Primary results of sedimetological research on the upper Jurassic to lower Cretaceous carbonate rocks in NW Zagros Mountains, Iran

The upper Jurassic-lower Cretaceous carbonate extensively distributed in Zagros Mountains (southern Iran) is correlated to hydrocarbon reservoir rocks, however has not been studied with sedimentological aspects. The studied section of about 1000 m thick exposed in Kuh-d-Yaghma (Aligdaz Province) mainly consists of shallow marine facies exhibiting sedimentary structures, such as paleosols, paleokarsts, biostromes, and stromatolites. The section was subdivided into nine units based on the results of observation of outcrops and thin sections. Depositional ages were estimated by fossil occurrences and strontium stable isotope. Units 1 and 2 represent subaerial-meteoric diagenetic structures (paleosols. paleokarsts, and banded cements) and dolomite of a mixed-water origin. Originally, the dolostone was highly-permeable coarse-grained sediment, in which dolomitization selectively subjected. These diagenetic processes may have been associated with global sea-level low or a regional tectonic event during Kimmeridgian, and formed lithified substrate, which is suitable for sedentary organisms. Unit 3 abundantly yields potential reef-building organisms, such as stromatoporoids, corals, and calcareous algae. However, the dominant constituents are broken uniserial branching stromatoporoids, their constructions should be regarded as biostromes and did not form reef framework. Fossil association and strontium isotopic ratio indicate that this unit was deposited in Tithonian. Units 4～7 are alternations of two deeper and two shallower facies. The deeper units (units 4 and 6) mainly consists of micritic limestone with biofacies characterized by ostracodes, bryozoans, and sponge spicules. The shallower units (units 5 and 7) represents stromatolites, oncoids, and ooids with rich assemblage of calcareous algae. Jurassic/Cretaceous boundary was placed in unit 5. First appearance of orbitolinid foraminifers at the base of unit 7 was interpreted to correspond to the base of Barremian. Units 8 and 9 consist of four upward-shallowing sequences. The base of each cycle consists of thinly bedded limestone containing brachiopod shell, and change into thickly bedded and massive limestone with shallow marine stromatolies and fauna, such as corals and rudists. Gradual decrease in thickness of the sequence indicates that the platform was in progradation due to accumulation of the carbonate deposits

Microscopic dissection of the process of stress granule assembly

AbstractStress granules (SGs) are mRNA triage sites that are formed in response to a variety of cellular stress. To study how SGs bring about the massive spatial compartmentalization, we monitored the localization of various RNA-binding proteins (RBPs) targeted to SGs upon exposure to stress. We discovered that concomitant with the onset of eIF2α phosphorylation, RBPs accumulate locally in the cytoplasm, which leads to increased inter-molecular interactions and the formation of robustly detergent-resistant foci. Subsequently, microtubules (MTs) mediate 1) the ordered spatial organization of SGs and 2) the recruitment of a set of nuclear-localized SG components to the cytoplasm. Meanwhile, MTs did not appear to be required for the maintenance of SG distribution after its assembly. Our data suggest that the process of SG formation is composed of MT-independent and -dependent pathways, which take place sequentially during stress response

Direct observation of Pt-terminating carbyne on graphene

Theoretical studies predict that carbynes (single-atomic linear carbon chains) have unique properties that rival those of graphene and carbon nanotubes. However, experimental studies on carbynes are rare due to the lack of reliable and effective means of production. Here, we report a direct observation of carbyne formation and dynamics by in situ transmission electron microscopy. Using Pt atoms on graphene, we succeeded in forming and observing carbynes reproducibly. Free carbon adatoms on graphene were trapped by Pt atoms, which served as nucleation sites for carbyne formation. Each end of the carbyne chain was eventually terminated by a Pt atom, and the Pt-terminating carbyne chains exhibited a variety of straight, curved, and ringed shapes

Raman scattering study of ca-modified lead titanate

The paraelectric to ferroelectricphase transitionswere studied by Raman scattering in Ca-doped leadtitanate ceramics. The soft optic modes responsible for theferroelectricphase transitions were clearly observed. TheAi(lTO) mode, which softens toward Tc, contains four subpeaks.The frequencies of these subpeaks depend to a greatextent on the Ca content and the temperature. These behaviorsare discussed on the basis of the anharmonicity oflatticevibrations

Mechanistic Insights into Indigo Reduction in Indigo Fermentation : A Voltammetric Study

Indigo is one of the oldest natural blue dyes. Microorganisms and their enzymatic activities are deeply involved in the traditional indigo staining procedure. To elucidate the mechanism of the microbial indigo reduction, we directly performed cyclic voltammetry on alkaline fermenting dye suspensions. A pair of characteristic redox peaks of leuco-indigo was observed in a supernatant fluid of the fermenting dye suspension. On the other hand, it was found that the indigo/leuco-indigo redox couple mediated two-way microbially catalyzed oxidation and reduction in a sediment-rich suspension of the fermenting suspension. Acetaldehyde was supposed to be the electron donor and acceptor of the catalytic reactions. In order to verify the bioelectrocatalytic reaction, we isolated indigo-reducing bacterium K2-3′ from the fermenting suspension, and the two-way bioelectrocatalysis was successfully restaged in a model system containing K2-3′ and methyl viologen (as a soluble mediator instead of indigo) as well as acetaldehyde at pH 10