JOURNAL/nrgr/04.03/01300535-202504000-00027/figure1/v/2024-07-06T104127Z/r/image-tiff

Cardiac arrest can lead to severe neurological impairment as a result of inflammation, mitochondrial dysfunction, and post-cardiopulmonary resuscitation neurological damage. Hypoxic preconditioning has been shown to improve migration and survival of bone marrow-derived mesenchymal stem cells and reduce pyroptosis after cardiac arrest, but the specific mechanisms by which hypoxia-preconditioned bone marrow-derived mesenchymal stem cells protect against brain injury after cardiac arrest are unknown. To this end, we established an in vitro co-culture model of bone marrow-derived mesenchymal stem cells and oxygen-glucose deprived primary neurons and found that hypoxic preconditioning enhanced the protective effect of bone marrow stromal stem cells against neuronal pyroptosis, possibly through inhibition of the MAPK and nuclear factor κB pathways. Subsequently, we transplanted hypoxia-preconditioned bone marrow-derived mesenchymal stem cells into the lateral ventricle after the return of spontaneous circulation in an 8-minute cardiac arrest rat model induced by asphyxia. The results showed that hypoxia-preconditioned bone marrow-derived mesenchymal stem cells significantly reduced cardiac arrest-induced neuronal pyroptosis, oxidative stress, and mitochondrial damage, whereas knockdown of the liver isoform of phosphofructokinase in bone marrow-derived mesenchymal stem cells inhibited these effects. To conclude, hypoxia-preconditioned bone marrow-derived mesenchymal stem cells offer a promising therapeutic approach for neuronal injury following cardiac arrest, and their beneficial effects are potentially associated with increased expression of the liver isoform of phosphofructokinase following hypoxic preconditioning.

• Book : 20(4)
• Pub. Date : 2025
• Page : pp.1103-1123
• Keyword :

Abstract

Mitochondria are organelles with double-membrane structure of inner and outer membrane, which provides main energy support for cell growth and metabolism. Reactive oxygen species (ROS) mainly comes from mitochondrial and can cause irreversible damage to cells under oxidative stress. Thus, mitochondrial homeostasis is the basis for maintaining the normal physiological function of cells and mitophagy plays a pivotal role in the maintenance of mitochondrial homeostasis. At present, to enhance the sensitivity of cancer cells to radiotherapy and chemotherapy by regulating mitochondria has increasingly become a hot spot of cancer therapy. It is particularly important to study the effect of ionizing radiation (IR) on mitochondria and the role of mitophagy in the radiosensitivity of cancer cells. Most of the existing reviews have focused on mitophagy-related molecules or pathways and the impact of mitophagy on diseases. In this review, we mainly focus on discussing the relationship between mitophagy and radiosensitivity of cancer cells around mitochondria and IR.

• Book : 150(1)
• Pub. Date : 2025
• Page : pp.14
• Keyword :

Abstract

A single-feed circularly polarized antenna with electromagnetic band gap (EBG) has been developed for the Industrial, Scientific, and Medical (ISM) bands. The proposed antenna features a square patch with eight slits on each side and corner, along with a cross-slot in the middle. To prevent surface wave excitation caused by the patch antenna's thick substrate, new grounded like-mushroom EBG structures will surround the antenna. The frequency band gap characteristics of the EBG unit cells have been optimized at 5.8 GHz. A row of EBGs squares is 4.73 mm (0.063λo) away from the antenna square patch and surrounds it on all four sides. The proposed mushroom-like structure design improves the antenna's directivity by 43.31%, gain by 32.93%, reflection coefficient by 93%, and radiation efficiency by 35.22%. This topology enables a wide variety of wireless communications applications. Computer simulation technologies (CSTs) were used to generate simulation figures for the proposed antenna, operating at 5.8 GHz. Furthermore, the new Like-Mushroom EBG antenna simulation, experimental results, and other reported works confirm that our approach meets the studied objectives regarding polarization purity, radiation efficiency, high directivity, and gain.

• Book : 147(1)
• Pub. Date : 2025
• Page : pp.011002
• Keyword :

Abstract

In this paper, a frequency selective surface (FSS) for n41, n78, n257, n258, n260, and n261 bands electromagnetic interference (EMI) shielding is proposed using a deep learning method. The size of the FSS unit cell is 4.8 mm (0.071$ \lambda _{0} $), where$ \lambda _{0} $is the wavelength corresponding to the cutoff frequency of the −10 dB stopband where the n41 and n78 bands are located. This FSS exhibits three key characteristics. Firstly, it possesses ultrawideband capability, with a stopband frequency range of 23.922-40.023 GHz and a relative bandwidth reaching 50.4%. Secondly, it effectively shields against electromagnetic radiation in multiple 5 G bands, including n41, n78, n257, n258, n260, and n261. Thirdly, it demonstrates high selectivity, with a very narrow transition band of only 0.405 GHz between the passband and the stopband. To validate the designed FSS, a prototype of this structure was first fabricated for experimentation. The experimental results show that the measured S21 is highly consistent with the simulated S21. Secondly, the unit cell array of FSS is placed above the monopole antenna for co-simulation. It can be observed that after placing the FSS, the intensity of electromagnetic radiation propagating in space is significantly reduced by up to more than 90%. Therefore, the proposed FSS can be effectively applied for EMI shielding in 5 G bands.

• Book : 58(1)
• Pub. Date : 2025
• Page : pp.015110
• Keyword :

Abstract

Purpose

This study aims to assess how T2 heterogeneity biases IMPULSED‐derived metrics of tissue microstructure in solid tumors and evaluate the potential of estimating multi‐compartmental T2 and microstructural parameters simultaneously.

Methods

This study quantifies the impact of T2 relaxation on IMPULSED‐derived microstructural parameters using computer simulations and in vivo multi‐TE IMPULSED MRI in five tumor models, including brain, breast, prostate, melanoma, and colon cancer. A comprehensive T2 + IMPULSED method was developed to fit multi‐compartmental T2 and microstructural parameters simultaneously. A Bayesian model selection approach was carried out voxel‐wisely to determine if the T2 heterogeneity needs to be included in IMPULSED MRI in cancer.

Results

Simulations suggest that T2 heterogeneity has a minor effect on the estimation of d in tissues with intermediate or high cell density, but significantly biases the estimation of with low cell density. For the in vivo animal experiments, all IMPULSED metrics except are statistically independent on TE. For B16 tumors, the IMPULSED‐derived exhibited a notable increase with longer TEs. For MDA‐MB‐231 tumors, IMPULSED‐derived showed a significant increase with increasing TEs. The T2 + IMPULSED‐derived of all five tumor models are consistently smaller than .

Conclusions

The findings from this study highlight two key observations: (i) TE has a negligible impact on IMPULSED‐derived cell sizes, and (ii) the TE‐dependence of IMPULSED‐derived intracellular volume fractions used in T2 + IMPULSED modeling to estimate and . These insights contribute to the ongoing development and refinement of non‐invasive MRI techniques for measuring cell sizes.

• Book : 93(1)
• Pub. Date : 2025
• Page : pp.96-107
• Keyword :

Abstract

Purpose

Radiotherapy treatment planning (RTP) using MR has been used increasingly for the abdominal site. Multiple contrast weightings and motion‐resolved imaging are desired for accurate delineation of the target and various organs‐at‐risk and patient‐tailored planning. Current MR protocols achieve these through multiple scans with distinct contrast and variable respiratory motion management strategies and acquisition parameters, leading to a complex and inaccurate planning process. This study presents a standalone MR Multitasking (MT)-based technique to produce volumetric, motion‐resolved, multicontrast images for abdominal radiotherapy treatment planning.

Methods

The MT technique resolves motion and provides a wide range of contrast weightings by repeating a magnetization‐prepared (saturation recovery and T2 preparations) spoiled gradient‐echo readout series and adopting the MT image reconstruction framework. The performance of the technique was assessed through digital phantom simulations and in vivo studies of both healthy volunteers and patients with liver tumors.

Results

In the digital phantom study, the MT technique presented structural details and motion in excellent agreement with the digital ground truth. The in vivo studies showed that the motion range was highly correlated (R² = 0.82) between MT and 2D cine imaging. MT allowed for a flexible contrast‐weighting selection for better visualization. Initial clinical testing with interobserver analysis demonstrated acceptable target delineation quality (Dice coefficient = 0.85 ± 0.05, Hausdorff distance = 3.3 ± 0.72 mm).

Conclusion

The developed MT‐based, abdomen‐dedicated technique is capable of providing motion‐resolved, multicontrast volumetric images in a single scan, which may facilitate abdominal radiotherapy treatment planning.

• Book : 93(1)
• Pub. Date : 2025
• Page : pp.108-120
• Keyword :

• Book : 239()
• Pub. Date : 2025
• Page : pp.115507
• Keyword :

Abstract

In this paper, both semi-analytical method and numerical simulation is applied to investigate the hydrodynamic behavior of large arrays of point-absorber wave energy converters (WECs). To analyze wave interactions among multiple WECs within an array, a semi-analytical model is developed based on the potential flow theory and the matched eigen-function expansions method. The fluid domain is divided into two kinds of regions: interior regions underneath the cylinders and an exterior region surrounding all the cylinders. The matched eigen-function expansions method is employed to solve the radiation potential problem in each domain, and the hydrodynamic coefficients and motion response of the cylinders in the array are evaluated. To validate the accuracy of the semi-analytical method, wamit is adopted to simulate the wave energy park numerically and compared with the results by the semi-analytical model. The hydrodynamic characteristics and power absorption performance of the WECs within the wave energy park are analyzed. The power performance of a wave energy park is studied as functions of layout geometry, incident wave direction, and separation distance between WECs respectively. Finally, multi-objective particle swarm optimization based on a surrogate model is used to optimize the layout of wave energy array.

• Book : 147(4)
• Pub. Date : 2025
• Page : pp.042001
• Keyword :

Abstract

Purpose

Dual velocity encoding PC‐MRI can produce spurious artifacts when using high ratios of velocity encoding values (VENCs), limiting its ability to generate high‐quality images across a wide range of encoding velocities. This study aims to propose and compare dual‐VENC correction methods for such artifacts.

Theory and Methods

Two denoising approaches based on spatiotemporal regularization are proposed and compared with a state‐of‐the‐art method based on sign correction. Accuracy is assessed using simulated data from an aorta and brain aneurysm, as well as 8 two‐dimensional (2D) PC‐MRI ascending aorta datasets. Two temporal resolutions (30,60) ms and noise levels (9,12) dB are considered, with noise added to the complex magnetization. The error is evaluated with respect to the noise‐free measurement in the synthetic case and to the unwrapped image without additional noise in the volunteer datasets.

Results

In all studied cases, the proposed methods are more accurate than the Sign Correction technique. Using simulated 2D+T data from the aorta (60 ms, 9 dB), the Dual‐VENC (DV) error is reduced to: (Sign Correction); and (proposed techniques). The methods are found to be significantly different (p‐value ). Importantly, brain aneurysm data revealed that the Sign Correction method is not suitable, as it increases error when the flow is not unidirectional. All three methods improve the accuracy of in vivo data.

Conclusion

The newly proposed methods outperform the Sign Correction method in improving dual‐VENC PC‐MRI images. Among them, the approach based on temporal differences has shown the highest accuracy.

• Book : 93(1)
• Pub. Date : 2025
• Page : pp.353-368
• Keyword :

Abstract

Brittle materials such as concrete, rock, and coal emit weak electromagnetic radiation (EMR) signals during their cracking process. This study analyzed the time-frequency variation law during the concrete cracking process from the perspectives of energy changes and vibration processes. The relationship between EMR signals and concrete samples of different scales and strength standards, as well as between EMR signals and acoustic emission (AE) signals were investigated. The results indicate that the size and strength of the concrete samples primarily alter the dissipated energy stored within them. A positive correlation exists between the amplitude of EMR signals and the internal dissipated energy during the concrete cracking process. During the linear elastic stage, only a small amount of cracks form in concrete, resulting in negligible EMR signals. However, during the cracking process, EMR signals of various frequency bands are generated. The amplitude of low-frequency EMR signals exhibits minimal variation, showing a slight increase in the later stages of cracking. Medium and high-frequency EMR signals reach peak amplitudes at the point of maximum stress reduction and then rapidly decrease. Additionally, the primary frequency of the EMR signals closely matches the frequency of both crack vibration signals and AE signals. Therefore, analyzing the changes in amplitude and frequency of EMR signals during the concrete cracking process holds promise as a novel, non-destructive method for monitoring concrete cracks.

• Book : 36(1)
• Pub. Date : 2025
• Page : pp.015106
• Keyword :