Faulting of a turbidite sandstone-siltstone successions: the case study of the Macigno Formation, Tuscany, Italy

Faults in siliciclastic rocks are characterized by a great variability of fault zone architecture and relative permeability properties. This is because siliciclastic rocks (i.e turbidites) are often represented by alternating beds of various thickness and grain size forming a succession of strata with contrasting mechanical properties. For example, the presence of sandstone and clay-rich layers is responsible for the simultaneous occurrence of brittle and ductile deformation, known as “clay smear structures”. Moreover, numerous studies have identified grain size as one of the main influencing factors for fault nucleation processes and fracture intensity in the damage zone. In this work, we present the results of field and laboratory analyses performed on the Macigno Formation cropping out along the coast of western Tuscany. Here, the Macigno Formation is represented by Late Oligocene foredeep siliciclastic succession dominated by turbiditic sandstones with minor siltstones, mudstones, marls and shales. Thin section and 3D analyses, performed by X-ray Synchrotron tomography, allowed us to characterize the grain size and grain and cement composition of studied rocks. Grain size varies from channelized fine-grained sandstones to granule-conglomerates beds (0.006 mm to 4 mm) alternating with heterolithic levee strata of siltstones to fine-grained sandstones (0.0035-0.008 mm). The lithic components consist of metamorphic rocks by 70-80%, magmatic rocks by 15-20% and sedimentary rocks by 5-15%. The turbidite beds are normally well-cemented (by quartz and calcite) and heavily faulted and fractured. Investigated faults show dip-, oblique- and and strike-slip motion and their displacement range from 10s of centimetres to 10s of metres. We documented how both the grain size and the mechanical properties of the alternating beds strongly control the fault zone architecture, in particular in terms of damage zone thickness and fracture frequency. The fault rock types (i.e. breccia vs. gauge) are strictly related to the amount of displacement as well as to the grain size and the cementation of the sandstone. Furthermore, the development of clay smear structures are enhanced by the presence of interbedded thin clay-rich layers

Optimizing Formulation Conditions of PLGA Microparticles to Enhance Indomethacin Encapsulation

Drug delivery systems can avoid the drawbacks of Indomethacin (IND), a non-steroidal anti-inflammatory drug used to treat osteoarthritis and arthritis, which requires high doses to reach therapeutic plasma levels leading to significant systemic side effects. This study aims to optimize poly(lactic-co-glycolic acid) (PLGA) microparticles (MPs) for intra-articular IND administration. MPs are prepared by solvent evaporation and freeze-dried for stability. Initial formulations with Tween 80 yield rubbery samples with low drug loading (1%); replacement of Tween 80 with Gelatin produces a stable powder with syringable MPs (particles size: 7 mu m), although, DL (3%) and EE (30%) remain suboptimal, due to IND polymorphic transformation. Differential Scanning Calorimetry and Fourier-Transform Infrared spectroscopy demonstrate a molecular dispersion of IND in PLGA. Adjusting the aqueous phase to pH 3 in the formulation process, i.e below IND pKa, significantly enhances EE (90%) due to the reduction of drug solubility in the external aqueous phase. In vitro release study shows prolonged IND release over several days, confirming an effective drug encapsulation. This study provides a foundational framework toward the optimization of the successful encapsulation of IND in PLGA MPs, potentially advancing future clinical applications of such drug delivery systems.This study aims to optimize PLGA microparticles for intra-articular delivery of Indomethacin (IND). The use of Gelatin as a surfactant in place of Tween 80 limited the plasticizer effect on the polymer, improving stability. Adjusting pH to 3 in the external phase enhanced encapsulation efficiency (90%), leading to prolonged IND release, demonstrating effective drug encapsulation for potential clinical use. imag

Augmentation of endogenous neurosteroid synthesis alters experimental status epilepticus dynamics

Neurosteroids can modulate γ-aminobutyric acid type A receptor-mediated inhibitory currents. Recently, we discovered that the neurosteroids progesterone, 5α-dihydroprogesterone, allopregnanolone, and pregnanolone are reduced in the cerebrospinal fluid of patients with status epilepticus (SE). However, it is undetermined whether neurosteroids influence SE. For this reason, first we evaluated whether the inhibitor of adrenocortical steroid production trilostane (50 mg/kg) could modify the levels of neurosteroids in the hippocampus and neocortex, and we found a remarkable increase in pregnenolone, progesterone, 5α-dihydroprogesterone, and allopregnanolone levels using liquid chromatography tandem mass spectrometry. Second, we characterized the dynamics of SE in the presence of the varied neurosteroidal milieu by a single intraperitoneal kainic acid (KA; 15 mg/kg) injection in trilostane-treated rats and their controls. Convulsions started in advance in the trilostane group, already appearing 90 minutes after the KA injection. In contrast to controls, convulsions prevalently developed as generalized seizures with loss of posture in the trilostane group. However, this effect was transient, and convulsions waned 2 hours before the control group. Moreover, electrocorticographic traces of convulsions were shorter in trilostane-treated rats, especially at the 180-minute (P < .001) and 210-minute (P < .01) time points. These findings indicate that endogenous neurosteroids remarkably modulate SE dynamics

Characterization of a fluvial aquifer at a range of depths and scales: the Triassic St Bees Sandstone Formation, Cumbria, UK

Fluvial sedimentary successions represent porous media that host groundwater and geothermal resources. Additionally, they overlie crystalline rocks hosting nuclear waste repositories in rift settings. The permeability characteristics of an arenaceous fluvial succession, the Triassic St Bees Sandstone Formation in England (UK), are described, from core-plug to well-test scale up to ~1 km depth. Within such lithified successions, dissolution associated with the circulation of meteoric water results in increased permeability (K~10−1–100 m/day) to depths of at least 150 m below ground level (BGL) in aquifer systems that are subject to rapid groundwater circulation. Thus, contaminant transport is likely to occur at relatively high rates. In a deeper investigation (> 150 m depth), where the aquifer has not been subjected to rapid groundwater circulation, well-test-scale hydraulic conductivity is lower, decreasing from K~10−2 m/day at 150–400 m BGL to 10−3 m/day down-dip at ~1 km BGL, where the pore fluid is hypersaline. Here, pore-scale permeability becomes progressively dominant with increasing lithostatic load. Notably, this work investigates a sandstone aquifer of fluvial origin at investigation depths consistent with highly enthalpy geothermal reservoirs (~0.7–1.1 km). At such depths, intergranular flow dominates in unfaulted areas with only minor contribution by bedding plane fractures. However, extensional faults represent preferential flow pathways, due to presence of high connective open fractures. Therefore, such faults may (1) drive nuclear waste contaminants towards the highly permeable shallow (< 150 m BGL) zone of the aquifer, and (2) influence fluid recovery in geothermal fields

Stratigraphic framework of the late Miocene to Pliocene Pisco Formation at Cerro Colorado (Ica Desert, Peru).

This paper describes a 200 m-thick section of the Pisco Formation exposed at Cerro Colorado, an important fossiliferous site in the Ica desert. In order to properly place the fauna in its correct relative position, this study establishes the stratigraphic framework within which the different fossil-bearing intervals of this site can be compared and may prove invaluable in future high-resolution studies on the faunal change. Most of the Pisco Formation deposits exposed at Cerro Colorado consist of gently dipping fine-grained sandstones, diatomaceous siltstones and diatomites with minor ash layers and dolomites deposited within nearshore and offshore settings. To facilitate detailed stratigraphic correlations within the Pisco strata for a 30 km2 area, eight marker beds have been defined and large-scale (1:10,000 scale) geological mapping conducted to determine fault positions, styles and offsets. The geological map shows that there are two important angular unconformities in the study area. The first one is the interformational basal unconformity of the Pisco Formation against folded, faulted, and planated Oligo-Miocene rocks of the Chilcatay Formation. The second is a low-angle intraformational erosional discontinuity of up to 4° angular discordance that allows the subdivision of the Pisco stratigraphy exposed in the study area into two informal allomembers. Dating of the exposed succession by diatom biostratigraphy suggests that the age of the lower allomember is late Miocene, whereas the upper allomember is late Miocene or younger

Stratigraphic framework of the late Miocene Pisco Formation at Cerro Los Quesos (Ica Desert, Peru)

The enormous concentration of marine vertebrates documented within the Pisco Formation is unique for Peru and South America and places this unit among the prime fossil Lagerstätten for Miocene to Pliocene marine mammals worldwide. In order to provide a robust stratigraphic framework for the fossil-bearing locality of Cerro Los Quesos, this study presents a 1:10,000 scale geological map covering an area of about 21 km2, a detailed measured section spanning 290 m of strata, and a refined chronostratigraphy for the studied succession well constrained by diatom biostratigraphy and high-resolution 40Ar/39Ar isotopic dating of three interbedded ash layers. Within the apparently monotonous, diatomite-dominated sedimentary section, the Pisco Formation has been subdivided into six local members, with stratigraphic control over the different outcrops facilitated by the establishment of a detailed marker bed stratigraphy based on fifteen readily distinguishable sediment layers of different nature