Dissolution Period Research Articles

To Formulate and Evaluate the Metformin Hydrochloride Floating Tablet

The aim of the research was to create a gastro retentive system for prolonged release of metformin HCl in the proximal part of the gastrointestinal tract (GIT) in the form of an oral floating tablet. Metformin HCl is an antidiabetic biguanide with poor bioavailability and an absorption window in the upper GIT. Floating tablets were prepared using a wet granulation method containing the natural polymers guar gum and kcarrageenan and the synthetic polymer HPMC K100 (HPMC) either alone or in combination. Sodium bicarbonate and citric acid were used as gas generators. Floating tablets were evaluated for weight variation, hardness and friability, drug content, swelling index, in vitro buoyancy and in vitro drug release. The formulation is optimized based on buoyancy, matrix integrity and in vitro drug release in simulated gastric fluid at pH 1.2. A formulation formulated with a combination of 6 wt. % k-carrageenan and 11 wt. % guar gum showed good gel strength, stable and continuous buoyancy for 12 hours, minimal buoyancy delay of 58 seconds, and good matrix integrity during dissolution period. The drug release of the optimized formulation followed the Korsmeyer- Peppas model and the mechanism was non-Fickian/divergent. PXRD and DSC studies showed partial amorphization of the drug. The mechanism of drug release appeared to be a diffusion mechanism. Stability studies have shown that the drug does not degrade when stored for 3 months at 40˚C.

A mono-layer matrix for pelleting marigold (Tagetes erecta) seeds

Marigold growers in Thailand face challenges in the cultivation from seeds of marigold owing to the elongated, slender and sometimes fragile shape of the seeds. These characteristics often result in a high number of seedlings with abnormal traits, making them susceptible to diseases and insects. The objective of this study was to develop a pellet formulation for marigold seeds to increase their size and facilitate cultivation from seeds. Seven pellet matrices, including a commercial product (pre-pelleted seeds), were assessed for integrity, including friability, dissolution period germination, shoot length, and root length under both laboratory and greenhouse conditions. Methylhydroxyethyl cellulose (MHEC) was used as the binding agent for each pellet matrix. Seeds pelleted with MHEC-bentonite and MHEC-zeolite resulted in irregularly shaped pellets, whereas the other matrices appeared smoother and more similar to commercially-pelleted seeds. CaCO3 and talc-pelleted seeds had a high friability, whereas CaSO4 -, pumice- and bentonite-pelleted seeds had friability values similar to those of the commercially- pelleted seeds. CaSO4 -pelleted seeds exhibited germination rates that were the closest to those of non-pelleted and commercially-pelleted seeds under both laboratory and greenhouse conditions. In conclusion, the MHEC- CaSO4 matrix is the most suitable choice for pelleting marigold seeds.

Residual carbonate karst reservoir reconstructed by karst planation: A case study of Ordovician paleokarst reservoir characterization in Ordos Basin, North China

Based on the global typical karst characteristics reported in recent decades and the latest petroleum and gas exploration results, it is found that the characteristics of the karst reservoirs in the Ordos Basin are dramatically different from those of traditional karst reservoirs, indicating that the main contribution to the formation of the karst reservoirs in the region may not have been karst dissolution. The previous view of the formation mechanism of karst reservoirs suggests that we should think about the formation and development processes of Ordovician karst and the reservoir pores in the Ordos Basin from another perspective. In this investigation of reservoir formation, karstology, geography, sedimentology, and reservoir geology were all utilized. On the basis of the initial understanding of the control of large-scale landforms on the sediments in sedimentary basins, this study focuses more on the dynamic spatial-temporal relationships between the evolutions of the landforms, karsts, and reservoirs. By studying the petrological characteristics, pore filling, karst zonation, and planation model of the weathering crust reservoir in the study area, it has been determined that the primary reservoir space was formed in advance rather than in the supergene dissolution period. A gypsum-containing dolomite flat served as the material foundation for reservoir construction and later karst planation transformation. The penecontemporaneous dissolution dominated the spatial development of the early dolomite reservoir. The traditional karst cycle is actually caused by the erosion of the bottom of the karst floor on the double-layer leveling surface. The karst planation during the Caledonian period played a discontinuous and destructive filling role throughout the entire reservoir zone by changing the diagenetic environment, the main contribution of which was communication between the pores. Therefore, this weathered crust reservoir is actually a residual reservoir controlled by karst planation rather than a traditional karst reservoir. The “sweet spots” are primarily dispersed in the upper portion of the karst slope and the top of the karst residual hillock in the gypsum-containing dolomitic flat environment.

Ottoman palace weavings between different periods: material characterization, comparison and suggestions for conservation

Historical textiles, which are an invaluable part of the cultural material heritage, and the materials used in their production bear witness to the social past. Although a textile object was originally produced out of necessity, later it became a symbol of magnificence, power, and might. The most important basic elements that contribute to these properties are the materials used in its production, among which silk fiber, and metallic threads containing gold and silver are the leading ones. In addition to the aging behavior of textile objects due to their organic structure, the deterioration process is accelerated due to various factors such as use, environmental factors, mismanagement, inappropriate storage and display conditions, incorrect restoration-conservation practices, natural disasters, etc. In this study, a total of 7 metallic threaded textile works dated between the 16 and 19 centuries and used by the Ottoman Palace dynasty in the textile collection of the Topkapı Palace Museum (TPM) were examined. In this context, visual evaluation/documentation, color measurement, technical analysis, dyestuff analysis, elemental composition, and corrosion products were determined in the historical textiles. In this study, the following analytical instruments were used for the analyses: a CIEL*a*b* spectrophotometer, an optical microscope (OM), high-performance liquid chromatography with photodiode array detection (HPLC–PDA), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM–EDX). Thanks to this study, it was aimed to document the palace fabrics containing silk and metallic yarn used in the Ottoman period, to characterize the materials they contain, to determine the production method, and to determine of the deterioration products that occur over time. According to the results obtained from the analyses, insect-origin dyestuffs in red, pink, and purple were used. When the fabrics of the sixteenth century and the fabrics of the nineteenth century were compared, it was determined that there was a decrease in the quality of weaving. In addition, it was determined that the fiber in the metallic yarn core in the textile object dated to the end of the 19th/beginning of the twentieth century was produced by using cotton instead of silk, and also the thickness of the metal strip and the wrapping density were decreased. No significant difference was detected in the chemical composition of the strips in the metallic yarns found in the examined historical textiles, but only the silver element was detected in the metal strip, although the metallic yarn core in the last period textile object was yellow in color. All these results showed that there was a difference between the sixteenth-century textiles of the rise of the Ottoman Empire and the nineteenth-century textiles of the dissolution period. This difference is especially evident in the quality of the weaving, the density of the materials used, and the chemical composition of the metal strip. In addition, all these analyses will guide textile experts in possible restoration-conservation studies.

Experimental study of gas evolution and dissolution process

Changes in pressure above the saturated liquid in an airtight container can cause gas evolution and dissolution. In this study, a mathematical model was developed based on the relationship between the amount of dissolved gas and saturated solution pressure according to Henry’s law. The model can be utilized to predict changes in the pressure above the liquid, the rate of gas evolution and dissolution, and variations in free gas as the under- (over-)saturated solution reaches the saturated solution. The proposed model was built according to the solubility constant, gas-liquid volume ratio, initial equilibrium pressure of the saturated solution, and the half-life of gas evolution and dissolution. An experiment was also conducted to investigate gas evolution and dissolution; the setup included an electric vibration platform and an airtight container used to generate vibration. When the measured pressure above the liquid showed no change in the airtight container under sustained vibration, an equilibrium state was considered to be achieved. With industrial gear oil, anti-wear hydraulic oil, and water, respectively, as subjects, changes in the pressure and half-life period of gas evolution and dissolution in each liquid were measured under various gas-liquid volume ratios. Comparison against the experimental data and mathematical model pressure curves validated the models feasibility and effectiveness, and revealed that the half-life of gas evolution and dissolution decreases as the gas-liquid volume ratio increases.

Use of coal-fired slag in filling bodies with early strength for mining applications

The global output of coal-fired slag (CS) has far exceeded 300 million tons, and the annual output in China is 4.5 billion tons, which seriously affects the ecological security. Additionally, with the continuous increases in mine production capacities, the filling cost continues to rise, which seriously affects the normal production levels of the mines. To reduce the filling cost and make full use of the CS, this study was designed to realize diversified application of coal-fired slag (CS) as a backfill with early strength. First, physical and chemical analyses were conducted for coal-fired slag powder (CSP), fly ash (FA), flue gas desulfurization gypsum (FGDG) and mine waste rock (MWR). Based on the alkali excitation theory, mixture design, response surface theory and early strength testing of the backfill, the optimal ratio for the solid waste cementitious material and the backfill with early strength was determined. The primary and interaction effects of the backfill were analysed. Finally, the hydration mechanism for the CS-based cementing materials was revealed by monitoring the resistivity and water content and with scanning election microscopy (SEM), X-ray diffraction (XRD) and thermogravimetry/differential scanning calorimetry (TG-DSC) analyses of the hydration products. The results showed that (1) the total amount of SiO2 and Al2O3 in the CS was 61.08%, and the content of CaO was 17.3%, which indicated potential gelling activity. (2) The backfill with early strength was prepared by mixing CSP, FGDG and FA at 70%, 3% and 27%, with MWR and CS exhibiting a specific mass fraction (81%), binder-sand ratio (4:6) and CS-MWR ratio (5:5). The 3 d and 7 d uniaxial compressive strengths of the backfill were 1.7 MPa and 3 MPa. (3) The CS-MWR ratio of the backfill and the interaction between the CS-MWR ratio and binder-sand ratio significantly influenced on the early uniaxial compressive strength. (4) The early hydration process for the CS-based cementitious materials included the dissolution period, the induced formation and induction period and the condensation and hardening period. At 3 d, the hydration products were mainly generated by the CSP (the total amount of hydration products produced was 7.01%), while at 4 d–7 d, the FA was involved (the total amount of hydration products produced was 7.37%. The results of this research provide theoretical guidance for using CS to develop low-cost backfills with early strengths for application in mines.

Media and Majesty

The relationship between media and the British monarchy is one that dominates the institution in its modern form. An important chapter in this relationship was the 1953 Coronation of Queen Elizabeth II, the first ever to be televised. Despite being a key cultural figure in most Britons’ lives, scholars have only begun to critically historicize the late Queen alongside the events she ruled over. This article contributes to conversations about the historical significance of the monarch by analysing the planning of her coronation, the themes invoked within the event itself, and public response to the event. It does so by situating the British Broadcasting Corporation (BBC) as a principal force in mobilizing themes of social unity, mediated intimacy, the ‘magic’ of monarchy, and the Queen as a feminized maternal figure to reify monarchist, conservative, and colonial ideas. Ultimately, the BBC mobilized new technologies to uphold traditional, historical ideas about the role of the monarchy, in a period of imperial dissolution and waning British prestige.

Mineralogy and geochemistry of pattern formation in zebra rock from the East Kimberley, Australia

Rhythmic patterns are widespread in geological materials. A particularly striking, macroscale example is zebra rock from the East Kimberley region of northwestern Australia. The rock is famous for its distinctive, rhythmically ordered, iron-oxide pattern, which transforms an Ediacaran-aged siltstone into an attractive semi-precious gemstone. Several different formation mechanisms of this pattern have been proposed in previous studies, with the two most prominent being redoximorphic banding in acid-sulfate soils and Liesegang banding in an acidic hydrothermal system. Using a combination of mineralogy, geochemistry and geological context, this study attempts to confirm both the occurrence and relative timing of acid-sulfate fluid rock interactions in zebra rock and seeks to determine whether pedogenic processes or hydrothermal alteration can better explain the origin of these patterns. We present the first evidence that the iron-oxide banding developed simultaneously with a period of aluminosilicate dissolution, clay precipitation, and fluid flow, consistent with the infiltration of an acidic fluid. This conclusion was evidenced through the hexagonal-platelet morphology of the hematite pigment, kaolinite-hematite textural relationships, and a paleoflow direction preserved in the asymmetric intensity of the hematite concentration. However, while the mineralogy of zebra rock strongly suggests interactions with acid-sulfates, the origin and temperature of the fluid could not be conclusively determined. Supporting a hydrothermal origin, a thorough analysis of zebra rock mineralogy revealed a mineral assemblage consistent with advanced argillic hydrothermal alteration, wherein pyrophyillite, kaolinite, and dickite indicate minimum palaeotemperatures upwards of 120 °C and the presence of alunite and a svanbergite-woodhouseite solid solution suggests oxidising, acidic (pH <5) conditions. The low Rb/Sr ratio and relative immobility of rare earth elements in most zebra rock deposits are also consistent with an acidic hydrothermal origin. Further support was also observed in the mineralogical trends between examined outcrops, grading from alunite-type to kaolinite/dickite-type facies in a south-west direction. But despite this evidence, the acid-sulfate soil hypothesis could not be refuted and was itself supported by the large number of pyrite dissolution voids both underlying and within the patterned layer. Furthermore, the consistent compaction of reduction spheroids, dissolution voids, and pseudomorphic inclusions within the light banding of zebra rock are in agreement with near-surface supergene weathering, ruling out hypogene hydrothermal alteration. A mechanism of pattern formation is proposed whereby zebra rock banding is formed by the Liesegang phenomenon, driven by the oxidation of Fe2+ ions during the infiltration of an Fe2+-rich, acid-sulfate fluid into oxidising host sediments.

Isotropic conductive paste for bioresorbable electronics.

Bioresorbable implantable medical devices can be employed in versatile clinical scenarios that burden patients with complications and surgical removal of conventional devices. However, a shortage of suitable electricalinterconnection materials limits the development of bioresorbable electronic systems. Therefore, this study highlights a highly conductive, naturally resorbable paste exhibiting enhanced electrical conductivity and mechanical stability that can solve the existing problems of bioresorbable interconnections. Multifaceted experiments on electrical and physical properties were used to optimize the composition of pastes containing beeswax, submicron tungstenparticles, and glycofurol. These pastes embody isotropic conductive paths for three-dimensional interconnects and function as antennas, sensors, and contact pads for bioresorbable electronic devices. The degradation behavior in aqueous solutions was used to assess its stability and ability to retain electrical conductance (∼7​kS/m) and structural form over the requisite dissolution period. In vitro and in vivo biocompatibility tests clarified the safety of the paste as an implantable material.

The Influence of Alkali Content on the Hydration of the Slag-Based Geopolymer: Relationships between Resistivity, Setting, and Strength Development.

This study investigated the influence of alkali content on the early-age hydration process of slag-based geopolymer and the feasibility of non-destructive resistivity. Results showed that there existed a threshold of alkali content in adjusting the early-age hydration. Initially, increasing the alkali content tended to accelerate the dissolution period (detected by resistivity and heat release rate) and resulted in a denser microstructure (detected by TEM). When the alkali content surpassed 6 wt%, the increasing alkali content mitigated the structural development of a slag-based geopolymer, as it lowered the liquid water content and caused local precipitation, which trapped the early-age ions transmission and, therefore, the later-age mechanical development was inhibited. It was proven that the resistivity acted as a linkage among the reaction degree, workability, and strength development.

Effects of the phosphogypsum on the hydration and microstructure of alkali activated slag pastes

Effects of phosphogypsum (PG) on hydration process and microstructure of the alkali activated slag (AAS) pastes were discussed in this study, taking the natural gypsum (NG) as a reference. Hydration process was monitored by several kinds of measurements including the isothermal calorimetry, the electrical resistivity, the autogenous shrinkage and the 1H nuclear magnetic resonance. Hydration product assemblages were analyzed by the XRD, NMR, SEM and the mercury intrusion porosimetry (MIP)test. Results showed that less than 10 % of gypsums could retard the setting process of AAS pastes. PG could enhance the late strength although the early strength was decreased, but the addition of NG would reduce the strength at all ages. Induction period and the autogenous shrinkage were both reduced by gypsum gradually. Additionally, PG conducts to the higher MCL and higher polymerization degree of CASH gels than NG. And the addition of PG would refine the pore structure and produce a lower porosity than NG. Furthermore, the comprehensive analysis showed that the setting behavior happened at the initial dissolution period. And PG would delay the acceleration period, indicating the slower development of microstructure.

The effect of meteoric water on the very fine crystalline dolomite reservoir in the shallow burial zone: A case study of the Ma55 submember of Majiagou Formation in Ordos Basin

The meteoric water has obviously changed the physical properties of dolostone reservoirs in the vertical vadose zone and the horizontal phreatic zone, but its influence on the dolostone reservoirs in the shallow burial zone beneath the phreatic surface is still unclear. This study aims to reveal the effect of meteoric water on the dolostone reservoirs in the shallow burial zone through X-ray diffraction, cathodoluminescence, C, O, and Sr isotope using the sample from Majiagou Formation in the Daniudi gas field, Ordos Basin. The diagenesis and paragenesis of the Ma 55 submember were identified and interpreted through petrological study, combined with data from electron probe, X-ray diffraction analysis, and geochemical parameters of diagenetic minerals. The color of the very fine crystalline dolomite under the cathodeluminescence is dark red and red. The order degree of dolomite ranges from 0.54 to 0.91, showing the origin of early seepage-reflux dolomitization. There are a large number of different calcite cements as fills within the pores and fractures. The color of the calcite cement under the cathodoluminescence is orange-yellow, with a zonal structure. Hydrothermal fluid during late diagenesis could be identified by the authigenic fluorite filling in the fractures. According to the assembly of diagenetic minerals, the very fine crystalline dolostones have experienced the seepage-reflux dolomitization, meteoric water dissolution, shallow burial cementation and late cementation. The void spaces of the very fine crystalline dolostones are intercrystalline pores and microfractures. Although a large number of dissolved pores and caves developed in the period of meteoric water dissolution, these caves and dissolved pores has been mostly filled by multi-stages of cementation. Therefore, the effect of meteoric water on dolostone reservoirs in the shallow burial zone beneath the phreatic surface is not obvious. The main controlling factor for the quality of dolostone reservoir was dolomitization. This study provides a new understanding of the influence of meteoric water on reservoir quality in the shallow burial zone during the paleokarst period.

Solubility Enhanced Formulation Approaches to Overcome Oral Delivery Obstacles of PROTACs.

PROteolysis TArgeting Chimaeras (PROTACs) offer new opportunities in modern medicine by targeting proteins that are undruggable to classic inhibitors. However, due to their hydrophobic structure, PROTACs typically suffer from low solubility, and oral bioavailability remains challenging. At the same time, due to their investigative state, the drug supply is meager, leading to limited possibilities in terms of formulation development. Therefore, we investigated the solubility enhancement employing mini-scale formulations of amorphous solid dispersions (ASDs) and liquisolid formulations of the prototypic PROTAC ARCC-4. Based on preliminary supersaturation testing, HPMCAS (L Grade) and Eudragit® L 100-55 (EL 100-55) were demonstrated to be suitable polymers for supersaturation stabilization of ARCC-4. These two polymers were selected for preparing ASDs via vacuum compression molding (VCM), using drug loads of 10 and 20%, respectively. The ASDs were subsequently characterized with respect to their solid state via differential scanning calorimetry (DSC). Non-sink dissolution testing revealed that the physical mixtures (PMs) did not improve dissolution. At the same time, all ASDs enabled pronounced supersaturation of ARCC-4 without precipitation for the entire dissolution period. In contrast, liquisolid formulations failed in increasing ARCC-4 solubility. Hence, we demonstrated that ASD formation is a promising principle to overcome the low solubility of PROTACs.

Kinetic studies on acidic wet chemical etching of silicon in binary and ternary mixtures of HF, HNO3 and H2SiF6.

The etching of silicon with mixtures of hydrofluoric acid (HF), nitric acid (HNO3) and hexafluorosilicic acid (H2SiF6) proceeds in a complex reaction scenario consisting of interacting side reactions. Almost no other dissolution reaction is so massively dependent on the reaction conditions that influence the etching rate and the mechanism of the individual reactions. Extensive studies of the reaction rate of silicon etching in binary and ternary acid mixtures have allowed the transition point between the reaction-controlled and diffusion-controlled reaction regimes to be determined as a function of the composition of the etching mixture. It was verified that the reaction mechanism for binary and ternary mixtures does not differ and only the lower water content in ternary mixtures favours an enhanced formation of the reactive N(III) intermediate HNO2 in side reactions. Based on the exact knowledge of the point of mechanism change, determination of the reaction rate under quasi-isothermal conditions in the bulk etching range allows, for the first time, deriving formal kinetic terms from the kinetic data to describe the dissolution rate in both the reaction-controlled and diffusion-controlled regimes. The formal kinetic terms were designed both for the kinetically correct quasi-isothermal approach to the dissolution rate in the Si bulk and for the application-oriented approach that includes induction phases and temperature increases in the considered dissolution period as well as influences of the surface properties. Moreover, by using the water content of the etching mixtures as a proxy variable, uniform calculation of the etching rates in HF/HNO3 as well as in HF/HNO3/H2SiF6 mixtures in the entire composition range of the application can be formulated.

The Testaments: The Difference within the Gileadean World

Margaret Atwood’s recent dystopian novel The Testaments (2019) revisits The Handmaid’s Tale by depicturing Gilead’s nightmarish world of the patriarchal order, which is established especially against women’s potency. The sequel reminds the contemporary readers of Offred and her miseries who told the categorised women of Gilead functioning as the Wives, Handmaids, and Marthas. This time, with three different female figures, Baby Nicole, Agnes, and Aunt Lydia, as protagonists/ narrators, who take place on the edges of the Gileadean order, Atwood transforms the events of The Handmaid’s Tale, told by Offred. The novel encircles Offred’s tale by shedding light on the subsequent events told by the second-generation women (Agnes and Nicole) and comprises the prequel parts that Aunt Lydia provides. In this way, to “destabilise [the] unitary vision of the subject and open it up to the multiple and complex reconfigurations of diversity and multiple belongings, so as to [emphasise] … the internal fractures within each subject-position, or the ‘difference within’” with this follow-up text. With the streaming narratives of the three women who set forth the intersected phases to destroy the totalitarian regime and reached “identities of their own,” the sequel maintains the intriguing magic of the Gileadean tales. This article aims to trace the outlooks of different female narrators who procure a dimension of “gynesis” through which the re-exhibited Gilead comes to its end via women who have taken part in the period of dissolution.

Tailored Supersaturable Immediate Release Behaviors of Hypotensive Supersaturating Drug-Delivery Systems Combined with Hot-Melt Extrusion Technique and Self-Micellizing Polymer.

The short-term immediate release of supersaturated drug-delivery systems (SDDSs) presents an interesting process that can be tailored to multi-stage release events including initial release after dosing and dissolution, evolved release over longer dissolution periods for biological absorption, and terminal release following the end of immediate release. However, although comprehensive analysis of these critical release behaviors is often ignored yet essential for understanding the supersaturable immediate-release events for supersaturable solid formations when employing new techniques or polymers matched to a particular API. Hot-melt extrusion (HME) has become a popular continuous thermodynamic disordering technique for amorphization. The self-micellizing polymer Soluplus® is reported to be a potential amorphous and amphiphilic graft copolymer frequently used in many nano/micro supersaturable formulations. Our current work aims to develop hypotensive supersaturating solid dispersion systems (faSDDSHME) containing the BCS II drug, felodipine, when coordinately employing the HME technique and self-micellizing Soluplus®, and to characterize their amorphization as well as immediate release. Other discontinuous techniques were used to prepare control groups (faSDDSSE and faSDDSQC). Tailored initial/evolved/terminal three-stage supersaturable immediate-release behaviors were identified and possible mechanisms controlling the release were explored. HME produced the highest initial release in related faSDDSHME. During the evolved-release period, highly extended "spring-parachute" process was found in HME-induced amorphization owing to its superior supersaturation duration. Due to the enhanced crystallization inhibition effect, faSDDSHME displayed the strongest terminal release as measured by solubility. For release mechanisms associated with HME, molecular interaction is not the likely dominant mechanism responsible for the improved properties induced by faSDDSHME. For release mechanisms involved with the polymer Soluplus® itself, they were found to inhibit drug recrystallization, spontaneously solubilize the drug and lead to improved molecular interactions in all SDDS systems, which were the factors responsible for the improved release. These mechanisms play an important role for the generation of an extended multi-stage immediate release produced via HME or self-micellizing polymer. This study provides a deeper understanding on amorphization and superior multi-stage supersaturable immediate-release behaviors for a particular hypotensive supersaturated delivery system combined with an HME-based continuous manufacturing technique and self-micellizing polymer strategy.

Pore matrix dissolution in carbonates: An in-situ experimental investigation of carbonated water injection

Carbonate rock dissolution during the reactive transport of carbon dioxide (CO2)-enriched brine has been studied extensively in the context of carbon storage in saline aquifers. However, there is limited knowledge of CO2-induced reactive transport in multiphase systems (containing oil and brine), which is more relevant to carbon sequestration in depleted oil reservoirs. In this work, we uncover the pore-scale dynamics of fluid flow and rock dissolution during carbonated water injection (CWI) in hydrophilic porous media containing two fluid phases (oil and brine). We combine novel core flooding and high-resolution imaging techniques to visualize and characterize changes in fluid occupancy and pore morphology. It is observed that the sequence of flow and transport in two-phase systems involves a pre-dissolution period, where CWI induces the displacement of waterflood-trapped oil, and a dissolution period typified by channel flow. Improved oil recovery during pre-dissolution emanates from an oil swelling mechanism that drives reconnection and mobilization of trapped oil globules. Additionally, CO2 is stored in both oil and carbonated water. Channel flow during dissolution results in the formation of wormholes with two distinct dissolution patterns. The first is a conical wormhole at lower injection rates where diffusion rates are significant. The second is a dominant wormhole at higher injection rates where advection dominates the transport of reactive species to the flow boundaries. We find that the oil displacement efficiency during dissolution is significantly lower than pre-dissolution levels and is dependent on the wormhole pattern, with dominant wormholes providing a high-permeability and high-velocity flow path for trapped oil movement. Therefore, unlike the injectivity losses that originate from salt precipitation during direct CO2 injection, CWI in depleted carbonate oil reservoirs enhances the injectivity of injection wells allowing for an energy efficient CO2 storage.

Formulation and Comparison of Glucomannan Metallocomplexes Made of Cobalt and Copper

The broad category of pharmaceutical science in which drugs are complex with metals like platinum, zinc iron, etc is defined as Metallopharmaceutics. The earliest work on Metallopharmaceutics is around 700 BC. In this work, Glucomannan, which is a plant-based drug, is used as a ligand to prepare anti-diabetic metal complexes of Cobalt and copper. Glucomannan is basically a polymer thought up of -(14)-linked D-mannose and D-glucose in a straight chain in a ratio of 8:5. Various pre-formulation studies were performed including swelling index and angle of repose for the pure drug only. The pre-formulation parameters inferred that the pure drug has fair flow properties with a swelling index of 81.8%. Formulations were analyzed spectrophotometrically using ATR-IR and UV-spectroscopy. In UV spectroscopy, it was analyzed that Glucomannan showed a distinct peak at 267 nm. Formulation of metal complexes was performed using the solvent-assisted method. The dissolution studies and release kinetics were performed for prepared Formulations (F1-F9). The Formulation F9 proved to be the best formulation following the Higuchi Diffusion plot with maximum linearity of 0.997. Thus, 500 mg Glucomannan + 1000 mg Cobalt (F9) had the sustained drug release throughout the dissolution period.

Seismic characterization and depositional significance of the Nahr Menashe deposits: Implications for the terminal phases of the Messinian salinity crisis in the north‐east Levant Basin, offshore Lebanon

AbstractOver the last decade, there has been a resurgence of interest in the climatic and tectonic mechanisms that drove the Messinian salinity crisis (MSC) and the associated deposition of thick evaporites. The MSC represents an unprecedented palaeoceanographic change that led to a very short (ca. 640 kyr) ecological and environmental crisis. However, across the Levantine offshore basin, the sedimentological nature of the top evaporitic units and the mechanisms that controlled the transition from a hypersaline evaporitic unit to brackish deposits (final MSC stage 3) are still disputed. Here, we re‐evaluate the deposits associated with the terminal phase of the MSC, named in offshore Lebanon as the Nahr Menashe Unit (NMU). We describe the NMU seismic facies, characterize and map its internal seismic stratigraphy and provide a new interpretation of its depositional environment, which persisted during the late Messinian and then evolved through a regional reflooding event. The base of the NMU overlies semicircular depressions, randomly distributed linear marks and surface collapse features, which are indicative of a period of intense evaporite dissolution. The NMU seismic facies observed from the slope to the deep part of the basin support the interpretation of a layered salt‐evaporite‐sand depositional system subject to complex reworking, dissolution, deposition and final erosion. A drainage network of valleys and complex tributary channels incising into the top NMU shows marked erosional characteristics, which indicate a dominant southwards sediment transfer following deposition of the NMU. The drainage network was subsequently infilled by layered sediments interpreted here to represent the post‐MSC marine sediments. Our analysis adds important details regarding previous interpretations of the NMU as fluvial in origin. Specifically, the presence of subcircular, linear dissolution features coupled with mound‐like features indicates that the NMU is composed dominantly of evaporites that were subject to dissolution prior to erosion associated with the drainage network. The NMU is interpreted to represent the deposition/redeposition of a mixed evaporite‐siliciclastic succession in a shallow marine or lacustrine environment during the tilting of the offshore Lebanese basin.

The effects of nano-silica on early-age hydration reactions of nano Portland cement

The hydration reactions of nano Portland cement (NPC) with and without nano-silica (NS) additives were realized and tracked for the first time in a liquid cell transmission electron microscope (LC-TEM), coupled with isothermal calorimetry and quantitative X-ray diffraction (QXRD). We revealed the different hydration mechanisms in NPC and PC in the presence of NS. The results showed that NS shortened the dissolution and induction periods of the hydration reaction significantly in normal PC systems. The fact that NS contributed less to hydration reactions in NPC systems resulted from the size effect. Nano cement with a much higher surface area and reactivity hydrated much faster to a high degree by itself. The LC-TEM observations found that NS was adsorbed on the surfaces of needle-like ettringite crystals accelerating their conversion into monosulfate, and thus achieving lower contents of ettringite in NPC with NS.