X-ray Tomographic Microscopy Research Articles

The Role of Thermal Conductivity on Liquid Water Distribution in GDLs

Operating polymer electrolyte fuel cells (PEFCs) at increasingly higher current density and efficiency necessitates overall improvements in fuel cell water management [1]. A crucial role facilitating these improvements is played by the gas diffusion layer (GDL) within the membrane electrode assembly (MEA) [2]. The GDL is responsible for distributing the reactant gases from the flow field towards the catalyst layer as well as removing reaction products from the catalyst layer to the flow fields. For example, at the cathode, the electrochemical reaction of oxygen ions with protons and excess electrons yields water and heat, which must be removed through the GDL to the flow field. The removal of water through the GDL can lead to blocked pores in the GDL [2], thereby restricting the reactants’ gas flow towards the catalyst layer causing mass transport losses. GDL design is crucial towards improving the performance of PEFCs, especially at high current densities, such that it minimizes these transport losses. Additionally, removal of the excess heat generated at the cathode catalyst layer through the GDL indicates that the GDL thermal conductivity (k) plays a crucial role affecting the temperature distribution within the MEA [3].In this work, two GDLs varying in thermal conductivity were selected and assembled in MEAs which were then imaged in-operando using X-ray tomographic microscopy [4]. In-Operando imaging allowed the evaluation of the liquid water distribution at steady state over a range of operational conditions such as temperature and current density. Water distribution results for a range of current densities will be presented for selected cell temperatures between 40 and 70 °C. For GDL I with the lower thermal conductivity, the channels are completely dry at 40 °C. For GDL II with the higher thermal conductivity, a wet-dry transition was observed in between 50 and 70°C. High saturations were observed in both the channel and the land regions at 50 °C, while at 70 °C the channels appear to be dry with liquid water only being present under the lands (see Figure 1). These results provide experimental evidence of a major influence of GDL thermal conductivity on liquid water distribution and overall water management in fuel cells. Keywords – operando, X-ray tomographic microscopy, GDL, water visualization Acknowledgement Funding for this research was provided by the Natural Sciences and Engineering Research Council of Canada, Ballard Power Systems, Canada Foundation for Innovation, British Columbia Knowledge Development Fund, and Canada Research Chairs.

Capillary Pressure Controlled Water Pathways in Gas Diffusion Layers for Polymer Electrolyte Fuel Cells Designed By Additive Manufacturing

Polymer electrolyte fuel cells (PEFC) are considered to make a significant contribution to the transition towards carbon free energy conversion, as they produce electric power from hydrogen and oxygen with water as the only by-product [1]. On its way to widespread commercialization, in particular the water management in PEFC is challenging. On one hand, the electrolyte membrane needs to be humidified to be highly conductive for the hydrogen protons. On the other hand, accumulation of the product water in the gas diffusion layer (GDL) on the cathode side mitigates the oxygen transport towards the catalytic surface, which leads to severe performance limitations [2-3]. Previous work has shown that structured GDLs can enhance PEFC performance [5] and additive manufacturing (AM) has been identified as a viable method to fabricate just such [4,6].Currently available AM technologies are struggling to fulfill the needs in terms of minimal feature size (~8 um fiber diameter) and sample size (at least some cm2). Initial AM prepared GDLs were coarse with finest structures of about 120 um [6] which is in the range of typical GDL thickness. Here, we present AM prepared GDL like structures with 20 um printed features that can reach sizes of some tens of mm2.The 3D printed structures are designed to guide the product water through the GDL by adjusting the throat size [7] and therefore the capillary pressure, which is required in the water phase to percolate through the throats to the neighboring pore as described by Young-Laplace law. Figure 1 shows tomographic data of a test lattice structure manufactured by high-resolution projection micro stereolithography (PµSL). The concept is validated by measuring the pressure in the water phase as a function of the throat size under ex-situ conditions. The desired percolation path of the water is monitored by 2D as well as 3D image data acquired by X-ray radiography and X-ray tomographic microscopy (XTM), respectively. Figure caption: XTM scan of a lattice structure manufactured by P µ SL: a) 3D rendering, b) x-z-plane cross section, c) x-y-plane cross section. Slight deformation in the base layers of the lattice structure is observed.

Importance of Directed Water Removal: Intruding Microporous Layer Material into the Gas Diffusion Layer Substrate

Proton exchange membrane fuel cells (PEMFC) are an essential component of net zero emission scenarios by the International Energy Agency (IEA), most prominent in the heavy-duty transportation sector.[1-2] During operation, the PEMFC is subject to different operating conditions, particularly wet conditions where liquid water removal is crucial. It was observed that a microporous layer (MPL), commonly consisting of a carbon component (e.g. carbon black, carbon fibers) and a hydrophobic binder (e.g. PTFE), placed at the interface of the catalyst layer (CL) and the gas diffusion layer substrate (GDL-S), has a large impact on the water removal properties. Among other advantages, the addition of an MPL can guide the localization of water clusters in the GDL.[3] However, if interfaces exhibit large interfacial gaps, as was demonstrated for the CL/MPL interface,[4] liquid water can accumulate in the large openings, thereby creating a mass transport barrier. Seeking to understand the importance of interfaces, which can either guide water formation or create obstacles, this study further investigates the MPL/GDL-S interface.We created an intruding MPL by pressing the MPL slurry into the GDL-S using mechanical force (further on referred to as “intruded-GDL”) and compared it to a GDL, where the MPL sits quasi on top (further on referred to as “sheet-GDL”). Figure 1a shows a cross-sectional scanning electron microscopy (SEM image) of the sheet-GDL, while Figure 1b shows an intruded-GDL. The boundaries between the MPL material and the GDL-S are marked in red. The MPL/GDL-S interface of the sheet-GDL is relatively flat, following only the surface contour of the GDL-S, while the MPL/GDL-S interface of the intruded-GDL is pressed into the GDL-S and locally penetrates deeper into the GDL-S. It is also visible that the penetration into the GDL-S is inhomogeneous. We characterized the altered morphology using SEM (see Figure 1), mercury intrusion porosimetry (MIP), and x-ray tomographic microscopy (XTM). We found that the MPL of the intruded-MPL intrudes significantly into the GDL-S and preferably fills the larger pores of the GDL-S.Both types of GDLs were subject to single-cell fuel cell testing under various operating conditions. We found that the intruding MPL poses an additional oxygen transport resistance at dry conditions compared to the sheet-GDL. Under conditions where liquid water formation can be expected, the intruded-GDL starts to have an advantage compared to the sheet-GDL. From the data obtained in this study, a delicate interplay between the additional dry transport resistance, the missing macropores that were filled with MPL material, and the guided water removal properties can be deduced. We can derive an improved water removal mechanism for the intruded-GDL as a cause of the structural changes, which can serve as a guideline to improve GDL design parameters.

Degradation Processes in Bipolar Membrane CO2-Electrolysis Studied by Time-Resolved X-Ray Tomography

Electrochemical reduction of carbon dioxide via CO2 co-electrolysis (CO2ELY) is an essential process to produce non-fossil chemical feedstock acting as CO2 sink. The required electrical energy can be harvested from temporal surplus of renewable energy sources like solar or wind. Employing a bipolar electrolyte membrane (BPM) in forward-bias is a promising approach to mitigate fundamental problems of the current technological fore-runner design that employs an anion exchange membrane (AEM). We employed synchrotron time-resolved X-ray tomographic microscopy (XTM) to study degradation processes in BPM CO2ELY.In forward-bias BPM co-electrolysis, the cation exchange layer (CEL) faces the anode to provide favorable acidic conditions for the oxygen evolution reaction. Such acidic anode allows using pure water as electrolyte eliminating the salt precipitation at the cathode observed for AEM CO2ELY. As the second major issue in AEM CO2ELY, (bi)carbonate ions formed at the cathode are transported to the anode presenting a major obstacle for high CO2 conversion efficiency. The then required effort to separate CO2 from the electrolyte further reduces the overall energy efficiency. Employing a BPM and introducing the CEL prevents (bi)carbonate ions reaching the anode. BPM CO2ELY retains at the same time the advantages of AEM CO2ELY of performing CO2 reduction under alkaline conditions with the anion exchange layer (AEL) of the BPM facing the cathode.However, BPM CO2ELY suffers from low current density and poor stability in the range of only a few hours. Current limiting factors and degradation processes as well as the affected components are rarely investigated and poorly understood. Processes that have been brought forward are cathode flooding similar to fuel cells or catalyst poisoning. We employ synchrotron XTM to investigate structural dynamics in CO2ELY during operation. The brilliant synchrotron source allows us to acquire one full high-quality scan with a voxel size of 2.75 um in 1 s. We acquired one scan every minute for one hour during electrochemical operation.The image data reveals the formation of gas bubbles at the AEL-CEL junction and ultimately delamination of the BPM. We explain the gas formation as the recombination of (bi)carbonate ions with hydrogen ions at the junction producing gaseous CO2. This CO2 additionally reaches the anode by diffusion causing partial delamination of the anode catalyst layer. CO2 escaping from the AEL surface at the anode forms high-pressure gas bubbles that break the water wet catalyst layer. A diffusive model considering the transport of ions and neutral CO2 is able to capture the mechanism.Our imaging experiments provide insights not attainable by other diagnostic methods and highlight the need for fundamental research on forward-bias BPM CO2ELY. Knowledge based on AEM CO2ELY and fuel cells is not necessarily directly applicable and specific studies on BPM CO2ELY are required to increase performance and stability.We gratefully acknowledge provision of beamtime at TOMCAT, SLS, Paul Scherrer Insititut, Villigen PSI, Switzerland.Figure 1: Tomographic slice of CO2-electrolyser (cathode to the left) a) before operation and running water through anode b) after 23 minutes operation at 3.5V constant potential showing liquid water dynamics at cathode, membrane swelling, gas formation within the membrane and anode catalyst layer disintegration. Figure 1

Visualization of Lithium Plating Morphologies on Graphite Electrode By O perando X-Ray Tomography

The plating of lithium metal on graphite electrodes in Li-ion batteries is a major factor limiting the fast charging of electric vehicles. Lithium metal plating leads to the growth of dendritic structures that can pierce through the battery’s separator resulting in an internal short circuit and catastrophic failure of the battery. Moreover, the plating of lithium metal on graphite is not reversible, manifesting in poor Coulombic efficiency, severe reduction of the battery’s life expectancy, and safety issues. Understanding how and when plating occurs in Li-ion batteries is crucial in the development of strategies to prevent plating under fast charging conditions. Thus, we have conducted an operando X-ray tomographic microscopy experiment to directly monitor the plating of lithium metal in a Li/Graphite cell when applying electrolytes with the additives vinylene carbonate (VC) and Lithium bis(fluorosulfonyl)imide (LiFSI). The experiment was performed at the ID19 beamline (ESRF, France) where tomographic scans, linked with the lithiation state of graphite, made it possible to gain a strong understanding of the mechanisms behind Li-deposition and stripping at high current rates in addition to understand the effect of the VC and LiFSI additives.

Microporous Transport Layers Facilitating Low Iridium Loadings in Polymer Electrolyte Water Electrolyzers

Minimizing iridium content in the anodic catalyst layer (CL) of polymer electrolyte water electrolyzers (PEWE) is essential for facilitating the needed rapid scale-up of hydrogen production capacity. However, reducing the iridium loading inevitably produces thinner CLs (if not changing the catalyst itself). This can have severe effects on performance and stability, mainly due to the losses in the connectivity of the 3D structure. Microporous layers (MPLs) have the potential to improve the performance and catalyst layer utilization of PEWE cells[1], especially at low Ir-loadings since they minimize the in-plane transport length of the required species (i.e. electric and fluidic transport).In this work, we characterized the 3D structure and transport properties of typical IrO2/TiO2 core-shell PEWE catalyst layers[2] by synchrotron-based ptychographic X-ray laminography (PyXL)[3]. Furthermore, we fabricated CLs at different Ir-loadings between 2.5 – 0.1 mgIr cm-2 depositing them either on the membrane i.e. catalyst-coated membranes (CCM) or on the MPL/PTL i.e. porous transport electrode (PTE). We tested the electrodes in PEWE cells using novel MPLs and standard commercial porous transport layers (PTLs) and compared their electrochemical performance and overpotentials. We observe that ultra-low iridium loadings (0.1 mgIr cm-2) with only relatively small setbacks in performance are possible when using Pt-coated MPLs. Moreover, we correlate the electrochemical results with the 3D structure of the CL by PyXL and the MPL/CL interface by lab-based X-ray tomographic microscopy (Figure 1). Finally, we will discuss the challenges of fabricating low-loaded anodic CLs in CCM and PTE configuration and the advantages of using an MPL in both scenarios.[1] T. Schuler, J. M. Ciccone, B. Krentscher, F. Marone, C. Peter, T. J. Schmidt, F. N. Büchi, Adv. Energy Mater. 2020, 10, 1903216.[2] S. De Angelis, T. Schuler, M. Sabharwal, M. Holler, M. Guizar-Sicairos, E. Müller, F. N. Büchi, Sci Rep 2023, 13, 4280.[3] M. Holler, M. Odstrcil, M. Guizar-Sicairos, M. Lebugle, E. Müller, S. Finizio, G. Tinti, C. David, J. Zusman, W. Unglaub, O. Bunk, J. Raabe, A. F. J. Levi, G. Aeppli, Nature Electronics 2019, 2, 464.Figure 1. Surface renderings from XTM/PyXL and SEM images of porous transport electrodes (PTE, left) and catalyst-coated membranes (CCM, right) of selected samples used in this work. Figure 1

Rosa Indica flower petal anthocyanin mediated biogenic synthesis of PdNPs: Catalyst intended for the Suzuki-Miyaura reactions

In the present work, theRosa Indicaflowerpetals anthocyanin extract has been employed as a “green” natural source for the synthesis and topping of noble metal nanoparticles [palladium nanoparticles (PdNPs)]. TheRosa Indicaflowerpetals anthocyanin extract effectively replaces the toxic chemicals and stabilizers. The formed PdNPs were exposed to their structural properties examination by the Ultraviolet–Visible absorption, Energy-dispersive X- ray and Fourier TransformInfrared spectroscopic analysis. The diffractionpattern of the PdNPs@ rose-anthocyanin to the X-ray recognizes their crystalline nature. In addition, the detailed analysis of the X-ray pattern and microscopic images ofFESEM, TEM reveals that formed PdNP@ rose-anthocyanin possesses FCC crystal lattice with average dimensions of the particle ∼ 12 nm. The EDS analysis shows that the PdNPs@ rose-anthocyanin contains ∼ 80 wt% PdNPs. Further, the PdNP@ rose-anthocyanin were efficiently catalyses the Suzuki-Miyaura cross-coupling (CC) reactions between an aryl halide and phenylboronic acid in the presence of K2CO3 as a suitable base. To catalyse the reaction, PdNPs@ rose-anthocyanin works as heterogeneous catalyst in the absence of heating. Moreover, it provides a good to high yield of the corresponding coupled products under aerobic conditions with optimum reaction time in the aqueous medium, particularly at room temperature with a virtuous Turnover number relative to several synthesized PdNPs. Further, the catalyst PdNP@ rose-anthocyanin shows righteous catalytic activity without significant loss in its efficiency up to four reusable cycles.

Silk Fibroin/Amino Acid Hybrid Organic Piezoelectric-Triboelectric Nanogenerator

Triboelectric nanogenerators (TENG) with great performance and biodegradability are desired for the expansion of novel medical devices and wearable electronics. The present study aims at the preparation of natural silk in the form of silk fibroin (SF) film for utilization in TENG and further improving its output efficiency by embedding organic-piezoelectric gamma-glycine (γ-gly) amino acid to be a hybrid-organic piezoelectric/triboelectric nanogenerator (HO-P/TENG). The attenuated total reflectance infrared spectroscopy (ATR-IR) results demonstrated the N-H, C = O, and C-N bonding for SF and SF/γ-gly, confirming its dominant effect with a strong electron-donating tendency from those amino groups. The scanning electron microscope (SEM) and synchrotron radiation X-ray tomographic microscopy (SR-XTM) images show good dispersibility of incorporated γ-gly on the surface and also inside the SF matrix relating to its content to improve the electrical performance homogeneously. By fabricating the device in the vertical contact-separation mode, the present SF/γ-gly HO-P/TENG at 15 wt% provides the maximum output voltage (VOC ) and current (ISC ) of 81 V and 121 μA with a maximum output power (Pmax ) of 205 μW at the external load resistance of 5 MΩ. This SF-based HO-P/TENG has the advantage of being cost-effective with simple fabrication, demonstrating great promise for practical uses.

Airspace Diameter Map-A Quantitative Measurement of All Pulmonary Airspaces to Characterize Structural Lung Diseases.

(1) Background: Stereological estimations significantly contributed to our understanding of lung anatomy and physiology. Taking stereology fully 3-dimensional facilitates the estimation of novel parameters. (2) Methods: We developed a protocol for the analysis of all airspaces of an entire lung. It includes (i) high-resolution synchrotron radiation-based X-ray tomographic microscopy, (ii) image segmentation using the free machine-learning tool Ilastik and ImageJ, and (iii) calculation of the airspace diameter distribution using a diameter map function. To evaluate the new pipeline, lungs from adult mice with cystic fibrosis (CF)-like lung disease (βENaC-transgenic mice) or mice with elastase-induced emphysema were compared to healthy controls. (3) Results: We were able to show the distribution of airspace diameters throughout the entire lung, as well as separately for the conducting airways and the gas exchange area. In the pathobiological context, we observed an irregular widening of parenchymal airspaces in mice with CF-like lung disease and elastase-induced emphysema. Comparable results were obtained when analyzing lungs imaged with μCT, sugges-ting that our pipeline is applicable to different kinds of imaging modalities. (4) Conclusions: We conclude that the airspace diameter map is well suited for a detailed analysis of unevenly distri-buted structural alterations in chronic muco-obstructive lung diseases such as cystic fibrosis and COPD.

Application of neutron imaging in observing various states of matter inside lithium batteries.

Lithium batteries have been essential technologies and become an integral part of our daily lives, powering a range of devices from phones to electric vehicles. To fully understand and optimize the performance of lithium batteries, it is necessary to investigate their internal states and processes through various characterization methods. Neutron imaging has been an indispensable complementary characterization technique to X-ray imaging or electron microscopy because of the unique interaction principle between neutrons and matter. It provides particular insights into the various states of matter inside lithium batteries, including the Li+ concentration in solid electrodes, the Li plating/stripping behavior of Li-metal anodes, the Li+ diffusion in solid ionic conductors, the distribution of liquid electrolytes and the generation of gases. This review aims to highlight the capabilities and advantages of neutron imaging in characterizing lithium batteries, as well as its current state of application in this field. Additionally, we discuss the potential of neutron imaging to contribute to the ongoing development of advanced batteries through its ability to visualize internal evolution.

Learning heterogeneous reaction kinetics from X-ray videos pixel by pixel

Reaction rates at spatially heterogeneous, unstable interfaces are notoriously difficult to quantify, yet are essential in engineering many chemical systems, such as batteries1 and electrocatalysts2. Experimental characterizations of such materials by operando microscopy produce rich image datasets3–6, but data-driven methods to learn physics from these images are still lacking because of the complex coupling of reaction kinetics, surface chemistry and phase separation7. Here we show that heterogeneous reaction kinetics can be learned from in situ scanning transmission X-ray microscopy (STXM) images of carbon-coated lithium iron phosphate (LFP) nanoparticles. Combining a large dataset of STXM images with a thermodynamically consistent electrochemical phase-field model, partial differential equation (PDE)-constrained optimization and uncertainty quantification, we extract the free-energy landscape and reaction kinetics and verify their consistency with theoretical models. We also simultaneously learn the spatial heterogeneity of the reaction rate, which closely matches the carbon-coating thickness profiles obtained through Auger electron microscopy (AEM). Across 180,000 image pixels, the mean discrepancy with the learned model is remarkably small (<7%) and comparable with experimental noise. Our results open the possibility of learning nonequilibrium material properties beyond the reach of traditional experimental methods and offer a new non-destructive technique for characterizing and optimizing heterogeneous reactive surfaces.

Morphological and lipid metabolism alterations in macrophages exposed to model environmental nanoplastics traced by high-resolution synchrotron techniques.

The release of nanoplastics (NPs) in the environment is a significant health concern for long-term exposed humans. Although their usage has certainly revolutionized several application fields, at nanometer size, NPs can easily interact at the cellular level, resulting in potential harmful effects. Micro/Nanoplastics (M/NPs) have a demonstrated impact on mammalian endocrine components, such as the thyroid, adrenal gland, testes, and ovaries, while more investigations on prenatal and postnatal exposure are urgently required. The number of literature studies on the NPs' presence in biological samples is increasing. However, only a few offer a close study on the model environmental NP-immune system interaction exploited by advanced microscopy techniques. The present study highlights substantial morphological and lipid metabolism alterations in human M1 macrophages exposed to labeled polypropylene and polyvinyl chloride nanoparticles (PP and PVC NPs) (20 μg/ml). The results are interpreted by advanced microscopy techniques combined with standard laboratory tests and fluorescence microscopy. We report the accurate detection of polymeric nanoparticles doped with cadmium selenide quantum dots (CdSe-QDs NPs) by following the Se (L line) X-ray fluorescence emission peak at higher sub-cellular resolution, compared to the supportive light fluorescence microscopy. In addition, scanning transmission X-ray microscopy (STXM) imaging successfully revealed morphological changes in NP-exposed macrophages, providing input for Fourier transform infrared (FTIR) spectroscopy analyses, which underlined the chemical modifications in macromolecular components, specifically in lipid response. The present evidence was confirmed by quantifying the lipid droplet (LD) contents in PP and PVC NPs-exposed macrophages (0-100 μg/ml) by Oil Red O staining. Hence, even at experimental NPs' concentrations and incubation time, they do not significantly affect cell viability; they cause an evident lipid metabolism impairment, a hallmark of phagocytosis and oxidative stress.

MicroCT data provide evidence correcting the previous misidentification of an Eocene amber beetle (Coleoptera, Cicindelidae) as an extant species

The fossil record suggests some insect species have a marked longevity. The oldest fossils purported to represent extant insect species are from the Oligocene and Eocene. One of the most cited fossils is the extant tiger beetle Tetracha carolina (Coleoptera: Cicindelidae) that was identified over a century ago by Walther Horn in Eocene Baltic amber. We examined this and compared it to the previously described cincindelid Baltic amber fossil Palaeoiresina cassolai using X-ray microscopy and 3D imaging techniques. We conclude that Horn’s fossil tiger beetle specimen is conspecific with the Eocene P. cassolai and is a member of an extinct stem group lineage of Cicindelidae. Based on a review of all the tiger beetle fossils described from Cretaceous and Paleogene deposits, we found that the assignment of these fossil species to extant lineages is not supported. There are currently no synapomorphies known from fossils that can provide evidence for Cretaceous Manticorni or Megacephalini nor is there evidence for Eocene Iresina. We provide evidence that rejects the idea of a recent beetle species persisting since the Eocene period, which is crucial for using the currently known fossil Cicindelidae species to calibrate divergence dating of beetle phylogenies.

Development of soft X-ray ptychography and fluorescence microscopy system using total-reflection wolter mirror and application to measurement of drug-treated mammalian cells

We developed a soft X-ray microscopic imaging system, CARROT, that combines ptychography and fluorescence X-ray microscopy using a total-reflection Wolter mirror illumination system. The system offers advantages such as achromaticity and long working distances, enabling seamless application to a wide wavelength range. We demonstrated high-resolution imaging of cellular structures and sub-micrometer-scale changes induced by drug administration in mammalian cells. We further showcased the capability to seamlessly switch from ptychography measurements to X-ray fluorescence measurements at different wavelengths to map elemental distributions within cells. Our findings suggest that this system can be used for investigating the correlation between intracellular structures and elemental distribution, as well as for multimodal measurements of visible light fluorescence, Raman scattering, and soft X-rays to provide valuable insights into understanding intracellular dynamics.

X-ray ptychographic and fluorescence microscopy using virtual single-pixel imaging based deconvolution with accurate probe images.

Simultaneous measurement of X-ray ptychography and fluorescence microscopy allows high-resolution and high-sensitivity observations of the microstructure and trace-element distribution of a sample. In this paper, we propose a method for improving scanning fluorescence X-ray microscopy (SFXM) images, in which the SFXM image is deconvolved via virtual single-pixel imaging using different probe images for each scanning point obtained by X-ray ptychographic reconstruction. Numerical simulations confirmed that this method can increase the spatial resolution while suppressing artifacts caused by probe imprecision, e.g., probe position errors and wavefront changes. The method also worked well in synchrotron radiation experiments to increase the spatial resolution and was applied to the observation of S element maps of ZnS particles.

Structural, optical, and electrical properties of cellulose/titanate nanosheets composite with enhanced protection against gamma irradiation

Two-dimensional (2D) materials have emerged as a promising functional filler in nanocomposites due to their unique anisotropy and resilience to harsh conditions. We report herein the use of Ti0.91O2 nanosheets as a protective component against γ-irradiation to cellulose paper. The titanate nanosheets were prepared via a sequence of solid-state synthesis of lepidocrocite-type Cs0.7Ti1.825O4, proton exchange to H0.7Ti1.825O4·H2O, and exfoliation with tetrabutylammonium hydroxide. The nanosheets were incorporated into the commercial cellulose filter paper by a simple dip coating up to 0.6 mg cm−2, equivalent to 10 wt% TiO2. The nanosheets distribution was demonstrated by energy dispersive X-ray (EDX) mapping, synchrotron radiation X-ray tomographic microscopy (SRXTM), and atomic force microscopy (AFM). It is found that γ-irradiation (up to 50 kGy) destroyed the cellulose Iβ crystallinity of uncoated paper, but this is less pronounced in the cellulose/titanate nanosheets composite. This was also confirmed by the lack of a 235 nm-absorption characteristics of irradiation-induced decomposition product(s) in nanosheets-containing papers, which also exhibit UVA shielding property. The coated samples remained white while the uncoated ones were darkened with γ-irradiation. In addition, the nanosheets-coated papers showed dielectric permittivity, loss tangent, and AC conductivity which were invariant of the γ-dose, unlike those from the uncoated ones. Our work demonstrates the use of lead-free Ti0.91O2 nanosheets as a γ-shielding component to slow down/prevent structural, optical, and electrical properties damages in cellulose paper, which could extend to other nature-derived materials.

Deformity or variation? Phenotypic diversity in the zebrafish vertebral column.

Vertebral bodies are composed of two types of metameric elements, centra and arches, each of which is considered as a developmental module. Most parts of the teleost vertebral column have a one-to-one relationship between centra and arches, although, in all teleosts, this one-to-one relationship is lost in the caudal fin endoskeleton. Deviation from the one-to-one relationship occurs in most vertebrates, related to changes in the number of vertebral centra or to a change in the number of arches. In zebrafish, deviations also occur predominantly in the caudal region of the vertebral column. In-depth phenotypic analysis of wild-type zebrafish was performed using whole-mount stained samples, histological analyses and synchrotron radiation X-ray tomographic microscopy 3D reconstructions. Three deviant centra phenotypes were observed: (i) fusion of two vertebral centra, (ii) wedge-shaped hemivertebrae and (iii) centra with reduced length. Neural and haemal arches and their spines displayed bilateral and unilateral variations that resemble vertebral column phenotypes of stem-ward actinopterygians or other gnathostomes as well as pathological conditions in extant species. Whether it is possible to distinguish variations from pathological alterations and whether alterations resemble ancestral conditions is discussed in the context of centra and arch variations in other vertebrate groups and basal actinopterygian species.

Artefacts from Ban Chiang, Thailand: Pre-metal Age cord-marked pottery

Abstract Pottery excavated from the archeological UNESCO world heritage site Ban Chiang in Thailand stem from distinct periods. Black vessels with cord-mark design from Pre-metal Age (ca. 3000–1000 BC), Bronze Age pottery (ca 1000–300 BC) with yellow-brown surface and Iron Age samples (ca. 300 BC–200 AD) with red pictorial surface patterns. In a previous work [Bismayer U., Srilomsak S., Treekamol Y., Tanthanuch W., Suriyatham K. Artefacts from Ban Chiang, Thailand: pottery with hematite-red geometric patterns. Z. Kristallogr. 2020, 235, 559–568] we studied the mineralogical composition and their surface colour materials of shards from Bronze and Iron Age. In this work we focus on bulk features of the dark Pre-metal Age cord-marked ceramic shard PSN2-S10E13 and compare its elemental and mineralogical composition with bulk composition of sample 5412-S6E15 from Bronze Age. Experimental techniques are electron microprobe, X-ray powder diffraction, FTIR spectroscopy, optical microscopy and X-ray tomographic microscopy (XTM). Sample PSN2-S10E13 contains more quartz than 5412-S6E15. In the bulk of the Pre-metal Age shard, diffraction signals of mullite occur, indicating higher firing temperatures compared to the younger sample. Phyllosilicate signals are seen in FTIR spectra of both shards. E-modes of quartz dominate FTIR spectra of both samples. Optical thin sections show voids around micro-particles in PSN2-S10E13 and XTM indicates that the pore volume percentage of sample PSN2-S10E13 is higher than in 5412-S6E15. Because of the large age gap to younger samples from Ban Chiang, the proper age of our oldest sample PSN2-S10E13 was determined using an accelerator mass spectrometer (AMS) by simultaneous 14C/12C and 13C/12C isotope ratio measurements which yielded a radiocarbon age of 3609 ± 29 BP (resp. 1659 ± 29 BC).

Contact electrification of porous PDMS-nickel ferrite composites for effective energy harvesting

Energy harvesting technologies are becoming popular owing to their usage in the operation of low-power consumer electronics and as an alternative power source. Specifically, triboelectric nanogenerators (TENGs) have drawn much attention as they can efficiently scavenge waste mechanical energy into electrical output. Careful material selections can further improve the performance of TENGs. In this work, a spinel ferrite material with the chemical formula NiFe2O4 (NFO abbreviated further) is synthesized using a solid-state reaction route. The structural and magnetic property of the NFO has been studied, showing the cubic symmetry and ferromagnetic nature of the sample. The 3D tomography images of the PDMS-NFO composites were carried out using X-ray tomographic microscopy. To enhance the performance of the TENGs, we adopted a porous media by evaporation of water during the curing process of PDMS-NFO composites. A single-electrode operating mode was adopted for TENG fabrication. The electrical response of the device was carried out using different wt% and frequencies. The 12 wt% of NFO in PDMS (PN12 device) delivered a voltage, current, and charge of 60 V, 300 nA, and 34 nC, respectively. The charge density of the plain and porous composite-based TENG was compared to confirm the enhancement of the charge produced on the triboelectric layers. The commercial capacitors and energy harvesting based on a smart home were demonstrated using the TENG devices.

X-ray tomographic microscopy of Eocene coprolites from Pipestone Springs Main Pocket, southwest Montana

The Eocene Pipestone Springs Main Pocket (Renova Formation, Jefferson County, Montana, United States of America) is a locality renowned for its diverse Chadronian (late Eocene; ∼38–33.9 million years ago) mammalian fauna and abundant coprolites. Two distinct coprolite size classes were previously identified in the trace fossil assemblage from which we selected representatives to investigate feeding behaviors and dietary selection of the producers. A subset of the selected coprolites was analyzed based on their compositional and taphonomic attributes using non-destructive x-ray tomographic microscopy in combination with more traditional methods including thin-section petrography, scanning electron microscopy, and energy dispersive spectroscopy. Among the features extracted in the tomographic data were skeletal fragments, including those showing evidence of bone-crushing; delicate hair molds; encrusted lithic fragments; and several irregular pores and cracks throughout the coprolites. Segmentation and volumetric renders permit quantitative assessment of the relative proportions of inclusions, revealing porosity as a primary volumetric element aside from the matrix and bone inclusions. There was no significant difference in the total volume of bone extracted between coprolite size class, though the smaller coprolites preserved a relatively higher volumetric proportion of undigested skeletal material. This multi-visualization approach provides a means to observe and evaluate differences in the coprolite gross morphology and inclusions across the two size classes, thereby offering valuable insights into the broader paleoecology of the Pipestone Springs Main Pocket coprolite producers and holding promise for comparable paleo-dietary studies of other coprolite-rich deposits.