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Solid-Binding Peptide-Enabled Allosteric Regulation of CO2 Reductase Adsorption on Activated Graphite Electrodes for Augmented Electrocatalytic Interfacing
No full textThe research was performed using NAD+/NADH-dependent CO2 reductase (CR)/formate dehydrogenase (FDH) enzymes sourced from Candida methylica (E.C 1.17.1.9) against their enzyme constructs for CO2 to formate conversion. Investigations were performed using a genetically introduced non-native carbon-binding peptide (cbp) with terminus-specific fusion to CR for synthetic enzyme construct alterations (CR-cbpN, CR-cbpC, and CR-cbpNC) and evaluated against the native enzyme (CR-WT). Augmentation of CR biocatalytic activity with enzyme adsorption on the carbon surface was validated relative to their topographical binding and nitrogen adsorption/desorption isotherms. Structural modifications with terminus-specificity and amino acid positioning evidenced efficient enzyme-electrode binding affinity toward increasing their catalytic performance. Statistical analysis also inferred electrical transduction and CO2 reduction, documenting the efficient enzyme-material interfacing with peptide-based alterations. Holistically, the optimal enzyme-electrode signal transduction upgraded the direct electron transfer with proximal CR orientation and active site accessibility by peptide-enabled allosteric regulation on the carbon surface that proportionated for increased biocatalytic efficiency and system performance for CO2 reduction.FALSEscopu
Enzymatic valorization of an agricultural by-product
No full textAgro-industrial by-products derived from sugar crops represent a significant source of waste and an environmental burden. Among these, molasses, a by-product of sugar processing, is particularly cost-effective and rich in sugars such as sucrose, glucose, and fructose, making it an ideal substrate for bioconversion processes. This research focuses on valorizing molasses by converting it into a high-value product, D-mannitol. This study aims to develop and optimize a three-enzyme cascade reaction utilizing invertase, NADH-dependent mannitol dehydrogenase (MDH), and NAD⁺-dependent glucose dehydrogenase (GDH) to produce D-mannitol. Invertase was used to hydrolyze sucrose into D-glucose and D-fructose, enhancing substrate availability for downstream reactions. Subsequently, a coupled MDH- GDH cascade converted D-fructose into D-mannitol while regenerating the NADH cofactor through the oxidation of D-glucose. The invertase-catalyzed step achieved efficient sucrose hydrolysis, generating high yields of D-fructose and D-glucose. The introduction of invertase maximized the utilization of carbon source, sucrose in molasses, increasing substrate availability for downstream reactions. This step ultimately enhanced overall D-mannitol production efficiency compared to systems without invertase. The MDH-GDH cascade demonstrated approximately 95.6% conversion efficiency for D-fructose to D- mannitol, maintaining high enzyme activity and stability in the complex mixture of sugar beet molasses without requiring additional cofactor supplementation. The study highlights the feasibility of utilizing sugar beet molasses as an economical and renewable feedstock for value-added D-mannitol production. The three-enzyme cascade offers an efficient and sustainable approach for industrial applications, valorizing agro-industrial by-products into high-value products.MasterAbstract i
Contents ii
List of Figures iv
List of Tables iv
List of Schemes iv
I. Introduction 1
1.1. Agro-Industrial By-products and the Potential of Molasses 1
1.2. Enzymatic Conversion of Molasses to D-Mannitol 2
II. Materials and Methods 5
2.1. Materials 5
2.2. Expression and Purification 5
2.3. Enzyme Kinetics 7
2.4. Assessment of pH and Thermal Stability for MDH and GDH 8
2.5. Preparation of Invertase 9
2.6. Quantification of monosaccharides Produced by Invertase Using PAHBAH Assay ·· 9
2.7. Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE) Analysis
10
2.8. Sugar beet Molasses Pretreatment with Carrez Reagent 10
2.9. Cascade Reaction Conditions and Enzyme Removal Method 11
2.10. HPLC Analysis 11
III. Results and Discussion 13
3.1. Preparation of Strep-Tagged MDH and GDH 13
3.2. Preparation and Activity Confirmation of Invertase 14
3.3. Optimal pH and Thermal stability of MDH and GDH 15
3.4. Qualitative and Quantitative Analysis of Sugar beet Molasses 17
3.5. D-mannitol production from D-glucose and D-fructose 19
3.6. D-Mannitol Production from Sucrose Using Invertase-GDH-MDH Cascade 20
3.7. D-Mannitol Production from Sugar beet Molasses via MDH-GDH Cascade 21
3.8. D-mannitol production from Sugar beet molasses via Invertase-MDH-GDH cascade
reaction 22
IV. Conclusions 24
Summary 25
Reference 27
Acknowledgement 3
Reinforcement learning with low-rank adaptation for targeted antimicrobial peptide design
No full textAntimicrobial peptides (AMPs) are emerging as promising alternatives to traditional antibiotics, offering solutions to antimicrobial resistance through diverse mechanisms. Despite their potential, current computational approaches for AMP design rarely address strain-specific targeting, limiting their clinical efficacy as bacterial strains exhibit unique membrane compositions and susceptibility profiles requiring tailored interventions. Furthermore, the limited availability of strain-specific training data presents a significant challenge, necessitating parameter-efficient learning approaches that can optimize AMP properties with minimal overfitting. This study introduces a novel AMP generation framework that integrates reinforcement learning with a Generative Pre-trained Transformer (GPT) model enhanced by Low-Rank Adaptation (LoRA) parameter-efficient fine-tuning. This approach enables the design of peptides optimized for multiple objectives, specifically antimicrobial activity and toxicity, tailored to individual pathogen strains. Our framework employs a two-stage learning process: pretraining on a large-scale peptide and AMP database to capture linguistic and contextual features, followed by reinforcement learning that leverages MIC (Minimum Inhibitory Concentration) and hemolysis prediction models to optimize antimicrobial potency and safety profiles. The integration of LoRA is crucial for efficiently adapting the model to strain-specific characteristics while addressing limited training data. The comparative analysis demonstrated our model’s superior performance over existing AMP generation approaches in both activity and hemolytic toxicity metrics. An ablation study confirmed the contributions of reinforcement learning and LoRA. Furthermore, the model can generate peptides satisfying both activity and toxicity conditions for unseen strains, highlighting its capability to design AMPs for emerging pathogens. In addition, molecular dynamics (MDs) simulations confirmed that the generated peptides penetrate bacterial membranes, supporting antimicrobial activity. © The Author(s) 2025. Published by Oxford University Press.FALSEsciescopu
Enhancing cathode-electrolyte interface stability in high-voltage lithium metal batteries through phase-separated cyano-containing copolymer-based elastomeric electrolytes
No full textSolid-state polymer electrolytes (SPEs) are a promising alternative to conventional liquid electrolytes in lithium metal batteries (LMBs). However, their low ionic conductivity and poor oxidation stability hinder the operation of LMBs, particularly when paired with high-voltage, Ni-rich cathodes. To address this challenge, our aim is to integrate the cyano group, known for its ability to enhance oxidation stability through its electron-withdrawing property, into the phase-separated SPEs that exhibit superior ionic conductivity and mechanical properties. Specifically, we synthesize cyano-containing SPEs by incorporating cyanoethyl acrylate (CEA) into an elastomeric electrolyte featuring a bicontinuous structure composed of cyano-containing copolymers and plastic crystals. The phase-separated structure of various SPEs is controlled by adjusting the molar ratio of butyl acrylate (BA) and CEA. At the optimal molar ratio of BA to CEA (specifically, 9:1), this tailored electrolyte shows high ionic conductivity (9.8 × 10−4 S cm−1 at 30 °C) and cycling performance at high cut-off voltage of 4.7 V vs. Li/Li+. The cyano-containing bicontinuous SPEs are expected to play a pivotal role in enhancing oxidation stability and developing robust interfaces consisting of transition metal-anchored framework and inorganic-rich components. These interfaces effectively suppress degradation of cathode structure, thereby achieving high-energy solid-state LMBs. © 2024 Elsevier B.V.FALSEsciescopu
Synchronized Delay Measurement of Multi-Stream Analysis over Data Concentrator Units
No full textAutonomous vehicles (AVs) rely heavily on multi-modal sensors to perceive their surroundings and make real-time decisions. However, the increasing complexity of these sensors, combined with the computational demands of AI models and the challenges of synchronizing data across multiple inputs, presents significant obstacles for AV systems. These challenges of the AV domain often lead to performance latency, resulting in delayed decision-making, causing major traffic accidents. The data concentrator unit (DCU) concept addresses these issues by optimizing data pipelines and implementing intelligent control mechanisms to process sensor data efficiently. Identifying and addressing bottlenecks that contribute to latency can enhance system performance, reducing the need for costly hardware upgrades or advanced AI models. This paper introduces a delay measurement tool for multi-node analysis, enabling synchronized monitoring of data pipelines across connected hardware platforms, such as clock-synchronized DCUs. The proposed tool traces the execution flow of software applications and assesses time delays at various stages of the data pipeline in clock-synchronized hardware. The various stages are represented with intuitive graphical visualization, simplifying the identification of performance bottlenecks. © 2024 by the authors.TRUEsciescopu
Diagnostic Method for Structural Degradation of Porous Catalyst Layers in PEMFCs Using Low-Frequency Impedance and Undershoot Variations in Current Steps
No full textIn this study, we developed an in situ electrochemical diagnostic method for polymer electrolyte membrane fuel cells (PEMFCs), utilizing voltage drop and specific frequency impedance responses observed during current steps. At lower current densities, efficient gas supply and water removal ensure stable cell operation. However, at higher current densities, increased load leads to excessive water generation, which can obstruct reactant gas inflow and hinder water removal, resulting in increased internal resistance. By leveraging these degradation mechanisms, we propose a diagnostic method to predict pore structures and accurately assess degradation in PEMFCs. Current steps ranging from 200 mA cm⁻² to 600 mA cm⁻² were employed to analyze voltage undershoot and impedance at 1 Hz. The voltage undershoot is linked to increased contact resistance caused by ionomer instability, indicating structural degradation in the carbon support. Meanwhile, the impedance at 1 Hz correlates with mass transport resistance, providing an indirect method for predicting pore structure. This method enables efficient diagnostics without requiring complex equivalent circuit fitting, and allows measurements to be conducted under stable operational conditions, avoiding changes in temperature, humidity, or gas composition, which prevents further degradation during the diagnostic process. This approach offers a straightforward and effective means for diagnosing degradation in PEMFCs, enhancing fuel cell performance and durability by enabling rapid identification of problematic components and timely maintenance.MasterAbstract i
Contents ii
List of Tables iii
List of Figures iv
1. Introduction 1
2. Theoretical Background 6
2.1. Current Density and Internal Mechanisms in PEMFCs 6
2.1.1. Mechanisms at Low Current Density 6
2.1.2. Mechanisms at High Current Density 6
2.2. Voltage Undershoot in PEMFCs: Characteristics and Significance 7
2.3. 1 Hz Impedance and Mass Transport Phenomena 8
3. Experiments 10
3.1. Preparation of a Single PEMFC Cell 10
3.2. Accelerated stress test (AST) protocols 10
3.3. Electrochemical analysis 11
3.4. Ex-situ surface analysis 11
4. Results and Discussion 12
4.1. Effect of Accelerated Degradation Testing on PEMFC Performance: Electrochemical Analysis 12
4.1.1. Performance degradation and overpotential analysis during AST 12
4.1.2. Analysis of EIS measurements based on TLM equivalent circuit with a faradaic process 12
4.1.3. Analysis of EIS measurements on CL using the TLM-RH30 with a non-faradaic process 13
4.2. Diagnostic analysis using current steps from 200 to 600 mA cm⁻² 14
4.2.1. Diagnosis of internal structural degradation via 1 Hz impedance analysis 14
4.2.2. Diagnosis of internal structural degradation via undershoot analysis 15
5. Conclusion 31
6. References 32
Acknowledgement 3
Cellular changes in an in vitro neural circuit system under simulated microgravity
No full textPhysiological changes, some of which lead to neurological alterations and cognitive decline, have been reported to occur in space. To date, it has not been possible to identify the direct effect of microgravity alone on neural circuits in vitro. Therefore, this study aimed to elucidate the impact of simulated microgravity (s mu G) on neural circuit dynamics using a microphysiological system (MPS). A unidirectional neural circuit MPS was engineered, and primary neurons from embryonic day 17 (E17) rat brains were extracted, seeded onto the system, and maintained under terrestrial conditions for two weeks to establish functional connectivity. Subsequently, cultures were exposed to either ground conditions or s mu G using a rotating clinostat for an additional week. Neurons subjected to s mu G exhibited a significant increase in oxidative stress and spontaneous Ca2+ activity, accompanied by a marked reduction in axonal density and synapsin-1 expression. Notably, s mu G did not affect neuronal viability. Finally, transcriptomic analysis further revealed significant alterations in HSPA4 and SNCA expression, genes implicated in cellular stress responses and neurodegenerative pathology. This study represents the first practical application of a neural circuit MPS for physiological research. These findings underscore the utility of neural circuit MPSs as robust platforms for modeling the neurobiological consequences of microgravity and evaluating countermeasures to mitigate neural dysfunction in long-duration spaceflight. Statement of Significance: Long-term exposure to space environments, including microgravity and cosmic radiation, induces physiological changes, some leading to neurological impairments. However, the direct effects of microgravity on neural circuits remain unclear. Using a system that isolates microgravity, we demonstrate increased ROS generation, inhibited axon growth, altered synapse formation, and gene expression changes linked to neurodegenerative diseases. These findings highlight the potential risks of microgravity on neural function. MPS technologies, such as neural circuits on chips, are essential for space medicine and can provide platforms for drug testing to prevent space-induced cognitive decline. We anticipate that our technology will pave the way for examining the interaction between space environments and brain tissue at the cellular level in a practical and multifaceted manner.TRUEsciescopu
Can a Machine Feel Vibrations?: Predicting Roughness and Emotional Responses to Vibration Tactons via a Neural Network
No full textVibrotactile signals offer new possibilities for conveying sensations and emotions in various applications. Yet, designing vibrotactile tactile icons (i.e., Tactons) to evoke specific feelings often requires a trial-and-error process and user studies. To support haptic design, we propose a framework for predicting roughness and emotional ratings from vibration signals. We created 154 Tactons and conducted a study to collect acceleration data from smartphones and roughness, valence, and arousal user ratings (n = 36).We converted the Tacton signals into two-channel spectrograms reflecting the spectral sensitivities of mechanoreceptors, then input them into VibNet, our dual-stream neural network. The first stream captures sequential features using recurrent networks, while the second captures temporal-spectral features using 2D convolutional networks. VibNet outperformed baseline models, with 82% of its predictions falling within the standard deviations of ground truth user ratings for two new Tacton sets. We discuss the efficacy of our mechanoreceptive processing and dual-stream neural network and present future research directions.FALSEsciescopu
Einstein structure of four-manifolds
No full textIt is known that the moduli space of Einstein structures in four dimensions is generally considered to be rigid so that Einstein metrics tend to be isolated modulo diffeomorphisms under infinitesimal Einstein deformations. We examine the rigidity of the Einstein structure by considering deformations of the round four-sphere. We show that any deviation from the standard metric of the round four-sphere (except for scaling) breaks the Einstein condition. This further supports the idea of rigidity. We analyze the Einstein structure of four-manifolds based on the irreducible decomposition of the self-dual structure of Einstein manifolds. © 2025 Elsevier B.V., All rights reserved.FALSEsciescopu
Martian mineral exploration: Insights from orbital spectroscopy and rover-based analyses
No full text지난 반세기 동안 화성 탐사는 표면 광물 분석을 통해 화성의 고대 환경과 기후 변천사를 규명하는 데 결정적인 역할을 해왔다. 본 논평에서는 궤도 원격탐사와 착륙선·로버를 이용한 현장 탐사라는 두 가지 주요 탐사 방법을 중심으로 화성 표면의 광물학적 특성과 그 진화를 종합적으로 검토하고자 한다. 기존의 탐사들을 종합해보면, 화성 표면의 광물학적 진화는 필로시안(Phyllosian, 점토광물 우세)-테이키안(Theiikian, 황산염 우세)-시데리키안(Siderikian, 무수 산화철 우세)으로 이어지는 세단계의광물학적 연대기로 정립될 수 있다. 이는 화성이 초기의 온난·습윤 환경에서 점차 산성·건조 환경으로 변화했음을 명확히 보여준다. 이러한 광물학적 연대기 정립은 화성의 물 순환, 대기 진화, 그리고 생명체 거주 가능성에 대한 근본적인 단서를 제공한다. 본논평은 이러한 탐사 성과를 통합적으로 고찰하고, 여전히 남아 있는 주요 과학 난제를 조명한다. 나아가 향후 시료 귀환 임무와 현지자원활용을 위한 미래 광물 탐사의 중요성을 논의함으로써, 한국을 포함한 차세대 화성 광물 탐사의 방향 설정에 필요한 기초자료를 제공하고자 한다.FALSEscopuskc