Solid Source Research Articles

Preparation and surface nanostructural characterization of multi-emitter sources based on superionic conductor CsAg4Br3-xI2+x (x=0.25)

Since the fabrication of micro-/nano-electronic devices is approaching nanoscales and demanding low energy, high dose ion beam processing with controlled area and dense patterns to meet the current semiconductor industry demands, continuous advancement is needed in terms of material design and ion beam techniques. In this perspective, development of new ion sources may provide advanced technologies useful in the manufacture of high-performance devices. Silver ion beams have salient features including simple generating process, nanoscale beam spot size and high intensity ion current. In this paper, we have developed a solid electrolyte multi emitter ion source (SEIS) with CsAg4Br3-xI2+x (x = 0.25) films deposited on silver tips. Ag+ ion emission is significantly enhanced with the added number of emitters and the ion current of 1.95 μA (with four emitter tips) has been obtained at 168 °C temperature and 20 kV accelerating voltage. The stability and cooling/heating curves of the multi-emitter ion beam are measured, and the interrelation between ion current intensity and mechanism of shape geometry of the emitter tips are discussed. Finally, both the solid electrolyte multi-tip emitters and the collector surfaces are analyzed, with an attempt to precisely control of formation of the nanoparticles (NPs) including their size and height through the control of the ion implantation parameters.

Biogeochemical behavior, health risk assessment and source identification of antimony and arsenic in soil from a legacy antimony smelter in Gansu, Northwest China

The study of the contamination patterns and characteristics of Sb and As in the soils of the legacy contaminated sites of antimony smelters is important for the redevelopment and utilization of industrial sites. In this study, 13 heavy metals were determined in the soil and plants of an antimony smelter in Gansu Province to study the biogeochemical behavior, health risk, and pollution source. The results showed that the Nemerow index of Sb (728) exceeded the value of As (43.6) by 17.6 times, and the average geoaccumulation index (Igeo) of Sb and As were 10.1 and 1.97, respectively, categorized as extremely and moderately contaminated classes. Compared to As, Sb had a larger proportion of oxidizable fraction and a smaller proportion of reducible fraction (Fe/Mn oxides), suggesting that Sb possessed a higher content of organic matter and sulfide forms. Even though the bioaccumulation factor (BAF) for As was about 10 times higher than that for Sb, the accumulation of Sb in plants was not negligible. For the USEPA model, the mean hazard quotient (HQ) values of As by oral ingestion, dermal absorption, and inhalation accounted for 99.0%, 0.97%, and 0.0002% of the total, and 54.2%, 45.3%, and 0.51% for MEEPRC model, respectively. There were significant positive correlations between Sb, As, Zn, Se, Cd, and Ba (P < 0.05). The results of the source identification analysis revealed that antimony smelting, solid waste pollution, and natural origin were identified as the main pollution sources. The principal component analysis (PCA) and positive matrix factorization (PMF) methods differed by more than 20% in the analysis of the contribution of antimony smelting activities and solid waste pollution sources, suggesting the differences in the models themselves and in the uncertainty parameters chosen during the application.

Sludge Treatment and Disposal in MENA Countries

Sludge, or residual solids, is the end products of wastewater treatment processes, whether it is biological or physical-chemical treatment. Sludge production in MENA countries is increasing because of the growth in wastewater treatment systems. This chapter presents sludge management practices in some MENA countries, where there are various alternative processes available for sludge treatment and disposal. The processes selected depend primarily on the nature and characteristics of the sludge and on the final disposal method employed, in addition to the economic evaluation, beneficial use requirements, and local conditions. The system selected must be able to receive the sludge produced and to economically convert it to a product that is environmentally acceptable for disposal. The sources of sludge and solids produced by wastewater treatment plants related to the wastewater types and sources. However, the characteristic of sludge is depending on its origin and on the treatment methods of wastewater treatment operational process. Various sludge treatment and disposal processes will be presented in this study, with emphasis on the most used technologies in MENA region. There are some technologies are applied to produce sludge treatment process like dewatering, Thickening, and sludge drying to minimizing sludge volume by removing water from sludge. Aerobic or anaerobic digestion and composting are used to treat or stabilize the organic material in the sludge. Final disposal methods like incineration, land application and sanitary landfill will be discussed in terms of environmental constraints, and public health, as well as legislation for the reuse and disposal of sludge. Case studies will be provided to discuss practices and trends in sludge management in selected MENA countries.

A facile solid state synthesis route to tantalum oxynitride, β-TaON

Tantalum oxynitride is a prospective pigment and has attracted considerable recent attention as a photocatalyst for the overall splitting of water under visible light irradiation. Conventionally, TaON is synthesised by the thermal ammonolysis of Ta2O5, a process which remains challenging to scale up. The use of ammonia/water or ammonia/oxygen within a narrow temperature window is required to produce high purity TaON material; otherwise Ta3N5 forms as the favoured ammonolysis product. It would be highly beneficial to develop a reliable, simpler and reproducible synthesis route to TaON without the use of gaseous ammonia under such complex conditions. This paper describes a facile synthesis route to monoclinic β-TaON (space group P21/c) using Ta3N5 itself as a solid state nitrogen source. After 6 h of reaction at 900 °C under vacuum followed by post-synthesis calcination at 580 °C for 30 min, the bright yellow oxynitride is produced as spherical particles ca. 80 nm in diameter with a direct band gap of 2.9 eV.

Innovative cation exchange-driven carbon migration and recovery patterns in anaerobic fermentation of waste activated sludge

Despite numerous treatments have been developed to enhance anaerobic fermentation of waste activated sludge, the innovative cation exchange (CE) approach has been rarely reported, little attempt was conducted to revealcarbon source fate. The interphase carbon balance was illustrated to clarify endogenous carbon dissolution, biotransformation,and recovery patterns. By CE-mediated divalent cation removal, almost 34.72 % of particulate carbon sources were dissolved in 2-day treatment, corresponding to soluble carbon content of 1165.58 mg C/L. Most of the originally dissolved carbon sources (58.01–66.81 %) were bio-transformed to volatile fatty acids with high bioavailability, while the further transformation to biogas was inhibited, contributing to recoverable carbon source accumulation. Overall, 21.38 % of total solid carbon sources were recovered through 8-day fermentation, the carbon extraction was implemented by solid–liquid separation with carbon loss of 14.21–22.91 %, manifesting the valid carbon recovery of 85.05–87.96 mg C/g VSS. Such CE-driven carbon recovery provided negentropy benefits in sustainable cycle economy.

Mechanochemical Pd-Catalyzed Amino- and Oxycarbonylations using FeBr2(CO)4 as a CO Source.

Herein, we describe the development of mechanochemical amino- and oxycarbonylation employing FeBr2(CO)4 as a solid CO source. This Pd/XantPhos-catalyzed reaction affords a range of carboxamides and esters from aryl iodides and various amines or phenols. Both primary and secondary amines, including amino acids, can be employed as N-nucleophiles.

An examination of the carbon metabolic pathways in Acinetobacter sp. TAC-1 in the context of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) utilization

The present study aimed to unravel the carbon metabolism pathway of Acinetobacter sp. TAC-1, a heterotrophic nitrification-aerobic denitrification (HN-AD) strain that utilizes poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) as a carbon source. Sodium acetate was employed as a control to assess the gene expression of carbon metabolic pathways in the TAC-1 strain. The results of genome sequencing demonstrated that the TAC-1 strain possessed various genes encoding carbon metabolic enzymes, such as gltA, icd, sucAB, acs, and pckA. KEGG pathway database analysis further verified the presence of carbon metabolism pathways, including the glycolytic pathway (EMP), pentose phosphate pathway (PPP), glyoxylate cycle (GAC), and tricarboxylic acid (TCA) cycle in the TAC-1 strain. The differential expression of metabolites derived from distinct carbon sources provided further evidence that the carbon metabolism pathway of TAC-1 utilizing PHBV follows the sequential process of PHBV (via the PPP pathway)→gluconate (via the EMP pathway)→acetyl-CoA (entering the TCA cycle)→CO2+H2O (generating electron donors and releasing energy). This study is expected to furnish a theoretical foundation for the advancement and implementation of novel denitrification processes based on HN-AD and solid carbon sources.

On the use of solid 133Ba sources as surrogate for liquid 131I in SPECT/CT calibration: a European multi-centre evaluation

IntroductionCommissioning, calibration, and quality control procedures for nuclear medicine imaging systems are typically performed using hollow containers filled with radionuclide solutions. This leads to multiple sources of uncertainty, many of which can be overcome by using traceable, sealed, long-lived surrogate sources containing a radionuclide of comparable energies and emission probabilities. This study presents the results of a quantitative SPECT/CT imaging comparison exercise performed within the MRTDosimetry consortium to assess the feasibility of using 133Ba as a surrogate for 131I imaging.Materials and methodsTwo sets of four traceable 133Ba sources were produced at two National Metrology Institutes and encapsulated in 3D-printed cylinders (volume range 1.68–107.4 mL). Corresponding hollow cylinders to be filled with liquid 131I and a mounting baseplate for repeatable positioning within a Jaszczak phantom were also produced. A quantitative SPECT/CT imaging comparison exercise was conducted between seven members of the consortium (eight SPECT/CT systems from two major vendors) based on a standardised protocol. Each site had to perform three measurements with the two sets of 133Ba sources and liquid 131I.ResultsAs anticipated, the 131I pseudo-image calibration factors (cps/MBq) were higher than those for 133Ba for all reconstructions and systems. A site-specific cross-calibration reduced the performance differences between both radionuclides with respect to a cross-calibration based on the ratio of emission probabilities from a median of 12–1.5%. The site-specific cross-calibration method also showed agreement between 133Ba and 131I for all cylinder volumes, which highlights the potential use of 133Ba sources to calculate recovery coefficients for partial volume correction.ConclusionThis comparison exercise demonstrated that traceable solid 133Ba sources can be used as surrogate for liquid 131I imaging. The use of solid surrogate sources could solve the radiation protection problem inherent in the preparation of phantoms with 131I liquid activity solutions as well as reduce the measurement uncertainties in the activity. This is particularly relevant for stability measurements, which have to be carried out at regular intervals.

Unveiling vulnerable smart contracts: Toward profiling vulnerable smart contracts using genetic algorithm and generating benchmark dataset

Smart contracts (SCs) are crucial in maintaining trust within blockchain networks. However, existing methods for analyzing SC vulnerabilities often lack accuracy and effectiveness, while approaches based on Deep Neural Networks (DNNs) struggle with detecting complex vulnerabilities due to limited data availability. This paper proposes a novel approach for analyzing SC vulnerabilities. Our method leverages an advanced form of the Genetic Algorithm (GA) and includes the development of a comprehensive benchmark dataset consisting of 36,670 Solidity source code samples. The primary objective of our study is to profile vulnerable SCs effectively. To achieve this goal, we have devised an analyzer called SCsVulLyzer based on GAs, designed explicitly for profiling SCs. Additionally, we have carefully curated a new dataset encompassing a wide range of examples, ensuring the practical validation of our approach. Furthermore, we have established three distinct taxonomies that cover SCs, profiling techniques, and feature extraction. These taxonomies provide a systematic classification and analysis of information, improving the efficiency of our approach. Our methodology underwent rigorous testing through experimentation, and the results demonstrated the superior capabilities of our model in detecting vulnerabilities. Compared to traditional and DNN-based approaches, our approach achieved higher precision, recall, and F1-score, which are widely used metrics for evaluating model performance. Across all these metrics, our model showed exceptional results. The customization and adaptations we implemented within the GA significantly enhanced its effectiveness. Our approach detects SC vulnerabilities more efficiently and facilitates robust exploration. These promising results highlight the potential of GA-based profiling to improve the detection of SC vulnerabilities, contributing to enhanced security in blockchain networks.

Characterization of simultaneous ammonium and nitrate removal and microbial communities in airlift reactor using 3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) as carbon source and biofilm carrier

As a novel trend, solid carbon sources are applied to act as electron donors and biofilm carrier in biological denitrification process. In this study, simultaneous nitrate and ammonium removal process in an airlift sequencing batch reactor using 3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) as carbon source and biofilm carrier under intermittent aeration conditions was established to treat effluent of synthetic marine recirculating aquaculture system. The results showed that maximum nitrate and ammonia nitrogen removal rates of 0.45 and 0.09 kg m−3 d−1 were achieved. No significant nitrite accumulation was found during 200-day operation, while effluent dissolved organic carbon accumulation and particle size reduction significantly increased. Microbial community analysis and batch tests illuminate that the generated sludge and attached biofilm played important roles in nitrogen removal. This study demonstrates the potential mechanism for the nitrogen removal process mediated by 3-hydroxybutyrate-co-3-hydroxyvalerate and provide a new idea for the alternative solutions of solid carbon sources.

Chemical vapor deposition growth of [formula omitted] on Si- and C- face off-axis 4H–SiC at high temperature

Realization of β‐Ga2O3 on a high-thermal-conductivity substrate is crucial to overcome the poor thermal conductivity of β‐Ga2O3 which is one of the major roadblocks against its era in power electronics. We investigated low-pressure chemical vapor deposition (LPCVD) growth on both Si and C- face (0001) 4H–SiC at a high growth temperature of 925 °C using Ga metal and O2 gas source. Growths on C-face 4H–SiC resulted polycrystalline β‐Ga2O3 for the entire O2-flow range, whereas under optimized O2-flow conditions, step flow growth of (−201) β‐Ga2O3 was achieved on Si-face 4H–SiC with 3.7 nm rms surface roughness and rocking curve FWHM of 0.54° at a growth rate reaching 2.48 μm/h 4° off-axis nature of the substrate promoted the growth of some of the in-plane rotational domains while suppressing others. Raman measurements further verified the pure β‐Ga2O3 nature of the grown films. Using a customized LPCVD with solid source Ga, a cost-effective, safe and industrially scalable method was shown to pave the way to enable β‐Ga2O3 heteroepitaxy on 4H–SiC for high-power electronics.

One‐Pot Synthesis of Substituted Benzoxazoles Using Aminophenols and α‐Diazoesters via Annulation of Amide Intermediate Using Co2(CO)8 as a Solid Carbonyl Source

AbstractSynthesis of benzoxazoles via amide formation from amino phenols and α‐diazoesters using dicobalt octacarbonyl as a solid CO source is reported. Our methodology provides a strategy for synthesizing substituted benzoxazoles with methylene linker between the benzoxazole and aromatic ring systems. Substrates with different substituents were employed to produce corresponding benzoxazoles. The synthesized compounds were characterized by using standard spectroscopic and analytical techniques including single crystal XRD studies.

Joint measurement of electron density, temperature, and emission spectrum of Nd:YAG laser-produced tin plasma

We present the results of joint measurements of electron density (ne), temperature (Te), and emission spectra of an Nd:YAG-driven tin plasma. Collective Thomson scattering provides space- and time-resolved ne and Te data during drive laser irradiation, and extreme ultraviolet (EUV) emission spectra, which is space-resolved in the target normal, are measured using a flat-field grazing incidence spectrometer (GIS). As the distance from the target increased, the emission intensity quickly decreases, and the peaks of the spectra gradually shift to longer wavelengths. This can be explained by the rapid decrease in ne, and thus, self-absorption, with an increase in distance. We obtain the EUV spectra by calculating the transfer of photons along the line-of-sight of the GIS, using theoretical emissivity and opacity, and applying the measured spatial distribution of ne and Te. The results quantitatively demonstrate that the self-absorption effect is significant; the emission from the core regions is mostly reabsorbed by the surrounding plasma. The calculated spectra are compared with the measured spectra. While good agreement is achieved in the spectral region of 13.3 and 15.3 nm, considerable differences are found in the 12.5–13 and 15.5–17.5 nm region. The results demonstrate the significance of this joint measurement for further validation of the atomic process model considering self-absorption effect, which is critical for the future high-density, solid laser-driven EUV source.

Targeted synergy of cation exchange-driven extracellular carbon release and lysozyme-catalyzed intracellular carbon release for maximizing carbon source recovery from waste activated sludge

Short-chain fatty acids as superior carbon recovery from waste activated sludge have received rising attentions. This study quantified contributions of cation exchange (CE) and lysozyme on the targeted carbon source migration. The innovative targeted pattern for extracellular and intracellular carbon source release was proposed. The 1-day synergetic treatment at optimal CE resin dosage of 1.75 g/g SS and lysozyme dosage of 10 % drove considerable carbon source release and particulate carbon source solubilization, which occupied 35.31 % of total sludge solid carbon sources. The CE dominantly contributed to extracellular polymeric substances disruption and extracellular carbon source release, with the percentage of 39.47–48.13 %. In this case, The Lyso was the strongest contributor to microbial cell lysis and intracellular carbon source release, with the proportions of 49.53–75.76 %. Subsequently, approximately 56.54–58.49 % of the originally dissolved carbon sources (mostly proteins and carbohydrates) were bio-degraded into micromolecular carbon sources with high bioavailability in a short-term anaerobic fermentation (2 days). Correspondingly, satisfactory carbon recovery rate of 23.06 % was obtained, which was 7.30 times higher than the control. The synergy of CE and lysozyme greatly improved kinetic speeds and performances of endogenous carbon source migration and recovery. Such synergetic treatment of CE and lysozyme not only provided novel insights into carbon fate in anaerobic fermentation, but also achieved remarkable carbon source release and recovery benefits with economic incomes of 190.8–283.4 CNY/ton sludge.

Influencing factors and controlled release kinetics of H2O2 from PVP-coated calcium peroxide NPs for groundwater remediation

Calcium peroxide nanoparticles (nCP) as a versatile and safe solid source of hydrogen peroxide (H2O2) receive substantial attention from researchers as a potential groundwater remediation reagent. In this study, we synthesized polyvinylpyrrolidone-coated calcium peroxide nanoparticles (PVP@nCP-PVP) to control the release rate of H2O2 and modulate pH fluctuation simultaneously. The PVP@nCP-PVP is fully characterized and the H2O2 releasing kinetics and mechanisms are investigated. The H2O2 release longevity of nCP increased with the concentration of controlled release material (CRM) encapsulated shell, while the production of H2O2 decreased inversely. The acidic condition is favorable for increasing H2O2 production by promoting the complex decomposition of nCP. The low temperature prolonged the longevity of nCP and suppressed the competitive side reaction for producing O2. The release of H2O2 is consistent with zero-order reaction kinetics and the release of O2 is consistent with first-order reaction kinetics. At last, different nCP composites were employed to construct a Fenton-like system for the degradation of nitrobenzene (NB). The degradation rate was raised from 57.6% by Fe (II)/nCP to 70.0% and 93.7% by Fe (II)/nCP-PVP and Fe (II)/PVP@nCP-PVP systems, respectively. These findings demonstrate that PVP@nCP-PVP has significant advantages in repairing organically contaminated groundwater. Environmental implicationGroundwater contamination poses a great threat to human health and ecosystems. In-situ chemical oxidation (ISCO) is a widely used groundwater remediation technology. Calcium peroxide (CP) as solid hydrogen peroxide showed merits of low cost and high stability, but the further application was limited due to its violent chemical reaction and short longivity in groundwater . In this work, we prepared polyvinylpyrrolidone-coated controlled release nCP (PVP@nCP-PVP) for modulating the release of H2O2. The investigation of H2O2 release kinetics under various environmental conditions enhances the understanding of the inherent relationship between the H2O2 release performance of controlled-release materials and contamination remediation. The feasibility using macromolecules preparing controlled-release oxidizing agents was confirmed, providing a novel solution for groundwater contamination remediation.

Development of a multifunctional real-time data processing system for interferometers on EAST

In the latest campaign of EAST experiments, two new interferometers were installed, a dispersion interferometer (DI) based on a Carbon Dioxide laser and a solid source interferometer (SSI) based on microwave multiplier sources. To make them available for the Plasma Control System (PCS) system, each of them needs to be provided with a real-time processing system to extract the detector output signal and afterward obtain the electron density information through signal processing. To obtain interferometer data quickly and reliably, a unified hardware template was applied to both interferometers. Three main parts are included in this hardware template — digitization, digital signal processing, and output modules. In particular, the digitization section uses a multi-channel Analog-to-Digital Convertor (ADC) to acquire the signals that need to be calculated. The digital signal processing part is implemented by an FPGA, which is the hardware basis of this multifunctional template that can be used for multiple interferometers. This section includes two main parts, wrapped density signal extraction and signal unwrapping. For DI it is a phase calculation based on the intensity ratio, while for SSI it is a phase calculation by means of FFT or phase demodulation. Both computational approaches form independent IP cores to build systems quickly, while these IP cores provide parameter interfaces to adapt to different application scenarios. The output module provides a variety of data transmission methods, including fiber optic transmission and Digital-Analog-Convertor (DAC) based analog transmission, to interface with PCS or other subsequent systems.This data processing system template has been applied to each of the above two interferometers and valid data were obtained in a recent EAST experiment campaign. It demonstrates the usefulness of the template and provides a reference for the design of data processing systems on future devices.

Complexity of graphite formation in response to metamorphic methane generation and transformation in an orogenic ultramafic body

The fate of carbon in subduction is explored by considering fluid-rock interactions in a body of metamorphosed ultramafic rocks from the Appalachian belt as potential proxies for metasomatism and carbon recycling (e.g., infiltration, solution, precipitation) in the mantle wedge at convergent margins. Ultramafic rocks may record intense redox variations affecting the exchanges between solid and fluid carbon-bearing phases. The Belvidere Mountain Complex (BMC) in Vermont, USA is an ultramafic body that underwent Ordovician Taconic subduction metamorphism up to 510–520 °C and 0.9–1.3 GPa. Previous investigations indicate that the BMC experienced partial serpentinization and carbon recycling in the subduction zone. Here bulk δ11B, 87Sr/86Sr and δ13C, data, in-situ microRaman spectroscopy and bulk δ13CCH4 and δ2HCH4 on fluid inclusions, and numerical modeling results aim to constrain the origin and formation mechanisms of carbon-bearing solid and fluid phases in the BMC. Bulk 87Sr/86Sr ratios and δ11B of the BMC rocks suggest infiltration of metasediment-derived fluids inside the mafic/ultramafic body. Carbonates present in the studied ultramafic and mafic rocks have δ13C values ranging from −7.26 to −1.27 ‰. This range was found to record progressive reduction of an initial isotopically light carbonate to methane under reducing conditions. MicroRaman spectroscopy on fluid inclusions confirms CH4-rich gaseous compositions, along with N2, NH3, and S-H compounds, which support a metasedimentary origin for the fluid infiltrating the BMC. Methane-rich fluid inclusions were observed in partially serpentinized peridotites, in carbonate veins, and in amphibolite bodies associated with the ultramafic body, and as well in the surrounding metasedimentary rock units. The δ13C and δ2H of methane in fluid inclusions show a wide range of values in ultramafic rocks from −45.2 ‰ to −12.6 ‰ for carbon and −226 ‰ to −140 ‰ for hydrogen. The methane stable isotope data suggest the presence of two types of methane preserved in studied samples, formed by high-temperature thermogenic processes of metamorphosed graphitic carbon and by abiotic conversion of more oxidized carbon bearing species in the presence of H2-rich fluids produced during metamorphic serpentinization. The BMC also hosts a remarkable example of graphite deposit, with up to 3.90 wt% graphite, along a ∼ 6 m-thick zone within the serpentinized ultramafic body and along lithologic contacts. The δ13C composition of the graphite clusters at −15 ‰ (VPBD), which is consistent with the composition of graphite precipitating from the mixing of the two types of methane-bearing fluids identified in fluid inclusions. The mixing between metasediment-derived and serpentinization-related methane-rich fluids is proposed as the mechanism leading to graphite precipitation. Further complexity is suggested by carbonate reduction evidenced in the samples, which may have locally contributed to the formation of graphite on the precursor carbonate domains. The BMC rocks highlight the variability of carbon recycling processes, including carbon mobilization from multiple solid sources, and mixing of multiple carbon-bearing fluids in a dynamic fluid-rock system, with carbon mobilization and sink adapting to evolving redox conditions.

Zeolite enhanced iron-modified biocarrier drives Fe(II)/Fe(III) cycle to achieve nitrogen removal from eutrophic water

The problem of nitrogen removal in eutrophic water needs to be solved. Two new autotrophic nitrogen removal technologies, ammonia oxidation coupled with Fe(III) reduction (Feammox) and Nitrate-dependent Fe(II) oxidation (NDFO), have been shown to have the potential to treat eutrophic water. However, the continuous addition of iron sources not only costs more, but also leads to sludge mineralization. In this study, nano-sized iron powder was loaded on the surface of K3 filler as a solid iron source for the extracellular metabolism of iron-trophic bacteria. At the same time, due to the high selective adsorption of zeolite for ammonia can improve the low nitrogen metabolism rate caused by low nitrogen concentrations in eutrophic water, three kinds of modified functional biological carriers were prepared by mixing zeolite powder and iron powder in different proportions (Z1, Zeolite:iron = 1; Z2, Zeolite:iron = 2; Z3, Zeolite:iron = 3). Z3 exhibited the best performance, with removal efficiencies of 54.8% for total nitrogen during 70 days of cultivation. The chemical structure and state of iron compounds changed under microorganism activity. The ex-situ test detected high NDFO and Feammox activities, with values of 1.02 ± 0.23 and 0.16 ± 0.04 mgN/gVSS/h. The enrichment of NDFO bacteria (Gallionellaceae, 0.73%-1.43%–0.74%) and Feammox bacteria (Alicycliphilus, 1.51%-0.88%–2.30%) indicated that collaboration between various functional microorganisms led to autotrophic nitrogen removal. Hence, zeolite/iron-modified biocarrier could drive the Fe(II)/Fe(III) cycle to remove nitrogen autotrophically from eutrophic water without carbon and Fe resource addition.

Phosphorus mobilization in sulfidic sediments in the Baltic Sea

It is well-known that the geochemical behavior of phosphorus (P) in sediments is closely related to that of Fe and Mn, but their relations remain unclear in long-term sulfidic sediments such as those of the Gotland Basin in the Baltic Sea. Therefore, P mobilization in these sediments at both shallow and deep sites was investigated in relation to that of Fe, Mn, and S. To achieve that aim, classic sediment slicing and subsequent solid phase sequential extraction were combined with in situ DGT (Diffusive Gradients in Thin-films) sampling, DIFS (DGT induced flux in sediments) modelling, and Visual MINTEQ calculations. Correlations between total dissolved and labile dissolved concentrations of P, Mn, and Fe in porewater, and the associations between labile fractions of these elements in the solid phase suggested two kinds of sources for P: The dissolution of P-bearing Fe oxides and/or Mn carbonates was observed in the shallower sites, while P and Mn release from different solid sources was observed in the deepest sites. Although the formation of Fe sulfides leads to extremely low dissolved Fe level in porewater, the simultaneous release of P with Mn/Fe was confirmed by theoretical calculations with Visual MINTEQ. The DIFS model showed that the resupply ability of P from sediment solids is determined by labile pool size. The application of experimental and theoretical methods made it possible to clarify the relationships between P, Fe, Mn and S in sulfidic sediments which may contribute to a better understanding of the P cycle in other sulfidic regions.

Armor for Steel: Facile Synthesis of Hexagonal Boron Nitride Films on Various Substrates

AbstractWhile hexagonal boron nitride (hBN) has been widely used as a buffer or encapsulation layer for emerging electronic devices, interest in utilizing it for large‐area chemical barrier coating has somewhat faded. A chemical vapor deposition process is reported here for the conformal growth of hBN on large surfaces of various alloys and steels, regardless of their complex shapes. In contrast to the previously reported very limited protection by hBN against corrosion and oxidation, protection of steels against 10% HCl and oxidation resistance at 850 °C in air is demonstrated. Furthermore, an order of magnitude reduction in the friction coefficient of the hBN coated steels is shown. The growth mechanism is revealed in experiments on thin metal films, where the tunable growth of single‐crystal hBN with a selected number of layers is demonstrated. The key distinction of the process is the use of N2 gas, which gets activated exclusively on the catalyst's surface and eliminates adverse gas‐phase reactions. This rate‐limiting step allowed independent control of activated nitrogen along with boron coming from a solid source (like elemental boron). Using abundant and benign precursors, this approach can be readily adopted for large‐scale hBN synthesis in applications where cost, production volume, and process safety are essential.