Image Research Articles

DSM Quality Assessment of GF-7 Satellite

Abstract. The Gaofen-7 (GF-7) satellite was launched on November 3, 2019. It can achieve 1:10000 scale stereo mapping and serve the application needs of basic surveying and mapping, natural resources monitoring and geographic information resource construction. These application rely on high-precision digital surface model (DSM) products as data support. Therefore, it is of great significance to analyze the quality of DSM products produced by Gaofen-7. This paper uses GF-7 optical stereo images from the regions of Zhaodong and Tianjin in China to extract DSMs. And the difference DSM is produced by subtracting the 0.5m resolution aerial reference DEM and the 30m resolution COP30 product in the same area. The quality of DSM products is evaluated by comparing and analyzing the difference DSM. The results show that when the DSM produced by the GF-7 satellite uses the aerial DEM as a reference, the elevation accuracy can reach 0.97 m in the Zhaodong area and 1.54 m in the Tianjin area, and the details of the objects are well depicted; when the COP30 product is used as a reference, the elevation positioning accuracy can reach 1.29 m in the Zhaodong area and 2.42 m in the Tianjin area, which can correctly show the overall situation of the surface objects. Among them, the elevation accuracy in the Tianjin area is relatively poor, mainly because there are many water areas and buildings in this area, and the COP30 product has data missing in this area, which affects the accuracy. In general, the quality of the DSM products generated by the GF-7 satellite is good. Through effective ground control and further processing, the DSM products can fully meet the needs of practical applications such as 1:10000 scale mapping.

FABRICATION AND CHARACTERIZATION OF DISSOLVING MICRONEEDLE PATCH USING 3D PRINTED MASTER

Objective: The purpose of this study was to fabricate a dissolving microneedle patch using a 3D-printed master and characterize it using various techniques. Methods: Dissolving microneedle patches were developed using Computer-Aided Design (CAD) software and 3D printing. Polydimethylsiloxane (PDMS) reverse molds were cast from the 3D-printed masters and filled with a solution of 20% Chitosan Oligosaccharide (COS) and 20% Polyvinyl Alcohol (PVA). The patches were dried at room temperature and characterized using Scanning Electron Microscopy (SEM), Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR), X-ray diffraction (XRD), Thermogravimetric Analysis (TGA), Differential Scanning Calorimetry (DSC), and in vitro skin penetration studies. Results: Optical microscopy and SEM images showed the formation of a uniform microneedle. The peak at 1248 cm⁻¹ in the ATR-FTIR spectrum indicates the formation of cross-links between certain PVA radical groups and COS. XRD revealed that both polymers blended well and showed partial crystallinity, with peaks at 2θ = 11.39°, 2θ = 20°, and 2θ = 41°. DSC and TGA analyses revealed that the blend could withstand high temperatures with good stability at temperatures up to 200 °C. In vitro skin penetration studies confirmed that microneedles could successfully penetrate the skin, indicating their potential for effective transdermal drug delivery. Conclusion: This study demonstrated that COS/PVA dissolving microneedles fabricated using 3D printing and micro-molding have significant potential for transdermal drug delivery.

Cascaded compressed-sensing single-pixel camera for high-dimensional optical imaging

Single-pixel detectors are popular devices in optical sciences because of their fast temporal response, high sensitivity, and low cost. However, when being used for imaging, they face a fundamental challenge in acquiring high-dimensional information of an optical field because they are essentially zero-dimensional sensors and measure only the light intensity. To address this problem, we developed a cascaded compressed-sensing single-pixel camera, which decomposes the measurement into multiple stages, sequentially reducing the dimensionality of the data from a high-dimensional space to zero dimension. This measurement scheme allows us to exploit the compressibility of a natural scene in multiple domains, leading to highly efficient data acquisition. We demonstrated our method in several demanding applications, including enabling tunable single-pixel full-waveform hyperspectral light detection and ranging (LIDAR) for the first time.

Targeting c-MET for Endoscopic Detection of Dysplastic Lesions Within Barrett's Esophagus Using EMI-137 Fluorescence Imaging.

Esophageal cancer (EC) carries a poor prognosis with 5-year overall survival of less than 20%. Barrett's esophagus (BE) increases the risk of esophageal adenocarcinoma (EAC). The aim of this study was to investigate the ability of EMI-137, a mesenchymal-epithelial transition factor (c-MET)-targeting optical imaging tracer, to detect dysplasia in BE. c-MET expression in human esophageal tissue was investigated using Gene Expression Omnibus (GEO) datasets, tissue microarrays and BE biopsies. EMI-137 was tested in a dual xenograft mouse model bearing OE33 (c-MET high expression) and FLO-1 (c-MET low expression) tumors. Fluorescence molecular endoscopy (FME) was performed in a mouse model of Barrett's-like metaplasia and dysplasia (L2-IL1β). Tumors and organs-of-interest were evaluated through ex vivo fluorescence imaging. MET mRNA expression analyses and c-MET immunostaining confirmed upregulation of c-MET in BE and EAC compared to normal epithelium. There was strong accumulation of EMI-137 in OE33 xenografts 3 h post injection decreasing by more than 50% on co-injection of a 10-fold molar excess of unlabeled EMI-137. The target-to background ratio (TBR) at 3 h p.i. for OE33 and FLO-1 tumors was 10.08 and 1.42, respectively. FME of L2-IL1β mice showed uptake of EMI-137 in dysplastic lesions within BE with a TBR of 1.9 in vivo, and greater than 2 in ex vivo fluorescence imaging. EMI-137 accumulates in dysplastic lesions within BE and in c-MET positive EAC. EMI-137 imaging has potential as a screening and surveillance tool for patients with BE and as a means to detecting dysplasia and EAC.

In Situ and Label-Free Quantification of Membrane Protein–Ligand Interactions Using Optical Imaging Techniques: A Review

Membrane proteins are crucial for various cellular processes and are key targets in pharmacological research. Their interactions with ligands are essential for elucidating cellular mechanisms and advancing drug development. To study these interactions without altering their functional properties in native environments, several advanced optical imaging methods have been developed for in situ and label-free quantification. This review focuses on recent optical imaging techniques such as surface plasmon resonance imaging (SPRi), surface plasmon resonance microscopy (SPRM), edge tracking approaches, and surface light scattering microscopy (SLSM). We explore the operational principles, recent advancements, and the scope of application of these methods. Additionally, we address the current challenges and explore the future potential of these innovative optical imaging strategies in deepening our understanding of biomolecular interactions and facilitating the discovery of new therapeutic agents.

Clickable HaloTag ligands for live cell labeling and imaging

Self-labeling protein (SLP) tags, such as HaloTag, have gained considerable interest as advanced tools for live cell labeling. However, the chloroalkane-based substrates that can be directly used for protein labeling are limited. Here, we report two bioorthogonal small molecule linkers, chloroalkane-tetrazine (CA-Tz) and chloroalkane-azide (CA-N3), which can penetrate cell membranes and facilitate click chemistry-based labeling in live cells. We compare their labeling capability using two clickable silicon rhodamine dyes (SiR-PEG3-TCO and SiR-PEG4-DBCO). Confocal imaging results demonstrate that using CA-Tz and SiR-PEG3-TCO dye exhibits superior intracellular labeling with low nonspecific signals. We subsequently compared the photostability of SiR dyes with that of green fluorescent proteins (mEmerald). Total internal reflection fluorescence (TIRF) imaging indicates that SiR dyes exhibit superior photostability under identical excitation conditions, making them suitable for long-term cell imaging. Furthermore, SiR dyes labeling also shows high structure retention for the fourth-order super-resolution optical fluctuation imaging (SOFI) compared to fluorescent proteins. This study presents clickable HaloTag linkers as effective tools for live cell labeling and imaging, highlighting the high-quality labeling of chloroalkane linkers and clickable dyes for live cell imaging.

Initial Experience of Implementing a Pre-treatment Dry Run for HyperArc Stereotactic Radiosurgery Treatments With Optical Surface Imaging for Intra-fraction Motion Monitoring

Initial Experience of Implementing a Pre-treatment Dry Run for HyperArc Stereotactic Radiosurgery Treatments With Optical Surface Imaging for Intra-fraction Motion Monitoring

Rhythmic Contractions of Lymph Vessels and Lymph Flow Are Disrupted in Hypertensive Rats.

Hypertension increases the risk of lymphedema in patients with comorbidities, but whether hypertension directly compromises lymph vessel (LV) function and lymph flow is unclear. We compared the contractions of mesenteric LVs ex vivo and lymph flow in vivo between normotensive and Ang II (angiotensin II)-induced hypertensive rats and explored the ionic basis of contractile patterns. Key studies were recapitulated in spontaneously hypertensive rats and control Wistar-Kyoto rats. Video microscopy continuously recorded the diameters of cannulated rat mesenteric LVs, and high-speed optical imaging estimated mesenteric lymph flow in vivo. Jess capillary Western electrophoresis evaluated expression levels of ion channel proteins. Isolated LVs from Ang II-induced hypertensive rats exhibited dysrhythmic contractions, whereas LVs from both Ang II-induced hypertensive rats and spontaneously hypertensive rats exhibited reduced diastolic diameters and cross-sectional flow. Mesenteric lymph flow in vivo was 2.9-fold lower in Ang II-induced hypertensive rats compared with normotensive rats. Surprisingly, the LVs from Ang II-induced hypertensive rats expressed fewer intact L-type Ca2+ channel pore proteins and more modulatory cleaved C-terminal fragments. However, pharmacological block of voltage-gated K+ channels but not other K+ channel types in control LVs established the pattern of contractile dysfunction observed in hypertension. Jess capillary Western electrophoresis analysis confirmed a loss of Shaker-type KV1.2 channels in LVs from hypertensive rats. We provide initial evidence of lymphatic contractile dysfunction and compromised lymph flow in hypertensive rats, which may be caused by a loss of KV1.2 channels in the lymphatic muscle cells.

A Parametric Study on the Stability, Geometry and Hardness of AISI 308LSi WAAM-GMAW

Wire arc additive manufacturing (WAAM) has been established to be an efficient and cost-effective additive manufacturing technique for fabricating functional metallic parts from scratch. However, there is need to determine optimal processing condition for each material system to produce high-quality parts. In this work, a parametric study of WAAM of AISI 308LSi was performed to determine the processing condition(s) at which single tracks of high dimensional accuracy, excellent geometry, no visible crack and pore, and high hardness required for high-quality multi-track deposition can be achieved. The track geometries were investigated using a combination of optical microscopy and image processing software. The microstructure and hardness of the deposited single tracks were examined using optical microscopy and Vickers hardness tester respectively. A process map predicting the process stability of WAAM of AISI 308LSi was developed within a process window. Continuous single tracks of high dimensional accuracy were produced from a stable deposition process. The process becomes unstable whenever the wire deposition volume per unit length of track is in excess of the available heat energy per unit length of track. The wire feed rate and traverse speed significantly influence the stability and geometry of the single tracks. The processing conditions at which single tracks of low wetting angle (<90◦), high aspect ratio (>1.5), high surface quality, and high hardness (close to the as-received material) can be deposited were determined. These processing conditions were considered suitable for the fabrication, surface modification and repair of functional engineering parts made of 308LSi stainless steel.

Optical asymmetric image encryption using DNA through vortex beam encoding

Optical asymmetric image encryption using DNA through vortex beam encoding

Enhanced auditory responses in visual cortex of blind rats using intrinsic optical signal imaging

Functional maturation of the visual cortex is induced by visual experiences during critical periods. Blind animals and humans exhibit improved auditory abilities after losing their vision. Here we investigated the response of the visual cortex to white noise stimuli during the progression of photoreceptor degeneration in a rat model of blindness (Royal College of Surgeons [RCS] (rdy/rdy) rats). Optical coherence tomography of RCS (+/+) rats with normal visual function revealed normal photoreceptor cells, whereas 3-month-old RCS (rdy/rdy) rats demonstrated photoreceptor cell degeneration. Visual cortex responses (VCRs) to a single flash stimulus were negligible in 3-month-old photoreceptor-degenerated rats. However, VCRs with white noise stimuli were significantly increased in blind versus RCS rats (+/+). Slight changes in the intrinsic optical signals of the control rats were observed on the ventral side of the visual cortex. In contrast, responses were markedly increased throughout the visual cortex of RCS (rdy/rdy) rats. These results indicate that the visual cortex rapidly acquires auditory system function over the first 3 months of life and that the entire visual cortex, rather than just the portion close to the auditory cortex, responds to white noise.

Evidence of the Quantum Optical Nature of High-Harmonic Generation

High-harmonic generation is a light up-conversion process occurring in a strong laser field, leading to coherent bursts of extreme ultrashort broadband radiation [Lewenstein , Phys. Rev. A , 2117 (1994)]. As a new perspective, we propose that ultrafast strong-field electronic or photonic processes such as high-harmonic generation can potentially generate nonclassical states of light well before the decoherence of the system occurs [Gorlach , Nat. Commun. , 4598 (2020); Stammer ., Phys. Rev. Lett. , 123603 (2022)]. This could address fundamental challenges in quantum technology such as scalability, decoherence, or the generation of massively entangled states [Lewenstein , Luca Argenti Michael Chini, 27 (2024)]. Here, we report experimental evidence of the nonclassical nature of the harmonic emission in several semiconductors excited by a femtosecond infrared laser. By investigating single- and double-beam intensity cross-correlation [Loudon, Rep. Prog. Phys. , 913 (1980)], we measure characteristic nonclassical features in the single-photon statistics. We observe two-mode squeezing in the generated harmonic radiation, which depends on the laser intensity that governs the transition from super-Poissonian to Poissonian photon statistics. The measured violation of the Cauchy-Schwarz inequality realizes a direct test of multipartite entanglement in high-harmonic generation [Wasak, Phys. Rev. A , 033616 (2014)]. This result is supported by the theory of multimodal detection and the Hamiltonian from which the effective squeezing modes of the harmonics can be derived [Gonoskov , Phys. Rev. B , 125110 (2024); Christ New J. Phys. , 033027 (2011)]. With this work, we show experimentally that high-harmonic generation is a new quantum bosonic platform that intrinsically produces nonclassical states of light with unique features such as multipartite broadband entanglement or multimode squeezing. The source operates at room temperature, using standard semiconductors and a standard commercial fiber laser, opening up new routes for the quantum industry, such as optical quantum computing, communication, and imaging. Published by the American Physical Society 2024

Identifying Damaged Areas Caused by the Noto Peninsula 2024 Earthquake Using Change Detection from Optical Satellite Images

Abstract. Strategic response during disasters requires the swiftness of the flow of data and information. Simple change detections can be used from Optical Satellite Images to achieve fast results that can be used for analysis and planning. In response to the earthquake that devastated the Noto Peninsula of Japan on New Year’s Day, news reports and early optical satellite images were utilized to identify areas that were damaged by the earthquake. The changes in the reflectance values and indicators, such as NDBI and NDVI were analyzed to identify the areas with damages such as collapsed buildings and landslides. From the after-event satellite images of PlanetScope and Sentinel-2, three areas were identified as severely affected based on news reports namely, Wajima City, Niemachi, and Noto Town. To verify the results of the analysis, aerial images provided by the Geographical Survey Institute of Japan, and Google Earth Street View Images were used. Through change detection methods, the locations of damaged areas were pinpointed using Optical Satellite Images after the earthquake incident.

Deep network based approaches to mitigate seasonal effects in SAR images for deforestation monitoring

Abstract. Most deforestation monitoring programs are based on optical images, which are severely affected by clouds, especially in tropical regions. As an alternative, Synthetic Aperture Radar (SAR) data are minimally affected by atmospheric conditions. However, one of the challenges inherent in such approaches is the effect of seasonal rainforest variations over the SAR images. Recently proposed stabilization algorithms mitigate this effect with significant accuracy gains, however, at the cost of higher computational resources, needed to accommodate long temporal SAR image sequences. This work addresses this issue and presents two alternative solutions that attain similar or better accuracy at a much lower computational requirements. One solution is based on a ResUnet, while the second combines an LSTM and a UNet. Both approaches were tested using raw and stabilized pairs as well as raw sequences. Experiments have indicated that both approaches can mitigate the seasonality effect using a much shorter SAR image sequences than modern stabilization methods require. The results with the multitemporal input outperformed those with the preprocessed bitemporal set by 4.3% in Recall, 1.7% in Precision, and 2.7% in F1-Score, also delivering the best deforestation probability maps.

3D morphometry of Martian craters from HRSC DEMs using a multi-scale semantic segmentation network and morphological analysis

The morphology of impact craters reveals the structure and composition of the Martian surface, especially the subsurface conditions and Martian geological history, which have increasing importance in Mars exploration missions. This work presents a 3D morphometric method for detecting and delineating Martian craters, and a 3D morphological analysis was conducted. Specifically, this work first focused on the segmentation of Martian craters. Based on the segmentation results, clustering of crater instances was then carried out. Finally, with the individual craters that were extracted, a morphological analysis involving the measurements of their diameter, depth, area, RMS height, rim height, circularity, and the statistics thereof was performed. Unlike previous studies, which have mainly used optical images and object detection approaches, this work regards crater extraction as a semantic segmentation task instead of an object detection task to better delineate the precise shape and boundary information. Digital elevation model (DEM) was utilized as primary data to directly obtain 3D information, which was converted into 3D point cloud format and fed to a multi-scale semantic segmentation network. The semantic segmentation results achieved an overall accuracy of 0.932 and mIOU of 0.871 on the test data. We automatically counted 63 craters in Noachis Terra and 40 craters in Terra Cimmeria. The 3D morphological measurements showed that 66% of the impact craters in the first region were larger than 10 km in diameter, while 50% of the impact craters in the second region were larger than 10 km. In both areas, craters could reach a maximum depth of 2000 m. With the proposed method, we can automatically conduct 3D morphological measurements of Martian craters with high efficiency that is improved by 15 times compared with that of manual crater analysis tools. The achieved 3D morphometric results can provide a reference and support for future research on Martian landforms.

200mm Optical synthetic aperture imaging over 120 meters distance via Macroscopic Fourier ptychography

200mm Optical synthetic aperture imaging over 120 meters distance via Macroscopic Fourier ptychography

Fundamental effects of array density and modulation frequency on image quality of diffuse optical tomography.

Diffuse optical tomography (DOT) provides three-dimensional image reconstruction of chromophore perturbations within a turbid volume. Two leading strategies to optimize DOT image quality include, (i) arrays of regular, interlacing, high-density (HD) grids of sources and detectors with closest spacing less than 15mm, or (ii) source modulated light of order ∼100MHz. However, the general principles for how these crucial design parameters of array density and modulation frequency may interact to provide an optimal system design have yet to be elucidated. Herein, we systematically evaluated how these design parameters effect image quality via multiple key metrics. Specifically, we simulated 32 system designs with realistic measurement noise and quantified localization error, spatial resolution, signal-to-noise, and localization depth of field for each of ∼85000 point spread functions in each model. We found that array density had a far stronger effect on image quality metrics than modulation frequency. Additionally, model fits for image quality metrics revealed that potential improvements diminish with regular arrays denser than 9mm closest spacing. Further, for a given array density, 300MHz source modulation provided the deepest reliable imaging compared to other frequencies. Our results indicate that both array density and modulation frequency affect the spatial sampling of tissue, which asymptotically saturates due to photon diffusivity within a turbid volume. In summary, our results provide comprehensive perspectives for optimizing future DOT system designs in applications from wearable functional brain imaging to breast tumor detection.

High‐Fidelity Information Transmission Through the Turbulent Atmosphere Utilizing Partially Coherent Cylindrical Vector Beams

As the demand for high‐capacity and high‐fidelity communication systems continues to increase, addressing the challenges posed by noise and atmospheric turbulence disturbances is imperative. This study introduces and experimentally implements a novel free‐space optical communication protocol. This protocol combines the advantages of reducing the spatial coherence of light at the source with the capabilities of convolutional neural networks at the receiver to encode and transmit optical images through a noisy link. Light beams that are robust against noise are generated and atmospheric turbulence is modeled in a laboratory setting by decreasing the degree of spatial coherence of the source. Eight orbital angular momentum states, four polarizations, and eight coherence states of a light source that generates partially coherent cylindrical vector beams are utilized. These elements are employed to achieve a 256‐ary encoding/decoding data transmission within our protocol. This study is expected to catalyze further research into the utilization of partially coherent light and neural networks in the realm of free‐space optical communications.

Molecular Imaging Biomarkers for Early Cancer Detection: A Systematic Review of Emerging Technologies and Clinical Applications.

Early cancer detection is crucial for improving patient outcomes. Molecular imaging biomarkers offer the potential for non-invasive, early-stage cancer diagnosis. To evaluate the effectiveness and accuracy of molecular imaging biomarkers for early cancer detection across various imaging modalities and cancer types. A comprehensive search of PubMed/MEDLINE, Embase, Web of Science, Cochrane Library, and Scopus was performed, covering the period from January 2010 to December 2023. Eligibility criteria included original research articles published in English on molecular imaging biomarkers for early cancer detection in humans. The risk of bias for included studies was evaluated using the QUADAS-2 tool. The findings were synthesized through narrative synthesis, with quantitative analysis conducted where applicable. In total, 50 studies were included. Positron emission tomography (PET)-based biomarkers showed the highest sensitivity (mean: 89.5%, range: 82-96%) and specificity (mean: 91.2%, range: 85-100%). Novel tracers such as [68Ga]-PSMA for prostate cancer and [18F]-FES for breast cancer demonstrated promising outcomes. Optical imaging techniques showed high specificity in intraoperative settings. Molecular imaging biomarkers show significant potential for improving early cancer detection. Integration into clinical practice could lead to earlier interventions and improved outcomes. Further research is needed to address standardization and cost-effectiveness.

Research Progress of Spectral Imaging Techniques in Plant Phenotype Studies.

Spectral imaging technique has been widely applied in plant phenotype analysis to improve plant trait selection and genetic advantages. The latest developments and applications of various optical imaging techniques in plant phenotypes were reviewed, and their advantages and applicability were compared. X-ray computed tomography (X-ray CT) and light detection and ranging (LiDAR) are more suitable for the three-dimensional reconstruction of plant surfaces, tissues, and organs. Chlorophyll fluorescence imaging (ChlF) and thermal imaging (TI) can be used to measure the physiological phenotype characteristics of plants. Specific symptoms caused by nutrient deficiency can be detected by hyperspectral and multispectral imaging, LiDAR, and ChlF. Future plant phenotype research based on spectral imaging can be more closely integrated with plant physiological processes. It can more effectively support the research in related disciplines, such as metabolomics and genomics, and focus on micro-scale activities, such as oxygen transport and intercellular chlorophyll transmission.