., 2003; Parkinson et al., 2005). Concerns about the influence of vital effects on the stable isotope composition of brachiopod shells (Popp et al., 1986), led to isotope analyses of different parts of brachiopod shells in order to identify those parts of the shell that are influenced by any vital effect and those parts that may be suitable recorders of seawater temperature via stable oxygen isotope composition (Carpenter and Lohmann, 1995; Parkinson et al., 2005). Such detailed studies demonstrated that the outer primary layer of acicularcalcite is isotopically light in both δ18O and δ13C while the secondary layer, composed of calcite fibres, is in oxygen-isotope equilibrium with ambient seawater(Fig. 1) (Parkinson et al., 2005).

Electron backscatter diffraction (EBSD) is used to determine the detailed crystallographic orientation of calcite crystals of craniid brachiopods in the context of shell ultrastructure. Sections of shells of two Recent species, Novocrania anomala and Novocrania huttoni, are analysed to provide 3D crystallographic patterns at high spatial resolution. The c-axis of semi-nacre calcite crystals is oriented parallel to the laminae that define the ultrastructure of the secondary layer. This orientation differs from that of rhynchonelliform calcitic brachiopods where the c-axis is perpendicular to the length of morphological fibres and to the shell exterior.

With their extensive fossil record and shells of stable low-Mg calcite, rhynchonelliform brachiopods are attractive sources of climate information via seawater temperature proxies such as stable oxygen isotope composition. In Terebratalia transversa (Sowerby) there is a progression towards oxygen isotope equilibrium in the calcite of the innermost secondary layer. This study confirms the lack of any vital effects influencing oxygen isotope composition of T. transversa, even in specialised areas of the innermost secondary layer. Calcite Mg/Ca ratio is another potential seawater temperature proxy, that has the advantage of not being influenced by salinity. Mg concentrations measured by electron microprobe analyses indicate that there is no concomitant decrease in Mg concentration towards the inner secondary layer, associated with the progressive shift towards oxygen isotope equilibrium. Mg distribution is heterogeneous throughout the shell and correlates with that of sulphur, which may be a proxy for organic components, suggesting that some of the Mg may not be in the calcite lattice. It is essential therefore, to determine the chemical environment of the magnesium ions to avoid any erroneous temperature extrapolations in brachiopods or any other calcite biomineral.

A brachiopod fauna from the Hogan Formation near Skunk Springs, western Utah, in the eastern Great Basin, USA, includes only the new taxon Duartea bruntoni n. sp., and other brachiopod taxa described for the first time in North America. the faunas are considered to be late Moscovian (late Desmoinesian) in age, which represents the first record of post-middle Desmoinesian brachiopod faunas within the Pennsylvanian of the Great Basin. Systematic analyses of the faunas suggest strong affinities with brachiopods previously described in South America and Russia, confirming the idea of faunal migration into the Great Basin. the migration of these faunas appears to correlate with the development of new oceanic currents in response to paleogeographic changes related to the formation of the Late Paleozoic Pangea.