Carbon-based Research Articles

Geological Features and Ore Formation Pattern of Jinzhong Bauxite Mine, Shanxi Province, China

Bauxite is located in the lower part of the Benxi Formation, and the prospecting project shows that the distribution of bauxite ore bodies in the area is discontinuous, and there are differences in the thickness of the ore bodies. To have a clearer understanding of the bauxite ore bodies and metallogenic pattern in the census area, this study has made use of the prospecting project data, sample analysis results, etc., and combined with the geological and tectonic background of the area, the stratigraphic spreading characteristics of the bauxite ore body spatial spreading, ore characteristics and ore controlling factors in the area have been explored and researched. The bauxite ore bodies in the study area are stratified but the ore-bearing rock system is influenced by the Ordovician paleokarst geomorphology and intermittently distributed horizontally, which can be distinguished into three different ore bodies. The bauxite ore body and Shanxi-style iron ore are associated with hard clay ore, in which the ore minerals are mainly monohydrate duralumin. The natural ore type can be divided into dense bauxite and oolitic bauxite. Bauxite in this area mainly originated from the basal Ordovician carbonate rocks, with a combination of iron-rich and aluminum-rich layers, and is a typical carbonate rock sedimentary deposit of ancient weathering crust.

Ce-doped NiFe-layered-double-hydroxide hierarchical nanocomposite and metal/imidazolate framework carbon nanotube nanocomposite: A bifunctional material for OER electrocatalyst and supercapacitor electrode applications

The development of nanocomposites as electrocatalysts with low cost and high efficiency for OER and as electrode material enhancing the electrochemical performance of supercapacitors are the most popular investigations in this field. Herein, a new bifunctional composite including Ce-doped NiFe-LDH Nanosheets and ZIF-derived carbon base incorporating neodymium and Fe into the structure of Zeolitic Imidazolate Framework is proposed and the construction was through entering Fe-ZIF8@Nd-ZIF67 into the structure of NiFeCe-LDH in different ratios of 10, 20 and 30 %. Various physical and electrochemical tests were conducted to evaluate the nanocomposites. Results indicated that the composite presented a hierarchical porous structure and exhibited outstanding performance for OER and supercapacitor applications. According to the results, the 30 % composite of NiFeCe-LDH/ Fe-ZIF8@Nd-ZIF67 exhibits a superior onset overpotential of 170 mV and an overpotential of 300 mV at a current density of 10 mA·cm−2. Besides, it shows an excellent specific capacitance of 345.36 (F.g−1) at 1 A.g−1. Hence, the synthesized nanocomposite demonstrated outstanding performance in both OER and supercapacitor applications.

Effect of CO2 and H2SO4 on the dissolution of a carbonate basement and alteration of silicates in a volcano-sedimentary system in central Mexico

This study explores the hydrogeochemical and isotopic characteristics of groundwater in the Irapuato Valley and Celaya Valley Aquifers in central Mexico, specifically focusing on the role of CO2 in mineral alteration during water-rock interaction. The study is grounded in the principles of hydrogeochemistry and stable isotope geochemistry, analyzing the impact of CO2 and H2SO4 on the weathering of carbonates and silicates. Hydrogeochemical analysis, including Piper diagrams, and isotopic measurements (δ13C, δ18O, δ2H), were conducted on water samples from wells in four municipalities (Irapuato, Salamanca, Villagrán, and Juventino Rosas). The data was statistically evaluated using Shapiro-Wilk tests to assess normality, skewness, and kurtosis, ensuring the reliability of the findings. The results indicate that HCO3− dominates the groundwater composition, with CO2 and H2SO4 significantly influencing mineral alteration processes. The isotopic data suggest that CO2 is primarily released from carbonate rock degassing, with slight isotopic enrichment in δ13C due to water-carbonate interaction. Hydrothermal fluids contribute to the geochemical evolution of the aquifer, leading to the formation of minerals such as tridymite, alunite, and kaolinite. Additionally, some groundwater samples exhibit evidence of thermalism and water-rock interactions, influencing their isotopic signatures and temperatures. These findings underscore the importance of CO2 in groundwater chemistry and highlight the need for further studies to understand regional flow dynamics and the potential impact of geothermal systems on water quality.

Unraveling the Role of Intrinsic Carbon Defects for the Heterogeneous Reduction of NO with NH3

ABSTRACT This study investigates the impact of intrinsic carbon defects on the reduction of nitrogen oxides (NOx) during coal combustion, with a focus on the synergistic effect of ammonia (NH3) and pulverized coal. Two representative computational models containing intrinsic carbon defects are described, and their influence on NH3 reduction of NO is studied. Stable species and transition states present in the pathways are calculated using B3LYP/6-31 G(d). Results indicate that exposed edge carbon atoms exhibit higher charge density distribution, affecting NH3 adsorption and NO reduction. The maximum energy barriers for both pathways do not exceed 45 kcal/mol, achievable in practical coal combustion systems. This paper also calculates the heterogeneous reduction process of a model without intrinsic carbon defects (Char model), with the aim of observing the specific effects of intrinsic carbon defects on the processes of migration of H/O atoms, migration and recombination of N atoms, and formation and desorption of N2 molecules. Furthermore, the analyses demonstrated an increase in the rate of heterogeneous reduction of NH3 and NO on defective carbon surfaces in comparison to the Char/NH/NO system, indicating that the intrinsic defects of the carbon have a contributory effect on the catalytic activity. With regard to the magnitude of the increase in reaction rate with increasing temperature, the presence of intrinsic defects in the carbon base serves to reinforce the role of temperature in the rate-determining step. Overall, this study provides insights into the role of intrinsic defects in carbon-based catalysis and offers implications for nitrogen oxide emission control strategies.

Advances in manufacturing of carbon-based molecular nanomaterials based on rice husk/hull waste

This review highlights potential application areas for carbon-based molecular nanoparticles, such as carbon dots, carbon nanotubes, graphene quantum dots, and carbon quantum dots. The success of nano-manufacturing hinges on robust collaboration between academia and industry to advance applicable manufacturing techniques. Choosing the right approach is crucial, one that integrates the carbon base of nanomaterials with the required properties and impurities, as well as the scalability of the process. Molecular, in this context, refers to the nanoscale carbon structures that form the basis of these materials, including their arrangement, bonding, and properties at the molecular level. The article also explores the characterization of different types of molecular nanomaterials. Nanomaterials are increasingly used in almost every contemporary industry, including construction, textiles, manufacturing, and computing. This article reviews the most prominent sectors globally that employ nanomaterials. Biomasses containing lignin, cellulose, and hemicellulose have become some of the most extensively studied. Initially, rice waste was utilized for bulk materials, but lately, the production of multifunctional materials has surged in interest. Carbon nanostructures derived from rice waste offer a broad spectrum of applications and enhanced biocompatibility. Recent advancements, challenges, and trends in the development of multifunctional carbon-based nanomaterials from renewable rice waste resources are considered.

Pedogenic variables with color indices of rubified Alfisols in the Kakalachinte microwatershed, Karnataka, South India

Soil properties and processes can often be estimated by soil color, which provides valuable information about composition and other properties. We focused on the morphology, particle size distribution, and chemical properties of Alfisols in Kakalachinte microwatershed, Karnataka, India. Soil redness indices were calculated: Buntley's and Westin's rate (BWR), Hurst's rate (HR); Torrent’ rates (TR1 and TR2); Barrón's and Torrent's rates (BTR1 and BTR2), and Viscarra's rate (VR). The Munsell notation was converted to the CIE (Commission Internationale del'Eclairage, CIE) Lab system, Lab model: L*, luminance, a*, redness, and b*, yellowness of moist soil samples. Forty-five soil samples were characterized for texture, soil reaction (pH), electrical conductivity, calcium carbonate content, organic carbon (OC) content, exchangeable cations (sodium, Na; potassium, K; magnesium, Mg; and calcium, Ca), base saturation (BS), and cation exchange capacity (CEC). The pH of the soils ranged from strongly acid (pH of 5.25) to strongly alkaline (pH of 8.73). These soils exhibited low CEC, with a mean of 8.36 cmol(+)/kg and a coefficient of variation of >35%. The BS was found to be >70%, with a dominance of exchangeable Ca (6.93 ± 1.08 cmol(+)/kg). Correlation analysis revealed strong positive relationships between OC and the L* value (r = 0.6**). The correlation results revealed a strong positive correlation of a* value with TR1 (r = 0.54**), significant negative relationship between L* and BTR1 (r = −0.54*), BTR2 (r = −0.525*), and VR (r = −0.53*). Regression between soil OC and the L* value showed R2 of 0.40 and RMSE of 0.01; soil exchangeable K and Mg with the R2 = 0.74; RMSE = 0.12 and the R2 = 0.42; RMSE = 0.11 at p < 0.001. The study highlights the importance of converting Munsell color notation to the CIELab system for understanding the rubification process in relation to soil properties in Alfisols at the microwatershed level.

Involvement of Hg-bearing methane seeps in forming Ediacaran cap carbonate in South China

During the Cryogenian-Ediacaran transition, an extremely cold climate transitioned into a warm climate which was accompanied by the worldwide precipitation of cap carbonates showing striking negative carbonate carbon isotope (δ13Ccarb) anomalies. High mercury (Hg) contents up to 180 ppb have been reported from the Doushantuo cap carbonates, but the origin of Hg anomalies and its relationship with cap carbonate precipitation remain unclear. To address these issues, we measured Hg concentrations and isotopes along with total organic carbon (TOC) content and δ13Ccarb from the basal Ediacaran carbonates at the Jiulongwan section of western Hubei Province, South China. The results show that in laterally persistent intervals, Hg spikes (as high as 77 ppb) co-occur with decrease of Δ199Hg values (as low as 0.07‰), increase of δ202Hg values (−1.47‰), and conspicuous negative δ13Ccarb shifts (as low as ca. -17‰). Such Hg isotopic signature with high Hg concentration are comparable to those of natural gas hydrates and thus are ascribed to be an involvement of Hg-bearing methane seeps in precipitation of cap carbonate after melting of ice-sheets of the Marinoan glaciation (latest Cryogenian). Anaerobic oxidation of methane from hydrates via sulfate reduction may have produced bicarbonate (HCO3−), which was transformed into cap carbonate when combining with alkaline ions transported from continent to seawater via weathering process. This study provides the first evidence for Hg-bearing methane oxidation during cap carbonate precipitation.

Transcending Carbon Life: A Vision for Sustainable Future

Abstract The concept of “transcending carbon life” proposes a shift from traditional carbon-based biological existence to a data-centric, digital form of life. This is driven by the need to address escalating environmental crises caused by carbon-intensive human activities. The main challenges of carbon-based life include climate change, resource depletion, and environmental degradation. “Transcending Carbon Life” aims to address these issues by leveraging advancements in digital technologies and data science. The core principles involve digital existence, where life forms could be replicated and preserved as data, and data-centric living, emphasizing the use of high-quality data and synthetic data to drive decision-making and innovation. Potential benefits include improved environmental sustainability, enhanced medical research and life extension, and better global connectivity and knowledge sharing. However, significant technological development, ethical considerations, and infrastructure challenges need to be addressed to make this vision a reality. Overall, “transcending carbon life” represents a transformative approach to ensuring the long-term survival, superior intelligence governance, and ecological balance of all living entities on earth.

Saps1-3 Antigens in Candida albicans: Differential Modulation Following Exposure to Soluble Proteins, Mammalian Cells, and Infection in Mice.

The secreted aspartic peptidases (Saps) of Candida albicans play crucial roles in various steps of fungal-host interactions. Using a flow cytometry approach, this study investigated the expression of Saps1-3 antigens after (i) incubation with soluble proteins, (ii) interaction with mammalian cells, and (iii) infection in immunosuppressed BALB/c mice. Supplementation strategies involving increasing concentrations of bovine serum albumin (BSA) added to yeast carbon base (YCB) medium as the sole nitrogenous source revealed a positive and significant correlation between BSA concentration and both the growth rate and the percentage of fluorescent cells (%FC) labeled with anti-Saps1-3 antibodies. Supplementing the YCB medium with various soluble proteins significantly modulated the expression of Saps1-3 antigens in C. albicans. Specifically, immunoglobulin G, gelatin, and total bovine/human sera significantly reduced the %FC, while laminin, human serum albumin, fibrinogen, hemoglobin, and mucin considerably increased the %FC compared to BSA. Furthermore, co-cultivating C. albicans yeasts with either live epithelial or macrophage cells induced the expression of Saps1-3 antigens in 78% (mean fluorescence intensity [MFI] = 152.1) and 82.7% (MFI = 178.2) of the yeast cells, respectively, compared to BSA, which resulted in 29.3% fluorescent cells (MFI = 50.9). Lastly, the yeasts recovered from the kidneys of infected immunosuppressed mice demonstrated a 4.8-fold increase in the production of Saps1-3 antigens (MFI = 246.6) compared to BSA, with 95.5% of yeasts labeled with anti-Saps1-3 antibodies. Altogether, these results demonstrated the positive modulation of Saps' expression in C. albicans by various key host proteinaceous components, as well as by in vitro and in vivo host challenges.

Optimal bidding strategy for multi-energy virtual power plant participating in coupled energy, frequency regulation and carbon trading markets

Multi-energy virtual power plant (MEVPP) with diversified flexible resources can participate in energy market (EM), frequency regulation market (FRM) and carbon trading market (CM) to obtain extra benefits. However, the complicated market environment provokes grant challenges in the bidding strategy of MEVPP that coordinates heterogenous supply-side devices and demand-side users. To the end, this study proposes a multi-objective bidding strategy for MEVPP comprising various energy flows and multi-energy demand response (MDR) in EM, FRM and CM. Results are delivered that: 1) Compared to the only profit-oriented optimization, the profit of comprise solution under the multi-objective declines by 46% but the satisfaction level improves 8%. Relative to the single satisfaction-oriented optimization, a 5.2% satisfaction loss allows for an approximately 103% growth in profit, realizing a win-win result for MEVPP and users. 2) There were negative profits in the pure EM (Case 1) as well as EM and CM (Case3). Compared with positive profit in EM and FRM (Case 2), the profit in coupled EM, FRM and CM (Case 4) increases by 48.9%. Relative to the CO2 emission in EM and CM, the emission under the proposed strategy mitigates by 9.36%. 3) A carbon base price at 200 CNY/t CO2 and an emission interval length of 5–10 t are recommended to maintain the low-carbon economic operation for MEVPP.

New insights into the growth characteristics and crystal morphology of α-hemihydrate gypsum induced by organic acid crystallization agents during PG conversion

The stockpiling of phosphogypsum (PG) poses a substantial risk of environmental pollution.To reduce the stockpile of PG and enhance its value, this research utilized phosphogypsum to produce α-hemihydrate gypsum (a-HH).The study elucidates the crystallization process of α-HH, which involves Ca2+ helical growth and coordinated filling by SO42- and H2O. Succinic acid, malic acid, L-aspartic acid are used as agents to transform PG into α-HH. α-HH is developed using a modified vapor pressure method. XRD, XPS, FT-IR, SEM, zeta potential, intensity testing, and molecular dynamics simulations are some methods used to study its crystal growth characteristics, morphological structure, and mechanical strength. These analyses aim to explore the impact and mechanism of succinic acid, malic acid, L-aspartic acid on the properties of α-HH. The results indicate that α-HH assumes a monoclinic crystal form, appearing as needles. Upon the addition of succinic acid, malic acid, and L-aspartic acid, the aspect ratio of α-HH crystals decreases, and the crystal morphology transitions from a rod-like needle structure to a short and stout structure.Notably, Malic acid demonstrates the most effective results.The study further demonstrates that the flexural and compressive strengths of all α-HH specimens surpass 4.5 MPa and 30 MPa, respectively, meeting the requirements for high-strength gypsum, specifically α30.Simultaneously, this study reveals that succinic acid, malic acid, L-aspartic acid form cyclic chelates with Ca2+ on the prominent surface of α-HH through oxygen atoms in the carbon base of the molecules, thereby altering the crystalline morphology of α-HH. The regulation of α-HH crystalline morphology depends primarily on the spacing and electron-donating ability between carbon-based oxygen atoms in the molecules of succinic acid, malic acid, L-aspartic acid. Introducing conjugated electron-donating groups into the adjacent positions of organic acids can more effectively enhance their ability to regulate the crystalline morphology of α-HH. This study further demonstrates that the regulation ability is directly proportional to the polarity of the organic acid molecules.

Aggregate Boid behavior to aid in artificial autopoietic organization

Analyzing carbon-based life on earth can lead to biased inferences on the nature of life as might exist in elsewhere in the universe in alternative forms, therefore, scientists have looked into either abstracting life into constituent systems it is comprised of, or logics of life, or lists of essential criteria, or essential dynamic patterning that characterizes the living. A system-level characterization that is and referred to as a general pattern of minimal life is autopoiesis (Varela et al., 1974) including production, maintenance and replacement of required constituents for setting up and maintaining an internal environment with self/other separation that regulates and is constitutive of processes that produce the environment and components for processes that comprise this ongoing activity of self-production in ‘recursively’, i.e., in a manner that allows the organizational pattern to continually reconstitute the conditions, components and processes required for its own perpetuation. This seminal concept of an autopoiesis is instantiated in life as we know it, but might also be instantiated in different media and in unforeseen ways. Other researchers have argued life is more than autopoiesis and that it is a co-emergent property of autopoiesis and cognition. Life produces many emergent properties such as synchronization and patterns as seen in flocks and herds of different animal species. The mechanics of this synchrony displayed in flocks and herd animals has been extracted by Craig Reynolds into a generative model referred to as “Boids”. With these concepts in mind, we address the following research question: How can the synchronous maneuvers and aggregate behavior of Boids contribute to constitutive subsystems in realizing an autopoietic system? Can such a system exhibit minimal cognition? This work attempts to answer these questions with a bottom-up approach to constructing an artificial life system. We exhibit a computational model of autopoiesis and a minimal level of cognition in the sense of M. Bitbol and P. Luigi Luisi, whereby an autopoietic entity engages in active assimilation of external components as part of its activity of self-production.

Synthesis of WL.nZVI/ GAC adsorbent green for chromium removal from aqueous solutions (Characterization, kinetics, isotherms, and thermodynamics)

This paper aims to synthesize zero-valent iron green nanoparticles to remove chromium from aqueous solutions. A granular activated carbon base was used to solve the problem of nanoparticle agglomeration. This study produced zero-valent iron nanoparticles using walnut leaf extract and immobilization on granular activated carbon (WL.nZVI/ GAC). Then, the specifications of the nanocomposite were studied using FE-SEM, EDX, BET, FTIR, and XRD analysis. This study investigated the parameters affecting adsorption, such as pH, adsorbent dose, contact time, pollutant concentration, and temperature. The WL.nZVI/ GAC nanocomposite specifications showed that the nanoparticles are spherical, and the diameter of the iron nanoparticles immobilized on activated carbon was determined in the range of 16.77 to 27.72 nm. XRD results also indicated that the Wl.nZVI/ GAC adsorbent was amorphous. According to EDX analysis, the loaded iron content in WL.nZVI/ GAC was about 1.86 %. pHPZC for WL.nZVI/ GAC nanocomposites was determined in the range of 6.1; In other words, at pH less than 6.1, the adsorbent’s surface charge is positive and can absorb the chromium existing in solution, which is in the form of chromate, well. The results of adsorption process optimization showed that the adsorption of Cr(VI) is optimal at pH = 4, contact time of 780 min, concentration of 80 ppm, and temperature of 298 K. Experimental studies showed that the chromium removal by adsorbent is strongly dependent on pH. The adsorption kinetics of chromium by WL.nZVI/ GAC adsorbent follow the Pseudo-second-order, and the adsorption isotherm follows the Langmuir model. The adsorption of Cr(VI) ions on the Wl.nZVI/ GAC adsorbent is a spontaneous and exothermic process.

Application of Hydrogen Permeation Techniques to Assess the Effect of Inhibitors in Hydrochloric Steel Pickling of Low‐C Steels and Interstitial‐Free Steels

The acid pickling phase, generally entrusted to HCl‐based solutions, plays a fundamental role in the production of low‐C and interstitial‐free steel coils. Very often, however, pickling operations are challenging due to the possible onset of surface defects (underpickling, overpickling, appearance of surface defects, etc.) linked to complex phenomena involving numerous factors, such as acid concentration, Fe ions in solution, temperature, time, steel type, and scale structure. Moreover, the use of inhibitors, which is essential for controlling the pickling process, represents one of the major challenges. Their dosage, although minimal, must be carefully chosen based on the type of processed coils and other plant engineering variables. The flow of hydrogen that is generated on the surface of the steel during etching causes absorption of hydrogen by the metal and its measurement is strictly linked to the phenomena occurring during scale removal. The correlation of data obtained from a Devanathan double‐cell hydrogen permeation system to results of other techniques, such as weight loss, surface analysis, metallography, and electron microscopy shows that this system can be effectively used to indirectly measure the solution aggressiveness. This experimental approach is applied to two industrial steels: a simple carbon base and an interstitial free Ti steel.

Exploring the improving role of MWCNTs on the electrochemical behavior of electrophoretically prepared Ti/nanoZnO metal oxide electrode: A comparative study

In recent years, a growing amount of attention has been paid to the investigation and modification of metal oxide anodes as a critical parameter in electrochemical removal. In this way, this research attempts to bring out an effective comparison between modified Ti/nanoZnO electrode by multi-walled carbon nanotubes (MWCNTs) and base Ti/nanoZnO electrode. The electrophoretic deposition (EPD) method was used to prepare electrodes. The morphological and chemical composition of the surface for both electrodes were obtained by using characterization tests including field emission scanning electron microscope - energy dispersive spectrometer (FESEM-EDS), elemental mapping, and X-ray diffraction (XRD). Furthermore, the electrochemical behavior of Ti/nanoZnO as well as Ti/nanoZnO-MWCNTs electrodes were compared using linear sweep voltammetry (LSV), chronopotentiometry (CP), and chronoamperometry (CA) analysis. In the final step, the chemical oxygen demand (COD) removal in addition to the decolorization rate of a dyes mixture was used to evaluate the electrochemical performance in the same conditions. Presented results in this study showed the importance of metal oxide anode modification by improved deposited coating properties of Ti/nanoZnO-MWCNTs electrode compared with base ZnO electrode.

Is It Possible to Know Cosmological Fine-tuning?

Fine-tuning studies whether some physical parameters, or relevant ratios between them, are located within so-called life-permitting intervals of small probability outside of which carbon-based life would not be possible. Recent developments have found estimates of these probabilities that circumvent previous concerns of measurability and selection bias. However, the question remains whether fine-tuning can indeed be known. Using a mathematization of the concepts of learning and knowledge acquisition, we argue that most examples that have been touted as fine-tuned cannot be formally assessed as such. Nevertheless, fine-tuning can be known when the physical parameter is seen as a random variable and it is supported in the nonnegative real line, provided the size of the life-permitting interval is small in relation to the observed value of the parameter.

Superlative and Selective Sensing of Serotonin in Undiluted Human Serum Using Novel Polystyrene Sulfonate Conductive Polymer.

In the past 5 years, real-time health monitoring has become ubiquitous with the development of watches and rings that can measure and report on the physiological state. As an extension, real-time biomarker sensors, such as the continuous glucose monitor, are becoming popular for both health and performance monitoring. However, few real-time sensors for biomarkers have been made commercially available; this is primarily due to problems with cost, stability, sensitivity, selectivity, and reproducibility of biosensors. Therefore, simple, robust sensors are needed to expand the number of analytes that can be detected in emerging and existing wearable platforms. To address this need, we present a simple but novel sensing material. In short, we have modified the already popular PEDOT/PSS conductive polymer by completely removing the PEDOT component and thus have fabricated a polystyrene sulfonate (PSS) sensor electrodeposited on a glassy carbon (GC) base (GC-PSS). We demonstrate that coupling the GC-PSS sensor with differential pulse voltammetry creates a sensor capable of the selective and sensitive detection of serotonin. Notably, the GC-PSS sensor has a sensitivity of 179 μA μM-1 cm-2 which is 36x that of unmodified GC and an interferent-free detection limit of 10 nM, which is below the concentrations typically found in saliva, urine, and plasma. Notably, the redox potential of serotonin interfacing with the GC-PSS sensor is at -0.188 V versus Ag/AgCl, which is significantly distanced from peaks produced by common interferants found in biofluids, including serum. Therefore, this paper reports a novel, simple sensor and polymeric interface that is compatible with emerging wearable sensor platforms.

Lithofacies and cyclicity of sulphate dominated tidal-lagoon deposits of Late Triassic age in Northeast Iberia (western Europe)

Thick gypsum‑carbonate sequences were deposited in different periods and basins of Europe during the westward opening of the Tethys Ocean. Although they seem to represent widespread perimarine sulphate-dominated lagoons in shallow epeiric platforms, the sedimentary characteristics and interpretation of these deposits are still poorly constrained. To advance in the knowledge of these deposits, a detailed study is presented of two distinctive sulphate dominated sequences of Late Triassic age located in NE Iberia (Western Europe), which correspond to the Canelles and Espinagosa units, found in the southern Pyrenees and the Catalan Coastal Ranges respectively. These sequences present a diverse suite of carbonate and sulphate lithofacies, which are stacked in several recurring sedimentary cycles. These cycles consistently present a carbonate base that transitions to a sulphate top, and can be correlated along several tens of kilometres. Each of the observed cycles depicts an initial sudden flooding of a tidal-lagoon system by marine water, which led to carbonate-dominated sedimentation. Progressive evaporation under dominant arid climate conditions triggered the shallowing of the lagoon and salinisation of its water. Then, a transition from carbonate to gypsum/anhydrite precipitation and the early dolomitisation of the underlying carbonate sediments by brine reflux occurred. Gypsum precipitated in the water column as cumulate crystals and deposited at the bottom of the lagoon, forming laminations or being incorporated into microbial mats. Anhydrite precipitated as early diagenetic crystals in the different subaqueous and subaerial environments of the tidal-lagoon system, leading to a variated set of lithofacies until now largely undocumented. It mainly formed as displacive lath-shaped crystals randomly oriented within carbonate muds at the bottom of the lagoon, which were mostly reworked at the lagoon margins by wave and tidal currents resulting in aligned fabrics in cross-lamination structures. Anhydrite also formed as pure massive beds by anhydritisation of subaerially exposed gypsum sediments during the main retraction stages of the lagoon, as well as typical nodular (sabkha) lithofacies. Such sulphate lithofacies are not easy recognisable due to the lack of modern analogues to compare and to their current transformation into secondary gypsum in the outcrops. These are aspects to be taken into account in future sedimentological studies on similar evaporitic materials.

Exposure of Cryptococcus neoformans to low nitrogen levels enhances virulence

Previous studies have shown a correlation between nitrogen levels and Cryptococcus neoformans pathogenicity. Here we report on the in vivo effects of cryptococcal pre-exposure to ecologically relevant nitrogen levels. C. neoformans H99 was cultured in yeast carbon base (YCB) supplemented with 0.53 g/L NH4Cl and 0.21 g/L NH4Cl, respectively, and used to infect larvae of the Greater Wax moth, Galleria mellonella. Cells cultured in low nitrogen YCB (LN) were more virulent compared to cells cultured in high nitrogen YCB (HN). Microscopic examination of haemolymph collected from infected larvae revealed that cells cultured in LN were larger than cells cultured in HN, with the majority of LN cells exceeding 10 µm and possibly entering titanisation. Additionally, compared to HN-cultured cells, fewer LN-cultured cells were engulfed by macrophages. The enhanced virulence of LN-cultured cells was attributed to the increased cell size in vivo. In contrast, reduced macrophage uptake was attributed to increased capsule thickness of in vitro cells. Not only do these findings demonstrate the effects of culture conditions, specifically nitrogen levels, on C. neoformans virulence, but they also highlight the importance of isolate background in the cryptococcal-host interaction.

Comparison of the effect of intravenous phenylephrine and norepinephrine boluses for post-spinal hypotension on neonatal outcome in elective caesarean section: A randomised controlled trial.

There is limited data on the effects of norepinephrine on neonatal outcomes and maternal complications relative to other vasopressors. The study aimed to compare neonatal outcomes and maternal complications after bolus intravenous doses of phenylephrine and norepinephrine for post-spinal hypotension in elective caesarean section women. This randomised study was done on 100 elective caesarean section women under spinal anaesthesia. Block randomisation divided women into two groups to receive intravenous phenylephrine 50 μg bolus (Group A) or norepinephrine 5 μg bolus (Group B) following post-spinal hypotension. Groups were evaluated and compared for umbilical arterial blood gas analysis, birth weight, APGAR (appearance, pulse, grimace, activity, and respiration) score, maternal haemodynamics, and complications. Kolmogorov-Smirnov and Shapiro-Wilk tests were used to verify data normality. Independent samples t-test or Mann-Whitney U test was employed to compare continuous variables based on data normality, and the Chi-square test was used to determine categorical variable associations. Demographic characteristics of women were found to be comparable between groups. Umbilical arterial potential of hydrogen, partial pressure of oxygen, partial pressure of carbon dioxide, base excess, bicarbonate, birth weight, and APGAR scores were comparable across groups, showing no significant differences (P > 0.05). Groups had similar maternal haemodynamic characteristics and episodes of nausea, vomiting, and chest pain across groups without statistical significance (P > 0.05). No notable distinction was found between neonatal outcomes and maternal complications between phenylephrine and norepinephrine bolus regimens. Norepinephrine can be used as an alternative to phenylephrine post-spinal hypotension in women undergoing elective caesarean section.