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  1. Irvine, John (Ed.)
    Abstract

    Here, the radiation hardness of metal halide perovskite solar cells exposed to space conditions versus the effects of environmental degradation are assessed. The relative response of the constituent layers of the architecture to radiation is analyzed, revealing a general resilience of the structure when assessed across varying proton energy levels and fluences. However, despite the tolerance of the structure to irradiation, sensitivity to environmental degradation is observed during the transit of the device between the radiation and characterization facilities. Experimental evidence suggests the NiOx/perovskite interface is particularly sensitive to the effects of humidity and/or temperature exposure, while the irradiation of the devices appears to induce thermally activated annealing: improving the solar cells upon radiation exposure.

     
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    Free, publicly-accessible full text available August 12, 2025
  2. Ikeda, Tokihiro (Ed.)
    We have investigated the concentration and correlation between the macro and micro-elements found in an herbal plant named Ocimum sanctum (Tulsi) leaf, using Particle-Induced X-ray Emission (PIXE) spectroscopy. The leaf area was analyzed with a 2 MeV scanning proton micro-beam with a spot size of ~ 1 square micrometer. This study is focused on exploring the correlation between the elemental maps generated using X-ray spectra with micro-PIXE. Two types of correlations i.e., elemental, and concentration-phase correlations were examined. The elemental maps are used to find the relation between the spatial distribution of the elements present in the scanned region while the correlation maps help in understanding which phase corresponds to the region of selected concentration ratios. All the elemental concentrations were determined with the detection limits in ng/mg. The analysis of macro-elements showed that the potassium concentration was highest and phosphorus exhibited the lowest concentration whereas iron was found to be highest in the category of trace or microelements. Moreover, broad-beam runs were also performed on the samples to examine the trend for elemental concentrations. 
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    Free, publicly-accessible full text available June 8, 2025
  3. Free, publicly-accessible full text available May 1, 2025
  4. This article presents a novel hardware-assisted distributed ledger-based solution for simultaneous device and data security in smart healthcare. This article presents a novel architecture that integrates PUF, blockchain, and Tangle for Security-by-Design (SbD) of healthcare cyber–physical systems (H-CPSs). Healthcare systems around the world have undergone massive technological transformation and have seen growing adoption with the advancement of Internet-of-Medical Things (IoMT). The technological transformation of healthcare systems to telemedicine, e-health, connected health, and remote health is being made possible with the sophisticated integration of IoMT with machine learning, big data, artificial intelligence (AI), and other technologies. As healthcare systems are becoming more accessible and advanced, security and privacy have become pivotal for the smooth integration and functioning of various systems in H-CPSs. In this work, we present a novel approach that integrates PUF with IOTA Tangle and blockchain and works by storing the PUF keys of a patient’s Body Area Network (BAN) inside blockchain to access, store, and share globally. Each patient has a network of smart wearables and a gateway to obtain the physiological sensor data securely. To facilitate communication among various stakeholders in healthcare systems, IOTA Tangle’s Masked Authentication Messaging (MAM) communication protocol has been used, which securely enables patients to communicate, share, and store data on Tangle. The MAM channel works in the restricted mode in the proposed architecture, which can be accessed using the patient’s gateway PUF key. Furthermore, the successful verification of PUF enables patients to securely send and share physiological sensor data from various wearable and implantable medical devices embedded with PUF. Finally, healthcare system entities like physicians, hospital admin networks, and remote monitoring systems can securely establish communication with patients using MAM and retrieve the patient’s BAN PUF keys from the blockchain securely. Our experimental analysis shows that the proposed approach successfully integrates three security primitives, PUF, blockchain, and Tangle, providing decentralized access control and security in H-CPS with minimal energy requirements, data storage, and response time. 
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    Free, publicly-accessible full text available February 1, 2025
  5. Mixed organic–inorganic halide perovskite-based solar cells have attracted interest in recent years due to their potential for both terrestrial and space applications. Analysis of interfaces is critical to predicting device behavior and optimizing device architectures. Most advanced tools to study buried interfaces are destructive in nature and can induce further degradation. Ion beam techniques, such as Rutherford backscattering spectrometry (RBS), is a useful non-destructive method to probe an elemental depth profile of multilayered perovskite solar cells (PSCs) as well as to study the inter-diffusion of various elemental species across interfaces. Additionally, PSCs are becoming viable candidates for space photovoltaic applications, and it is critical to investigate their radiation-induced degradation. RBS can be simultaneously utilized to analyze the radiation effects induced by He+ beam on the device, given their presence in space orbits. In the present work, a 2 MeV He+ beam was used to probe the evidence of elemental diffusion across PSC interfaces with architecture glass/ITO/SnO2/Cs0.05(MA0.17FA0.83)0.95Pb(I0.83Br0.17)3/spiro-OMeTAD/MoO3/Au. During the analysis, the device active area was exposed to an irradiation equivalent of up to 1.62 × 1015 He+/cm2, and yet, no measurable evidence (with a depth resolution ∼1 nm) of beam-induced ion migration was observed, implying high radiation tolerance of PSCs. On the other hand, aged PSCs exhibited indications of the movement of diverse elemental species, such as Au, Pb, In, Sn, Br, and I, in the active area of the device, which was quantified with the help of RBS.

     
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    Free, publicly-accessible full text available March 1, 2025
  6. The rapid adoption of Internet-of-Medical-Things (IoMT) has revolutionized e-health systems, particularly in remote patient monitoring. With the growing adoption of Internet-of-Medical-Things (IoMT) in delivering technologically advanced health services, the security of Medtronic devices is pivotal as the security and privacy of data from these devices are directly related to patient safety. PUF has been the most widely adopted hardware security primitive which has been successfully integrated with various Internet-of-Things (IoT) based applications, particularly in smart healthcare for facilitating device security. To facilitate security and access control to IoMT devices, this work proposes a novel cybersecurity solution using PUF for facilitating global access to IoMT devices. The proposed framework presents an approach that enables the patient’s body area network devices supported by PUF to be securely accessible and controllable globally. The proposed cybersecurity solution has been experimentally validated using state-of-the-art SRAM PUF, a delay based PUF, and a trusted platform module (TPM) primitive. 
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    Free, publicly-accessible full text available December 13, 2024
  7. ACIGS solar cells are exposed to targeted radiation to probe the front and back interfaces of the absorber to assess the impact of space environments on these systems. These data suggest ACIGS cells are more radiation‐hard than early CIGS devices likely due to the lower defect densities and more ideal interfaces in the ACIGS system. A combination ofJVand external quantum efficiency measurements indicates some improvement in the performance of the device due to the effects of local heating in the dominant ionizing electronic energy loss regime of proton irradiation that anneal the upper CdS/ACIGS interface. However, nonionizing energy losses at the base of the solar cell also appear to inhibit minority carrier collection from the back of the cell at the ACIGS/Mo interface, which is discussed in terms of defect‐mediated changes in the doping profile, the Ga/Ga+In ratio, and impurity composition after proton irradiation.

     
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    Free, publicly-accessible full text available February 1, 2025
  8. Natalie Lok Kwan Li, PhD (Ed.)
    Perovskite photovoltaics have been shown to recover, or heal, after radiation damage. Here, we deconvolve the effects of radiation based on different energy loss mechanisms from incident protons which induce defects or can promote efficiency recovery. We design a dual dose experiment first exposing devices to low-energy protons efficient in creating atomic displacements. Devices are then irradiated with high-energy protons that interact differently. Correlated with modeling, high-energy protons (with increased ionizing energy loss component) effectively anneal the initial radiation damage, and recover the device efficiency, thus directly detailing the different interactions of irradiation. We relate these differences to the energy loss (ionization or non-ionization) using simulation. Dual dose experiments provide insight into understanding the radiation response of perovskite solar cells and highlight that radiation-matter interactions in soft lattice materials are distinct from conventional semiconductors. These results present electronic ionization as a unique handle to remedying defects and trap states in perovskites. 
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    Free, publicly-accessible full text available January 24, 2025
  9. Fernanda Kastensmidt Ricardo Reis Aida Todri-Sanial Hai (Ed.)
    The scope of Smart electronics and its increasing market worldwide has made cybersecurity an important challenge. The Security-by-Design (SbD) principle, an emerging cybersecurity area, focuses on building security/privacy-enabled primitives at the design stage of an electronic system. This paper proposes a novel Physical Unclonable Function (PUF) based Trusted Platform Module (TPM) for SbD primitive. The proposed SbD primitive works by performing secure verification of the PUF key using TPM’s Encryption and Decryption engine. The securely verified PUF Key is then bound to TPM using Platform Configuration Registers (PCR). PCRs in TPM facilitate a secure boot process and effective access control to TPM’s NonVolatile memory through an enhanced authorization policy. By binding PUF with PCR in TPM, a novel PUF-based access control policy can be defined, bringing in a new security ecosystem for the emerging Internet-of-Everything era. The proposed SbD approach has been experimentally validated by successfully integrating various PUF topologies with Hardware TPM. 
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  10. his work presents a sustainable cybersecurity solution using Physical Unclonable Functions (PUF), Trusted Platform Module (TPM), and Tangle Distributed Ledger Technology (DLT) for sustainable device and data security. Security-by-Design (SbD) or Hardware- Assisted Security (HAS) solutions have gained much prominence due to the requirement of tamper-proof storage for hardwareassisted cryptography solutions. Designing complex security mechanisms can impact their efficiency as IoT applications are more decentralized. In the proposed architecture, we presented a novel TPM-enabled PUF-based security mechanism with effective integration of PUF with TPM. The proposed mechanism is based on the process of sealing the PUF key in the TPM, which cannot be accessed outside the TPM and can only be unsealed by the TPM itself. A specified NV-index is assigned to each IoT node for sealing the PUF key to TPM using the Media Access Control (MAC) address. Access to the TPM's Non-Volatile Random Access Memory (NVRAM) is defined by the TPM's Enhanced Authorization policies as specified by the Trust Computing Group (TCG). The proposed architecture uses Tangle for sustainable data security and storage in decentralized IoT systems through a Masked Authentication Messaging (MAM) scheme for efficient and secure access control to Tangle. We validated the proposed approach through experimental analysis and implementation, which substantiates the potential of the presented PUFchain 4.0 for decentralized IoT-driven security solutions. 
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