Carbon Oxygen Research Articles

Characterizations of the pullulan/sodium alginate coatings incorporated with sodium silicate and EDTA-2Na and the antifungal effect on citrus green mold

Citrus has suffered great losses from postharvest fungal diseases. The strategy of polysaccharide-based coating combined with antimicrobial salts was introduced to preserve citrus and control green mold. Sodium silicate and ethylene diamine tetraacetic acid-2Na (EDTA-2Na) (SE) were incorporated with pullulan (PUL)/sodium alginate (SA) solutions to fabricate PSA-SE systems. The results indicated that the PSA-SE films had good biocompatibility based on hydrogen bonds and showed uniform and dense. The molecular of PUL and SA were assembled through entanglement to form a network structure and the surface roughness of the PSA-SE films increased with the addition of SA. The P3SA2-SE film indicated appropriate tensile strength and elongation at break, as well as the lowest water vapor permeability. The carbon dioxide and oxygen permeability and dissolution of P3SA2-SE film were at low values. The P3SA2-SE film had the highest water contact angle (66°). With the addition of SA, the absorbance of the PSA-SE films increased, which was conducive to light blocking. The antifungal experiments revealed that the P3SA2-SE coating showed a significant effect on controlling citrus green mold, especially in Citrus sinensis Osbeck ‘Lane Late’ almost completely inhibited Penicillium digitatum (P44). This study will promote the development of citrus postharvest disease control.

Spatio-temporal dynamics of net primary productivity and the economic value of Spartina alterniflora in the coastal regions of China

This study employs an improved Carnegie–Ames–Stanford Approach (CASA) model to calculate the Net Primary Productivity (NPP) of Spartina alterniflora (SA) and various other land use/land cover types (LULC) across coastal China over multiple years. The research aims to provide significant theoretical and practical insights into carbon sink research in coastal zones, sustainable development, and resource management. Key findings include identifying the first εmax value of 2.219 g C/MJ for SA, addressing a critical data gap in CASA modeling research on invasive plants. SA's NPP exhibited higher values in Shanghai and Zhejiang due to factors such as genetic diversity, invasion duration, and tidal dynamics. In contrast, other LULC exhibited higher NPP values in southern and inland regions, characterized by greater vegetation cover and favorable growing conditions. In 2020, SA and other LULC sequestered 16.352 kt C and 0.821*106 kt C, respectively. From 2000 to 2020, the average annual NPP and total carbon storage of SA and other LULC increased significantly, primarily driven by Shanghai and deciduous needleleaf forests, respectively. Seasonal NPP trends followed summer> spring> autumn> winter, influenced by climate conditions and plant life activities. Economic assessments in 2020 estimated SA's carbon storage value at RMB0.409 billion (Market Value method) or RMB5.562 billion (Carbon Tax method), with RMB2.054 billion attributed to oxygen release values, underscoring its economic and ecological potential. Among other LULC, evergreen broadleaf forests showed the highest carbon storage value (RMB183.463 billion). The study emphasizes the critical role of all LULC in carbon storage and oxygen release, advocating for targeted conservation and land management strategies. It suggests that managing SA should balance stringent control in high-risk areas, lenient measures in low-risk areas, eradication of scattered populations, and maximizing ecological benefits in retention areas, with continuous monitoring and adaptive management strategies to balance conservation and development efforts.

Ecological restoration amplifies riverine fish catch of Gudusia chapra (Hamilton, 1822): an impact study in the river Ganga using multivariate statistical tools and water quality indices.

Fish residing in the aquatic ecosystem are considered the best ecological indicator for monitoring environmental habitat. To evaluate the changes that occurred due to relative restoration in the ecological habitat, a study was conducted in the freshwater zone of the river Ganga between Buxar, Bihar, and Ballia, Uttar Pradesh, between July 2021 and July 2022. In the monitoring, the physico-chemical condition, as well as the food and feeding habits of the fish Gudusia chapra, were monitored with the help of various pollution evaluating indices, namely, the algal pollution index (API) for planktons, the comprehensive pollution index (CPI-WQI), and the National Sanitation Foundation Water Quality Indices (NSF-WQI) for water. The study showed that the relative restoration facilitated the amplification of the fish catch from 5.60 to 98.98% in two consecutive years. The reduction in the API (15 to 4) as well as CPI (0.80 to 0.72) during both years signified the reduction of the pollution status of the river in the region. The NSF-WQI also decreased from 88.27 to 79.27 from 2021 to 2022. The electivity index for the fish showed that fish preferred the groups Cyanobacteria, Rotifera, and Copepoda. The multivariate, as well as univariate analyses, revealed that the fish G. chapra is significantly influenced by multiple abiotic as well as biotic variables, among which the major contributors are riverine velocity, transparency, conductivity, pH, dissolved oxygen, total alkalinity, carbonate, bicarbonate, salinity, total hardness, calcium, silicate, and biochemical oxygen demand.

Younger age for the oldest magnetic white dwarfs

Abstract Sufficiently old white dwarfs cool down through a convective envelope that directly couples their degenerate cores to the surface. Magnetic fields may inhibit this convection by stiffening the criterion for convective instability. We consistently implemented the modified criterion in the stellar evolution code mesa, and computed the cooling of white dwarfs as a function of their mass and magnetic field B. In contrast to previous estimates, we find that magnetic fields can significantly change the cooling time t even if they are relatively weak $B^2\ll 8\pi P$, where P is the pressure at the edge of the degenerate core. Fields B ≳ 1 MG open a radiative window that decouples the core from the convective envelope, effectively lowering the luminosity to that of a fully radiative white dwarf. We identified a population of observed white dwarfs that are younger by Δt ∼ Gyr than currently thought due to this magnetic inhibition of convective energy transfer – comparable to the cooling delay due to carbon–oxygen phase separation. In volume-limited samples, the frequency and strength of magnetic fields increase with age. Accounting for magnetic inhibition is therefore essential for accurate cooling models for cosmic chronology and for determining the origin of the magnetic fields.

Fabrication of double modified electrocatalyst by dual flame synthesis for enhancing electrochemical reduction of carbon dioxide

A rapid dual flame synthesis is developed for one-step preparation and modification of double modified ZnO catalysts with carbon doping and oxygen vacancies. The growth mechanism and nanostructure evolution are also investigated. The double modified ZnO with carbon doping and oxygen vacancies exhibies excellent performance in CO2 reduction to syngas, with a high current density of 14.02 mA/cm2 at −1.1 V vs. RHE and a maximum Faradaic efficiency of 71% for CO production. The maximum adjustable range of the CO/H2 ratio from 0.5 to 2.7. In a flow cell, the double modified ZnO exhibits a large current density of 126.8 mA/cm2 at −1.2 V vs. RHE. The maximum Faradaic efficiency for CO2 reduction to CO is 74.8% at 50 mA/cm2. Double modified ZnO maintains stable potential and Faradaic efficiency for over 5 h of electrolysis. Operando X-ray absorption spectroscopy and density functional theory calculations reveal that the active site is the Zn–Zn configuration, and that carbon dopant and oxygen vacancy promote CO2 activation and CO desorption, and reduce reaction overpotential of CO2RR.

Kinetic analysis of solid fuel combustion in chemical looping for clean energy conversion

Chemical looping combustion (CLC) offers an advanced, eco-friendly method for converting solid fuels into energy with inherent CO2 capture, presenting a cost-efficient solution. The kinetics of solid fuel CLC, crucial for reactor design, are not well-understood, limiting its application and optimisation. Conducting a comprehensive kinetic analysis of solid fuel CLC is crucial, as it examines the combustion of both volatiles and fixed carbon, thereby addressing existing knowledge gaps and advancing clean conversion of solid fuels. In this study, a comprehensive kinetic analysis method for the first time has been applied to investigate the kinetics of CLC of low-volatile semi-anthracite coal with CuO at temperatures of 700–950 °C under varied oxygen excess ratios (0.5, 1.0, and 2.0). The results show that the combustion of coal in CLC can be divided into three distinct stages. The combustion of coal with CuO initiates with the combustion of volatiles interacting with solid CuO at 450–580 °C, where the combustion efficiency varies between 3–6 wt%. This is followed by a complex simultaneous mechanism involving gas-phase volatiles and solid-phase CuO, as well as gas-phase oxygen and solid-phase fixed carbon under non-isothermal conditions. The combustion efficiency is ranged 19–71 wt% at the temperature ranges from 580 °C to the isothermal temperatures of 750–950 °C. The activation energy for the combustion of volatiles was determined as Ea = 119 kJ/mol, whereas the initial combustion of fixed carbon in the non-isothermal stage ranged between Ea = 39–53 kJ/mol. The rate of combustion is initially limited by the oxygen diffusion rate from CuO, but with additional oxygen carriers and increased temperature, the reaction becomes constrained by first-order kinetics. Upon reaching the isothermal stage, the final combustion phase between fixed carbon and gas phase oxygen occurs, and the combustion efficiency increases to 77–96 wt% at 750–950 °C. The activation energy for fixed carbon combustion under the isotherm stage was approximately Ea = 234 kJ/mol, with a reaction rate constant (k0) of 7.84 × 109 min−1. This pioneering study not only clarifies the multi-stage kinetics of solid fuel CLC, bridging significant gaps in current knowledge but also sets the foundation for the enhanced design and efficiency of CLC systems for cleaner energy production.

Role of intrinsic point defects on electrocatalytic activity of a metal-free two-dimensional Polyaramid for enhanced hydrogen evolution reaction

Despite the current research aims at replacing expensive metals like Platinum with non-noble metals for producing hydrogen via hydrogen evolution reaction (HER), practical challenges like oxidation continue to be a significant concern. Our study aims at providing the metal-free alternative to such noble Pt-based catalysts. Taking care of the fact that the defects are inevitable during the material's growth process, we propose thermodynamically and thermally stable two-dimensional (2D) Polyaramid (2DPA) with possible intrinsic point defects as HER active materials with overpotentials comparable to that of Pt catalysts using density functional theory (DFT). Creating single carbon (VC), single nitrogen (VN), and single oxygen (VO) vacancies helps reducing its wide band gap upon creation of several defect states, thereby improving conductivity. VO-2DPA exhibits lowest ΔGH* value of −0.04 eV which is closest to thermoneutrality condition, i.e., ΔGH*≈0 while VN-2DPA is not found suitable for HER. The calculated low formation energies for generating point-vacancies under defect-poor growth conditions and the minimal bond length fluctuations within, serve as strong validation for the feasibility of their synthesis. Furthermore, underlying reaction mechanisms are also investigated for the HER process favouring the Heyrovsky reaction path over Tafel as the former requires lesser activation energy: 0.53 eV v. 0.86 eV for VC-2DPA and 0.34 eV v. 1.01 eV for VO-2DPA.

Long-term hypothermic storage of oocytes of the European common frog Rana temporaria at various pressure regimes in gas mixtures based on oxygen, carbon monoxide, and nitrous oxide

In recent years, the challenge of preserving amphibian biodiversity has increasingly been addressed through technologies for the short-term storage of unfertilized spawn at low positive temperatures. Previously the possibility of using a 6.5 atm gaseous mixture of carbon monoxide and oxygen for prolonged hypothermic preservation of unfertilized oocytes for more than 4 days was shown. This study aimed to investigate the viability of oocytes R. temporaria preserved under conditions of hypothermia at 2.5, 3 and 6.5 excess atm pressure in the various gas mixture compositions (CO, N2O, O2) and pure oxygen. The use of pressure up to 3 excess atmospheres was significantly beneficial compared to 6.5 atm at the 7 days storage period. The results indicate that oxygen pressure is a critical factor in maintaining oocyte viability. Admixing CO or N2O to oxygen reduced variability in the results but did not significantly affect the measured indicators (fertilization, hatching) in the experimental groups. The composition CO + O2 (0.5/3.5 ratio, 3 excess atm) reliably extended the shelf life of viable oocytes, indistinguishable from native controls by fertilization and hatching rates, to 4 days. After 7 days, oocytes exhibited fertilization and hatching rates that were 79 % and 48 % compared to native control. Reducing the pressure of the preserving gas mixture to 3 atm, as utilized in this study, simplifies the practical implementation of gas preservation technology for maintaining endangered amphibian species during breeding in laboratory conditions.

Decoupling the air sensitivity of Na-layered oxides.

Air sensitivity remains a substantial barrier to the commercialization of sodium (Na)-layered oxides (NLOs). This problem has puzzled the community for decades because of the complexity of interactions between air components and their impact on both bulk and surfaces of NLOs. We show here that water vapor plays a pivotal role in initiating destructive acid and oxidative degradations of NLOs only when coupled with carbon dioxide or oxygen, respectively. Quantification analysis revealed that reducing the defined cation competition coefficient (η), which integrates the effects of ionic potential and sodium content, and increasing the particle size can enhance the resistance to acid attack, whereas using high-potential redox couples can eliminate oxidative degradation. These findings elucidate the underlying air deterioration mechanisms and rationalize the design of air-stable NLOs.

Metallurgical and technological features of forming the connection zone between the welded layer and base metal during repair welding of cast iron parts with carbon dioxide and oxygen

Metallurgical and technological features of forming the connection zone between the welded layer and base metal during repair welding of cast iron parts with carbon dioxide and oxygen

Carbon and oxygen recycling strategies in CO2-to-sustainable synthetic fuel production: Recycling route, techno-economics and carbon intensity

Anthropogenic carbon utilization and recycling into fuel using renewably sourced or nuclear energy and water is a potentially valuable strategy for replacing fossil fuels. The high-level elemental balance of the CO2-to-Fuel system involves oxygen rejection, with CO2 and H2O reduction dependent on crucial process steps that determine performance metrics such as energy efficiency, element utilization, economics, and carbon footprint. This study elaborates on carbon and oxygen recycling strategies for producing sustainable synthetic hydrocarbon fuels. It covers electrolysis routes, internal recycling pathways, and additional processes to increase synfuel yield. An element balance was derived for four process schemes with systematic recycling route variations, facilitating a comparison of elemental efficiencies: (1) carbon utilization (80.7–90.6 %), (2) hydrogen efficiency (4.8–30.8 %), and (3) oxygen gas rejection rate (56.8–63.1 %). A process flow diagram was proposed to discuss techno-economics through the existing route via the Fischer-Tropsch process. The energy intensity ranged from 118.5 to 177.4 GJ per tonne of synfuel, and the energy conversion efficiency varied from 0.24 to 0.36. We further evaluated the carbon intensity, considering the primary energy efficiency to show the different energy supply scenarios, including (i) 100 % fossil-based (506–1416 kgCO2eq/GJFuel), (ii) grid power with fossil fuel (246–687 kgCO2eq/GJFuel), (iii) hybridization of renewable sources (biomass and wind power) (42–78 kgCO2eq/GJFuel), and (iv) nuclear energy (7–18 kgCO2eq/GJFuel). This work considers the interplay between oxygen rejection, syngas conversion, and combustion, undertaking a novel analysis to bridge the high-level elemental analysis with detailed metrics calculations.

Study on strength and reduction characteristics of iron ore powder-green carbon composite briquettes

The metallurgical industry is a key sector for carbon emissions, and in recent years, there has been widespread attention on the use of biomass resources as a green, renewable, and carbon–neutral energy source material for low carbon ironmaking processes. The waste wood after hydrothermal-pyrolysis carbonization has the characteristics of low content of harmful elements and high content of fixed carbon. In this study, the waste wood after hydrothermal-pyrolysis two-step carbonization treatment was used as a reducing agent for the reduction of iron ore to prepare iron ore powder- green carbon composite briquettes (ICCB) with two carbon–oxygen ratios. The study investigated the effects of reduction behavior and reaction temperature on the reduction performance of the ICCB. The results indicate that with the increase in reaction temperature, the volume of the ICCB gradually contracts, leading to a reduction in mass. The shrinkage rate of the ICCB during self-reduction at 1200℃ is significantly higher than during co-reduction, and the shrinkage effect of the C/O 0.5 ICCB is more pronounced than that of the C/O 0.8 ICCB. Due to the excessive carbon content in the C/O 0.8 ICCB, the carbon cannot be fully consumed during the reaction process, resulting in consistently low compressive strength of the ICCB, with a compressive strength of 12 N after reduction at 1200℃. In contrast, the iron phase in the C/O 0.5 ICCB gradually recrystallizes during the reduction process, ultimately yielding plastic iron briquettes with compressive strengths exceeding 3000 N after different reaction behaviors at 1200℃. In summary, reducing the carbon-to-oxygen ratio and increasing the reaction temperature contribute to the volume contraction and enhanced compressive strength of the ICCB during the reduction process.

Carbon Nanotube Support, Carbon Loricae and Oxygen Defect Co-Promoted Superior Activities and Excellent Durability of RuO2 Nanoparticles Towards the pH-Universal H2 Evolution.

This work reports a strategy that integrates the carbon nanotube (CNT) supporting, ultrathin carbon coating and oxygen defect generation to fabricate the RuO2 based catalysts toward the pH-universal hydrogen evolution reaction (HER) with high efficiencies. Specifically, the CNT supported RuO2 nanoparticles with ultrathin carbon loricae and rich oxygen vacancies at the surface (C@OV-RuO2/CNTs-325) have been synthesized. The C@OV-RuO2/CNTs-325 shows superior activities and excellent durability for the HER. It only requires overpotentials of 36.1, 18.0, and 19.3mV to deliver -10mA cm-2 in the acidic, neutral, and alkaline media, respectively. Its HER activities are comparable to that of the Pt/C in the acidic media but higher than those of the Pt/C in the neutral and alkaline media. The C@OV-RuO2/CNTs-325 shows excellent HER durability with no activity losses for > 500h in the acidic, neutral or alkaline media at -250mA cm-2. The density-functional-theory calculations indicate that the CNT supporting, the carbon coating, and the OVs can modulate the d-band centers of Ru, increasing the HER activities of C@OV-RuO2/CNTs-325, and stabilize the Ru atoms in the catalyst, increasing the durability of the C@OV-RuO2/CNTs-325. More interestingly, the C@OV-RuO2/CNTs-325 shows great potential for practical applications toward overall seawater splitting.

Rhombohedral ZnIn2S4-Catalysed Anodic Direct Electrochemical Oxidative Cleavage of C-O Bond in α-O-4 Linkages in Ambient Conditions

The electrochemical selective oxidative transformation of biomass feedstocks into valuable oxygenated fine chemicals that are essential to the bio-commodity chemical markets. In this study, we used a rhombohedral ZnIn2S4 (R-ZIS) electrocatalyst to realise the efficient anodic cleavage of C-O bonds in benzyl phenyl ether (BPE), an α-O-4 lignin model compound, to a series of industrially relevant oxygenated mono-aromatics (benzyl alcohol, benzaldehyde, benzoic acid, etc.). In optimised conditions, the reaction achieved over 99% conversion rate with a Faraday efficiency of 51.6% that greater than most known electrocatalytic oxidative cleavage examples. The ZnIn2S4 electrocatalyst was deposited on a carbon support, and its structural properties and surface morphology were extensively investigated. Systematic chronoamperometric electrolysis coupled with18O isotopic labelling confirmed that C-O scission occurred exclusively between the benzylic carbon and phenolic oxygen. The experimental results were supported by density functional theory calculations. The substrate scoping study revealed the suitability of the R-ZIS induced electrocatalytic system for a variety of substituted lignin α-O-4 and β-O-4 model dimers. Overall, this work demonstrates an efficient anodic process that can enable the atom-efficient valorisation of lignin to produce oxygenated fine chemicals. Figure 1

Incorporation of nitrogen and oxygen in carbon: A highly tuned electrochemistry with facile synthesis and its influence on optical and electrode performance in supercapacitors

A new approach for synthesizing heteroatom-doped carbon nanostructures has been developed, in which nitrogen and oxygen have been effectively infused into the graphitic core using the required precursors. The heteroatoms incorporated into the carbon matrix and their corresponding structural features are examined. The observed X-ray diffraction pattern reveals the presence of amorphous carbon forms that resemble carbon nitride in their structure. The presence of additional N–O and C–O bonds gives strong evidence of a graphitic structure with oxygen and nitrogen incorporation, as shown by the Fourier transform-infrared peaks. The X-ray photoelectron spectroscopy analysis reveals important information regarding the bond formation in the graphitic core of the sample. The study focused on examining the porous and intricately interconnected network structures, showcasing a variety of particle morphologies, and was carried out using scanning electron and transmission electron microscopy. The lattice defects are investigated using transmission electron microscopy-high angle annular dark field technique to explore the surface morphology. The influence of incorporated O and N in carbon structure drastically reduced the electron density of the graphitic core. As a result, the absorption bands observed were around 300–400 nm, showing the semiconductors' absorption characteristics. Three-electrode electrochemical systems are fabricated with working electrodes based on COx and CNx materials. The COx and CNx-modified electrodes were meticulously tested for their performance in supercapacitor applications. The COx samples exhibit a significant specific capacity value of 439.20 C g−1 under a low current density of 4 A g−1. The CNx samples demonstrate a specific capacity of 420.00 C g−1 under 4 A g−1 current density.

Evolution characteristics and meteorological impacts of ecosystem regulation service functions in Jiangxi Province, China from 2000 to 2022.

Jiangxi Province is one of the first ecological civilization demonstration provinces in China. Understan-ding the impacts of meteorological conditions on ecosystem regulatory services is beneficial for conducting ecological protection and restoration work. Based on MODIS data, net primary productivity data, and monthly meteorological data from 2000 to 2022, we used models such as water balance equation and soil loss equation to measure the four regulatory service functions of ecosystem in Jiangxi Province, including carbon sequestration, oxygen release, water conservation and soil conservation. We used trend analysis and partial correlation analysis methods to analyze the spatio-temporal patterns and meteorological influencing factors of those four regulation service functions. The results showed that from 2000 to 2022, the annual average values of carbon sequestration and oxygen release in Jiangxi Province were 178.8 and 130.0 g·m-2, respectively, with annual increases of 0.4 and 0.3 g·m-2. The spatial distribution of both services was consistent, and the average annual carbon sequestration and oxygen release showed an upward trend in 77.3% regions of Jiangxi Province. The average water conservation and soil retention in Jiangxi Province were 591.8 mm and 723.8 t·hm-2, respectively, with similar spatial distributions. The annual increases were 5.6 mm and 3.7 t·hm-2. The soil conservation and water conservation functions of 73.3% and 69.3% regions in Jiangxi Province were steadily improved. Vegetation carbon sequestration and oxygen release was significantly correlated with temperature at monthly scale and seasonal scale. The partial correlation coefficient of those two factors was higher than other factors, which was an important meteorological factor affecting the carbon sequestration and oxygen release function of ecosystem. Precipitation, which was the most important meteorological factor, had a significant positive correlation with water conservation and soil conservation at monthly, seasonal and annual scales. Our results revealed the impacts of climate change on ecosystem regulatory service functions in Jiangxi Province from 2000 to 2022, which could provide scientific and technological support for effectively guaranteeing ecosystem protection and restoration in Jiangxi Province and improving the quality and efficiency of ecological civilization construction.

Radiation pressure-driven Rayleigh–Taylor instability in compressible strongly magnetized ultra-relativistic degenerate plasmas

The radiation pressure and strong magnetic fields are prominent in the structures of Rayleigh–Taylor (R–T) instability in the interior of white dwarfs. This paper investigates the radiation pressure-driven R–T instability in a compressible and magnetized ultra-relativistic degenerate strongly coupled plasma. The equation of state has been derived for such systems incorporating ultra-relativistic degenerate electrons with their radiation pressure and ion gas compressibility. The dispersion relation of the density gradients driven R–T instability is analyzed using the generalized hydrodynamic fluid model in the strongly coupled and weakly coupled limits. It is observed that the R–T instability criterion has been modified significantly due to radiation pressure, ion gas compressibility and degeneracy parameters. In the kinetic limit, the instability region is shorter than the hydrodynamic limit due to the dominance of plasma frequency over the viscoelastic relaxation frequency. The outcomes are explored in analyzing the development of R–T instability in the strongly magnetized carbon–oxygen white dwarfs. The radiation pressure, electron temperature and ion density strongly suppress the growth rate of the R–T instability in the interior of white dwarfs. The strong magnetic fields introduce asymmetry to the system by destabilizing the R–T unstable modes. The present results are also useful for understanding the R–T instability in the star formation and dense plasmas in inertial confinement fusion in some limiting cases.

Indirect Voltammetry Detection of Non-Electroactive Neurotransmitters Using Glassy Carbon Microelectrodes: The Case of Glutamate

Glassy carbon (GC) microelectrodes have been successfully used for the detection of electroactive neurotransmitters such as dopamine and serotonin through voltammetry. However, non-electroactive neurotransmitters such as glutamate, lactate, and gamma-aminobutyric acid (GABA) are inherently unsuitable for detection through voltammetry techniques without functionalizing the surface of the microelectrodes. To this end, we present here the immobilization of the L-glutamate oxidase (GluOx) enzyme on the surface of GC microelectrodes to enable the catalysis of a chemical reaction between L-glutamate, oxygen, and water to produce H2O2, an electroactive byproduct that is readily detectable through voltammetry. This immobilization of GluOx on the surface of bare GC microelectrodes and the subsequent catalytic reduction in H2O2 through fast-scan cyclic voltammetry (FSCV) helped demonstrate the indirect in vitro detection of glutamate, a non-electroactive molecule, at concentrations as low as 10 nM. The functionalized microelectrodes formed part of a four-channel array of microelectrodes (30 μm × 60 μm) on a 1.6 cm long neural probe that was supported on a flexible polymer, with potential for in vivo applications. The types and strengths of the bond between the GC microelectrode surface and its functional groups, on one hand, and glutamate and the immobilized functionalization matrix, on the other hand, were investigated through molecular dynamic (MD) modeling and Fourier transform infrared spectroscopy (FTIR). Both MD modeling and FTIR demonstrated the presence of several covalent bonds in the form of C-O (carbon–oxygen polar covalent bond), C=O (carbonyl), C-H (alkenyl), N-H (hydrogen bond), C-N (carbon–nitrogen single bond), and C≡N (triple carbon–nitrogen bond). Further, penetration tests on an agarose hydrogel model confirmed that the probes are mechanically robust, with their penetrating forces being much lower than the fracture force of the probe material.

Hydrocarbon Accumulation and Overpressure Evolution in Deep–Ultradeep Reservoirs in the Case of the Guole Area of the Tarim Basin

Usually, deep oil and gas accumulation is often controlled by strike–slip faults. However, in the Tarim Basin, deep Ordovician oil and gas accumulations are also found in areas far from the fault zone. The process of oil and gas accumulation in deep reservoirs far from strike–slip fault zones is still unclear at present. The source and evolution of Ordovician fluids were analyzed using inclusion geochemical methods and the U–Pb dating technique. The analysis of rare earth elements and carbon–oxygen–strontium isotopes in the reservoirs showed that the reservoirs were weakly modified by diagenetic fluid. The fluid was derived from the fluid formation during the same period as the seawater, and no oxidizing fluid invaded the reservoir. The late oil and gas reservoirs had good sealing properties. The U–Pb dating results combined with homogenization temperature data revealed that the first-stage oil was charged during the Late Caledonian Period, and the second-stage natural gas was charged during the Middle Yanshanian Period. The evolution of the paleo-pressure showed that the charging of natural gas in the Middle Yanshanian was the main reason for the formation of reservoir overpressure. The strike–slip fault zone was basically inactive in the Middle Yanshanian. During this period, the charged natural gas mainly migrated to the reservoir along the unconformity surface and the open strike–slip fault zone in the upper part of the Ordovician reservoir. The source of the fluid shows that the reservoir in the late stage had good sealing properties, and there was no intrusion of exogenous fluid. The overpressure in the reservoir is well preserved at present.

Facile Construction Engineering of Pr6O11@C with Efficient Photocatalytic Activity.

In this study, facile construction engineering of Pr6O11@C with efficient photocatalytic activity was established. Taking advantage of the flocculation of Pr3+ in the base medium, acid red 14 (AR14) was flocculated together with Pr(OH)3 precipitate, in which Pr(OH)3 and AR14 mixed highly uniformly. Calcinated at high temperature in N2, a novel Pr6O11@C was successfully synthesized. The resulting materials were characterized by XRD, SEM, FT-IR, Raman, and XPS techniques. The results show that the cubic Pr6O11@C with Fm3m space group, similar to that of Pr6O11, was obtained. From the results of the photodegradation of AR14, it is found that the photocatalytic efficiency of Pr6O11@C is higher than that of pure Pr6O11 due to the formation of abundant carbon bonds and oxygen vacancies. Compared with pure Pr6O11 and other carbon-based composites, the acid resistance of Pr6O11@C is greatly improved due to the highly uniform dispersion of Pr6O11 and C, which lays a solid foundation for the practical application of Pr6O11@C. Moreover, the role of NH3·H2O and NaOH used as precipitants for the photocatalytic efficiency of Pr6O11 was investigated in detail.