Explore the vast range of titles available.

Over the past two decades, organic–inorganic hybrid perovskite materials (OHP) have been extensively explored across various scientific disciplines, including physics, chemistry, and materials science, with a primary focus on solar cells. Building on numerous studies, the development of OHP‐based solar cells has transitioned into practical product realization, instilling the anticipation of novel solar cell advancements. Notably, OHP demonstrates versatility beyond its conventional application in solar cell materials. The physical properties of OHP materials exhibit a unique signature, thereby underscoring their potential utility as innovative functional materials, encompassing light‐emitting diodes, lasers, and photodetectors. Recent reports on terahertz (THz)‐wave absorption properties of OHP materials indicate a high possibility of their potential application as THz sensors. From the viewpoint of medical devices, which hold the most promising application potential, the exploration of optical phonon vibrational modes in the 0.5–3 THz frequency range is important. Moreover, understanding the correlations between atomic structure and lattice vibration modes is indispensable. In this concise review, the THz‐wave absorption properties exhibited by 3D OHP materials are meticulously explored. Furthermore, future research directions for THz sensors using OHP materials are suggested.

We thoroughly investigated the optical properties of surfactant-free deoxyribonucleic acid (SF-DNA) solid films across a broad spectral gamut from ultraviolet (UV) to terahertz (THz). Demonstrating potential as a transparent dielectric material, SF-DNA films could potentially form optical elements, such as lenses, prisms, and waveguides, for dual-band, near-IR and THz applications. SF-DNA films were classified according to their thickness. Nanometer scale films, ranging from 40 to 200 nm, were created by employing spin coating techniques with aqueous DNA solutions on silicon or fused silica substrates. Micrometer scale films, ranging from 1 to 300 μm, were formed as freestanding DNA films using drop-casting methods. Additionally, we have achieved the successful fabrication of an SF-DNA solid cylinder, positioned between two optical fiber ends, featuring a diameter of 100 to 110 μm and an axial length of 65 to 200 μm. SF-DNA films exhibited a unique dual-band transparency in the near-IR spectral range of 1260 to 1870 nm, and in the terahertz range of 0.22 to 0.64 THz. The refractive index dispersion of nanometer-scale films and their birefringence were also measured in the range of 400 to 2,600 nm. The systematic analysis of optical characteristics from UV to THz wavelengths will serve as a critical foundation for further applications of SF-DNA films in the photonic and optoelectronic device fields.

Terahertz (THz) waves are electromagnetic waves in the 0.1 to 10 THz frequency range, and THz imaging is utilized in a range of applications, including security inspections, biomedical fields, and the non-destructive examination of materials. However, THz images have a low resolution due to the long wavelength of THz waves. Therefore, improving the resolution of THz images is a current hot research topic. We propose a novel network architecture called J-Net, which is an improved version of U-Net, to achieve THz image super-resolution. It employs simple baseline blocks which can extract low-resolution (LR) image features and learn the mapping of LR images to high-resolution (HR) images efficiently. All training was conducted using the DIV2K+Flickr2K dataset, and we employed the peak signal-to-noise ratio (PSNR) for quantitative comparison. In our comparisons with other THz image super-resolution methods, J-Net achieved a PSNR of 32.52 dB, surpassing other techniques by more than 1 dB. J-Net also demonstrates superior performance on real THz images compared to other methods. Experiments show that the proposed J-Net achieves a better PSNR and visual improvement compared with other THz image super-resolution methods.

The valid strong THz absorption at 1.58 THz was probed in the organic-inorganic hybrid perovskite thin film, CH 3 NH 3 PbI 3 , fabricated by sequential vacuum evaporation method. In usual solution-based methods such as 2-step solution and antisolvent, we observed the relatively weak two main absorption peaks at 0.95 and 1.87 THz. The measured absorption spectrum is analyzed by density-functional theory calculations. The modes at 0.95 and 1.87 THz are assigned to the Pb-I vibrations of the inorganic components in the tetragonal phase. By contrast, the origin of the 1.58 THz absorption is due to the structural deformation of Pb-I bonding at the grain boundary incorporated with a CH 3 NH 2 molecular defect.

Gastric cancer (GC) is recognized as the fifth most prevalent malignant tumor worldwide. It is characterized by diverse clinical symptoms, treatment responses, and prognoses. In GC prognosis, the promotion of epithelial–mesenchymal transition (EMT) fosters cancer cell invasion and metastasis, thereby triggering the dissemination of tumor cells. This study proposes a nucleic acid amplification circuit‐based hydrogel (NACH) assay for identifying exosomal miRNA derived from metastatic GC. The NACH assay employs the rolling circle amplification method and targets miRNA‐21, a tumor‐related oncogene, and miRNA‐99a, which promotes EMT. Specific amplification probes for each target are immobilized within the hydrogel, enabling a streamlined, one‐step amplification reaction. The NACH assay exhibits a detection limit of 1 fm for miRNA‐21 and miRNA‐99a, thereby enabling rapid and highly sensitive on‐site detection. Performance evaluation using exosomal miRNA extracted from cell culture media, mouse plasma, and human plasma revealed fluorescence intensity patterns similar to those obtained in qRT‐PCR. Furthermore, deploying a custom‐developed portable fluorometer for the NACH assay allows for diagnostic performance assessment and point‐of‐care testing using clinical samples from GC patients. These findings emphasize the potential of the NACH assay to be used as a robust tool for the genetic diagnosis of GC based on exosome detection. The Nucleic Acid Amplification Circuit‐Based Hydrogel (NACH) assay is developed to detect metastatic gastric cancer (GC)‐related exosomal miRNAs biomarkers. This assay can analyze exosomal miRNA expression levels in a one‐step, and its performance has been demonstrated using blood samples from GC patients at both early and metastatic stages. The NACH assay shows potential as a diagnostic tool for liquid biospy.

The potential negative impact of lymphatic dysfunction caused by head and neck cancer treatment remains underexplored. Emerging evidence suggests that waste clearance and fluidic balance in the brain are connected to the peripheral lymphatic system in the head and neck region, implying that lymphatic injury in this area could contribute to brain damage. This study aimed to investigate the pathological alterations in the brain induced by peripheral lymphatic dysfunction in the head and neck region using the lymphatic obstruction animal model. An animal model underwent cervical lymph node dissection combined with radiation therapy to simulate the condition with the peripheral lymphatic dysfunction in the head and neck region after cancer treatment. Lymphatic drainage impairment in the head and neck region was associated with significant swelling, disrupted lymphatic drainage, and immune cell infiltration in the white matter. The imaging techniques revealed ventricular enlargement and increased brain water content caused by fluid imbalance leading to significant structural alterations in the brain. Histopathological analysis demonstrated structural brain alterations similar to that of hydrocephalus and cerebral edema, while rotarod tests showed a substantial decline in motor performance. These findings highlight the impact of peripheral lymphatic dysfunction on brain integrity and function. This study provides evidence that brain damage in head and neck cancer patients may be influenced not only by chemotherapy or radiotherapy but also by lymphatic dysfunction caused by surgical interventions. Lymphatic injury in the head and neck region emerges as a potential risk factor for brain damage, underscoring the need for further research into preventive and therapeutic strategies.

The terahertz (THz)-wave absorption properties in organic-inorganic hybrid perovskite (OHP) materials are investigated with the in-depth development of OHP-based THz applications. In the THz range from 0.5 to 3 THz, OHPs typically show several interesting phonon modes such as transverse, longitudinal, and halogen self-vibrations. To modulate these frequencies, the density changes in defect-incorporated structures and element mixtures were tested and confirmed. In the literature, the origin of phonon modes in OHP materials have been mostly explained. However, we found new phonon vibration modes in formamidinium (FA)-based hybrid perovskite structures. FAPbI3 single crystals, organic–inorganic hybrid perovskites, of the δ-, δ/α-mixed-, and α-phases were prepared. We intriguingly found that the δ/α-mixed-phase exhibited significant THz-wave absorption peaks at 2.0 and 2.2 THz that were not related to any phonon modes from either the δ- or α-phases, although the δ/α-mixed-phase sample was confirmed to be formed by a physical combination of the δ- and α-phases without the creation of any new chemical states. Our theoretical study performed with ab initio calculations provides an explanation for these unusual THz-wave absorption behaviors; they originate from the novel vibration modes excited at the seamless interfaces in the mixed phase of FAPbI3.We found new phonon vibration modes in formamidinium (FA)-based hybrid perovskite structures. We intriguingly found that the δ/α-mixed-phase exhibited significant THz-wave absorption peaks at 2.0 and 2.2 THz that were not related to any phonon modes from either the δ- or α-phases, although the δ/α-mixed-phase sample was confirmed to be formed by a physical combination of the δ- and α-phases without the creation of any new chemical states. From the theoretical study, they originate from the novel vibration modes excited at the seamless interfaces in the mixed phase of FAPbI3.

The exploration of new physical properties for various THz-based applications, such as THz-wave sensing, modulation, and imaging devices, is a key challenge in the research on organic–inorganic hybrid perovskite materials. These THz-based applications require satisfactory, sensitive, and stable absorption properties with values between 0.5 and 3 THz. To achieve these properties, candidate materials should possess a purified structure that induces regular and fixed phonon modes without any defects or impurities. CH3NH3PbBr3, an organic–inorganic hybrid perovskite thin film produced by a sequential vacuum evaporation method on a flexible PET substrate, was investigated in this study. Although the thin film contains only molecular defects related to CH3NH2 incorporated into the perovskite structure, our THz-wave absorption measurement and first-principles simulation confirmed that these molecular defects do not influence the three phonon modes originating from the transverse vibration (0.8 THz), the longitudinal optical vibrations (1.4 THz) of the Pb–Br–Pb bonds, and the optical Br vibration (2.0 THz). After spin-casting an ultrathin PTAA polymer protective layer (5 nm) on the hybrid perovskite thin film, it was additionally observed that there was no significant effect on the phonon modes. Thus, this novel flexible organic–inorganic hybrid perovskite material is a potential candidate for THz-based applications.NPG Asia MaterialsOptical materials: a new choice for security imagingA material useful for security imaging has been identified by an international team of scientists. Radiation between the infrared and microwave parts of the electromagnetic spectrum can pass through clothing. This so-called terahertz radiation is valuable for security screening technology as it can identify a wider range of materials than metal detectors and is much quicker than a manual pat-down. A team led by Young-Kyun Kwon from Kyung Hee University, Seoul, South Korea, and Min-Cherl Jung from the University of Tsukuba, Ibaraki, Japan, demonstrated that a material already used with great success in optoelectronic and solar cell applications, known as an organic–inorganic hybrid perovskite, also has useful terahertz properties. The team created thin films of this material on a flexible substrate and showed that it absorbed radiation at fixed terahertz frequencies.

The utility of terahertz time-domain spectroscopy (THz-TDS) for the qualitative and quantitative analysis of edible oils remains underexplored. Therefore, we aimed to characterize an edible oil mixture consisting of perilla, soybean, and corn oils using THz-TDS spectroscopy and compare the findings with those from Fourier transform infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance ( 1 H NMR) spectroscopy. THz-TDS was used to obtain complex optical constants such as power absorption and refractive index of oils in the range of 0.2–2.0 THz. Perilla oil mixtures were quantitatively analyzed using complex dielectric constants in the THz frequency region. We characterized the double bond structure of omega-3 in perilla oil using THz-TDS. Furthermore, we used reflection-mode THz-TDS imaging to demonstrate its application as a non-destructive authenticity test for bottled edible oil.

Hole transport layers (HTL) are crucial materials to improve the power conversion efficiency in organohalide hybrid perovskite-based solar-cell applications. Two important physical properties are required in HTL materials: good hole mobility and air-protection. After HTL solution-based deposition, an intermixed chemical state at the interface between HTL and hybrid perovskite is key to confirming the physical property of HTL. We performed high-resolution x-ray photoelectron spectroscopy to investigate the chemical states at the interface between an ultra-thin P3 polymer and CH 3 NH 3 PbI 3 hybrid perovskite thin film. At the interface, we found no apparent intermixed chemical state. Furthermore, we confirmed that the P3 HTL with the ultra-thin layer (7 nm) protected the hybrid perovskite material against air-exposure for 2 weeks.