Synchrotron Sciences

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A Highly Sensitive Chitosan-Based SERS Sensor for the Trace Detection of a Model Cationic Dye
(MDPI, 2024-08-28) Vafakish, Bahareh; Wilson, Lee
The rapid detection of contaminants in water resources is vital for safeguarding the environment, where the use of eco-friendly materials for water monitoring technologies has become increasingly prioritized. In this context, the role of biocomposites in the development of a SERS sensor is reported in this study. Grafted chitosan was employed as a matrix support for Ag nanoparticles (NPs) for the surface-enhanced Raman spectroscopy (SERS). Chitosan (CS) was decorated with thiol and carboxylic acid groups by incorporating S-acetyl mercaptosuccinic anhydride (SAMSA) to yield CS-SAMSA. Then, Ag NPs were immobilized onto the CS-SAMSA (Ag@CS-SAMSA) and characterized by spectral methods (IR, Raman, NIR, solid state 13C NMR with CP-MAS, XPS, and TEM). Ag@CS-SAMSA was evaluated as a substrate for SERS, where methylene blue (MB) was used as a model dye adsorbate. The Ag@CS-SAMSA sensor demonstrated a high sensitivity (with an enhancement factor ca. 108) and reusability over three cycles, with acceptable reproducibility and storage stability. The Raman imaging revealed a large SERS effect, whereas the MB detection varied from 1–100 μM. The limits of detection (LOD) and quantitation (LOQ) of the biocomposite sensor were characterized, revealing properties that rival current state-of-the-art systems. The dye adsorption profiles were studied via SERS by fitting the isotherm results with the Hill model to yield the ΔG°ads for the adsorption process. This research demonstrates a sustainable dual-function biocomposite with tailored adsorption and sensing properties suitable for potential utility in advanced water treatment technology and environmental monitoring applications.
A Novel Device for Micro-Droplets Generation Based on the Stepwise Membrane Emulsification Principle
(MDPI, 2024-08) Lei, Lei; Achenbach, Sven; Wells, Garth; Zhang, Hongbo; Zhang, Wenjun
This paper presents a novel design of the device to generate microspheres or micro-droplets based on the membrane emulsification principle. Specifically, the novelty of the device lies in a proposed two-layer or stepwise (by generalization) membrane structure. An important benefit of the stepwise membrane is that it can be fabricated with the low-cost material (SU-8) and using the conventional lithography technology along with a conventional image-based alignment technique. The experiment to examine the effectiveness of the proposed membrane was conducted, and the result shows that microspheres with the size of 2.3 μm and with the size uniformity of 0.8 μm can be achieved, which meets the requirements for most applications in industries. It is noted that the traditional membrane emulsification method can only produce microspheres of around 20 μm. The main contribution of this paper is thus the new design principle of membranes (i.e., stepwise structure), which can be made by the cost-effective fabrication technique, for high performance of droplets production.
Caffeine and Nicotine with N-Substituted Diazirine Photoaffinity Labels Form Adducts at Tyrosine-39 of α-Synuclein
(ACS Publications, 0002-04) Mejia-Gutierrez, Melissa; Moser, Brigitte; Pirlot, Marissa; Zhang, Haixia; Chumala, Paulos; Katselis, George S.; Palmer, David R.; Krol, Ed S.
Aggregates of the protein α-synuclein are found in Lewy bodies in the brains of Parkinson’s disease (PD) patients. Small molecules that can attenuate or halt α-synuclein aggregation have been studied as potential therapeutics for PD. However, we have a limited understanding of how these molecules bind to α-synuclein. We previously identified that caffeine, nicotine, and 1-aminoindan all bind to both the N- and C-terminus of α-synuclein, although the binding location remains unknown. In an effort to identify these binding regions on α-synuclein, we synthesized diazirine photoaffinity probes attached to caffeine (C-Dz), nicotine (N-Dz), and 1-aminoindan (I-Dz) and allowed each to react with α-synuclein in vitro. We then treated the incubation mixture with trypsin and employed time-of-flight mass spectrometry to analyze the resulting peptides. Our findings reveal a distinctive binding pattern among the probes: C–Dz forms covalent bonds with Tyr-39 and Glu-20, while N-Dz selectively forms a covalent bond with Tyr-39. Intriguingly, we could not detect the labeling of I-Dz to any specific amino acids. All of the diazirine-bound peptides were found near the N-terminus. Our results suggest that the N-terminal region near Tyr-39 bears further study to elucidate the binding interactions of small molecules with α-synuclein and may be a target for anti-PD agents.
Data-driven exploration of weak coordination microenvironment in solid-state electrolyte for safe and energy-dense batteries
(Springer Nature, 2025) Lao, Zhoujie; Tao, Kehao; Xiao, Xiao; Qu, Haotian; Wu, Xinru; Han, Zhiyuan; Gao, Runhua; Wang, Jian; Wu, Xian; Chen, An; Shi, Lei; Chang, Chengshuai; Song, Yanze; Wang, Xiangyu; Li, Jinjin; Zhu, Yanfei; Zhou, Guangmin
The unsatisfactory ionic conductivity of solid polymer electrolytes hinders their practical use as substitutes for liquid electrolytes to address safety concerns. Although various plasticizers have been introduced to improve lithium-ion conduction kinetics, the lack of microenvironment understanding impedes the rational design of high-performance polymer electrolytes. Here, we design a class of Hofmann complexes that offer continuous two-dimensional lithium-ion conduction channels with functional ligands, creating highly conductive electrolytes. Assisting with unsupervised learning, we use Climbing Image-Nudged Elastic Band simulations to screen lithium-ion conductors and screen out five potential candidates that elucidate the impact of lithium coordination environment on conduction behavior. By adjusting the covalency competition between Metal−O and Li−O bonds within Hofmann complexes, we can manipulate weak coordination environment of lithium-ion for rapid conduction kinetics. Li | |sulfurized polyacrylonitrile (SPAN) cell using solid-state polymer electrolytes with predicted Co(dimethylformamide)2Ni(CN)4 delivers an initial discharge capacity of 1264 mAh g−1 with a capacity retention of 65% after 500 cycles at 0.2 C (335 mA g−1), at 30 °C ± 3 °C. The assembled 0.6 Ah Li | |SPAN pouch cell delivers an areal discharge capacity of 3.8 mAh cm−2 at the second cycle with a solid electrolyte areal mass loading of 18.6 mg cm−2 (mass-to-capacity ratio of 4.9).
Development of a Small-Scale Test Facility for Effectiveness Evaluation of Fixed-Bed Regenerators
(Elsevier, 2020-06-25) Krishnan, Easwaran Nampoothiry; Ramin, Hadi; Shakouri, Mohsen; Wilson, Lee D; Simonson, Carey
Fixed-bed regenerators (FBR) transfer heat (and moisture) between supply and exhaust air streams in heating, ventilating and air conditioning (HVAC) systems to reduce building energy consumption. This paper presents a new small-scale testing facility to evaluate the performance (i.e. sensible effectiveness) of FBRs for HVAC applications. The major contributions of this paper are: development of a new small-scale experimental facility and methodology for testing FBRs, quantification of uncertainties, and verification of small-scale test data over a large range of FBR design conditions. A numerical model and two well-known design correlations are used to verify the results and testing methodology. The advantages of small-scale testing are that it requires low volume of conditioned airflow, has low uncertainty, requires less exchanger material and has a low cost per test. Moreover, the small-scale testing methodology of FBR would benefit heat exchanger manufacturers to perform detailed sensitivity studies and optimize the exchanger performance over a wide range of design and operating parameters prior to the fabrication of full-scale exchangers.
Discovery of Ge2+ in quartz: Evidence from EPR/XAS experiments and DFT calculations, and implications for Ge/Si systematics
(Geochimica et Cosmochimica Acta, 2025-01) Mashkovtsev, Rudolf I.; Botis, Sanda M.; Lin, Jinru; Deevsalar, Reza; Cheung, Leo Ka Long; Wiens, Eli; Tunc, Ayetullah; Chen, Ning; Chernikov, Roman; Pan, Yuanming
The Ge/Si systematics as a biogeochemical tracer with diverse applications from paleo-climatic reconstructions to discrimination of magma sources and elucidation of Earth’s early evolution hinges on the coherent behavior of these elements in the tetravalent state. However, determination of Ge speciation in quartz and other silicate minerals is technically challenging because this element almost invariably occurs at several parts per million or lower concentrations. This contribution reports a detailed study of Ge speciation in quartz by combining single-crystal electron paramagnetic resonance spectroscopy, synchrotron X-ray absorption spectroscopy, and ab initio theoretical calculations. Our single-crystal and powder electron paramagnetic resonance spectra of artificially irradiated quartz reveal a suite of previously reported Ge electron centers (GECs) such as [GeHLi2]0 and [GeHH2]0 centers as well as a new GeHLi center. These multiply-compensated GECs in artificially irradiated quartz suggest that their precursors before irradiation involve the diamagnetic Ge2+ state. Ge K-edge X-ray absorption spectroscopic data of selected quartz samples further support the presence of Ge2+. Theoretical calculations reproduce the experimental 1H and 7Li hyperfine constants of the [GeHLi2]0 center and suggest the new GeHLi center to be a new variant of the multiply-compensated GECs with the second monovalent cation in a distant c-axis channel, again supporting the Ge2+ state. The presence of Ge2+ in sedimentary-diagenetic quartz, in particular, challenges existing thermodynamic data that Ge4+ is the only stable oxidation state in aqueous solutions under near-surface conditions. Incorporation of Ge2+ in quartz and other silicates can significantly affect Ge/Si fractionations, with important implications for their applications as a biogeochemical tracer from surficial environments to magmatic-hydrothermal systems, Earth’s core-mantle differentiation, and other planetary processes.
Discovery of Ge2+ in quartz: Evidence from EPR/XAS experiments and DFT calculations, and implications for Ge/Si systematics
(Elsevier, 2025-03-15) Mashkovtsev, Rudolf I.; Botis, Sanda M.; Lin, Jinru; Deevsalar, Reza; Cheung, Leo Ka Long; Wiens, Eli; Tunc, Ayetullah; Chen, Ning; Chernikov, Roman; Pan, Yuanming
The Ge/Si systematics as a biogeochemical tracer with diverse applications from paleo-climatic reconstructions to discrimination of magma sources and elucidation of Earth’s early evolution hinges on the coherent behavior of these elements in the tetravalent state. However, determination of Ge speciation in quartz and other silicate minerals is technically challenging because this element almost invariably occurs at several parts per million or lower concentrations. This contribution reports a detailed study of Ge speciation in quartz by combining single-crystal electron paramagnetic resonance spectroscopy, synchrotron X-ray absorption spectroscopy, and ab initio theoretical calculations. Our single-crystal and powder electron paramagnetic resonance spectra of artificially irradiated quartz reveal a suite of previously reported Ge electron centers (GECs) such as [GeHLi2]0 and [GeHH2]0 centers as well as a new GeHLi center. These multiply-compensated GECs in artificially irradiated quartz suggest that their precursors before irradiation involve the diamagnetic Ge2+ state. Ge K-edge X-ray absorption spectroscopic data of selected quartz samples further support the presence of Ge2+. Theoretical calculations reproduce the experimental 1H and 7Li hyperfine constants of the [GeHLi2]0 center and suggest the new GeHLi center to be a new variant of the multiply-compensated GECs with the second monovalent cation in a distant c-axis channel, again supporting the Ge2+ state. The presence of Ge2+ in sedimentary-diagenetic quartz, in particular, challenges existing thermodynamic data that Ge4+ is the only stable oxidation state in aqueous solutions under near-surface conditions. Incorporation of Ge2+ in quartz and other silicates can significantly affect Ge/Si fractionations, with important implications for their applications as a biogeochemical tracer from surficial environments to magmatic-hydrothermal systems, Earth’s core-mantle differentiation, and other planetary processes.
Distribution and speciation of uranium in pristine Tethyan phosphorites, Ionian Zone, Albania: Insights from synchrotron XRF/XANES analyses
(Elsevier, 2025) Tunc, Ayetullah; Celik, Yakup; Fociro, Ana; Deevsalar, Reza; Wang, Xinyi; Bondici, Viorica F.; Feng, Renfei; Chen, Ning; Pan, Yuanming
Tethyan phosphorites are globally the most important source of phosphate fertilizers and occasionally contain elevated contents of uranium (U) and rare-earth elements (REE). Extensive research has been conducted to elucidate Tethyan phosphorite occurrences, geochemistry, and formation mechanisms. However, the distribution and primary speciation of uranium in Tethyan phosphorites, during sedimentation and early diagenesis, remain unclear due to the scarcity of pristine phosphorites. This contribution integrates field and laboratory studies of Tethyan phosphorites of the Ionian Zone from Albania, including petrography, paragenetic relationships, chemical compositions, and bulk and microbeam synchrotron U L3-edge X-ray absorption near-edge structure (XANES) and microbeam synchrotron X-ray fluorescence (μsXRF) mapping. These data provide a molecular-level understanding of the distribution, speciation, and enrichment mechanisms of uranium in pristine (primary) phosphorites. The phosphorites in the Ionian Zone of Albania occur as stratiform beds reaching several meters thick, lateral extension of up to 200 m, and U concentrations of up to 210 ppm. The phosphorites show three stages of mineral assemblages: primary mineralization dominated by carbonate-rich fluorapatite, organic matter, and phosphatized thin bivalve shells; followed by vein-filling calcite and pyrite; and finally, pyrite oxidation to iron oxides during surface weathering. The μsXRF mapping reveals positive correlations between U vs. P, S, and Sr, while bulk and microbeam U L3-edge XANES data indicate dominant U4+ species in carbonate-rich fluorapatite. The results collectively suggest that uranium occurs as U4+ in pristine carbonate-rich fluorapatite, formed in a low-energy, oxygen-minimum marine environment. These findings not only enhance our understanding of the formation mechanisms of uranium-bearing Tethyan phosphorites but also provide a baseline for determining uranium enrichment mechanisms in marine phosphorites worldwide.
Drift-kinetic PIC simulations of plasma flow and energy transport in the magnetic mirror configuration
(AIP Publishing, 2025-03) Tyushev, Mikhail; Smolyakov, Andrei; Sabo, Andy; Groenewald, Roelof Erasmus; Necas, Ales; yushmanov, peter
Plasma flow and acceleration in a magnetic mirror configuration are studied using a drift-kinetic particles-in-cell model in the paraxial approximation, with an emphasis on finite temperature effects and energy transport. Energy conversion between electrons and ions, overall energy balance, and axial energy losses are investigated. The simulations of plasma flow, acceleration, and energy transport in the magnetic mirror are extended into the high-density regimes with implicit particle-in-cell simulations. It is shown that profiles of the anisotropic ion temperatures and heat fluxes obtained with the full drift-kinetic model compare favorably with the results of a fluid model, which includes collisionless ion heat fluxes beyond the two-pressure adiabatic equations. The effects of collisions on trapped electrons and the resulting impacts on electron temperature and electric field profiles are investigated using a model collision operator.
Examining Order–Disorder Structural Transition of Gd2Zr2–xCexO7 Using Synchrotron Techniques
(ASC, 2025-03) Kaur, Khushveer; King, Graham; Grosvenor, Andrew
Depending on the radius ratio of A and B site cations, A2B2O7-type oxides can adopt different crystal structures, including the pyrochlore-, defect fluorite-, or bixbyite-type structures. Gd2Zr2O7 with a rGd3+/rZr4+ ratio of 1.46 is an example that exhibits a polymorphic transition between the pyrochlore- and defect fluorite-type structures. To delve deeper into these polymorphic transitions, Ce was introduced as a substitute in the B-site of Gd2Zr2O7. Gd2Zr2–xCexO7 (0 ≤ x ≤ 2) was synthesized using a coprecipitation method and annealed at 1400 °C. Previous investigations yielded disparate results regarding the structures adopted due to the challenge of detecting the low-intensity superstructural peaks associated with the pyrochlore and bixbyite structures using conventional lab-based X-ray diffraction (XRD) instruments. Utilizing synchrotron XRD with a high signal/noise ratio resolves these contradictions and aids in the structure analysis for Gd2Zr2–xCexO7. Based on synchrotron XRD data, a combination of defect fluorite and pyrochlore phases was observed for x = 0–0.25, the defect fluorite structure was adopted when x = 0.5–1.75, and the bixbyite structure was observed when x = 2. Ce L3 and Zr K-edge X-ray absorption near edge spectroscopy (XANES) spectra revealed that both cations were present in 4+ oxidation states.
High-Sensitivity and Flexible Motion Sensing Enabled by Robust, Self-Healing Wood-Based Anisotropic Hydrogel Composites
(Wiley, 2025-02-07) Teng, Youchao; Zhang, Zhilei; Cui, Yunqi; Su, Zhe; Godwin, Matthew; Chung, TzuChun; Zhou, Yongzan; Leontowich, Adam L.G.; Islam, Muhammad Shahidul; Tam, Kam C.; Wu, Yimin A.
By integrating polyvinyl alcohol (PVA)-borate-tannic acid (TA)-sodium sulfate into cellulosic wood matrices, a novel wood-basedPVA-borate-TA-sodium sulfate (WPBTS) hydrogel is successfully synthesized. Through a multicomponent synergistic design combining natural lignocellulose, PVA, borax, TA, and sodium sulfate, multiple dynamic cross-linking mechanisms—dynamic borate bonding, hydrogen bonding, and metal-ligand interactions—are established, resulting in WPBTS hydrogels with exceptional mechanical properties and self-healing capabilities. The mechanical strength of the WPBTS hydrogel reached an impressive 19.8 MPa, a 45-fold increase compared to PVA-borax-tannic acid (PBTS) hydrogels. Furthermore, the assembled WPBTS hydrogel-based flexible sensor demonstrates a remarkably fast response time of just 20 ms and maintains excellent performance in challenging simulated saline environments. This innovation represents a significant advancement in sensor technology and highlights the potential for transformative applications in complex and demanding scenarios.
Hydrogen uptake and embrittlement behavior in pipeline steels: Insights from slow strain rate testing and synchrotron micro-CT imaging
(Engineering Failure Analysis, 2025-02) Jack, Tonye; Webb, Mark Adam; Rahman, K.M. Mostafijur; Fazeli, Fateh; Szpunar, Jerzy
Hydrogen embrittlement (HE) presents a major challenge to the integrity of steel pipelines, often leading to premature failure. Traditional methods using two-dimensional (2D) analysis of damaged structures, often overlook critical features related to failure. Hence, this study investigates the hydrogen embrittlement susceptibility of two pipeline steels, X60 and X65, using a combination of mechanical testing, hydrogen diffusion and trapping studies, microstructural characterization, and synchrotron micro-computed tomography (micro-CT) imaging. The results highlight the critical role of hydrogen trapping and retention in HE, with steel microstructure significantly affecting hydrogen uptake and diffusion as well as crack nucleation and propagation. Synchrotron micro-CT imaging provided more accurate crack pattern assessments than traditional 2D methods, revealing potential misinterpretations from 2D cross-sectional analysis. This study concludes that simultaneous hydrogen ingress and mechanical loading is more damaging than pre-charging with high hydrogen concentrations, and that hydrogen retention capacity plays a greater role in embrittlement behavior than crack initiation. The failure mechanism of the hydrogen-charged steels shifted from being plasticity-based to decohesion-driven, based on the hydrogen content and retention in the steel, which is in line with the unified HELP+HEDE model.
Impact of Radiofrequency and Microwave Heating on the Nutritional and Antinutritional Properties of Pulses: A Review
(Wiley, 2025-02) Das, Pabitra Chandra; Baik, Oon-Doo; Tabil, Lope G.; Rajagopalan, Nandhakishore
Pulses, which are the dry seeds of legume crops, have gained global popularity, leading to a notable rise in their production. They are rich in protein, minerals, fibers, and low in fat content. However, they have some antinutrients that need to be removed. Novel techniques like radiofrequency (RF) and microwave (MW) heating can enhance pulse quality by reducing the antinutrients. The key mechanism behind this improvement is the rapid heating that disrupts the native structure of the pulses. These technologies offer several advantages, including speed, consistency, sustainability, and energy efficiency. The effectiveness of RF and MW processing depends on the heating conditions used and the kind of pulses being treated. This review highlights the mechanisms and influencing factors of RF and MW heating as well as their effect on the nutritional and antinutritional qualities of various pulses. Additionally, the limitations of these technologies are summarized, and future research prospects focusing on pulse processing are identified.
Isolated iridium oxide sites on modified carbon nitride for photoreforming of plastic derivatives
(Springer Nature, 2025-03-24) Kumar, Pawan; Zhang, Hongguang; Yohannes, Asfaw G.; Wang, Jiu; Zeraati, Ali Shayesteh; Roy, Soumyabrata; Wang, Xiyang; Kannimuthu, Karthick; Askar, Abdelrahman M.; Miller, Kirsten A.; Ling, Kexin; Adnan, Muflih; Hung, Sung-Fu; Ma, Jian-Jie; Huang, Wei-Hsiang; Trivedi, Dhwanil; Molina, Maria; Zhao, Heng; Martí, Angel A.; Leontowich, Adam F. G.; Shimizu, George K. H.; Sinton, David; Adachi, Michael M.; Wu, Yimin A.; Ajayan, Pulickel M.; Siahrostami, Samira; Hu, Jinguang; Kibria, Md Golam
The rising concentration of plastics due to extensive disposal and inefficient recycling of plastic waste poses an imminent and critical threat to the environment and ecological systems. Photocatalytic reforming of plastic derivatives to value-added chemicals under ambient conditions proceeds at lower oxidation potential which galvanizes the hydrogen evolution. We report the synthesis of a narrow band gap NCN-functionalized O-bridged carbon nitride (MC) through condensation polymerization of hydrogen-bonded melem (M)-cyameluric acid (C) macromolecular aggregate. The MC scaffold hosts well-dispersed Ir single atom (MCIrSA) sites which catalyze oxidative photoreforming of alkali-treated polylactic acid (PLA) and polyethylene terephthalate (PET) derivatives to produce H2 at a rate of 147.5 and 29.58 μmol g−1cat h−1 under AM1.5G irradiation. Solid-state electron paramagnetic resonance (EPR) and time-resolved photoluminescence (TRPL) reveals efficient charge carrier generation and separation in MCIrSA. X-ray absorption spectroscopy (XAS) and Bader charge analysis reveal undercoordinated IrN2O2 SA sites pinned in C6N7 moieties leading to efficient hole quenching. The liquid phase EPR, in situ FTIR and density functional theory (DFT) studies validate the facile generation of •OH radicals due to the evolution of O-Ir-OH transient species with weak Ir--OH desorption energy barrier.
Microfabrication Process Development for a Polymer-Based Lab-on-Chip Concept Applied in Attenuated Total Reflection Fourier Transform Infrared Spectroelectrochemistry
(MDPI, 2023-07) Atkinson, Noah; Morhart, Tyler A.; Wells, Garth; Flaman, Grace T.; Petro, Eric; Read, Stuart; Rosendahl, Scott M.; Burgess, Ian J.; Achenbach, Sven
Micro electro-mechanical systems (MEMS) combining sensing and microfluidics functionalities, as are common in Lab-on-Chip (LoC) devices, are increasingly based on polymers. Benefits of polymers include tunable material properties, the possibility of surface functionalization, compatibility with many micro and nano patterning techniques, and optical transparency. Often, additional materials, such as metals, ceramics, or silicon, are needed for functional or auxiliary purposes, e.g., as electrodes. Hybrid patterning and integration of material composites require an increasing range of fabrication approaches, which must often be newly developed or at least adapted and optimized. Here, a microfabrication process concept is developed that allows one to implement attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) and electrochemistry on an LoC device. It is designed to spatially resolve chemical sensitivity and selectivity, which are instrumental for the detection of chemical distributions, e.g., during on-flow chemical and biological reaction chemistry. The processing sequence involves (i) direct-write and soft-contact UV lithography in SUEX dry resist and replication in polydimethylsiloxane (PDMS) elastomers as the fluidic structure; (ii) surface functionalization of PDMS with oxygen plasma, 3-aminopropyl-triethoxysilane (APTES), and a UV-curable glue (NOA 73) for bonding the fluidic structure to the substrate; (iii) double-sided patterning of silicon nitride-coated silicon wafers serving as the ATR-FTIR-active internal reflection element (IRE) on one side and the electrode-covered substrate for microfluidics on the back side with lift-off and sputter-based patterning of gold electrodes; and (iv) a custom-designed active vacuum positioning and alignment setup. Fluidic channels of 100 μm height and 600 μm width in 5 mm thick PDMS were fabricated on 2” and 4” demonstrators. Electrochemistry on-chip functionality was demonstrated by cyclic voltammetry (CV) of redox reactions involving iron cyanides in different oxidation states. Further, ATR-FTIR measurements of laminar co-flows of H2O and D2O demonstrated the chemical mapping capabilities of the modular fabrication concept of the LoC devices.
Microfluidic devices for the detection of viruses: aspects of emergency fabrication during the COVID-19 pandemic and other outbreaks
(The Royal Society Publishing, 2020-11) Berkenbrock, José Alvim; Grecco-Machado, Rafaela; Achenbach, Sven
Extensive testing of populations against COVID-19 has been suggested as a game-changer quest to control the spread of this contagious disease and to avoid further disruption in our social, healthcare and economical systems. Nonetheless, testing millions of people for a new virus brings about quite a few challenges. The development of effective tests for the new coronavirus has become a worldwide task that relies on recent discoveries and lessons learned from past outbreaks. In this work, we review the most recent publications on microfluidics devices for the detection of viruses. The topics of discussion include different detection approaches, methods of signalling and fabrication techniques. Besides the miniaturization of traditional benchtop detection assays, approaches such as electrochemical analyses, field-effect transistors and resistive pulse sensors are considered. For emergency fabrication of quick test kits, the local capabilities must be evaluated, and the joint work of universities, industries, and governments seems to be an unequivocal necessity.
MugenNet: A Novel Combined Convolution Neural Network and Transformer Network with Application in Colonic Polyp Image Segmentation
(Sensors, 2024-11) Peng, Chen; Qian, Zhiqin; Wang, Kunyu; Zhang, Lanzhu; Luo, Qi; Bi, Zhuming; Zhang, Wenjun
Accurate polyp image segmentation is of great significance, because it can help in the detection of polyps. Convolutional neural network (CNN) is a common automatic segmentation method, but its main disadvantage is the long training time. Transformer is another method that can be adapted to the automatic segmentation method by employing a self-attention mechanism, which essentially assigns different importance weights to each piece of information, thus achieving high computational efficiency during segmentation. However, a potential drawback with Transformer is the risk of information loss. The study reported in this paper employed the well-known hybridization principle to propose a method to combine CNN and Transformer to retain the strengths of both. Specifically, this study applied this method to the early detection of colonic polyps and to implement a model called MugenNet for colonic polyp image segmentation. We conducted a comprehensive experiment to compare MugenNet with other CNN models on five publicly available datasets. An ablation experiment on MugenNet was conducted as well. The experimental results showed that MugenNet can achieve a mean Dice of 0.714 on the ETIS dataset, which is the optimal performance on this dataset compared to other models, with an inference speed of 56 FPS. The overall outcome of this study is a method to optimally combine two methods of machine learning which are complementary to each other.
Negative Charge Transfer Energy in Correlated Compounds
(Physical Society of Japan, 2024-09-13) Green, Robert J.; Sawatzky, George A.
In correlated compounds containing cations in high formal oxidation states (assigned by assuming that anions attain full valence shells), the energy of ligand to cation charge transfer can become small or even negative. This yields compounds with a high degree of covalence and can lead to a self-doping of holes into the ligand states of the valence band. Such compounds are of particular topical interest, as highly studied perovskite oxides containing trivalent nickel or tetravalent iron are negative charge transfer systems, as are nickel-containing lithium ion battery cathode materials. In this report, we review the topic of negative charge transfer energy, with an emphasis on plots and diagrams as analysis tools, in the spirit of the celebrated Tanabe–Sugano diagrams which are the focus of this Special Topics Issue.
On the microstructure and dynamic mechanical behavior of Cu–Cr–Zr alloy manufactured by high-power laser powder bed fusion
(Elsevier, 2025) Azizi, Nadia; Asgari, Hamed; Hasanabadi, Mahyar; Odeshi, Akindele; Toyserkani, Ehsan
This study explores high-power laser powder bed fusion (LPBF) processing of Cu–Cr–Zr alloy, focusing on its high strain rate dynamic mechanical response and microstructural evolution. The alloy undergoes significant strain hardening during dynamic impact loading, primarily attributed to intensified dislocation interactions and multiplication. This is accompanied by thermal softening induced by adiabatic heating, therefore improving strain accommodation. As the strain rate increases from 4400 s−1 to 11300 s−1, the ultimate compressive strength (UCS) enhances from 173 ± 8 MPa to 489 ± 14 MPa, demonstrating a high strain rate sensitivity (SRS) of ∼ 1. Microstructural examinations reveal that higher strain rates intensify the occurrence of adiabatic shear bands (ASBs), leading to severe localized plastic deformation. These ASBs generate localized stress concentrations, which in turn accelerate crack initiation and propagation through pore formation and coalescence within the ASBs. Despite this severe plastic deformation, texture analysis indicates that the crystallographic texture remains largely stable which suggests that the deformation mechanism is primarily governed by dislocation motion and interaction, rather than by crystal structure reorientation. Overall, the alloy balances strain hardening and strain accommodation at high strain rates, making it well-suited for applications requiring strength and resilience under dynamic impacts.
Optimized Canceling Signals for PTS Schemes to Improve the PAPR of OFDM Systems Without Side Information
(IEEE, 2025-03) Nguyen, Khai; Bedeer, Ebrahim; Nguyen, Ha; Salt, J. Eric; Howlett, Colin
This paper introduces a novel blind partial transmission sequence (PTS) scheme to lower the peak-to-average-power ratio (PAPR) of orthogonal frequency division multiplexing (OFDM) systems. Unlike existing PTS schemes in which the first sub-block (SB) is preserved as a phase reference for other SBs, we propose to add an optimized canceling signal (CS) to the first SB to further reduce the PAPR. The CS is designed such that they can be reconstructed by the receiver, and subtracted from the received signals before demodulation without requiring side information (SI). Since errors in reproducing the CS at the receiver can degrade the error performance, we design a novel CS protection mechanism specifically to protect the reconstruction of the CS. The proposed method is shown to significantly reduce the PAPR and symbol error rate (SER) without sacrificing the data rate due to using SI as many other existing PTS schemes.

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