Mixture Atmosphere Research Articles

Study on the Production Mechanism of Fluorescent Species and Its Application to White LED of NH4-Form Y-Type Zeolite

Introduction Zeolites are aluminosilicates in which all vertices of SiO4 and AlO4 tetrahedra (TO4) are shared to build a three-dimensional framework and are classified on the basis of the framework structure. Assuming that SiO4 4− in neutral SiO2 is partially replaced with AlO4 5−, the zeolite framework becomes negatively charged by the same amount of Al3+. Various cations can be introduced into the framework cages to compensate for this negative charge. The charge-compensating cation is primarily an alkali metal ion such as Na+ or K+. This cation can be easily ion-exchanged for other monovalent and polyvalent cations. Zeolites are ideal host materials because they can easily give fluorescent light by introducing luminescent centers as charge-compensating cations and are composed only of ubiquitous elements. Hayashi et al., reported that NH4-form Y-type zeolite exhibited intense fluorescence upon calcination in air atmosphere without any addition of dopants. In their study, the following fluorescence mechanism was proposed: On the halfway conversion to the H-form by heating, NH4-form zeolite was decomposed to produce oxygen vacancies. Then new excited levels appeared leading to fluorescence. This zeolite phosphor does not contain any main transition-metal nor rare-earth elements and produces bright white emission, so it will become an ecological and economical fluorescent material. In this study, the dependence of the fluorescence properties of NH4-form Y-type zeolites on calcination atmosphere and temperature was investigated and the production mechanism of fluorescent species was elucidated from detailed analyses of the calcination samples. White LEDs were fabricated from the most fluorescent samples. It is demonstrated that they can be applied practical white phosphors without rare-earth nor main transition-metal elements.Experimental The thermal properties of a commercially available NH4-form Y-type zeolite (Sigma-Aldrich, ammonium Y zeolite) underwent thermogravimetric/differential thermal analysis under air, oxygen, nitrogen, and 4% hydrogen/nitrogen mixture atmospheres at a flow rate of 150 mL/min or in vacuo at approximately 27 Pa using a rotary pump. From the TG curves, 130, 230, 280, 350, 460, 500, and 600 °C were selected as the calcination temperatures. The zeolite was calcined for 2 h at these temperatures under the above-mentioned atmospheres in a tubular furnace. The following measurements were performed on the calcined zeolite samples; X-ray diffraction (XRD), fluorescence, ultraviolet-visual (UV-Vis) absorption, electron spin resonance (ESR), Fourier transform infrared (FT-IR) absorption, and 29Si and 27Al magic-angle spin nuclear magnetic resonance (MAS-NMR) by solid state. The phosphors with the most fluorescence intensities were mixed with silicone rubber sealant in 2:1 mass ratio and were applied to a near-ultraviolet (405 nm) LED. The coated LED was then heated at 80 ºC overnight for curing. This process was repeated three times to fabricate the white LED. These LED were driven at 3.0 V, 16 mA by a stabilized power supply and illuminance and emission spectrum were measured.Results and discussion The fluorescence intensity was higher when the zeolite was calcined at 350 °C for 2 h in nitrogen atmosphere than in other atmospheres. In atmospheres containing oxygen, quenching was observed at the higher temperatures. These results indicate that calcination caused oxygen vacancies under every atmosphere which brought fluorescence properties. The spectra of ESR showed two signals corresponding to the E'-center and the non-bridging oxygen hole center (NBOHC) which were generated by the collapse of the SiO4 tetrahedron. In FT-IR spectra, the absorptions assigned to Si–O vibration decreased in the fluorescent samples. Figure shows the production mechanism of the fluorescent species. The oxygen vacancy on the SiO4 tetrahedron created SiO3 and/or SiO2 radicals and brought the zeolites to generate fluorescence. The white LED constructed with the zeolite phosphors. Driving this LED with a regulated power source could obtain illumination with color temperature of 7500 K and the tristimulus values determined xy chromaticity coordinates parameters to x = 0.272 and y = 0.341. It will be a guidelines to be able to produce a practical white phosphor that does not contain rare-earth nor transition-metal elements. Figure 1

A quantitative classification method of land uses and assessment of per-and poly-fluoroalkyl substances (PFAS) occurrence in freshwater environments

We developed a quantitative method for classifying land uses for PFAS-related investigations in freshwater environments and determined PFAS ambient concentrations associated with specific land-use classes. Furthermore, our study presents a comprehensive assessment of the ambient occurrence and risks of PFAS mixtures beyond the usually studied PFOS-PFOA mixtures. Eighty-five inland (freshwater only) sites were sampled for water, sediment, and riparian soil in Victoria, south-east Australia, and analyzed for 33 PFAS. PFAS were detected in 91% of water samples, 34% of sediment samples, and 28% of riparian soil samples. Four land-use classes were defined: remote, agricultural, mixed, and urban. In the remote land-use class, only PFOS was detected at a low ambient concentration (0.0002 μg/L) in one water sample. Short-chain PFCA were frequently detected in the agricultural and mixed water samples. PFBA had the highest median ambient concentration in both land uses (ca. 0.01 μg/L), contributing to both ΣPFAS (40%) and ΣPFCA (50%) concentrations. In the urban land-use class, several congeners (PFBA, PFPeA, PFHxA, PFOA, PFHxS, and PFOS) had median ambient concentrations at or close to 0.01 μg/L and contributed similarly to ΣPFAS (10–20%). Elevated risk to the aquatic environment was found only for PFOS in two mixed and eight urban sites. This pattern was consistent with the finding for PFAS mixtures, where the elevated risk was driven by PFOS at those same sites. Our study provides critical information about environmentally relevant ambient concentrations and PFAS mixtures. This information, together with the land-use classification approach presented herein, can be used as reference levels for several critical purposes, including identifying PFAS-contaminated sites, informing land use planning and development decisions, setting standards and guidelines, and tracking changes over time.

Ambient Air Pollutant Mixture, Sleep Pattern, and Incident CKD: Results from a Prospective Cohort Study

Ambient Air Pollutant Mixture, Sleep Pattern, and Incident CKD: Results from a Prospective Cohort Study

Prenatal Ambient Air Pollutant and Climatic Factors Mixture Exposure and Fetal Growth

Prenatal Ambient Air Pollutant and Climatic Factors Mixture Exposure and Fetal Growth

Study on partial oxidation phenomena of post-injection fuel in diesel engines

In diesel engines, post fuel is injected in the expansion stroke, oxidized by the diesel oxidation catalysts and the high temperature gas re-generates the diesel particulate filters. However, it is empirically known that the post fuel at advanced injection timing is partially oxidized in the cylinder due to the high temperature-pressure conditions and it is a cause of the reduction of fuel consumption. The purpose of this research is to analyze post-injection fuel behaviors in cylinder and investigate the optimum fuel injections that maximize the unburnt hydrocarbons to the diesel oxidation catalysts. The engine employed in this research is a turbo charged 2.0 L four-cylinder DI diesel engine with two fuel injection systems to change the heterogeneity of air-fuel mixture and temperature distributions in cylinder; n-hexane is injected in the intake manifold to produce the homogeneous air-fuel mixture and diesel fuel is directly injected into the cylinder. The partial oxidation ratio of post fuel and the fuel loss mainly by fuel adhesion was calculated by injected fuel quantity, air quantity, and emission data. The 3D-CFD software was introduced to analyze the partial oxidation of post fuel and flow in the cylinder. The heterogeneity of burned gas mixture of post injection atmosphere and the post-injection timings were the parameters of engine tests and 3D-CFD simulations. The results suggest that the heterogeneity of equivalence ratio and the non-uniformity of gas temperature inside the cylinder at the start of post injection affect the partial oxidation of post-injection fuel. The more homogeneous these conditions are, the better the suppression of partial oxidation of post-injection fuel and the avoidance of fuel adhesion to the cylinder wall can be achieved.

Fabrication and Tribological Properties of Diamond-like Carbon Film with Cr Doping by High-Power Impulse Magnetron Sputtering

The present study aims to investigate the advantages of diamond-like carbon (DLC) films in reducing friction and lubrication to address issues such as the low surface hardness, high friction coefficients, and poor wear resistance of titanium alloys. Cr-doped DLC films were deposited by high-power impulse magnetron sputtering (HiPIMS) in an atmosphere of a gas mixture of Ar and C2H2. The energy of the deposited particles was controlled by adjusting the target powers, and four sets of film samples with different powers (4 kW, 8 kW, 12 kW, and 16 kW) were fabricated. The results showed that with an increase in target power, the Cr content increased from 3.73 at. % to 22.65 at. %; meanwhile, the microstructure of the film evolved from an amorphous feature to a nanocomposite structure, with carbide embedded in an amorphous carbon matrix. The sp2-C bond content was also increased in films, suggesting an intensification of the film’s graphitization. The hardness of films exhibited a trend of initially increasing and then decreasing, reaching the maximum value at 12 kW. The friction coefficient and wear rate of films showed a reverse trend compared to hardness variation, namely initially decreasing and then increasing. The friction coefficient reached a minimum value of 0.14, and the wear rate was 2.50 × 10−7 (mm3)/(N·m), at 8 kW. The abrasive wear was the primary wear mechanism for films deposited at a higher target power. Therefore, by adjusting the target power parameter, it is possible to control the content of the metal and sp2/sp3 bonds in metal-doped DLC films, thereby regulating the mechanical and tribological properties of the films and providing an effective approach for addressing surface issues in titanium alloys.

Stabilizing magnetic order of cobalt-based anisotropic nanoparticles prepared using NaBH4 as a reducing agent

A one-pot chemical method was used to prepare cobalt nanoparticles (Co NPs) by employing sodium borohydride (NaBH4) as a reducing agent, as well as graphite and activated carbon as stabilizer materials. The resulting NPs were characterized by XRD, FE-SEM, EDX mapping and VSM measurements before and after annealing under a mixture of argon and hydrogen atmosphere at 600 ℃, in order to study their structural, morphological, and magnetic properties. This study focused on the shape and size of Co NPs, involving the formation of Co and Co3O4 phases with the effect of oxygen as the main factor that can significantly contribute to the magnetic anisotropy. Co NPs exhibited a high saturation magnetization (Ms) value after performing the annealing process, achieving Ms> 99 emu/g when using the graphite stabilizer. The results indicate that surface atoms play a significant role in the modification of magnetic characteristics of Co NPs.

Experimental and simulation studies of degraded EPDM composite in the coupled gamma radiation-thermal environments

The degradation behaviors, mechanisms and compatibility are not well understood and hard to be harnessed for EPDM composite in the coupled gamma radiation-thermal environments. This contribution performs a thorough study accordingly with 0 ∼ 200 kGy dose under temperatures varying from room temperature to 90 °C in N2/O2 mixture atmosphere. Radiation-thermal aging leads to annealing effect and chemi-crystallization that rebuilds the semi-crystalline structure and invokes competitive filler migration, reconfiguration and loss. Crosslinking reactions prevail the scission during the investigated conditions. However, the surface oxidation and damage are not severe. In-situ nondestructive gas-phase FTIR sensitively find the formed various gaseous products, whose generation kinetics behaviors are temperature and dose dependent. Most surprisingly, the radiolysis caused carbonyl sulfide and carbon disulfide are discovered with indispensable gamma radiation, which manifest temperature reined conversion thermodynamics and kinetics behavior. The qualitative and quantitative analysis of gas products is also validated by GC and GC-MS tests. The evolved semi-crystalline structure, macromolecular chain network and filler network significantly impact the mechanical property, but the barrier property and hydrophobic property are slightly influenced. The inverse temperature effect occurred at 50 °C for the mechanical properties, which show abnormal rejuvenation behavior due to the counteraction between aging induced change in molecular structure, aggregation structure and filler reconfiguration, migration and loss. The multiscale structure-property-behavior relationships possess good interdependency, indicating the main aging mechanism and failure mode are almost invariant. By ReaxFF simulation, the complex degradation mechanism for EPDM composite at atomic scale is revealed for the first time.

Unravelling the oxidation behaviors of porous stainless steel 430L substrate for metal-supported solid oxide fuel cells

Metal-supported solid oxide fuel cell (MS-SOFC) has been attracting increasing attention due to relatively low materials cost and robust mechanic strength particularly for mobile applications. However, long term stability has been an issue for its application. It is challenging to isolate the degradation behavior and predict maximum lifetime of the metal substrate when assembled as full cell since many parameters may affect cell performance and life expectancy. We systematically investigated and reported the long-term oxidation behavior of porous stainless steel 430 L for up to 1500 h at 800°C under dry and 3 vol% H2O humidified H2/Ar mixture (10 vol% H2) atmosphere to simulate its applications in MS-SOFC. Our results show that the surface oxide scale of the porous 430Lsubstrate in both atmospheres are dominated by Cr2O3 and small amounts of MnCr2O4 or FeCr2O4 spinel oxides depending on the gas conditions, where the oxidation process could be divided into three stages with distinct characteristics. Stepwise surface color change, morphology and thickness of the formed oxide scale, elemental migration and distribution along the bulk alloy/oxide scale interface, and oxidation kinetics as a function of exposure time are systematically and thoroughly studied at high resolution. Based on the measured weight gains and thicknesses, oxidation kinetic parameters are extracted. These kinetic parameters are not only valuable for understanding the oxidation rate of porous 430 L in high temperature applications such as in MS-SOFC, but also can be used to predict the life expectancy of 430 L supported SOFC device which is critical for real and long-term applications.

Metabolomics signatures of air pollution mixtures and lung cancer risk: A large-scale metabolome-wide association study in the Cancer Prevention Study cohorts.

10571 Background: Despite the well-established link between air pollution exposure and lung carcinogenesis, the underlying mechanism remains underexplored. While metabolomics has provided valuable molecular insights, existing air pollution metabolomics studies only assess biological changes to single air pollutants, without examining the join effects of air pollutant mixtures. We sought to identify metabolic signatures mediating the association between ambient air pollution mixtures and lung cancer risk. Methods: A total of 603 matched lung cancer case-control pairs were selected from the Cancer Prevention Study cohorts. Controls were matched to cases on age at blood draw, sex, race/ethnicity, and blood draw date. Plasma metabolomics was conducted using ultrahigh-performance liquid chromatography-tandem mass spectrometry. Air pollution mixtures include carbon monoxide, nitrogen dioxide, particulate matter, sulfur dioxide, and ozone, matched to subjects’ residential address at blood draw. We conducted an untargeted metabolome-wide association study with multivariable-adjusted linear and conditional logistic regression models to assess associations between metabolites and individual air pollutants and lung cancer risk, respectively, adjusting for individual and lifestyle-related covariates. We used a meet-in-the-middle (MITM) approach to identify potential mediators. Quantile g-computation was used to examine the effects of air pollution mixtures on metabolome perturbations to analyze the collective effects of multiple air pollutants concurrently. Results: Among 1,138 extracted metabolic features, 162 were significantly associated with the combined mixture (false discovery rate < 0.2). Using MITM, no metabolites were associated with both air pollution mixture and lung cancer risk at FDR < 0.2. At raw p < 0.05, 16 metabolites were identified as potential mediators of the air pollution mixture and lung cancer risk. These metabolites, including 4-hydroxyphenylacetylglutamine, glutamate, and 3-aminoisobutyrate, were also significantly associated with the mixture at FDR < 0.2. Conclusions: Findings from this analysis demonstrate the feasibility of considering multiple air pollutants as mixtures when conducting air pollution-related metabolomics investigations. Future exploration of the underlying biological mechanisms will be critical for validating pathways that participate in air pollution carcinogenicity. As lung cancer cases in never smokers continue to increase, it is pertinent to study air pollution and other environmental risk factors on cancer incidence.

Association of ambient air pollutant mixtures with IVF/ICSI-ET clinical pregnancy rates during critical exposure periods

Abstract STUDY QUESTION Does exposure to a mixture of ambient air pollutants during specific exposure periods influence clinical pregnancy rates in women undergoing IVF/ICSI-embryo transfer (ET) cycles? SUMMARY ANSWER The specific exposure period from ET to the serum hCG test was identified as a critical exposure window as exposure to sulfur dioxide (SO2) or a combination of air pollutants was associated with a decreased likelihood of clinical pregnancy. WHAT IS KNOWN ALREADY Exposure to a single pollutant may impact pregnancy outcomes in women undergoing ART. However, in daily life, individuals often encounter mixed pollution, and limited research exists on the effects of mixed air pollutants and the specific exposure periods. STUDY DESIGN, SIZE, DURATION This retrospective cohort study involved infertile patients who underwent their initial IVF/ICSI-ET cycle at an assisted reproduction center between January 2020 and January 2023. Exclusions were applied for patients meeting specific criteria, such as no fresh ET, incomplete clinical and address information, residency outside the 17 cities in the Sichuan Basin, age over 45 years, use of donor semen, thin endometrium (<8 mm) and infertility factors unrelated to tubal or ovulation issues. In total, 5208 individuals were included in the study. PARTICIPANTS/MATERIALS, SETTING, METHODS Daily average levels of six air pollutants (fine particulate matter (PM2.5), inhalable particulate matter (PM10), SO2, nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3)) were acquired from air quality monitoring stations. The cumulative average levels of various pollutants were determined using the inverse distance weighting (IDW) method across four distinct exposure periods (Period 1: 90 days before oocyte retrieval; Period 2: oocyte retrieval to ET; Period 3: ET to serum hCG test; Period 4: 90 days before oocyte retrieval to serum hCG test). Single-pollutant logistic regression, two-pollutant logistic regression, Quantile g-computation (QG-C) regression, and Bayesian kernel machine regression (BKMR) were employed to evaluate the influence of pollutants on clinical pregnancy rates. Stratified analyses were executed to discern potentially vulnerable populations. MAIN RESULTS AND THE ROLE OF CHANCE The clinical pregnancy rate for participants during the study period was 54.53%. Single-pollutant logistic models indicated that for PM2.5 during specific exposure Period 1 (adjusted odds ratio [aOR] = 0.83, 95% CI: 0.70–0.99) and specific exposure Period 4 (aOR = 0.83, 95% CI: 0.69–0.98), and SO2 in specific exposure Period 3 (aOR = 0.92, 95% CI: 0.86–0.99), each interquartile range (IQR) increment exhibited an association with a decreased probability of clinical pregnancy. Consistent results were observed with dual air pollution models. In the multi-pollution analysis, QG-C indicated a 12% reduction in clinical pregnancy rates per IQR increment of mixed pollutants during specific exposure Period 3 (aOR = 0.89, 95% CI: 0.79–0.99). Among these pollutants, SO2 (33.40%) and NO2 (33.40%) contributed the most to the negative effects. The results from BKMR and QG-C were consistent. Stratified analysis revealed increased susceptibility to ambient air pollution among individuals who underwent transfer of two embryos, those with BMI ≥ 24 kg/m2 and those under 35 years old. LIMITATIONS, REASONS FOR CAUTION Caution was advised in interpreting the results due to the retrospective nature of the study, which was prone to selection bias from non-random sampling. Smoking and alcohol, known confounding factors in IVF/ICSI-ET, were not accounted for. Only successful cycles that reached the hCG test were included, excluding a few patients who did not reach the ET stage. While IDW was used to estimate pollutant concentrations at residential addresses, data on participants’ work locations and activity patterns were not collected, potentially affecting the accuracy of exposure prediction. WIDER IMPLICATIONS OF THE FINDINGS Exposure to a mixture of pollutants, spanning from ET to the serum hCG test (Period 3), appeared to be correlated with a diminished probability of achieving clinical pregnancy. This association suggested a potential impact of mixed pollutants on the interaction between embryos and the endometrium, as well as embryo implantation during this critical stage, potentially contributing to clinical pregnancy failure. This underscored the importance of providing women undergoing ART with comprehensive information to comprehend the potential environmental influences and motivating them to adopt suitable protective measures when feasible, thereby mitigating potential adverse effects of contaminants on reproductive health. STUDY FUNDING/COMPETING INTEREST(S) This work received support from the National Key Research and Development Program of China (No. 2023YFC2705900), the National Natural Science Foundation of China (Nos. 82171664, 81971391, 82171668), the Natural Science Foundation of Chongqing Municipality of China (Nos. CSTB2022NSCQ-LZX0062, CSTB2023TIAD-KPX0052) and the Foundation of State Key Laboratory of Ultrasound in Medicine and Engineering (No. 2021KFKT013). The authors report no conflicts of interest. TRIAL REGISTRATION NUMBER N/A.

Additive Water Uptake of the Mixtures of Urban Atmospheric HULIS and Ammonium Sulfate

AbstractThe hygroscopicity of atmospheric aerosols affect the global climate and human health. However, the hygroscopic behavior of mixtures of inorganic salts and organics in atmospheric aerosols have not been well characterized for ambient complex organic mixtures. Here, the hygroscopic growth of humic‐like substances (HULIS), which represent the complexity of organic aerosol compounds, from urban aerosols and their mixtures with ammonium sulfate were investigated with measurements from a hygroscopicity tandem differential mobility analyzer and model analyses. The Zdanovskii–Stokes–Robinson (ZSR) relationship, which assumes that the water uptake of each component is additive, was examined for the mixtures. The dependence of the hygroscopicity parameters (κ) of the mixtures on the volume fraction of HULIS is generally represented by the ZSR relationship with the deviations of κ on average of 16% (4%–27% in different mixing ratios), and 0.03 (0.02–0.04) on absolute basis. An assumption of asphericity for the dry particles reduced the deviations (14%). Approximations for the surface tension depression by surfactants and surface‐bulk partitioning were predicted to account for the deviations to a small extent. Furthermore, a thermodynamic model for simplified compound systems showed that the non‐ideality of the solutions potentially explained the deviations from the ZSR relationship. The results of this study support the use of the ZSR relationship for organic‒inorganic mixtures as a practical approximation in atmospheric models, provide a guide for the uncertainty associated with this approximation, and suggest directions for future studies.

Effects of ignition methods and control parameters on the lean combustion performance and flame geometry of jet ignition based on constant-volume combustion chamber

Pre-chamber jet ignition provides one of the most reliable thermal efficiency improvement technologies for future gasoline engines, especially hybrid gasoline engines. The effects of jet ignition control parameters on the jet flame morphology and combustion characteristics are still unclear, for example, the fuel injection mass in the pre-chamber and the time interval between low-flow injection and ignition. The paper explored the effects of jet ignition stoichiometric and lean combustion performance on the flame propagation process of high-energy spark ignition, passive and active pre-chamber, using direct flame imaging in a constant-volume combustion chamber. The jet ignition performance under lean combustion conditions is further enhanced by optimizing the jet ignition control parameters. Based on the luminance characterization of the image, the active pre-chamber with additional low-flow injection can provide 281% of the ignition intensity equivalent to high-energy spark plug ignition. Increasing the fuel injection mass in the pre-chamber can improve heat release and enhance ignition performance. However, the jet ignition performance will drop sharply due to the too-rich pre-chamber gas mixture. Extending the mixing time interval after ignition will enrich the lean ambient mixture outside the pre-chamber and increase the ignition performance. Over-mixing will occur if the mixing time interval is too long, especially under a few injected fuel mass situations. The radial stretch coefficient of the jet flame is defined to characterize the flame geometry during the jet flame propagation process. The jet ignition performance reaches its best when the jet flame propagates at high speed in both radial and circumferential directions, namely a wide jet flame.

Effect of gas atmospheres and SiO2 content on preparation and properties of SiO2–Si3N4 composite ceramics via nitridation of diamond-wire saw silicon waste powder

Composite ceramics are applied widely nowadays by combining superior properties of different ceramic materials. In this study, SiO2–Si3N4 composite ceramics with higher mechanical properties and lower dielectric constant were successfully fabricated by nitriding diamond-wire saw silicon waste. The effect of gas atmospheres (N2, NH3, N2–H2) and SiO2 content (0%, 10%, 20%, 30%, 40%) on the microstructure and properties of composite ceramics were studied. It shows that the synthesis of SiO2–Si3N4 composite ceramics can be obtained in the NH3 atmosphere, and it is inevitable to form the Si2N2O phase in N2 and N2–H2 mixture atmospheres. Furthermore, the shrinkage rate and dielectric constant of the ceramics decreased as SiO2 content increased from 0% to 40%. As for the porosity of the sintered ceramics, it first decreased and then increased, with a minimum of 1.73% at the SiO2 content of 20%. However, the flexural strength of the sintered ceramics was the inverse of the porosity, with a maximum of 160.72 MPa at the SiO2 content of 30%. For the sintered ceramic with 30% SiO2, the shrinkage rate, dielectric constant, porosity and flexural strength are 0.3%, 4.62, 1.97% and 160.72 MPa respectively. Thus, this study provides an environment-friendly and value-added approach to recycling photovoltaic waste and reducing the cost of the reactive sintering SiO2–Si3N4 composite ceramics with excellent mechanical and dielectric properties.

Pre-treatment through reductive calcination for CO2 mineralization and selective battery metal extraction from laterites

The world needs an increasing supply of nickel and cobalt production as battery materials for sustainable development. However, the complexity of laterite deposits and the need to control CO2 emissions challenge the enhanced global supply from laterites. This work investigates the effects of calcination as a pre-treatment for selective battery metal extraction from both limonite laterite and saprolite laterite together with concurrent achievement of CO2 mineralization. Calcination under a reducing atmosphere of CO-N2 or CO-CO2 gas mixtures can significantly enhance the extraction of critical metals from both limonite and saprolite laterites. With calcination, the hydrated silicate minerals and ferric oxides converted to reactive olivine and ferrous oxide. The calcines thus can participate in the CO2 mineralization process to stabilize CO2 as mineral carbonates and release nickel and cobalt arising from the CO2 mineral carbonation into solution as complex ions with a ligand (such as sodium nitrilotriacetate, NTA). The optimum calcination conditions are 20 ∼ 30 % CO in CO-CO2 gas mixture at 700 °C. Beyond the optimum range results in the inadequate conversion of ferric to ferrous at too low CO concentration or over calcination of ferric to metallic iron at too high CO concentration. At the optimum conditions, the nickel & cobalt extraction and CO2 mineralization can reach 90 %, 93 %, and 39 % from laterite. Each tonne saprolite with the pre-treatment of calcination can recover 20.5 kg nickel, 0.59 kg cobalt, and simultaneously sequester 142 kg CO2 as stable mineral carbonates. The pre-treatment through slightly reductive calcination enables the robust suitability of the developed process for all layers of laterites for both critical battery metal recovery and carbon mineralization.

Palladium-Mediated S-Arylation of Cysteine Residues with 4-[18F]Fluoroiodobenzene ([18F]FIB).

Transition-metal-mediated bioconjugation chemistry has been used extensively to design and synthesize molecular probes to visualize, characterize, and quantify biological processes within intact living organisms at the cellular and subcellular levels. We demonstrate the development and validation of chemoselective [18F]fluoro-arylation chemistry of cysteine residues using Pd-mediated S-arylation chemistry with 4-[18F]fluoroiodobenzene ([18F]FIB) as an aryl electrophile. The novel bioconjugation technique proceeded in excellent radiochemical yields of 73-96% within 15 min under ambient and aqueous reaction mixture conditions, representing a versatile novel tool for decorating peptides and peptidomimetics with short-lived positron emitter 18F. The chemoselective S-arylation of several peptides and peptidomimetics containing multiple reactive functional groups confirmed the versatility and functional group compatibility. The synthesis and radiolabeling of a novel prostate-specific membrane antigen (PSMA) binding radioligand [18F]6 was accomplished using the novel labeling protocol. The validation of radioligand [18F]6 in a preclinical prostate cancer model with PET resulted in favorable accumulation and retention in PSMA-expressing LNCaP tumors. At the same time, a significantly lower salivary gland uptake was observed compared to clinical PSMA radioligand [18F]PSMA-1007. This finding coincides with ongoing discussions about the molecular basis of the off-target accumulation of PSMA radioligands currently used for clinical imaging and therapy of prostate cancer.

Synthesis ranges for YBaFe4O7 and its topotactic oxidation in ambient air to YBaFeIII4O8.5

Conditions for YBaFe4O7 synthesis from oxide/carbonate amorphous precursors are investigated versus temperature and partial pressure of oxygen at high-temperature equilibrium with the sample in flowing atmosphere of humidified Ar and H2 gas mixtures. Upon topotactic oxidation in ambient air of the cooled-down product, YBaFeIII4O8.5 forms in a couple of minutes. Neutron powder diffraction suggests that added oxygens enter octahedral holes in the cubic closest packing of O and Ba atoms of YBaFe4O7. Up to two oxygen atoms add to some Fe coordination tetrahedra in the kagome-like layer of YBaFe4O7 in a disordered distribution described as partially occupied crystal-structure sites. The oxidized YBaFeIII4O8.5 is metastable and decomposes at high temperatures into FeIII oxides of barium or yttrium. The synthesized YBaFe4O7 is a powerful room-temperature O2 getter that can be reverted by annealing in the above gas mixture.

Experimental investigation of the effect of ammonia substitution ratio on an ammonia-diesel dual-fuel engine performance

This research experimentally examines an ammonia-diesel dual fuel system, not widely covered in existing literature but acknowledged as an effective approach to reduce engine carbon footprints in alignment with global decarbonization trends, focusing on enhancing understanding of performance, combustion, and emission characteristics vital for designing and optimizing these engines for commercialization. The results indicate that in an ammonia-air mixture atmosphere, diesel undergoes a prolonged ignition process, enhancing the role of premixed combustion. Increasing ammonia substitution at constant speed and load reduces the weight of mixing-controlled combustion, leading to larger areas in the chamber where diesel flames cannot reach. Ammonia oxidation mainly occurs near the diesel flame, as overly lean ammonia-air mixtures fail to sustain stable flame propagation. This results in considerable unburned ammonia emissions, particularly in regions beyond diesel flame reach and engine crevices, adversely affecting combustion efficiency and diminishing the thermal efficiency advantages of such operation. Furthermore, while ammonia combustion contributes to fuel-borne nitrogen oxides (NOx) formation, the overall NOx emissions from ammonia-diesel engines are reduced due to lower combustion temperatures and the deNOx properties of amino groups. However, the partial oxidation of ammonia during the late expansion stroke generates significant levels of nitrous oxide (N2O), a greenhouse gas, in the emissions, counteracting the intended reduction of carbon dioxide. These experimental findings highlight the necessity of focusing on both improving in-cylinder combustion quality and developing effective aftertreatment systems for NH3 and N2O capture, as crucial steps towards enhancing the environmental performance and market viability of ammonia-diesel dual fuel engines.

Hygienic study and forecast of atmospheric air pollution with sulfur compounds in the areas of sulfide-containing tailings

This article is devoted to the topical problem of the release into the atmosphere of mixtures of sulfur compounds from decommissioned facilities for the disposal of waste from the processing of sulfide ores of non-ferrous and noble metals. The purpose of the research was a hygienic study and forecast of atmospheric air pollution by volatile sulfur compounds emitted by decommissioned waste disposal facilities for processing sulfide ores of non-ferrous and precious metals, for information support of the system of medical and preventive technologies in mining regions. The objects of the study were two decommissioned tailing dumps of enterprises for the processing of gold ores. The assessment of the actual pollution of the surface layer of the atmosphere with dimethyl sulfide, dimethyl sulfoxide, carbon disulfide, sulfur dioxide and hydrogen sulfide was carried out according to under-flare observations. Non-linear models given by second and third order polynomials were used to predict pollution levels. A theoretical analysis of the in ‑ formation presented in the scientific literature on the interaction of structural elements of natural and technical systems that make up the mechanism of atmospheric pollution at the post-operational stage of mining technogenesis has been carried out. Based on a systematic analysis of under-flare observations conducted in the areas of location of two tailings of gold ore production, lists of priority sulfur compounds to be controlled, distinctive features of zonal atmospheric pollution for different forms of terrain adjacent to the sources were identified, non-linear models of the distribution of concentrations of priority pollutants in the surface were constructed. layer of the atmosphere, allowing a probabilistic quantitative assessment of pollution halos and inhalation risks to public health. The scientific information obtained as a result of a comprehensive study is intended for information support of the system of medical and preventive technologies in mining regions.

Maternal Exposure to Ambient Air Pollution Mixture and Premature Rupture of Membranes: Evidence from A Large Cohort in Southern California

Maternal Exposure to Ambient Air Pollution Mixture and Premature Rupture of Membranes: Evidence from A Large Cohort in Southern California