Loss Mechanisms Research Articles

Inflammation in the COVID-19 airway is due to inhibition of CFTR signaling by the SARS-CoV-2 spike protein

SARS-CoV-2-contributes to sickness and death in COVID-19 patients partly by inducing a hyper-proinflammatory immune response in the host airway. This hyper-proinflammatory state involves activation of signaling by NFκB, and unexpectedly, ENaC, the epithelial sodium channel. Post-infection inflammation may also contribute to "Long COVID"/PASC. Enhanced signaling by NFκB and ENaC also marks the airway of patients suffering from cystic fibrosis, a life-limiting proinflammatory genetic disease due to inactivating mutations in the CFTR gene. We therefore hypothesized that inflammation in the COVID-19 airway might similarly be due to inhibition of CFTR signaling by SARS-CoV-2 spike protein, and therefore activation of both NFκB and ENaC signaling. We used western blot and electrophysiological techniques, and an organoid model of normal airway epithelia, differentiated on an air–liquid-interface (ALI). We found that CFTR protein expression and CFTR cAMP-activated chloride channel activity were lost when the model epithelium was exposed to SARS-CoV-2 spike proteins. As hypothesized, the absence of CFTR led to activation of both TNFα/NFκB signaling and α and γ ENaC. We had previously shown that the cardiac glycoside drugs digoxin, digitoxin and ouabain blocked interaction of spike protein and ACE2. Consistently, addition of 30 nM concentrations of the cardiac glycoside drugs, prevented loss of both CFTR protein and CFTR channel activity. ACE2 and CFTR were found to co-immunoprecipitate in both basal cells and differentiated epithelia. Thus spike-dependent CFTR loss might involve ACE2 as a bridge between Spike and CFTR. In addition, spike exposure to the epithelia resulted in failure of endosomal recycling to return CFTR to the plasma membrane. Thus, failure of CFTR recovery from endosomal recycling might be a mechanism for spike-dependent loss of CFTR. Finally, we found that authentic SARS-CoV-2 virus infection induced loss of CFTR protein, which was rescued by the cardiac glycoside drugs digitoxin and ouabain. Based on experiments with this organoid model of small airway epithelia, and comparisons with 16HBE14o- and other cell types expressing normal CFTR, we predict that inflammation in the COVID-19 airway may be mediated by inhibition of CFTR signaling by the SARS-CoV-2 spike protein, thus inducing a cystic fibrosis-like clinical phenotype. To our knowledge this is the first time COVID-19 airway inflammation has been experimentally traced in normal subjects to a contribution from SARS-CoV-2 spike-dependent inhibition of CFTR signaling.

Fabrication of 3D micro-flower structured BiFeO3 growing on rGO nanosheets for enhanced electromagnetic wave absorption

Because of the distinctive structure and superior properties of graphene and its derivatives, which have been widely studied in the field of electromagnetic wave (EMW) absorption. However, the impedance mismatch caused by excessive conductivity of graphene and the single loss mechanism greatly limit its application. Herein, we prepare 3D micro-flower structured BiFeO3 grown on graphene oxide nanosheets (BiFeO3-rGO) to both improve the impedance matching and introduce abundant interfacial polarization loss. Moreover, the electromagnetic parameters of the materials are adjusted by changing the ratio of BiFeO3 and rGO to obtain prominent EMW absorption and satisfactory impedance matching performances. More importantly, the conductive loss and polarization loss of the materials are quantitatively analyzed to further explore the loss mechanism of EMW. As a result, the fabricated BiFeO3-rGO 1:1 and BiFeO3-rGO 2:1 both achieve remarkable EMW absorption performances with strong reflection loss (RL) of −49.5 and −45.3 dB and broad effective absorption bandwidth (EAB) of 8.12 and 8.08 GHz with a low filling contents of 5 %. This work demonstrates that polarization loss is as important as conduction loss and the key point to further improve the EMW absorption performance is to crack the code of polarization loss.

Hierarchical multi-interface Co1-xS/Co9S8@C hollow microsphere for enhancing dielectric polarization as an efficient microwave absorber

Recently, close attention has been devoted to exploring highly efficient microwave absorbing materials (MAMs). Owing to their tunable dielectric properties and controllable structure, materials doped with heteroatoms have been regarded as promising absorbers. Herein, the Co@C, CoSe2@C, and hierarchical Co1-xS/Co9S8@C hollow microspheres were prepared using hydrothermal and subsequent carbonization, selenium, and vulcanization processes, respectively. The existence of anionic sites immensely affects the permittivity and conductivity of a composite. As a result, CoSe2@C and Co1-xS/Co9S8@C hollow microspheres showed improved conductivity and dielectric losses. Particularly, due to the multiphase transformation in the vulcanization process, the Co1-xS/Co9S8@C hollow microsphere possessed numerous heterogeneous interfaces and rich lattice defects, which led to local electronic redistribution and reinforced dielectric polarization. It exhibited a minimum reflection loss (RLmin) of −61.0 dB at a thinner thickness of 2.0 mm. This study contributes to the insight into the polarization loss mechanisms of multi-component and heteroatom doping composites and stimulates the design of high-efficiency MAMs.

Structure evolution of the silica glass under the vibration field through molecular dynamics simulations

AbstractSilica glass has found wide applications, including space shuttle windows, optical fibers, and deep ultraviolet light lens elements, due to its excellent optical, electrical, and mechanical properties. However, understandings of its structure change under the vibration field are limited in literature. In this work, the structure of silica glass and its behavior under the vibration field have been investigated through molecular dynamics simulations. The short and medium‐range structures, including coordination number, Qn species distribution, pair distribution function, and bond angle distribution, were analyzed. It was found that the overall and local structures of silica glass showed periodic changes under the vibration field. The root‐mean‐square displacements as well as the kinetic energies of the atoms in the system were further analyzed. The results show that there is a periodic transformation of kinetic and potential energies. In addition, the kinetic energy decreases and is converted into the thermal energy during the vibration, which is confirmed by the increase of the system temperature. This can explain the thermoelastic loss mechanism in energy dissipation from literature. This work reveals the structure evolution and energy change of glass under the vibration field from atomistic level, which provides important understandings for related researches.

The human health burden of climate change: Non-economic losses and ethical considerations towards achieving planetary health

Climate change presents an urgent and growing threat to the health and well-being of people and the planet. More frequent and intense heatwaves, droughts and floods are breaching critical ecosystem boundaries, causing cascading impacts that are increasingly complex to govern. Unsustainable development pathways and economic choices that are fueling the climate crisis are also directly engendering global health issues. Furthermore, the global response to climate change has been uneven and the lack of a conceptual framework for loss and damage has allowed developed countries the latitude to adopt differing takes on its framing, undermining the urgency and progression of the loss and damage mechanism to the detriment of developing countries. Current research on the governance of climate ethics posits that while economic and legal considerations largely influence climate policies, decision-making processes in climate adjacent sectors such as health need to be further grounded on ethically sound principles. Framing the health impacts of climate change as a moral issue can therefore be viewed as an effort to reshape the current political discourse with a humanistic lens and move the international community and state-level actors to action. The framing of this issue is particularly important as it recenters the focus on human health as an imperative for effective climate policies rather than as a contributor to the cache of peripheral co-benefits. It also underscores climate change as an ethical issue, in which failure to respond to the climate impacts can worsen health inequities, especially for socially and economically marginalized communities and vulnerable groups.

Structure and Formation Mechanisms in Tantalum and Niobium Oxides in Superconducting Quantum Circuits.

Improving the qubit's lifetime (T1) is crucial for fault-tolerant quantum computing. Recent advancements have shown that replacing niobium (Nb) with tantalum (Ta) as the base metal significantly increases T1, likely due to a less lossy native surface oxide. However, understanding the formation mechanism and nature of both surface oxides is still limited. Using aberration-corrected transmission electron microscopy and electron energy loss spectroscopy, we found that Ta surface oxide has fewer suboxides than Nb oxide. We observed an abrupt oxidation state transition from Ta2O5 to Ta, as opposed to the gradual shift from Nb2O5, NbO2, and NbO to Nb, consistent with thermodynamic modeling. Additionally, amorphous Ta2O5 exhibits a closer-to-crystalline bonding nature than Nb2O5, potentially hindering H atomic diffusion toward the oxide/metal interface. Finally, we propose a loss mechanism arising from the transition between two states within the distorted octahedron in an amorphous structure, potentially causing two-level system loss. Our findings offer a deeper understanding of the differences between native amorphous Ta and Nb oxides, providing valuable insights for advancing superconducting qubits through surface oxide engineering.

Impact of the Li-loss mechanisms inherent to the physical vapor deposition of LiCoO2 cathode on its electrochemical performance

GPa-resistant conformal LiCoO2 cathodes grown by physical vapor deposition (PVD), with negative chemical expansion coefficients, are promising systems for mechanically stabilizing cathode/solid electrolyte interfaces in solid-state lithium-ion batteries. However, exploiting its potential preliminarily requires that we are able to control the reversibility of Li stoichiometry under PVD conditions, which represents a major challenge since metal Li is lightweight, volatile and has high diffusivity. By combining different chemical and structural analysis techniques, we identify the mechanisms of Li loss by PVD and demonstrate that unlike the electrochemical delithiation of LiCoO2, the crystallization of LiCoO2 admits only a small amount of Li vacancies, so that in a Li-deficient regime, segregated phases of fully stoichiometric LiCoO2 and Li-free Co oxides are formed. From the laterally- and depth-resolved concentrations of the coexisting phases, we can conclude that PVD-grown LiCoO2 is partially stabilized into morphological features with reduced specific surface areas (i.e., large isotropic faceted grains and thick films), resulting in an improvement of its specific electrochemical properties and performance.

Three-way decision-based Takagi–Sugeno–Kang fuzzy classifier for partially labeled data

The salient features of Takagi–Sugeno–Kang (TSK) fuzzy classifiers are their superior nonlinear fitting capability and better interpretability, rendering them widely applicable in the domains of data mining and machine learning. However, using TSK fuzzy classifiers for partially labeled data has received little attention. Based on the three-way decision (TWD) theory, this study proposed a TSK fuzzy model to learn from partially labeled data. First, an adaptive sample weight strategy is introduced for the fuzzy partition of the antecedent part and the cross-entropy loss of the consequent part, respectively. Subsequently, a prototype-based firing strength loss mechanism is proposed to constrain the optimization of the model in the fuzzy representation space. It employs a TWD strategy based on the entropy criterion to classify samples as useful, useless, and uncertain, where the proposed model enhances the performance by iteratively utilizing a certain number of useful pseudo-labeled samples. Finally, the validity of the model is theoretically analyzed based on the principle of noise learning. The experimental results on UCI datasets demonstrate that the proposed model exhibits superior performance compared with classical semi-supervised methods, even attaining a performance comparable to that of the model trained on all data with ground-truth labels.

Mapping the Nanoscale Heterogeneous Responses in the Dynamic Acceleration of Deformed Polymer Glasses.

Understanding the evolution of local structure and mobility of disordered glassy materials induced by external stress is critical in modeling their mechanical deformation in the nonlinear regime. Several techniques have shown acceleration of molecular mobility of various amorphous glasses under macroscopic tensile deformation, but it remains a major challenge to visualize such a relationship at the nanoscale. Here, we employ a new approach based on atomic force microscopy in nanorheology mode for quantifying the local dynamic responses of a polymer glass induced by nanoscale compression. By increasing the compression level from linear elastic to plastic deformation, we observe an increase in the mechanical loss tangent (tan δ), evidencing the enhancement of polymer mobility induced by large stress. Notably, tan δ images directly reveal the preferential effect of the large compression on the dynamic acceleration of nanoscale heterogeneities with initially slow mobility, which is clearly different from that induced by increasing temperature.

Bridging dielectric-magnetic synergistic units with MOFs on fibers structure for high-efficient microwave absorption at low filler loading

Metal-organic framework (MOF) capable of magnetic-dielectric synergy loss mechanisms shine in the field of electromagnetic wave (EMW) absorption, whereas their high filler loading in the matrix remains a challenge and limit their practical application. Here, we mono-disperse bimetallic CoZn-MOF on conductive carbon nanofibers precursor via electrospinning technique and a following heat-treatment was employed to construct a Co–ZnO@NC carbon nanofiber (CNF) composites. The Co–ZnO particles with a size of 2 μm are evenly distributed within the carbon fibers, forming a unique structure resembling a “pearl necklace”. The introduction of one-dimension (1D) CNF can prolong the electron transport path and effectively reduces the percolation threshold of the composites. The composites are endowed with abundant heterogeneous interfaces, excellent magnetic-dielectric synergy and improved impedance matching, benefiting from which the obtained Co–ZnO@NC CNF composites demonstrate a maximum reflection loss (RLmin) of −54.5 dB at a thickness of 2.3 mm and an effective absorption bandwidth (EAB) of 8.12 GHz at a filler loading of merely 10 %. This study provides a feasible strategy for the design of MOF-derived absorbers with enhanced microwave absorption capacity at low filler loading.

Measurements of low-energy nuclear recoil quenching factors for Na and I recoils in the NaI(Tl) scintillator

Elastic scattering off nuclei in target detectors, involving interactions with dark matter and coherent elastic neutrino nuclear recoil (CEνNS), results in the deposition of low energy within the nuclei, dissipating rapidly through a combination of heat and ionization. The primary energy loss mechanism for nuclear recoil is heat, leading to consistently smaller measurable scintillation signals compared to electron recoils of the same energy. The nuclear recoil quenching factor (QF), representing the ratio of scintillation light yield produced by nuclear recoil to that of electron recoil at the same energy, is a critical parameter for understanding dark matter and neutrino interactions with nuclei. The low energy QF of NaI(Tl) crystals, commonly employed in dark matter searches and CEνNS measurements, is of substantial importance. Previous low energy QF measurements were constrained by contamination from photomultiplier tube (PMT)-induced noise, resulting in an observed light yield of approximately 15 photoelectrons per keVee (kilo-electron-volt electron-equivalent energy) and nuclear recoil energy above 5 keVnr (kilo-electron-volt nuclear recoil energy). Through enhanced crystal encapsulation, an increased light yield of around 26 photoelectrons per keVee is achieved. This improvement enables the measurement of the nuclear recoil QF for sodium nuclei at an energy of 3.8±0.6keVnr with a QF of 11.2±1.7%. Furthermore, a re-evaluation of previously reported QF results is conducted, incorporating enhancements in low energy events based on waveform simulation. The outcomes are generally consistent with various recent QF measurements for sodium and iodine. Published by the American Physical Society 2024

In situ loading of ZnO on hierarchical porous carbon derived from banana-peel waste to enrich mechanism for microwave absorption

Biomass has received widespread attention due to its easy availability, low cost, and environmental friendliness as an electromagnetic wave absorber candidate. Inspired by the natural porosity of biomass, the three-dimensional (3D) porous carbon materials derived from banana peels were prepared via coordination and pyrolysis carbonization. A conductive network of biomass-zinc complexes was constructed by introducing Zn2+ to coordinate with organic polymers. Hierarchical porous carbon/ZnO composites with a 3D skeleton network were obtained, which demonstrated outstanding electromagnetic wave absorption performance with an effective absorption bandwidth (EAB) of 6.72 GHz and the reflection loss (RL) of −44.18 dB. The banana peel-derived porous carbon (BPC) embedded with ZnO particles brings about conductive loss and interface polarization, further enriching the microwave loss mechanisms. This work offers a fresh idea for creating a green, sustainable, and high-value functional carbon-based composite material.

Altered N6-methyladenosine methylation level in spermatozoa messenger RNA of the male partners is related to unexplained recurrent pregnancy loss.

Understanding the pathogenesis of unexplained recurrent pregnancy loss is paramount for advancing effective treatments. Various biological processes, including spermatogenesis and embryo development, are tightly regulated by N6-methyladenosine modifications. However, few studies have focused on the impact of sperm N6-methyladenosine modifications on embryonic development. Therefore, we aimed to study altered N6-methyladenosine-mediated messenger RNA methylation modifications in the spermatozoa of male partners from couples experiencing unexplained recurrent pregnancy loss, to identify potential diagnostic markers and explore their potential molecular mechanisms in pregnancy loss and embryogenesis. Methylated RNA immunoprecipitation (MeRIP) sequencing and RNA sequencing were conducted on the spermatozoa of men from couples in the 'unexplained recurrent pregnancy loss' group (n=6), and the fertility control group (n=6). To identify the role of the detected key genes, zebrafish model embryos were studied, and multi-omics (transcriptomics, proteomics, and metabolomics) analyses helped to explore the molecular mechanism of abnormal embryogenesis. Comparing unexplained recurrent pregnancy loss with the fertility control group, 217 N6-methyladenosine peaks were significantly upregulated, and 40 were downregulated in the spermatozoa. The combined analyses of spermatozoa-methylated RNA immunoprecipitation sequencing and RNA sequencing indicated that N6-methyladenosine methylation and the expression of SEMA5A, MT-ATP6, ZNF662, and KDM4C were significantly different. In zebrafish embryos, the altered expression of the four genes increased embryonic mortality and malformations by disturbing several key signaling pathways and zygotic genome activation. This study highlights the paternal epigenome, which could be one of the reasons for faulty embryogenesis leading to pregnancy loss. The N6-methyladenosine modification, the most prevalent RNA modification, contributes to the exploration and understanding of the paternal epigenome in the maintenance of pregnancy and fetal growth and development. The four genes identified in this study may serve as potential diagnostic markers and elucidate novel molecular mechanisms of embryogenesis.

In Fanconi anemia, impaired accumulation of bone marrow neutrophils during emergency granulopoiesis induces hematopoietic stem cell stress

Fanconi Anemia (FA) is an inherited disorder of DNA-repair due to mutation in one of 20+ interrelated genes that repair intra-strand DNA crosslinks and rescue collapsed or stalled replication forks. The most common hematologic abnormality in FA is anemia, but progression to bone marrow failure (BMF), clonal hematopoiesis, or acute myeloid leukemia (AML) may also occur. In prior studies, we found that Fanconi DNA-repair is required for successful emergency granulopoiesis; the process for rapid neutrophil production during the innate immune response. Specifically, Fancc-/- mice did not develop neutrophilia in response to emergency granulopoiesis stimuli, but instead exhibited apoptosis of bone marrow hematopoietic stem cells (HSCs) and differentiating neutrophils. Repeated emergency granulopoiesis challenges induced BMF in most Fancc-/- mice, with AML in survivors. In contrast, we found equivalent neutrophilia during emergency granulopoiesis in Fancc-/-Tp53+/- mice and wild type (WT) mice, without BMF. Since termination of emergency granulopoiesis is triggered by accumulation of bone marrow neutrophils, we hypothesize neutrophilia protects Fancc-/-Tp53+/- bone marrow from the stress of a sustained inflammation that is experienced by Fancc-/- mice. In the current work, we found that blocking neutrophil accumulation during emergency granulopoiesis led to BMF in Fancc-/-Tp53+/- mice, consistent with this hypothesis. Blocking neutrophilia during emergency granulopoiesis in Fancc-/-Tp53+/- mice (but not WT) impaired cell cycle checkpoint activity, also found in Fancc-/- mice. Mechanisms for loss of cell cycle checkpoints during infections challenges may define molecular markers of FA progression, or suggest therapeutic targets for bone marrow protection in this disorder.

Performance investigation of a novel free piston Stirling pump for reverse osmosis desalination systems

Renewable energy (RE)-powered desalination technology is considered a cleaner and promising alternative for alleviating energy exhaustion and environmental pollution resulting from traditional desalination. Currently available solar thermal reverse osmosis (RO) desalination systems are based on the organic Rankine cycle. With the aim to expand the driving mode of reverse osmosis desalination as well as simplify the transmission chain and reduce mechanical energy losses, a novel hydraulic free piston Stirling pump (FPSP) is developed and a simple model is designed and tested for conceptual validation. A free piston Stirling pump - powered reverse osmosis desalination system is presented, and a thermodynamic–dynamic coupling model is established. A parametric analysis is performed with an emphasis on the effects of temperatures, charge pressure, spring stiffnesses, damping coefficients, and masses on the system performance, including the frequency, power output, water yield, and efficiency. Results showed that the frequency in the pumping process was higher than that in the suction process because of the different loads. Within the range investigated, the performance improved as the hot-end temperature, charge pressure, spring stiffnesses, and damping coefficient of the power piston increased, while it deteriorated with a decrease in the damping coefficient of the displacer and the piston masses. Specifically, the power output and water yield reached the optimum value as the cold-end temperature was maintained around 310 K. Under representative parameter conditions, the power output could reach 12.15 kW and the water yield was approximately 6.07 × 10−4 m3/s. In addition, the temperatures and charge pressure influence the system efficiency most.

Tunable dielectric characteristics of the nanocomposite diode based on functionalized graphene quantum dots with and without gadolinium

In this study, we have separately synthesized and characterized solutions of gadolinium (Gd)-free and Gd-doped polyethyleneimine (PEI)-functionalized graphene quantum dots (GQDs) due to the excellent properties of Gd, a rare earth element, in fluorescence and magnetic resonance imaging (MRI). The dielectric properties of Gd-free/doped nanocomposite-based diodes have been compared using impedance spectroscopy (IS) in the frequency range from 1 kHz to 500 kHz and voltage range from −3 V to +5 V at 300 K. From our experimental results, the Gd-free diode was found to have a negative dielectric constant (ε′). In contrast, the Gd-doped nanocomposite diode exhibited positive ε′. The ε′ of the Gd-free diode is −80, while the ε′ of the Gd-doped diode is 35 at 5 V for 1 kHz. The experimental results showed that the dielectric properties of both structures were strongly dependent on the applied voltage and frequency. The Gd doping in the interface has prevented the domination of loss mechanisms within the structure, eliminated negative dielectric at lower frequencies, and conferred a unique micro-capacitor characteristic to the structure. All these efforts will contribute to the development of functional carbon-based materials and the creation of new electronic devices and tunable dielectric properties.

Mechanisms of biodiversity loss under nitrogen enrichment: unveiling a shift from light competition to cation toxicity.

The primary mechanisms contributing to nitrogen (N) addition induced grassland biodiversity loss, namely light competition and soil cation toxicity, are often examined separately in various studies. However, their relative significance in governing biodiversity loss along N addition gradient remains unclear. We conducted a 4-yr field experiment with five N addition rates (0, 2, 10, 20, and 50 g N m-2 yr-1) and performed a meta-analysis using global data from 239 observations in N-fertilized grassland ecosystems. Results from our field experiment and meta-analysis indicate that both light competition and soil cation (e.g. Mn2+ and Al3+) toxicity contribute to plant diversity loss under N enrichment. The relative importance of these mechanisms varied with N enrichment intensity. Light competition played a more significant role in influencing species richness under low N addition (≤ 10 g m-2 yr-1), while cation toxicity became increasingly dominant in reducing biodiversity under high N addition (>10 g m-2 yr-1). Therefore, a transition from light competition to cation toxicity occurs with increasing N availability. These findings imply that the biodiversity loss along the N gradient is regulated by distinct mechanisms, necessitating the adoption of differential management strategies to mitigate diversity loss under varying intensities of N enrichment.

Loss of Mitochondrial Tusc2/Fus1 Triggers a Brain Pro-Inflammatory Microenvironment and Early Spatial Memory Impairment.

Brain pathological changes impair cognition early in disease etiology. There is an urgent need to understand aging-linked mechanisms of early memory loss to develop therapeutic strategies and prevent the development of cognitive impairment. Tusc2 is a mitochondrial-resident protein regulating Ca2+ fluxes to and from mitochondria impacting overall health. We previously reported that Tusc2-/- female mice develop chronic inflammation and age prematurely, causing age- and sex-dependent spatial memory deficits at 5 months old. Therefore, we investigated Tusc2-dependent mechanisms of memory impairment in 4-month-old mice, comparing changes in resident and brain-infiltrating immune cells. Interestingly, Tusc2-/- female mice demonstrated a pro-inflammatory increase in astrocytes, expression of IFN-γ in CD4+ T cells and Granzyme-B in CD8+T cells. We also found fewer FOXP3+ T-regulatory cells and Ly49G+ NK and Ly49G+ NKT cells in female Tusc2-/- brains, suggesting a dampened anti-inflammatory response. Moreover, Tusc2-/- hippocampi exhibited Tusc2- and sex-specific protein changes associated with brain plasticity, including mTOR activation, and Calbindin and CamKII dysregulation affecting intracellular Ca2+ dynamics. Overall, the data suggest that dysregulation of Ca2+-dependent processes and a heightened pro-inflammatory brain microenvironment in Tusc2-/- mice could underlie cognitive impairment. Thus, strategies to modulate the mitochondrial Tusc2- and Ca2+- signaling pathways in the brain should be explored to improve cognitive health.

MXene-derived titanate heterojunctions with lightweight and heat-resistant properties for electromagnetic wave absorption

The development of high-efficiency titanate-based electromagnetic wave (EMW) absorbers presents a significant challenge, primarily due to the limited number of loss mechanisms available in such materials. Herein, an innovative approach has been employed, utilizing g-C3N4 as a connecting bridge linking KTi8O16.5 nanorods with Fe2O3 nanoparticles, thereby crafting a KTO/Fe2O3–CN absorber with a dual heterojunction architecture. This sophisticated structure is realized through a detailed freeze-drying process followed by heat treatment. In this structure, g-C3N4 and KTi8O16.5 originate from melamine and MXene precursors, respectively, while Fe2O3 component is derived from the thermal decomposition of FeSO4. The integrated KTO/Fe2O3–CN system fosters enhanced interfacial and dipole polarization, as well as conduction and magnetic loss, all collaboratively aiding in the attenuation of EM waves. In addition, the specially designed EMW absorber is notable for its lightweight nature, along with impressive heat dissipation and resistant performance. It demonstrates exceptional thermal stability, capable of withstanding temperatures as high as 500 °C and sustaining repeated thermal cycles at 400 °C. This strategy not only elevates the efficacy of titanate-based EMW absorbers but also paves the way for the conceptualization of high-performance, multifunctional EMW absorption materials. Such advancements hold the promise of transforming a wide range of applications that necessitate effective EM wave attenuation, marking a significant leap forward in the field.

Unveiling the Mechanism in Nickel Loss During the Neutralization of Pregnant Acid Leach Solution by Various Alkaline Chemicals Using Electron Imaging, X-Ray Diffraction, and Electron Energy Loss Spectroscopy Analyses

ABSTRACT Removal of iron and aluminum from nickel-bearing pregnant leach solution is imperative prior to recovering nickel. However, the mechanisms into the loss of both nickel and cobalt in precipitate products during the neutralization process remained unclear and debatable. In this study, the precipitation ratios of nickel, as well as other valuable metals in iron precipitate products, were investigated by examining bulk and surface properties of iron precipitates using X-ray diffraction, infrared spectroscopy, scanning electron microscopy, and electron energy loss spectroscopy. Amorphous ferrihydrite was identified as the major phase for iron precipitates. Over 99% precipitation ratio for iron and aluminum was achieved at pH 3. The loss of nickel in iron precipitates was strongly dependent on solution pHs, and the losses of nickel were found to be 3%, 8%, and 28% at pHs of 3, 4, and 5, respectively. The type of alkaline chemicals impacted the mineralogical composition of iron precipitate products and loss of valuable metals but had a minor impact on iron precipitation ratio. This work revealed three major mechanisms for the loss of nickel and cobalt during iron precipitation process: (1) entrainment of nickel-bearing PLS in filtered products, (2) surface adsorption on iron precipitates, and (3) lattice incorporation of nickel in iron precipitates. Additionally, the result of desorption experiments by H+ and Na+ ions showed that approximately 55–85% of lost nickel was incorporated within the lattice structure of iron precipitates, while the degree of nickel incorporation depends on the type of neutralizing reagents, precipitation conditions, and washing media.