Neutral Region Research Articles

Characterization of clonal dynamics using duplex sequencing in donor-recipient pairs decades after hematopoietic cell transplantation.

After allogeneic hematopoietic cell transplantation (HCT), a very small number of donor stem cells reconstitute the recipient hematopoietic system, whereas the donor is left with a near-normal pool of stem cells. We hypothesized that the increased replicative stress on transplanted donor cells in the recipient could lead to the disproportionate proliferation of clonal hematopoiesis (CH) variants. We obtained blood samples from 16 related donor-recipient pairs at a median of 33.8 years (range: 6.6 to 45.7) after HCT, including the longest surviving HCT recipients in the world. For 11 of 16 pairs, a donor sample from the time of HCT was available for comparison. We performed ultrasensitive duplex sequencing of genes recurrently mutated in myeloid malignancies and CH, as well as a set of functionally neutral genomic regions representative of human genomic content at large. CH variants were observed in all donors, even those as young as 12 years old. Where donor pre-HCT sample was available, the average mutation rate in donors compared to recipients post-HCT was similar (2.0% versus 2.6% per year, respectively) within genes recurrently mutated in myeloid malignancies. Twenty-two (5.6%) of the 393 variants shared between paired donors and recipients post-HCT showed ≥10-fold higher variant allele frequency (VAF) in the recipient. A longer time since HCT was positively associated with the expansion of shared variant VAFs in the recipient. In conclusion, even decades after HCT, there does not appear to be widespread accelerated clonal expansion in the transplanted cells, highlighting the immense regenerative capacity of the human hematopoietic system.

Purifying Selection Influences the Comparison of Heterozygosities between Populations.

Heterozygosity is a fundamental measure routinely used to compare between populations to infer the level of genetic variation and their relative effective population sizes. However, such comparison is highly influenced by the magnitude of selection pressure on the genomic regions used. Using over 2 million Single Nucleotide Variants (SNVs) from chimpanzee and mouse populations, this study shows that the heterozygosities estimated using neutrally evolving sites of large populations were two times higher than those of small populations. However, this difference was only ~1.6 times for the heterozygosities estimated using nonsynonymous sites. This suggests an excess in the nonsynonymous heterozygosities due to the segregation of deleterious variants in small populations. This excess in the nonsynonymous heterozygosities of the small populations was estimated to be 23-31%. Further analysis revealed that the magnitude of the excess is modulated by effective population size (Ne) and selection intensity (s). Using chimpanzee populations, this investigation found that the excess in nonsynonymous diversity in the small population was little (6%) when the difference between the Ne values of large and small populations was small (2.4 times). Conversely, this was high (23%) when the difference in Ne was large (5.9 times). Analysis using mouse populations showed that the excess in the nonsynonymous diversity of highly constrained genes of the small population was much higher (38%) than that observed for the genes under relaxed selective constraints (21%). Similar results were observed when the expression levels of genes were used as a proxy for selection intensity. These results emphasize the use of neutral regions, less constrained genes, or lowly expressed genes when comparing the heterozygosities between populations.

Repeat modules and N-linked glycans define structure and antigenicity of a critical enterotoxigenic E. coli adhesin.

Enterotoxigenic Escherichia coli (ETEC) cause hundreds of millions of cases of infectious diarrhea annually, predominantly in children from low-middle income regions. Notably, in children, as well as volunteers challenged with ETEC, diarrheal severity is significantly increased in blood group A (bgA) individuals. EtpA, is a secreted glycoprotein adhesin that functions as a blood group A lectin to promote critical interactions between ETEC and blood group A glycans on intestinal epithelia for effective bacterial adhesion and toxin delivery. EtpA is highly immunogenic resulting in robust antibody responses following natural infection and experimental challenge of volunteers with ETEC. To understand how EtpA directs ETEC-blood group A interactions and stimulates adaptive immunity, we mutated EtpA, mapped its glycosylation by mass-spectrometry (MS), isolated polyclonal (pAbs) and monoclonal antibodies (mAbs) from vaccinated mice and ETEC-infected volunteers, and determined structures of antibody-EtpA complexes by cryo-electron microscopy. Both bgA and mAbs that inhibited EtpA-bgA interactions and ETEC adhesion, bound to the C-terminal repeat domain highlighting this region as crucial for ETEC pathogen-host interaction. MS analysis uncovered extensive and heterogeneous N-linked glycosylation of EtpA and cryo-EM structures revealed that mAbs directly engage these unique glycan containing epitopes. Finally, electron microscopy-based polyclonal epitope mapping revealed antibodies targeting numerous distinct epitopes on N and C-terminal domains, suggesting that EtpA vaccination generates responses against neutralizing and decoy regions of the molecule. Collectively, we anticipate that these data will inform our general understanding of pathogen-host glycan interactions and adaptive immunity relevant to rational vaccine subunit design.

The impacts of positive selection on genomic variation in Drosophila serrata: Insights from a deep learning approach.

This study explores the impact of positive selection on the genetic composition of a Drosophila serrata population in eastern Australia through a comprehensive analysis of 110 whole genome sequences. Utilizing an advanced deep learning algorithm (partialS/HIC) and a range of inferred demographic histories, we identified that approximately 14% of the genome is directly affected by sweeps, with soft sweeps being more prevalent (10.6%) than hard sweeps (2.1%), and partial sweeps being uncommon (1.3%). The algorithm demonstrated robustness to demographic assumptions in classifying complete sweeps but faced challenges in distinguishing neutral regions from partial sweeps and linked regions under demographic misspecification. The findings reveal the indirect influence of sweeps on nearly two-thirds of the genome through linkage, with an over-representation of putatively deleterious variants suggesting that positive selection drags deleterious variants to higher frequency due to hitchhiking with beneficial loci. Gene ontology enrichment analysis further supported our confidence in the accuracy of sweep detection as several traits expected to be under positive selection due to evolutionary arms races (e.g. immunity) were detected in hard sweeps. This study provides valuable insights into the direct and indirect contributions of positive selection in shaping genomic variation in natural populations.

Complex genomic rearrangements of the Y chromosome in a premature infant

BackgroundChromoanagenesis is an umbrella term used to describe catastrophic “all at once” cellular events leading to the chaotic reconstruction of chromosomes. It is characterized by numerous rearrangements involving a small number of chromosomes/loci, copy number gains in combination with deletions, reconstruction of chromosomal fragments with improper order/orientation, and preserved heterozygosity in copy number neutral regions. Chromoanagesis is frequently described in association with cancer; however, it has also been described in the germline. The clinical features associated with constitutional chromoanagenesis are typically due to copy number changes and/or disruption of genes or regulatory regions.Case presentationWe present an 8-year-old male patient with complex rearrangements of the Y chromosome including a ring Y chromosome, a derivative Y;21 chromosome, and a complex rearranged Y chromosome. These chromosomes were characterized by G-banded chromosome analysis, SNP microarray, interphase FISH, and metaphase FISH. The mechanism(s) by which these rearrangements occurred is unclear; however, it is evocative of chromoanagenesis.ConclusionThis case is a novel example of suspected germline chromoanagenesis leading to large copy number changes that are well-tolerated, possibly because only the sex chromosomes are affected.

Tracing Magnetic Fields with the Gradient Technique: Spatial Filtering Effect and Use of Interferometers

Probing magnetic fields in astrophysical environments is both important and challenging. The Gradient Technique (GT) is a new tool for tracing magnetic fields, rooted in the properties of magnetohydrodynamic (MHD) turbulence and turbulent magnetic reconnection. In this work, we examine the performance of GT when applied to synthetic synchrotron emission and spectroscopic data obtained from sub-Alfvénic and trans-Alfvénic MHD simulations. We demonstrate the improved accuracy of GT in tracing magnetic fields in the absence of low spatial frequencies. Additionally, we apply a low-spatial-frequency filter to a diffuse neutral hydrogen region selected from the GALFA-H i survey. Our results show an increased alignment between the magnetic fields inferred from GT and the Planck 353 GHz polarization measurements.

Excitation of soliton like structures in radio-frequency capacitively coupled plasmas

In this study, we examine the kinetics of radio-frequency capacitively coupled plasma discharges using the Particle-In-Cell method. Plasma is generated by applying two radiofrequencies (60 MHz and 1MHz), which results in the formation of a plasma sheath in the entire discharge region with electron density that oscillates between the two electrodes. However, ions remain relatively stationary. By increasing the gas pressure and radio-frequency power, or replacing helium gas with argon gas, a neutral discharge region known as the plasma bulk is formed. In this neutral discharge regime, electrons oscillate only in the sheath. Prior to the formation of the plasma bulk, the discharge is referred to as a non-neutral discharge, in which soliton-like electron structures are present. An analytical model is presented to interpret the simulation results, and the Korteweg-de Vries equations predicted the existence of damped electron- and ion-soliton-like structures. In the non-neutral discharge regime, supersonic electron solitons can be observed when the driven radio-frequency is much smaller than the electron plasma frequency. Supersonic ion soliton-like structures are present in the non-neutral discharge generated via radio-frequencies comparable to or smaller than the ion plasma frequency.

On the piezo-phototronic effect in heterojunction photodiode with type-II energy band: Simulation on complex incident light illumination

A photodiode, a semiconductor device, is designed to convert light into an electric current. The piezo-phototronic effect, arising from the interplay of semiconductor properties, piezoelectric polarizations, and photo-excitations, presents a promising avenue for enhancing photodiode performance. This research is dedicated to analyzing the impact of the piezo-phototronic effects on p-Si/n-ZnO heterojunction photodiodes when subjected to 365 nm illumination, a situation more intricate than the commonly studied 648 nm illumination. Employing numerical simulation methods, we systematically investigated the influence of varying ZnO and Si lengths on the piezo-phototronic effect, with a focus on the depletion region and neutral region current perspectives. Our findings reveal that adjusting these lengths can heighten sensitivity at low currents or lead to increased base currents. Additionally, the study delves into the effects of doping concentration, minority carrier lifetime, and mobility on device characteristics. This investigation contributes essential insights for a comprehensive understanding of piezo-phototronic effects and establishes a foundational framework for the design of industrial devices.

Impact of radiation damage on the photoconductor and photodiode properties of GaN core–shell p–n junction microwires

GaN nano- and microwires have gained increasing interest due to their unique geometry and flexibility, and have already been successfully applied in optoelectronics. One important advantage is their superior crystalline quality in comparison to their thin-film counterparts. Beside this, GaN is also known for its high radiation hardness, owed to the large displacement energy of the atoms in its crystal lattice and efficient dynamic annealing properties. In this work, single GaN core–shell p–n junction microwires have been processed into radiation detectors and the induced damage effects on the electrical and optoelectrical characteristics, when irradiating the detectors with 1 and 2 MeV protons, have been studied. By measuring the dark and photocurrent as a function of the irradiation fluence we show that for fluences up to 1×1014 protons/cm2 there is no significant modification of any of the parameters and that serious degradation only occurs for fluences above 1×1015 protons/cm2. Furthermore, we also observe that the dark current decays at a lower irradiation fluence with respect to the photocurrent due to the different impact of the created irradiation defects on the properties of the neutral region and the p–n junction. As a consequence, the signal-to-noise ratio of the detector is strongly enhanced, especially when applying a higher reverse bias. Thermal treatments furthermore show that the degree of recovery of the properties of the detectors is strongly dependent on the irradiation fluence. The detector irradiated with a fluence of 5×1014 protons/cm2 almost completely retrieved its pre-irradiation characteristics whereas the detector irradiated with 5×1015 protons/cm2 only showed a minimal recovery.

What Drove the Carrington Event? An Analysis of Currents and Geospace Regions

AbstractThe 1859 Carrington event is the most intense geomagnetic storm in recorded history, and the literature provides numerous explanations for what drove the negative H perturbation on the Earth. There is debate on what dominated the event. Our analysis shows a combination of causes of similar orders of magnitude. Previous analyses generally rely upon the observed H perturbation at Colaba, India; historic newspaper reports; and empirical models. We expand the analysis using two Space Weather Modeling Framework simulations to examine what drove the event. We compute contributions from currents and geospace regions to the northward B field on Earth's surface, BN. We examine magnetospheric currents parallel and perpendicular to the local B field, ionospheric currents, and gap region field–aligned currents (FACs). We also evaluate contributions from the magnetosheath, near–Earth, and neutral sheet regions. A combination of currents and geospace regions significantly contribute to BN on the Earth's surface, changing as the storm evolves. At storm onset, magnetospheric currents and gap–region FACs dominate in the equatorial region. At auroral latitudes, gap–region FACs and ionospheric currents are the largest contributors. At storm peak, azimuthal magnetospheric currents and gap–region FACs dominate at equatorial latitudes. Gap–region FACs and ionospheric currents dominate in the auroral zone, down to mid‐latitudes. Both the magnetosheath and FACs contribute at storm peak, but are less significant than that from the near–Earth ring current. During recovery, the near–Earth ring current is the largest contributor at equatorial latitudes. Ionospheric currents and gap–region FACs dominate in the auroral zone.

A world-leading periphery: exploring representations of Northern Sweden in view of its green transition

In pursuit of the EU’s goal to become the world’s first climate neutral region, Northern Sweden is positioned as a centrepiece to the green transition development. Its innovative industries are hailed as crucial, not only for Sweden but for the sustainable future of Europe. Yet, previous research depicts the cultural region of Norrland as an inner periphery of Sweden, subjected to colonization and marginalization. This article delves into this paradox by examining discursive representations of Norrland in light of the current green transition narratives. Utilizing a qualitative research approach, this study employs critical discourse analysis to systematically examine representations from news media, political opinion, and government institutions, uncovering tensions and contradictions within the discourse. The analysis suggests the prevalence of two main themes, construing Norrland simultaneously as the future and as a struggle. By contextualizing these discourses within the concept of peripheralization, this research suggests that the future-oriented representations dominate the current understanding of Norrland, potentially perpetuating patterns of spatial disparities within the region. Thus, this research contributes with an updated understanding of processes of peripheralization under the guise of a green discourse, suggesting that the development in Norrland seems part of a broader narrative aiming to frame Sweden as the world leader within green transition initiatives.

Wearable, Machine Washable, Breathable Polyethylenimine/Sodium Alginate Layer-by-Layer-Coated Cotton-Based Multifunctional Triboelectric Nanogenerators.

Cotton-based textiles are ubiquitous in daily life and are prime candidates for application in wearable triboelectric nanogenerators. However, pristine cotton is vulnerable to bacterial attack, lacks antioxidant and ultraviolet (UV)-protective abilities, and shows lower triboelectric charge generation against tribonegative materials because it is present in the neutral region of the triboelectric series. To overcome such drawbacks, herein, a facile layer-by-layer method is proposed, involving the deposition of alternate layers of polyethylenimine (PEI) and sodium alginate (SA) on cotton. Such modified fabric remains breathable and flexible, retains its comfort properties, and simultaneously shows multifunctionalities and improved triboelectric output, which are retained even after 50 home laundering cycles. Also, the modified fabric becomes more tribopositive than nylon, silk, and wool. A triboelectric nanogenerator consisting of modified cotton and polyester fabric is proposed that shows a maximum power density of 338 mW/m2. An open-circuit voltage of ∼97.3 V and a short-circuit current of ∼4.59 μA are obtained under 20 N force and 1 Hz tapping frequency. Further, the modified cotton exhibits excellent antibacterial, antioxidant, and UV-protective properties because of the incorporation of PEI, and its moisture management properties are retained due to the presence of sodium alginate in the layer. This study provides a simple yet effective approach to obtaining durable multifunctionalities and improved triboelectric performance in cotton substrates.

Radiative transfer of 21-cm line through ionised cavities in an expanding universe

Abstract The optical depth parameterisation is typically used to study the 21-cm signals associated with the properties of the neutral hydrogen (H i) gas and the ionisation morphology during the Epoch of Reionisation (EoR), without solving the radiative transfer equation. To assess the uncertainties resulting from this simplification, we conduct explicit radiative transfer calculations using the cosmological 21-cm radiative transfer (C21LRT) code and examine the imprints of ionisation structures on the 21-cm spectrum. We consider a globally averaged reionisation history and implement fully ionised cavities (H ii bubbles) of diameters d ranging from 0.01 Mpc to 10 Mpc at epochs within the emission and the absorption regimes of the 21-cm global signal. The single-ray C21LRT calculations show that the shape of the imprinted spectral features are primarily determined by d and the 21-cm line profile, which is parametrised by the turbulent velocity of the H i gas. It reveals the spectral features tied to the transition from ionised to neutral regions that calculations based on the optical depth parametrisation were unable to capture. We also present analytical approximations of the calculated spectral features of the H ii bubbles. The multiple-ray calculations show that the apparent shape of a H ii bubble (of d = 5 Mpc at z = 8), because of the finite speed of light, differs depending on whether the bubble’s ionisation front is stationary or expanding. Our study shows the necessity of properly accounting for the effects of line-continuum interaction, line broadening and cosmological expansion to correctly predict the EoR 21-cm signals.

Effect of m-PEG modification on the properties and structure of recombinant lipase from Aspergillus niger GZUF36

Natural lipase is challenging to meet industrial demands because of its low activity, poor stability, and intolerance to organic solvents. Our research aimed to improve the catalytic performance of the extracellular lipase from Aspergillus niger GZUF36 (PEXANL1) by modifying it with a molecular weight of 5000 monomethoxy polyethylene glycol (m-PEG5000) activated by p-toluenesulfonyl chloride (m-PEG5000-OTe). After modification of PEXANL1 with m-PEG5000-OTe (m-PEG5000-OTe@PEXANL1), the activity of m-PEG5000-OTe@PEXANL1 increased by 2.38-fold, its stability at high temperatures improved, and the optimal pH shifted towards the neutral region (pH 6). The effect of surfactants Triton X-100, Tween 20, Tween 80, and SDS on the enzyme activity of m-PEG5000-OTe@PEXANL1 was 118.44%, 124.28%, 120.40%, and 108.53%, respectively. They all activated the enzyme activity. Additionally, m-PEG5000-OTe@PEXANL enhanced its tolerance in organic solvents such as xylene and isopropanol. We analyzed the electrostatic interactions using Zeta potential and characterized the secondary structure using circular dichroism (CD) spectroscopy. The results indicated that the chemical modification led to structural changes in PEXANL1, enhancing its performance. The m-PEG5000-OTe@PEXANL1 may be used to synthesize healthy lipid 1, 3-diglyceride. That study laid the foundation for further industrial applications of PEXANL1 or other lipase by improving the catalytic performance of lipase through chemical modification.

Reconstruction of Cosmological Initial Density Field with Observations from the Epoch of Reionization

The initial density distribution provides a basis for understanding the complete evolution of cosmological density fluctuations. While reconstruction in our local Universe exploits the observations of galaxy surveys with large volumes, observations of high-redshift galaxies are performed with a small field of view and therefore can hardly be used for reconstruction. Here, we propose reconstructing the initial density field using the H i 21 cm and CO line intensity maps from the epoch of reionization. Observations of these two intensity maps provide complementary information on the density field—the H i 21 cm field is a proxy of matter distributions in the neutral regions, while the CO line intensity maps are sensitive to the high-density, star-forming regions that host the sources for reionization. Technically, we employ the conjugate gradient method and develop the machinery for minimizing the cost function for the intensity mapping observations. Analytical expressions for the gradient of cost function are derived explicitly. We show that the resimulated intensity maps match the input maps of mock observations using semi-numerical simulations of reionization with an rms error ≲7% at all stages of reionization. This reconstruction is also robust with an rms error of ∼10% when an optimistic level of shot noise is applied to the CO map or white noise at the level of ≲10% of the standard deviation is applied to each map. Our proof-of-concept work demonstrates the robustness of the reconstruction method, thereby providing an effective technique for reconstructing the cosmological initial density distribution from high-redshift observations.

The associative pattern classifier: Progress in theoretical understanding

The Associative Pattern Classifier (APC) was designed as an associative memory, focusing particularly on pattern classification. This implies that the training memory is constructed in a single operation and pattern classification also occurs in a single process. It is important to note that the APC translates the input patterns through a translation vector, which represents the average of all input patterns. Until now, there is no theoretical framework to explain the inner workings of the APC. Its relevance is inferred from the fact that several studies have been conducted using it as a foundation. This paper seeks to provide a theoretical comprehension of the APC’s operation to facilitate future enhancements. We found the APC creates a system in static equilibrium through concurrent vectors at the origin (translation vector), resulting in a balanced separation of patterns. However, the APC cannot achieve complete pattern separation because of the presence of a neutral region. The neutral region is defined by all the points that define the separation hyperplanes. The points over the hyperplanes cannot be classified by the APC. Additionally, we discovered that the APC is unable to accurately classify the translation vector, which could be included as part of the input patterns. Our previous research showed that the APC is unsuccessful in achieving the linear separation of the AND function. In this research, we broaden the examination of the AND function to illustrate that achieving linear separation is not feasible because the separation line represents a neutral region. The APC demonstrated exceptional performance when tested with artificial datasets where patterns were distributed over balanced regions, thus operating as an efficient multiclass and non-linear classifier. Nevertheless, the performance of the APC is lower when tested with real-world databases, making the APC inaccurate due to its restricted inner workings.

Sputtering-grown undoped GeSn/Ge multiple quantum wells on n-Ge for low-cost visible/shortwave infrared dual-band photodetection

Multispectral photodetectors (PDs) operating in visible (VIS) to shortwave infrared (SWIR) wavelength ranges are highly desired for various civil and military applications. Traditional vertical p-i-n SWIR PDs lack the detection ability for VIS light due to photon dissipation in the neutral regions. Herein, an i-n type PD was proposed and demonstrated with sputtering-grown undoped Ge0.92Sn0.08/Ge multiple quantum wells (MQWs) on n-Ge substrate to realize VIS/SWIR dual-band detection from 400 to 2000 nm. Three response peaks resulted from the resonate cavity effect at 430, 660 and 1530 nm, respectively, were observed. Benefiting from the defect-free coherent GeSn/Ge MQWs and low-temperature surface plasma treatment, a remarkably low bulk leakage current density of 5.9 mA/cm2 and a low surface leakage current of 37.5 μA/cm were achieved at room temperature under −1 V, resulting in an ultralow dark current density of 13.36 mA/cm2 for a 200-μm-diameter PD. Temperature-dependent electrical characterizations revealed that the dark current was ideally dominated by carrier diffusion mechanism. Eminent detectivities of 5.2 × 108, 7.1 × 108 and 5.6 × 109 Jones at 410, 660 and 1530 nm, respectively, under −1 V were achieved simultaneously at room temperature. This work provides a path way for fabricating low-cost, VIS/SWIR dual-band PDs with complementary metal–oxide–semiconductor (CMOS) compatible technology.

Sorption and concentration anionic azo dyes on nanomagnetite modified with cationic polyelectrolytes

Using the chemical coprecipitation method, magnetic magnetite nanoparticles (MNP) were synthesized, the surface of which was modified with biocompatible cationic polyelectrolytes polyethylenimine (PEI) and chitosan (Cht). The MNP were characterised by transmission microscopy and zeta potential measurements. The initial MNP have a shape close to spherical and an average size of (10±3) nm. Immobilization of polyelectrolyte on the surface of MNP led to the appearance of aggregates with an interconnected porous network (shell) around individual particles, with average sizes of (12±2) and (15±2) nm for Fe3O4@PEI and Fe3O4@Cht, accordingly. The influence of various experimental parameters, such as pH, extraction time, amount of sorbent and initial dye concentration on the adsorption and desorption of food azo dyes Allure Red AC (E129) and Brilliant Black BN (E151) was studied. It has been shown that under optimal conditions the degree of extraction of these dyes from aqueous solutions is 96-100%, the concentration coefficient is 2.7×103 and sorption capacity of 56 and 94 mg/g for Fe3O4@PEI and 46 and 69 mg/g on Fe3O4@ХТЗ for E129 and E151, respectively. A comparison of sorption isotherms and process kinetics showed that the Langmuir model and pseudo-first order are preferable for describing the sorption of dyes. In the acidic and neutral regions, electrostatic interactions are responsible for sorption, and in the alkaline region, hydrogen bonding and hydrophobic interactions also play a significant role. The proposed sorbents can be used both for the sorption and concentration of dyes in chemical analysis, and for the purification of wastewater from them. Nanomagnetite modified with polyethylenimine, which allows absorbing and concentrating dyes over a wide pH range of 6-9 is preferable for use.

Insights into uranium sequestration by coal fly-ash-derived zeolites: Understanding via wet chemistry, and advanced spectroscopies

The operation of nuclear power plants requires a supply of nuclear fuel where uranium plays a substantial role as a primary fissile material. Its extraction from U-bearing minerals and handling may cause a leakage of heavily toxic radioactive pollution, which ends up in water bodies and soil. Therefore, tackling U-contaminated water is crucial to preserve water integrity and quality. Zeolites are known as profound ion exchangers with great affinity towards cationic species present in polluted waters. Various zeolite synthesis routes have made this group of aluminosilicates even more promising to be applied as water purification materials. Here, the synthetic gismondite, faujasite, and Linde type-A zeolites from coal fly-ash were synthesized via tailored, coupled fusion-hydrothermal method and applied to remove aqueous uranium (primarily as 238U) under varying pH, time (sorption kinetics), and initial U concentrations (sorption isotherms). The maximum U uptake was observed for Na–P1 (GIS) zeolite, which equals 48.72 mg U/g, the highest reported value on maximum U adsorption capacity for zeolitic materials. The U adsorption kinetics showed that equilibrium is reached after approximately 3 h of adsorption and that the removal process follows a Freundlich isothermal model for all zeolites, thus preferential adsorption onto heterogeneous surfaces. Advanced spectroscopic studies, including laboratory-scale X-ray Photoelectron Spectroscopy with synchrotron light X-ray Absorption Near Edge Structure in High Energy Resolution Fluorescence Detection mode, revealed that at acidic pH, predominantly an ion exchange between Na+ ions with hexavalent uranyl species takes place. In contrast, in the neutral pH region, the U is immobilized via precipitation in the form of μm-scale mineral aggregates of Na-schoepite: Na[(UO2)4O2(OH)5](H2O)5↓. The outcomes of the research study has demonstrated that synthetic zeolites, obtained from industrial by-products such as coal fly-ash, can be successfully valorized to efficient U adsorbents while unveiling the insights to understand the zeolites/U interactions at the nanoscale level.

Deep learning approach for identification of H ii regions during reionization in 21-cm observations – II. Foreground contamination

ABSTRACT The upcoming Square Kilometre Array Observatory will produce images of neutral hydrogen distribution during the epoch of reionization by observing the corresponding 21-cm signal. However, the 21-cm signal will be subject to instrumental limitations such as noise and galactic foreground contamination that pose a challenge for accurate detection. In this study, we present the SegU-Net v2 framework, an enhanced version of our convolutional neural network, built to identify neutral and ionized regions in the 21-cm signal contaminated with foreground emission. We trained our neural network on 21-cm image data processed by a foreground removal method based on Principal Component Analysis achieving an average classification accuracy of 71 per cent between redshift z = 7 and 11. We tested SegU-Net v2 against various foreground removal methods, including Gaussian Process Regression, Polynomial Fitting, and Foreground-Wedge Removal. Results show comparable performance, highlighting SegU-Net v2’s independence on these pre-processing methods. Statistical analysis shows that a perfect classification score with ${\rm AUC}=95~{{\ \rm per\ cent}}$ is possible for 8 < z < 10. While the network prediction lacks the ability to correctly identify ionized regions at higher redshift and differentiate well the few remaining neutral regions at lower redshift due to low contrast between 21-cm signal, noise, and foreground residual in images. Moreover, as the photon sources driving reionization are expected to be located inside ionized regions, we show that SegU-Net v2 can be used to correctly identify and measure the volume of isolated bubbles with $V_{\rm ion}\gt (10\, {\rm cMpc})^3$ at z > 9, for follow-up studies with infrared/optical telescopes to detect these sources.