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Nuclear Spin Singlet States in Photoactive Molecules: From Fluorescence/NMR Bimodality to a Bimolecular Spin Singlet State Switch
摘要： Nuclear spin singlet states are silent states in nuclear magnetic resonance (NMR). However, they can be probed indirectly and offer great potential for the development of contrast agents for magnetic resonance imaging (MRI). Here, we are introducing two novel concepts: Firstly, we investigate the bimodal NMR/fluorescence properties of 13C2-tetraphenylethylene. It possesses a long-lived singlet state in organic solvents, which shortens upon the addition of water. This simultaneously increases the fluorescence emission in a substantial enhancement of fluorescence. Secondly, we introduce a bimolecular singlet state switch based on 3-2H-coumarin containing an isolated proton. Upon UV-light exposure, a dimer forms leading to a coupling between two previously isolated protons. A nuclear spin singlet state can now be populated. Excitation with a wavelength of 254 nm results in partly cleavage of the molecule back into its monomer.
关键词： Photoswitches,NMR spectroscopy,Aggregation induced emission,Fluorescence,Nuclear spin singlet state
更新于2025-09-23 15:23:52
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Quaternion-based weighted nuclear norm minimization for color image denoising
摘要： The quaternion method plays an important role in color image processing, because it represents the color image as a whole rather than as a separate color space component, thus naturally handling the coupling among color channels. The weighted nuclear norm minimization (WNNM) scheme assigns different weights to different singular values, leading to more reasonable image representation method. In this paper, we propose a novel quaternion weighted nuclear norm minimization (QWNNM) model and algorithm under the low rank sparse framework. The proposed model represents the color image as a low rank quaternion matrix, where quaternion singular value decomposition can be calculated by its equivalent complex matrix. We solve the QWNNM by adaptively assigning different singular values with different weights. Color image denoising is implemented by QWNNM based on non-local similarity priors. In this new color space, the inherent color structure can be well preserved during image reconstruction. For high noise levels, we apply a Gaussian lowpass filter (LPF) to the noisy image as a preprocessing before QWNNM, which reduces the iteration numbers and improves the denoised results. The experimental results clearly show that the proposed method outperforms K-SVD, QKSVD and WNNM in terms of both quantitative criteria and visual perceptual.
关键词： Quaternion singular value decomposition,Non-local similarity priors,Quaternion weighted nuclear norm minimization,Low rank,Color image denoising
更新于2025-09-23 15:23:52
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<sup>125</sup> Te nuclear magnetic resonance and impedance spectroscopy study of topological insulator Bi <sub/>2</sub> Te <sub/>3</sub> nanoparticles mixed with insulating Al <sub/>2</sub> O <sub/>3</sub> nanoparticles
摘要： We have studied topological insulator Bi2Te3 nanoparticles mixed with insulating Al2O3 nanoparticles by means of 125Te nuclear magnetic resonance (NMR) and impedance spectroscopy. Our 125Te NMR lineshape measurements revealed the Knight shift of a satellite peak that increased with the mixing ratio of the Al2O3 nanoparticles, indicating that the mixing increases the surface-to-volume ratio of the Bi2Te3 nanoparticles. It is also shown that the impedance spectroscopy can be employed as a simple and effective means of distinguishing the surface electrical properties of the topological insulators in general.
关键词： surface electrical properties,topological insulator Bi2Te3 nanoparticles,125Te nuclear magnetic resonance,impedance spectroscopy
更新于2025-09-23 15:23:52
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HMGB1 siRNA can reduce damage to retinal cells induced by high glucose in vitro and in vivo
摘要： Background: Diabetic retinopathy (DR), one of the most common complications of late-phase diabetes, is associated with many risk factors, among which continuous low-grade inflammation is one of the principal ones. As such, lowering inflammation levels and maintain the viability of human retinal endothelial cells (HRECs) are critical for DR therapy. HMGB1 is a well-known proinflammatory cytokine. However, whether HMGB1 small interfering RNA (siRNA) can protect retina cells under a high-glucose environment from morphological changes and functional abnormalities remain undetermined. We aimed to investigate the effect of HMGB1 siRNA on retinal cells in DR. Materials and methods: A total of 80 adult Wistar rats were randomly divided into four groups (n=20 each): normal control, diabetes mellitus (DM), scrambled (Scr) siRNA, and HMGB1 siRNA. Rats in the DM, Scr siRNA, and siRNA groups were established by intraperitoneal injection of streptozotocin. At 16 weeks after injection, rats in the siRNA and Scr-siRNA groups were intravitreally injected with 2 μL HMGB1 siRNA and 2 μL Scr-siRNA, while rats in the control and DM groups were intravitreally injected with the same dose of sterile saline. At 1 week after injections, we performed the following experiments. Immunohistochemical staining and real-time quantitative polymerase chain reaction were performed to test HMGB1 protein and messenger RNA expression in retinas. We performed TUNEL assays to detect retinal cell apoptosis and electroretinography to detect retinal function. In HRECs treated with high glucose, proliferation, morphology, apoptosis, superoxide dismutase (SOD), and reactive oxygen species production were detected. Western blot was applied to determine the expressions of HMGB1 and its related protein and apoptosis protein. Results: Intravitreal injection of HMGB1 siRNA reduced protein and messenger RNA expression of HMGB1 (both P,0.05). Intravitreal injection of HMGB1 siRNA reduced apoptosis of retinal cells (P,0.05), protected morphological changes in the retina, and improved the function of the retina (P,0.05). In HRECs treated with high glucose, HMGB1 siRNA pretreatment increased cell viability, reduced cell apoptosis, and reduced oxidative damage to cells (all P,0.05). Western blot detection found that HMGB1 siRNA pretreatment can inhibit the expression of cleaved caspase 3 and improve the expression of BCL2 (P,0.05). HMGB1 and NFκB expression increased in a time-dependent manner in the high-glucose environment and IKKβ and NFκB protein expression decreased significantly after HMGB1 silencing. Conclusion: As a therapeutic target, HMGB1 siRNA can reduce retinal cell damage induced by high glucose in vitro and in vivo and delay DR progress through the HMGB1–IKKβ–NFκB signaling pathway.
关键词： small interfering RNA,diabetic retinopathy,human retinal endothelial cells,inhibitor of nuclear factor κB,nuclear factor κB,high-mobility group box 1
更新于2025-09-23 15:22:29
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PET Counting Response Variability Depending on Tumor Location, Activity, and Patient Obesity: A Feasibility Study of Solitary Pulmonary Nodule Using Monte Carlo
摘要： We aim to investigate the counting response variations of Positron Emission Tomography (PET) scanners with different detector configurations in the presence of Solitary Pulmonary Nodule (SPN). Using experimentally validated Monte Carlo simulations, the counting performance of four different scanner models with varying tumor activity, location, and patient obesity is represented using NECR (Noise Equivalent Count Rate). NECR is a well-established quantitative metric which has positive correlation with clinically perceived image quality. The combined effect of tumor displacement and increased activity shows a linear ascending trend for NECR with slope ranges of (12.5–18.2)*10-3 (kBq/cm3)-1 for three-ring (3R) scanners and (15.3–21.5)*10-3 (kBq/cm3)-1 for four-ring (4R). The trend for the combined effect of tumor displacement and patient obesity is exponential decay with 3R configurations weakly dependent on the patient obesity if the tumor is located at the center of the field-of-view with exponent’s range of (6.6-33.8)*10-2 cm-1. The dependency is stronger for 4R scanners (9.6–38.5)*10 -2 cm-1. The analysis indicates that quantitative PET data from the same SPN patient possibly examined in different time points (e.g. during staging or for the evaluation of treatment response) are affected by the different detector configurations and need to be normalized with patient weight, activity, and tumor location to reduce unwanted bias of the diagnosis. Our work provides also with a proof of concept for the ability of properly tuned simulations to provide additional insights into the counting response variability especially in tumor types where often borderline decisions have to be made regarding their characterization.
关键词： image quality assessment,nuclear imaging,lung
更新于2025-09-23 15:22:29
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Comparison of Clinical Outcomes between Torsional and Longitudinal Phacoemulsification
摘要： Purpose: To compare the clinical outcomes during phacoemulsification when using recently improved longitudinal (Stellaris?, Bausch & Lomb, Rochester, NY, USA) and torsional (Infiniti Ozil?, Alcon, Fort Worth, TX, USA) ultrasound. Methods: The present study included 74 eyes of 59 patients undergoing cataract surgery. Operated eyes with mild cataract (nuclear sclerosis grade 1 and 2), moderate cataract (nuclear sclerosis grade 3) and hard cataract (nuclear sclerosis grade 4 and 5) were compared in terms of the total phacoemulsification (phaco) time, average phaco power, total phaco energy and amount of fluid used during cataract surgery between the 2 modalities. Endothelial cell density, corneal edema, central corneal thickness (CCT), surgically induced astigmatism (SIA) and best-corrected visual acuity (BCVA) were also evaluated preoperatively and up to 3 month postoperatively. Results: In mild cataracts, the operative parameters and corneal changes were similar between the 2 modalities. In moderate cataracts, the total phaco time was significantly higher in the torsional group than the longitudinal group, but the average phaco power, total phaco energy, and amount of fluid were not significantly different. In patients with hard cataract, the torsional group showed higher total phaco time (27.50 ± 17.77 sec vs. 97.08 ± 12.67 sec), average phaco power, total phaco energy, persistent corneal edema at 1 week postoperatively and more endothelial cell loss at 3 month postoperatively (16.33 ± 15.50% vs. 38.71 ± 26.49%). Postoperative CCT, SIA and BCVA were not significantly different in hard cataracts between the 2 modalities. Conclusions: In mild and moderate cataracts, the efficiency of phaco and corneal changes were similar between the 2 modalities. However, recently improved longitudinal phaco showed superior efficiency for hard cataracts and induced less endothelial cell loss than torsional phaco.
关键词： Longitudinal,Cataract surgery,Phacoemulsification,Nuclear density,Torsional
更新于2025-09-23 15:22:29
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Diagnostic imaging and radiation exposure in inflammatory bowel disease
摘要： Diagnostic imaging plays a key role in the diagnosis and management of inflammatory bowel disease (IBD). However due to the relapsing nature of IBD, there is growing concern that IBD patients may be exposed to potentially harmful cumulative levels of ionising radiation in their lifetime, increasing malignant potential in a population already at risk. In this review we explore the proportion of IBD patients exposed to high cumulative radiation doses, the risk factors associated with higher radiation exposures, and we compare conventional diagnostic imaging with newer radiation-free imaging techniques used in the evaluation of patients with IBD. While computed tomography (CT) performs well as an imaging modality for IBD, the effective radiation dose is considerably higher than other abdominal imaging modalities. It is increasingly recognised that CT imaging remains responsible for the majority of diagnostic medical radiation to which IBD patients are exposed. Magnetic resonance imaging (MRI) and small intestine contrast enhanced ultrasonography (SICUS) have now emerged as suitable radiation-free alternatives to CT imaging, with comparable diagnostic accuracy. The routine use of MRI and SICUS for the clinical evaluation of patients with known or suspected small bowel Crohn’s disease is to be encouraged wherever possible. More provision is needed for out-of-hours radiation-free imaging modalities to reduce the need for CT.
关键词： Diagnostic medical radiation,Small intestine contrast-enhanced ultrasonography,Nuclear medicine,Computerised tomography,Inflammatory bowel disease,Magnetic resonance enterography,Small bowel follow-through
更新于2025-09-23 15:22:29
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Smart Supramolecular “Trojan Horse”-Inspired Nanogels for Realizing Light-Triggered Nuclear Drug Influx in Drug-Resistant Cancer Cells
摘要： Efficient nuclear delivery of anticancer drugs evading drug efflux transporters (DETs) on the plasma and nuclear membranes of multidrug-resistant cancer cells is highly challenging. Here, smart nanogels are designed via a one-step self-assembly of three functional components including a biocompatible copolymer, a fluorescent organosilica nanodot, and a photodegradable near-infrared (NIR) dye indocyanine green (ICG). The rationally designed nanogels have high drug encapsulation efficiency (≈99%) for anticancer drug doxorubicin (Dox), self-traceability for bioimaging, proper size for passive tumor targeting, prolonged blood circulation time for enhanced drug accumulation in tumor, and photocontrolled disassemblability. Moreover, the Dox-loaded nanogels can effectively kill multidrug-resistant cells via two steps: 1) They behave like a “Trojan horse” to escape from the DETs on the plasma membrane for efficiently transporting the anticancer “soldier” (Dox) into the cytoplasm and preventing the drugs from being excreted from the cells; 2) Upon NIR light irradiation, the photodegradation of ICG leads to the disassembly of the nanogels to release massive Dox molecules, which can evade the DETs on the nuclear membrane to exert their intranuclear efficacy in multidrug-resistant cells. Combined with their excellent biocompatibility, the nanogels may provide an alternative solution for overcoming cancer multidrug resistance.
关键词： nuclear delivery,photocontrollable drug release,cancer theranostics,silicon-based nanomaterials,supramolecular assembly
更新于2025-09-23 15:22:29
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[ACM Press the 2018 International Conference - Porto, Portugal (2018.07.15-2018.07.17)] Proceedings of the 2018 International Conference on Mathematics and Statistics - ICoMS 2018 - Singular Value Decomposition and its Applications in Image Processing
摘要： The Singular Value Decomposition (SVD) is a highlight of linear algebra and has a wide range application in computer vision, statistics and machine learning. This paper reviews the main theorem of SVD and illustrates some applications of SVD in image processing. More specifically, we focus on image compression and matrix completion. The former is to convert the original full-rank pixel matrix to a well-approximated low-rank matrix and thus dramatically save the space, the latter is to recover a pixel matrix with a large number of missing entries by using nuclear norm minimization, in which some singular value thresholding algorithm will be used. For both applications, we conduct numerical experiments to show the performance and point out some possible improvements in the future.
关键词： Nuclear norm minimization,Matrix completion,Image compression,SVD
更新于2025-09-23 15:22:29
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Edaravone protects the retina against ischemia/reperfusion-induced oxidative injury through the PI3K/Akt/Nrf2 pathway
摘要： Retinal ischemia/reperfusion (I/R) injury can occur as a result of a number of ocular diseases or ischemic events in the brain, leading to possible vision loss if not treated properly. The overproduction of reactive oxygen species is important in the process of I/R injury. Edaravone, a free radical scavenger, has been demonstrated to have a neuroprotective effect in cerebral ischemia; however, its effect against retinal I/R injury remains to be fully elucidated. Therefore, the present study investigated the effects of edaravone on the oxidative parameters, retinal inflammation and apoptosis induced by I/R injury, and treated photoreceptor-derived 661W cells with hydrogen peroxide (H2O2) and edaravone to examine the underlying mechanism. For the in vivo study, oxidative parameters (malondialdehyde, DNA fragmentation, total antioxidant status, superoxide dismutase and glutathione) in the retina, retinal thickness, and apoptotic index in the ganglionic cell layer and inner nuclear layer were measured. For the in vitro study, the effects of edaravone or nuclear factor erythroid-2-related factor 2 (Nrf2) small interfering RNA or phosphatidylinositol 3-kinase (PI3K)/Akt inhibitors on cell viability, membrane integrity, levels of phosphorylated-Akt, Akt and nuclear Nrf2 of H2O2-treated 661W cells were examined. The results demonstrated that edaravone inhibited the oxidative injury in the retina induced by the retinal I/R procedure and increased retinal inflammation, and apoptosis. The results of the in vitro experiments demonstrated that edaravone effectively protected the viability and the membrane integrity of the H2O2-treated 661W cells via the phosphatidylinositol 3-kinase (PI3K)/Akt/Nrf2 pathway. These results indicated the potential protective effect of edaravone against retinal I/R injury and provided a novel explanation for the protective effects of edaravone.
关键词： edaravone,ischemia/reperfusion injury,retina,oxidative injury,phosphatidylinositol 3-kinase/Akt/nuclear factor erythroid-2-related factor 2 pathway
更新于2025-09-23 15:22:29