Recently, the status of North Korea’s denuclearization has become an international issue, and there are also indications of potential nuclear proliferation among neighboring countries. So, the need for establishment of nuclear activity verification technology and strategy is growing. In terms of ensuring verification completeness, sample collection-based analysis is essential. The concepts of Chain of Custody (CoC) and Continuity of Knowledge (CoK) can be defined in the process of sample extraction as follows: CoC is interpreted as the ‘system for managing the flow of information subjected by the examinee’, and CoK is interpreted as the ‘Continuity of information collection through CoC subjected by the inspector’. In the case of sample collection process in unreported areas for nuclear activity verification, there are additional risks such as worker exposure/kidnapping or sample theft/tampering. Therefore, the introduction of additional devices might be required to maintain CoC and CoK in the unreported area. In this study, an Environmental Geometrical Data Transfer (EGDT) was developed to ensure the safety of workers and the CoC/CoK of the samples during the collection process. This device was designed for achieving both mobility and rechargeability. It is categorized into two modes based on its intended users: sample mode and worker mode. Through the sensors, which is positioned in the rear part of device, such as radiation, gyroscope, light, temperature, humidity and proximity sensors, it can be easily achievable various environmental information in real-time. Additionally, GPS information can also be received, allowing for responsiveness to various hazardous scenarios. Moreover, the OLED display positioned on the front gives us for checking device information such as the current status of the device such as the battery level, the connectivity of wifi, and etc. Finally, an alarm function was integrated to enable rapid awareness during emergency situations. These functions can be updated and modified through Arduino-based firmware, and both the device and the information collected through it can be remotely controlled via custom software. Based on the presented design conditions, a prototype was developed and field assessments were conducted, yielding results within an acceptable margin of error for various scenarios. Through the application of the EGDT developed in this study to the sample collection process for nuclear activity verification purposes, it is expected to achieve a stable maintenance of CoC/CoK through more accurate information transmission and reception.

Nuclear Forensics is recognized as a essential component in the nuclear non-proliferation verification sector by the international community. It is being advanced under the leadership of the IAEA, the U.S., and the EU. Both the U.S.’s Lawrence Livermore National Laboratory (LLNL) and the international collaborative organization, the Nuclear Forensics International Technical Working Group (ITWG), have proposed to establish a relationship between the production timing and radiochronometry of nuclear materials or samples to utilize in the field of nuclear forensics. Radiochronometry of nuclear materials is calculated based on the Bateman equation, incorporating factors with uncertainties derived from tests, experiments, and analyses. The results from the nuclear activity radiochronometry also encompass uncertainties, affecting their reliability. This study examined the mathematical uncertainty calculations related to the results of nuclear activity radiochronometry, focusing on calculation methods, contribution rates per factor, and sensitivities. Uncertainty factors for the Bateman equation-based radiochronometry were observed in the decay constants for each nuclide type and the uncertainty in the radioactive ratio of the tracer nuclide. The sensitivity for each factor revealed that the uncertainty in the radioactive ratio of the signature nuclide contributed more significantly than the uncertainty in decay constants for each nuclide type. Each factor displayed a distinct sensitivity curve relative to the radioactive ratio. As it approaches a radioactive equilibrium, the sensitivity tends to increase infinitely, indicating a corresponding trend of infinite increase in uncertainty. Because the time and curve shape to reach radioactive equilibrium vary depending on the signature nuclide, it’s essential to choose an appropriate signature nuclide based on the anticipated period and analysis requirements for nuclear activity radiochronometry. However, radiochronometry using mathematical methods is limited to the relationship between parent and daughter nuclides, presenting the potential for underestimation of uncertainty factors like decay constants. Future research will need to focus on uncertainty calculation methods through computational simulations, especially using the Monte Carlo method, to overcome the limitations of mathematical approaches and potential underestimations.

When exporting nuclear-related items, export control is required from two perspectives: the control of “Trigger List Items” as controlled by Nuclear Supplier Groups (NSG) and the control of the “Items Subject to the Agreement” as specified in bilateral Nuclear Cooperation Agreements. While Trigger List Items and Items Subject to the Agreement are largely similar, there are some items where they do not overlap. Furthermore, national law for controlling each item is different. The Trigger List Items are governed by the Foreign Trade Act, and the Items Subject to the Agreement (Internationally Controlled Items) are governed by the Nuclear Safety Act. As a result, the detailed procedures and requirements for controlling each item are quite distinct. For the Trigger List Items, export license must be obtained in accordance with the Foreign Trade Act. The details such as responsible authority, the items subject to license, license requirements and procedures, penalties are specified in the Public Notice on Import and Export of Strategic Goods. For the Items Subject to the Agreement, the process and obligations set forth in bilateral agreements and related administrative agreements are fulfilled in accordance with the Nuclear Safety Act. However, in contrast to the Trigger List Items, the details for complying with the agreements are not specified legally. Since most of the Items Subject to the Agreement are fall within the category of the Trigger List Items, the obligations in accordance with the agreements are reviewed and implemented during the export license assessment process. However, if the Items Subject to the Agreement are not are fall within the category of the Trigger List Items, there is a risk of control omission. For example, this applies to cases of exporting tritium and tritium removal facilities, which are not the Trigger List Items, to Canada and Romania. Moreover, since subjects to the agreement and compliance procedures are respectively different for 29 bilateral Nuclear Cooperation Agreements signed with different countries, it is difficult for enterprise to recognize the appropriate procedures and obligations under the agreement by their own. The bilateral Nuclear Cooperation Agreements establish legal obligations between state parties while NSG are non-legally binding arrangements. Therefore, it could be even more necessary to comply strictly with the agreements. Consequently, legal improvements are required for effective implementations of Nuclear Cooperation Agreements. While it may be challenging to institutionalize details of 29 Nuclear Cooperation Agreements, it is essential to legally specify key elements such as the list of items subject to agreements, responsible authority, requirements and procedures for implement the agreement obligations, and penalties. Furthermore, domestic awareness on compliance with Nuclear Cooperation Agreements is lower compared to the system of export license for Trigger List Items. The continuous outreach is also necessary, along with institutional improvements.

The National R&D Innovation Act emphasizes the improvement of the quality of R&D activities. The research institute is making efforts to improve the quality of research and effectively manage research implementation. KINAC has conducted various R&D projects regarding nuclear nonproliferation and nuclear security, and their scope and scale have been gradually more widened and increased. It consequently becomes important how to successfully manage research projects and ensure their qualification with the growth and complexity of research in KINAC. Unfortunately, no attempt was made to introduce and apply project management methodologies. Therefore, the objective of this study is to introduce project management standards and guidelines as an initial step towards improving the overall research quality of the institute. Project management is the well-organized application of knowledge and techniques to efficiently and effectively initiate, plan, control, and close projects, in order to achieve specific goals and meet success criteria. There are some guidelines regarding project management, including PMBOK (the Project Management Body of Knowledge), PRINCE2 (Projects in Controlled Environments), ISO 21500 (Guidance on Project Management), and PMP (Project Management Professionals), etc. They are international standards that consist of processes, guidelines, and best practices for project management. They provide structured processes and approaches to plan, execute, monitor, control, and complete projects. By reviewing the guidelines, the commonly important factors, including schedule, cost, quality, resources, communication, and risk management were introduced to apply to KINAC R&D project implementation. In addition to the management standards, systematic efforts are also continued to enhance the R&D qualities of the institute. These efforts include the implementation of a quality management system (ISO 9001:2015), development of an integrated research achievements management system, regulation development, and distribution of guidebooks for project managers and researchers. These efforts have been evaluated as improving the quality of the research.

ISO 9001:2005 is the international standard for implementing a Quality Management System (QMS), which provides a framework and principles for managing an organization’s quality management. The aim is to ensure that the organization continuously provides products and services that satisfy regulatory requirements. The “process approach” in ISO 9001 is defined as a systematic method of achieving organizational goals by comprehending and managing the interconnected processes as a cohesive system. Recently, KINAC has decided to develop standard processes in the field of R&D and performance management based on the framework of the ISO 9001:2015 quality management system. The objective of this study is to establish standardized processes for conducting research and development, as well as managing the outputs and performance of R&D activities. It involves identifying, designing, implementing, monitoring, and continually improving processes to ensure consistency, efficiency, and effective management of KINAC R&D and its achievements. Firstly, R&D and the research performance management process were defined, and the processes were categorized by function according to the requirements of ISO 9001:2015. Second, the ISO 9001 requirements were compared to the institute’s existing regulations and documents in order to identify any additional processes and procedures needed to meet the quality management requirements. Finally, the lists of quality documentation were determined for the institute’s QMS. As a result, a total of 30 QMS documents were listed, including 1 manual, 12 quality processes and procedures, and 17 quality instructions. The documents can be categorized into four process groups: the management and planning process group, the R&D and achievements management process group, the analysis and improvement process group, and the support process group. All input and output information of each process are connected and interrelated. The implementation of quality management standards and procedures for R&D in KINAC could lead to improved research practices, more reliable data collection and analysis, and increased efficiency in conducting R&D activities. For further study, it is planned to create detailed, high-quality documents that adhere to standard requirements and guidelines.

Korea has signed nuclear cooperation agreements (NCA) with 29 countries. Nuclear materials, materials, equipment, and technology transferred under the agreements are “internationally controlled materials (ICM)” under the Nuclear Safety Act. The main obligations imposed on those items include ensuring peaceful use, safeguards, physical protection, annual inventory reporting, and retransfer with supplier prior consent. The Nuclear Export and Import Control System (NEPS) handles the export control procedures for transferring ICM. After import, inventory management for ICM in Korea would be transitioning to an item-based system through the Obligation Tracking System for internationally controlled item (OTS) currently under development. A one-stop import and export control system for ICM can be established when information is well-linked between these two systems. This paper aims to derive a methodology for integrating NEPS and OTS. NEPS-OTS coupling begins at the receipt confirmation and shipment notification stages in NEPS. When importing ICM under NCA, the inventory change (code RF: receipt foreign) is entered in OTS by getting the information that has completed the receipt confirmation in NEPS. Conversely, during export, the information that has completed the shipment notification procedure in NEPS is linked to the OTS so that the entire cycle from import to re-export of the ICM can be concluded. Inventory verification for retransfer, checking that the book inventory remains positive value, is impossible under the current system. This issue can be resolved by enabling inventory information in OTS to be displayed in NEPS. Determining when and how to generate the obligation code for imported ICM is essential for NEPS-OTS coupling. Manual input may be necessary for some cases with multiple obligations. Nevertheless, it is more efficient from a system communication protocol to automatically generate and impose a single obligation based on the supplier country information in NEPS. Moreover, it is important to automatically link crucial information available in NEPS to reduce the administrative burden on OTS users and discrepancies between systems. Most required OTS data, such as country obligation, item categories, quantity, physical or chemical form, and receipt date, can be directly linked from NEPS. However, NEPS improvement is needed for digitizing the receiver information and facility data, like the material balance area. The NEPS-OTS integration involves sharing data as a system and encompasses the connection between export control and inventory management. Future work to link some information in NEPS -OTS with the KSIS could be suggested to enhance efficiency and effectiveness in managing ICM.

The ROK government has developed the Nuclear Export and Control System (NEPS) to implement export control activities. Although it was launched in 2008 as a system that can work with classification, licensing, nuclear material approval, government-to-government assurance, complying with nuclear cooperation agreement (NCA) handled through official documents. In order to enhance systematic management for items subject to NCA, KINAC developed a new module for the procedure (hereinafter referred to as “NCA module”) and opened it in 2022. This paper presents the module’s development background, key features, and current operation status. The NCA module prioritizes functional expansion and flexibility, distinct from other tasks for the following reasons. First, the export control duties of classification, export license, and approval for NM are based on domestic law, leading to predetermined target items, application forms, and processes that change only through statutory amendments. In contrast, the implementation of NCA has numerous procedural variables, varying across countries in scope, content, and procedures. Therefore, if the function is over-standardized, there would be many exceptions that the system cannot resolve in practice. Second, the existing NEPS process entails a one-time decision or approval for each application, while the implementation of the agreement encompasses four related procedures for each item: prior notification, written confirmation, shipment notification, and receipt confirmation. Even some steps may be omitted depending on the case. The other difference is the working process. The implementation of NCA must be initiated from the government, so the existing methods, beginning with the licensee filling a form, cannot be adopted as it is. The NCA module has adopted a new reference numbering system to resolve these challenges. It enables the creation of multiple procedures under one reference number on an item to expand the tasks and make it possible to omit some steps or to reflect case-by-case concerns in each stage. It also provides a consolidated view of multiple notifications related to a single item, ensuring to deal with even long-running tasks without missing any obligations until the final procedure. Moreover, some of the data in the NCA module is extensible by allowing users to manage the list themselves. For example, the system can respond to new agreements by allowing users to add and modify codes that distinguish counterparty countries. As a result, the current NCA module accommodates a variety of implementation scenarios, including split shipments, the procedural omissions, and the modification of additional counterparties, offering enhanced flexibility and adaptability.

The Republic of Korea (ROK), as a member state of the IAEA, is operating the State’s System of Accounting for and Control (SSAC) and conducting independent national inspections. Furthermore, an evaluation methodology for the material unaccounted for (MUF) is being developed in ROK to enhance capabilities of national inspection. Generally, physical and chemical changes of nuclear material are unavoidable due to the operating system and structure of facilities, an accumulation of material unaccounted for (MUF) has been issued. IAEA developed statistical MUF evaluation method that can be applied to all facilities around the world and it mainly focuses on the diversion detection of nuclear materials in facilities. However, in terms of the national safeguard inspection, an evaluation of accountancy in facilities is additionally needed. Therefore, in this research, a new approach to MUF evaluation is suggested, based on the Guide to the Expression of Uncertainty in Measurement (GUM) that an evaluation of measurement uncertainty factors is straightforward. A hypothetical list of inventory items (LII) which has 6,118 items at the beginning and end of the material balance period, along with 360 inflow and outflow nuclear material items at a virtual fuel fabrication plant was employed for both the conventional IAEA MUF evaluation method and the proposed GUM-based method. To calculate the measurement uncertainty, it was assumed that an electronic balance, gravimetry, and a thermal ionization mass spectrometer were used for a measurement of the mass, concentration, and enrichment of 235U, respectively. Additionally, it was considered that independent and correlated uncertainty factors were defined as random factors and systematic factors for the ease of uncertainty propagation by the GUM. The total MUF uncertainties of IAEA (σMUF) and GUM (uMUF) method were 37.951 and 36.692 kg, respectively, under the aforementioned assumptions. The difference is low, it was demonstrated that the GUM method is applicable to the MUF evaluation. The IAEA method demonstrated its applicability to all nuclear facilities, but its calculated errors exhibited low traceability due to its simplification. In contrast, the calculated uncertainty based on the GUM method exhibited high reliability and traceability, as it allows for individual management of measurement uncertainty based on the facility’s accounting information. Consequently, the application of the GUM approach could offer more benefits than the conventional IAEA method in cases of national safeguard inspections where factor analysis is required for MUF assessment.

The KINAC resident inspectors are responsible for conducting on-site regulatory and intergovernmental support tasks related to safeguards, physical protection, and cybersecurity in each NSSC regional office. In nuclear material accounting and control, resident inspectors primarily perform tasks such as national inspections and technical support for IAEA inspections. However, with the increasing cases of non-compliance with the advance notification procedure by operators, there is a growing need for improvement in the role of resident inspectors in on-site regulation. In response to this situation, the safeguards division in KINAC has analyzed and improved the on-site check procedures of resident inspectors at LWR facilities. The existing procedure outlines the process where resident inspectors receive the advance notification documents submitted by operators and utilize them as a reference for conducting weekly checks during the overhaul period when IAEA surveillance cameras are installed. Additionally, according to the attached forms specified in the procedure, resident inspectors are required to submit the check results report to the director of the safeguards division in KINAC every week and to the NSSC every month. The inspection items include checking the execution and changes of advance notification, verifying unnotified matters, discussing other issues, assessing the integrity of things such as the operational status of IAEA surveillance equipment, and so on. On April 13-14, 2023, the Safeguards division organized a two-day resident inspector’s work-sharing workshop to discuss improvements in the on-site check procedures of resident inspectors at LWR facilities. During the workshop, a comparison and analysis were conducted between the existing procedures and actual on-site activities. Unnecessary tasks such as advance notification document reception and monthly reporting were eliminated, and the focus was shifted towards emphasizing essential tasks. The opinions of resident inspectors were taken into account to derive directions for improvement. The existing procedure was applicable only during Overhaul periods for resident inspectors. It has been improved by removing this limitation, allowing its use during routine times. Furthermore, the procedure has been enhanced by clarifying its purpose, scope, users, and definitions of terms and specifying responsibilities and authorities. Unnecessary terminology has been eliminated. Remarkably, the definition of advance notification has been detailed, and the reporting of check results has been simplified through weekly task reporting. The Safeguards division in KINAC has strived to enhance the efficiency and simplification of on-site regulatory activities for resident inspectors at LWR facilities by improving their on-site check procedures. These improvement activities are expected to aid resident inspectors in effectively performing a wide range of tasks, including safeguards, physical protection, cybersecurity, and government support. In the future, it will be possible to continue refining the on-site check procedures by sharing the results of using the procedure in meetings and gathering various opinions from resident inspectors.

Among the public notices of the NSSC, five notices related to safeguards, including “Education of Nuclear Control, International Regulatory Materials, Preparation of Regulation of NMAC (Nuclear Material Accounting and Control), the National Inspection of NMAC, and Reporting of International Regulatory Materials” The regulations on the National Inspection of NMAC have remained the same since some revisions were made on December 26, 2017, raising the need to revise the public notice due to changes in the domestic and international safeguards regulatory environment. Accordingly, this paper analyzes the public notice of the National Inspection of NMAC and proposes the revision direction. The regulation regarding the National Inspection of NMAC comprises sections such as Purpose and Definition, Types - Scope - Frequency of the National Inspection, Notification of the National Inspection’s plan, and Management of Violation. Appendices include the contents of the violation table, explanations regarding types of violations, and various forms related to the National Inspection, which are attached separately. IAEA mentioned that ROK was selected as a pilot country for the Improved SLA (State-Level Approach) project starting in November 2020. IAEA explained that a quantitative and standardized methodology was adopted and developed for this purpose. As a result, the Unannounced Inspection at LWR facilities will transition to the Random Interim Inspection. Additionally, the Physical Inventory Verification in CANDU facilities will increase to once a year per reactor. This status will change the frequency and intensity of inspection at domestic nuclear facilities. Furthermore, domestically, there is an ongoing trend of continuous growth and diversification of nuclear facilities. In light of the changing domestic and international safeguards environment, it is necessary to set a direction for revising the regulation regarding the National Inspection of NMAC that was partially amended in 2017 to align with the current status. Firstly, due to the increased burden on operators resulting from the increased number of IAEA inspections following the application of Improved SLA, there is a need to streamline the National Inspection of NMAC frequency to enhance overall regulatory efficiency. Furthermore, the definition section should also be revised to include matters related to the regulation to reflect the current reality accurately. Considering the operation and name changes of new domestic nuclear facilities, there may be a need to add or modify computer input codes. While pursuing the revision of regulations regarding the National Inspection of NMAC, an analysis of the need for revision of other regulations related to safeguards should also be conducted, and directions should be set. Through this process, improving the regulatory framework that forms the basis of safeguards can help prevent confusion among operators and promote regulatory efficiency. We can better cope with these changes by proactively adapting to the rapidly changing domestic and international nuclear environment.

Uranium extraction from seawater has been a topic of considerable interest over the past decades. However, Commercial facilities for uranium extraction from seawater have not yet been constructed due to its lack of economic feasibility. With the increasing demand for sustainable energy sources, there is a growing interest in eco-friendly uranium extraction methods. Despite this, the safeguards associated with these extraction techniques remain relatively under-researched, necessitating comprehensive studies that address both the economic feasibility and safeguards approach. The Korea Hydro & Nuclear Power Central Research Institute is poised to elucidate the economic value of uranium extraction from seawater and embark on research to extract Yellow Cake from seawater on a laboratory scale. Given these advancements, it becomes imperative to consider the approach to safeguards. In this study, a comprehensive review was conducted to understand the relevant regulations that encompass both international obligations in partnership with the IAEA and domestic guidelines, specifically the Nuclear Safety Act. Emphasis was placed on a detailed examination of the IAEA’s comprehensive safeguards agreement and its additional protocol, focusing on deriving the necessary regulatory timings, subjects, and methodologies for effective reporting and verification. We reviewed the safeguards guidelines and the IAEA policy to confirm the international non-proliferation obligations. The study also reviewed the impact of the State-Level Approach promoted by the IAEA and its implications on state-specific factors and evaluations of state technological advancement. Additionally, the regulatory aspects of extracted uranium as an internationally regulated material under the Nuclear Safety Act were critically assessed. In conclusion, this study explains the international and domestic regulatory considerations for uranium extraction from seawater. Ultimately, this study will provide valuable understanding for policymakers, researchers, and practitioners involved in uranium extraction from seawater. Additionally, we expect that this study will contribute to establishing the safeguards approach and regulatory framework for the commercialization of uranium extraction from seawater in the ROK.

Regulators conduct inspections and issue non-compliance notice, and it is necessary to examine whether this is equivalent a corrective order. A corrective order imposes binding obligations on a business, and violations of it can result in sanctions such as fines, license revocation, or suspension. Therefore, if it is a corrective order, it must go through procedures such as prior notification under the Administrative Procedure Act. However, so far, no such procedures have been followed when issuing non-compliance notice. There are three possible interpretations of it: 1) the issuance of a non-compliance notice is not a corrective order but a part of an inspection, 2) the issuance of a non-compliance notice is a corrective order but not a disposition, and 3) the process of hearing opinions and prior notification was carried out during the inspection. However, if it is a part of an inspection, it should be issued by KINAC or KINS, which is entrusted with the inspection, but it is issued by the Nuclear Safety and Security Commission, and it is a disposition because it makes specific demands, and the corrective orders themselves have not gone through the procedure of hearing opinions. Therefore, in order for a non-compliance notice to be enforceable unlike a recommendation and to be issued by the Nuclear Safety and Security Commission instead of the inspection agency, the law should be amended and the procedure of prior notice and hearing opinions required by the Administrative Procedure Act should be carried out at the issuance stage.

Nuclear Material Accountancy (NMA) system quantitatively evaluates whether nuclear material is diverted or not. Material balance is evaluated based on nuclear material measurements based on this system and these processes are based on statistical techniques. Therefore, it is possible to evaluate the performance based on modeling and simulation technique from the development stage. In the performance evaluation, several diversion scenarios are established, nuclear material diversion is attempted in a virtual simulation environment according to these scenarios, and the detection probability is evaluated. Therefore, one of the important things is to derive vulnerable diversion scenario in advance. However, in actual facilities, it is not easy to manually derive weak scenario because there are numerous factors that affect detection performance. In this study, reinforcement learning has been applied to automatically derive vulnerable diversion scenarios from virtual NMA system. Reinforcement learning trains agents to take optimal actions in a virtual environment, and based on this, it is possible to develop an agent that attempt to divert nuclear materials according to optimal weak scenario in the NMA system. A somewhat simple NMA system model has been considered to confirm the applicability of reinforcement learning in this study. The simple model performs 10 consecutive material balance evaluations per year and has the characteristic of increasing MUF uncertainty according to balance period. The expected vulnerable diversion scenario is a case where the amount of diverted nuclear material increases in proportion to the size of the MUF uncertainty, and total amount of diverted nuclear material was assumed to be 8 kg, which corresponds to one significant quantity of plutonium. Virtual NMA system model (environment) and a divertor (agent) attempting to divert nuclear material were modeled to apply reinforcement learning. The agent is designed to receive a negative reward if an action attempting to divert is detected by the NMA system. Reinforcement learning automatically trains the agent to receive the maximum reward, and through this, the weakest diversion scenario can be derived. As a result of the study, it was confirmed that the agent was trained to attempt to divert nuclear material in a direction with a low detection probability in this system model. Through these results, it is found that it was possible to sufficiently derive weak scenarios based on reinforcement learning. This technique considered in this study can suggest methods to derive and supplement weak diversion scenarios in NMA system in advance. However, in order to apply this technology smoothly, there are still issues to be solved, and further research will be needed in the future.

As a promising anode for sodium-ion batteries (SIBs), cobalt sulfide ( CoS2) has attracted extensive attention due to its high theoretical capacity, easy preparation, and superior electrochemical activity. However, its intrinsic low conductivity and large volume expansion result in poor cycling ability. Herein, nitrogen-doped carbon-coated CoS2 nanoparticles (N–C@ CoS2) were prepared by a C3N4 soft-template-assisted method. Carbon coating improves the conductivity and prevents the aggregation of CoS2 nanoparticles. In addition, the C3N4 template provides a porous graphene-like structure as a conductive framework, affording a fast and constant transport path for electrons and void space for buffering the volume change of CoS2 nanoparticles. Benefitting from the superiorities, the Na-storage properties of the N–C@CoS2 electrode are remarkably boosted. The advanced anode delivers a long-term capacity of 376.27 mAh g− 1 at 0.1 A g− 1 after 500 cycles. This method can also apply to preparing other metal sulfide materials for SIBs and provides the relevant experimental basis for the further development of energy storage materials.

Graphene-based sensors have emerged as significant tools for biosensing applications due to their unique electrical, mechanical, and thermal properties. In this study, we have developed an innovative and sensitive aptasensor based on the surfacemodified graphene for the detection of lung cancer biomarker CA125. The sensor leverages the combination of graphene surface and gold nanoparticles (AuNPs) electrodeposition to achieve a high level of sensitivity and selectivity for the biomarker detection. A noticeable decrease in electron transfer resistance was observed upon the AuNPs deposition, demonstrating the enhancement of electrochemical performance. Our experimental findings showed a strong linear relationship between the sensor response and CA125 concentrations, ranging from 0.2 to 15.0 ng/mL, with a detection limit of 0.085 ng/ mL. This study presents a novel approach to lung cancer detection, surpassing the traditional methods in terms of invasiveness, cost, and accuracy. The results from this work could pave the way for the development of graphene-based sensors in various other biosensing applications.

Refined structured tin dioxide gets the amount of attraction because of its low cost and stability. The C@SnO2 nanospheres with mesoporous structures were produced using the hard template method in this work. The C@SnO2 is primarily gained attributed to the dehydration condensation of C6H12O6 and the hydrolysis of SnCl4 ·5H2O. The morphology of the C@SnO2 was analyzed by physical characterization and the diameter of the obtained C@SnO2 was around 138 nm. When C@SnO2 was applied to lithium-ion batteries as anode material, it performed outstanding electrochemical properties, with a capacity of 735 and 539 mA h g− 1 maintained at 1000 and 2000 mA g− 1, respectively. Furthermore, it exhibits favorable discharge/ charge cycle stability. This is probably because of the more chemically redox active sites provided by C@SnO2 nanocomposites and it also allows fast ion diffusion and electron migration.

The development of food packaging materials with mechanical and antimicrobial properties is still a major challenge. N, P-doped carbons (NPCs) were synthesized. Poly(butylene adipate-co-terephthalate) (PBAT), which has an adverse effect on the environment and affects petroleum resources, has been commonly used for applications as food packaging. The development of PBAT composites reinforced with NPCs and studies on their structure and antimicrobial properties are presented in this study. The composite materials in the PBAT/NPCs were processed by solution casting. The plasticizing properties of NPCs enhanced the mechanical strength of composites produced of PBAT and NPCs. The thermal properties of PBAT composites were enhanced with addition of NPCs, according to thermogravimetric analysis (TGA). After reinforcement, PBAT/NPCs composites became more hydrophobic, according to contact angle measurements. In studies against S. aureus and E. coli food-borne pathogenic bacteria, the obtained composites show noticeably improved antimicrobial activity. The composite materials, according to the results of PBAT and NPCs may be a good choice for packing for food that prevents microorganisms.

Flexible supercapacitors (FS) are ideal as power backups for upcoming stretchable electronics due to their high power density and good mechanical compliance. However, lacking technology for FS mass manufacturing is still a significant obstacle. The present study describes a novel method for preparing FS based on reduced graphene oxide (RGO) using the N+ plasma technique, in which N+ reduces graphene oxide on the surface of a cotton/polyester substrate. The effect of aloe vera (AV) as a natural reducing & capping agent and carbon nanotubes (CNT) as nanoconductors on the electrochemical performance of the electrodes is studied. FESEM and XPS were employed to investigate the electrodes' structural and chemical composition of electrodes. The galvanostatic charge–discharge curves of electrodes revealed the enhancement of the electrochemical activity of the as-prepared electrode upon additions of AV and CNT. The areal capacitance of the RGO, RGO/AV, and RGO/ AV/CNT supercapacitors at 5 mV/s was 511, 1244.5, and 1879 mF/cm2, respectively. The RGO electrode showed capacitive retention of 80.9% after 2000 cycles enhanced to 89.7% and 92% for RGO/AV and RGO/AV/CNT electrodes, respectively. The equivalent series resistance of the RGO electrode was 126.28 Ω, decreased to 56.62 and 40.06 Ω for RGO/AV and RGO/ AV/CNT electrodes, respectively.

Sulfur and nitrogen co-doped carbon dots (NSCDs) were quickly synthesized by the microwave-assisted method from triammonium citrate and thiourea. NSCDs showed a quantum yield of 11.5% with excitation and emission bands at 355 and 432 nm, respectively. Also, a fluorescence quenching was observed in the presence of Pb(II) ions, and the as-synthesized CDs were used as a sensitive probe for detecting Pb(II) in water and food samples. The results showed the optimal conditions for Pb(II) determination were CDs concentration of 0.02 mg mL− 1 at pH 6.0–7.0 and an incubation time of 20 min. The relative fluorescence intensity of NSCDs was proportional to Pb(II) concentrations in the range of 0.029–2.40 and 2.40–14.4 μmol L− 1 with a correlation coefficient (R2) of 0.998 and 0.955, respectively, and a detection limit of 9.2 × 10– 3 μmol L− 1. Responses were highly repeatable, with a standard deviation below 3.5%. The suggested method demonstrates the potential of a green, fast, and low-cost approach for Pb(II) determination in water, tea, and rice samples with satisfying results.

A novel kind of self-assembled graphene quantum dots-Co3O4 (GQDs-Co3O4) nanocomposite was successfully manufactured through a hydrothermal approach and used as an extremely effectual oxygen evolution reaction (OER) electrocatalyst. The characterization of morphology with scanning electron microscopy (SEM) and transmission electron microscopy (TEM) showed that Co3O4 nanosheets combined with graphene quantum dots (GQDs) had a new type of hexagonal lamellar selfassembly structure. The GQDs-Co3O4 electrocatalyst showed enhanced electrochemical catalytic properties in an alkaline solution. The start potential of the OER was 0.543 V (vs SCE) in 1 M KOH solution, and 0.577 V (vs SCE) in 0.1 M KOH solution correspondingly. The current density of 10 mA cm− 2 had been attained at the overpotential of 321 mV in 1 M KOH solution and 450 mV in 0.1 M KOH solution. Furthermore, the current density can reach 171 mA cm− 2 in 1 M KOH solution and 21.4 mA cm− 2 in 0.1 M KOH solution at 0.8 V. Moreover, the GQDs-Co3O4 nanocomposite also maintained an ideal constancy in an alkaline solution with only a small deterioration of the activity (7%) compared with the original value after repeating potential cycling for 1000 cycles.