Multimode Resonator Technique in Antennas:A

During the past several decades,the multimode resonator(MMR)technique has been extensively investigated and widely used,with successful exploration of a variety of high-performance patch antennas,slot antennas,dielectric resonant antennas,dipole antennas,and so on.In this review paper,we summarize the research milestones for these MMR antennas worldwide as one of the most contributive research teams in this field.First,the basic working principles of the MMR technique are clearly illustrated and studied,including mode excitation,mode suppression,impedance performance improvement,and radiation performance improvement.Next,the research topics regarding impedance performance enhancement,i.e.,widebandwidth operation,multibandwidth operation,and mutual coupling reduction,based on the MMR method are intensively described.After that,the relevant works on radiation performance enhancement,i.e.,high-gain,wide-beamwidth,multibeam,multipolarization,low-cross-polarization,filtering-response,and leaky-wave antennas,based on the MMR method are extensively illustrated.By using this technique,several ideas about operating frequency reallocation,electric-field null control,radiation pattern reshaping,and efficiency null generation of the antennas are proposed and demonstrated by our team for the first time.In addition,the application of the MMR technique for wireless communication systems is introduced and presented,such as implant communication,wireless power transfer,and multiple-input multiple-output communication.With these arrangements,exploration and reporting of more interesting and useful MMR design methods can be anticipated in the future.

Compact superconducting single-and dual-band filter design using multimode stepped-impedance resonator

This study presents two multimode stepped-impedance structures to design single-and dual-band filters. Transmission zeroes are introduced for the single-band filter by using dual-mode stepped-impedance resonators. The single-band filter with high selectivity is centered at 6.02 GHz and has a fractional bandwidth （FBW） of 25.6%. Four stubs （two low frequency and two high frequency ones） are connected to the rectangular patch in the center to construct a quadruple-mode resonator. The independent conditions of the center frequencies of the high and low bands of the resonator are analyzed. A dual-band filter, which operates at 1.53 GHz and 2.44 GHz with FWBs of 12.1% and 14.1%, respectively is designed. The single-and dual-band filters are both fabricated with double-sided YBCO films and they can be used in mobile and satellite communications.

Dual-polarized lens antenna based on multimode metasurfaces

We propose a dual-polarized lens antenna system based on isotropic metasurfaces for 12 GHz applications. The metasurface lens is composed of subwavelength unit cells（0.24λ0） with metallic strips etched on the top and bottom sides of the unit cell, and a cross-slots metallic layer in the middle that serves as the ground. The multimode resonance in the unit cell can realize a large phase shift（covering 0？–360？）, and the total transmission efficiency of the lens is above 80%.The feed antenna at the focal point of the lens is a broadband dual-polarized microstrip antenna. Both the simulated and the measured results demonstrate that the dual-polarized lens antenna system can realize a gain of more than 16.1 dB, and an input port isolation of more than 25.0 dB.

Nomogram based on multimodal magnetic resonance combined with B7-H3mRNA for preoperative lymph node prediction in esophagus cancer

Accurate preoperative prediction of lymph node metastasis(LNM)in esophageal cancer(EC)patients is of crucial clinical significance for treatment planning and prognosis.AIM To develop a clinical radiomics nomogram that can predict the preoperative lymph node(LN)status in EC patients.METHODS A total of 32 EC patients confirmed by clinical pathology(who underwent surgical treatment)were included.Real-time fluorescent quantitative reverse transcription-polymerase chain reaction was used to detect the expression of B7-H3 mRNA in EC tissue obtained during preoperative gastroscopy,and its correlation with LNM was analyzed.Radiomics features were extracted from multi-modal magnetic resonance imaging of EC using Pyradiomics in Python.Feature extraction,data dimensionality reduction,and feature selection were performed using XGBoost model and leave-one-out cross-validation.Multivariable logistic regression analysis was used to establish the prediction model,which included radiomics features,LN status from computed tomography(CT)reports,and B7-H3 mRNA expression,represented by a radiomics nomogram.Receiver operating characteristic area under the curve(AUC)and decision curve analysis(DCA)were used to evaluate the predictive performance and clinical application value of the model.RESULTS The relative expression of B7-H3 mRNA in EC patients with LNM was higher than in those without metastasis,and the difference was statistically significant(P<0.05).The AUC value in the receiver operating characteristic(ROC)curve was 0.718(95%CI:0.528-0.907),with a sensitivity of 0.733 and specificity of 0.706,indicating good diagnostic performance.The individualized clinical prediction nomogram included radiomics features,LN status from CT reports,and B7-H3 mRNA expression.The ROC curve demonstrated good diagnostic value,with an AUC value of 0.765(95%CI:0.598-0.931),sensitivity of 0.800,and specificity of 0.706.DCA indicated the practical value of the radiomics nomogram in clinical practice.CONCLUSION This study developed a radiomics nomogram that includes radiomics features,LN status from CT reports,and B7-H3 mRNA expression,enabling convenient preoperative individualized prediction of LNM in EC patients.

Imaging of hemorrhagic primary central nervous system lymphoma: A case report

BACKGROUND A primary central nervous system lymphoma(PCNSL)presenting with massive hemorrhage is a rare occurrence that is difficult to distinguish from a high-grade glioblastoma.Comprehensive descriptions of the imaging characteristics of such tumors have not yet been reported.Herein,we reported a case of a PCNSL with massive hemorrhage by presenting the imaging features of computed tomography(CT)imaging and structural and perfusion magnetic resonance imaging(MRI).CASE SUMMARY A 48-year-old man presented with headache lasting for 10 d.CT of the brain showed a round,heterogeneous,high-density lesion with surrounding edema in the right temporal lobe.For further diagnosis,a series of MRI examinations of the brain were subsequently performed,and a hemorrhagic lesion with ring-like enhancement was determined.The whole lesion was relatively hypoperfused on arterial spin labeling images.Surgical resection of the lesion and histopathological examination confirmed that the lesion was a diffuse large B-cell lymphoma with massive hemorrhage.CONCLUSION PCNSLs with hemorrhage occur very rarely,and structural and perfusion MRI examinations are requested exceedingly rarely.This case provided insight into some characteristics of a hemorrhagic lymphoma on CT and MRI examinations.Perfusion MRI examination may be useful for the differential diagnosis of PCNSLs and other brain tumors.

Multimodal MRI diagnosis and transvenous embolization of a basicranial emissary vein dural arteriovenous fistula:A case report

A dural arteriovenous fistula(DAVF) is an abnormal linkage connecting the arterial and venous systems within the intracranial dura mater. A basicranial emissary vein DAVF drains into the cavernous sinus and the ophthalmic vein, similar to a cavernous sinus DAVF. Precise preoperative identification of the DAVF location is a prerequisite for appropriate treatment. Treatment options include microsurgical disconnection, endovascular transarterial embolization(TAE), transvenous embolization(TVE), or a combination thereof. TVE is an increasingly popular approach for the treatment of DAVFs and the preferred approach for skull base locations, due to the risk of cranial neuropathy caused by dangerous anastomosis from arterial approaches. Multimodal magnetic resonance imaging(MRI) can provide anatomical and hemodynamic information for TVE. The therapeutic target must be precisely embolized in the emissary vein, which requires guidance via multimodal MRI. Here, we report a rare case of successful TVE for a basicranial emissary vein DAVF, utilizing multimodal MRI assistance. The fistula had vanished, pterygoid plexus drainage had improved, and the inferior petrosal sinus had recanalized, as observed on 8-month follow-up angiography. Symptoms and signs of double vision, caused by abduction deficiency, disappeared. Detailed anatomic and hemodynamic assessment by multimodal MRI is the key to guiding successful diagnosis and treatment.

Hexagonal boron nitride nanomechanical resonators with spatially visualized motion

Atomic layers of hexagonal boron nitride(h-BN)crystal are excellent candidates for structural materials as enabling ultrathin,two-dimensional(2D)nanoelectromechanical systems(NEMS)due to the outstanding mechanical properties and very wide bandgap(5.9 eV)of h-BN.In this work,we report the experimental demonstration of h-BN 2D nanomechanical resonators vibrating at high and very high frequencies(from~5 to~70 MHz),and investigations of the elastic properties of h-BN by measuring the multimode resonant behavior of these devices.First,we demonstrate a dry-transferred doubly clamped h-BN membrane with~6.7 nm thickness,the thinnest h-BN resonator known to date.In addition,we fabricate circular drumhead h-BN resonators with thicknesses ranging from~9 to 292 nm,from which we measure up to eight resonance modes in the range of~18 to 35 MHz.Combining measurements and modeling of the rich multimode resonances,we resolve h-BN’s elastic behavior,including the transition from membrane to disk regime,with built-in tension ranging from 0.02 to 2 N m−1.The Young’s modulus of h-BN is determined to be EY≈392 GPa from the measured resonances.The ultrasensitive measurements further reveal subtle structural characteristics and mechanical properties of the suspended h-BN diaphragms,including anisotropic built-in tension and bulging,thus suggesting guidelines on how these effects can be exploited for engineering multimode resonant functions in 2D NEMS transducers.

Individualized brain mapping for navigated neuromodulation

The brain is a complex organ that requires precise mapping to understand its structure and function.Brain atlases provide a powerful tool for studying brain circuits,discovering biological markers for early diagnosis,and developing personalized treatments for neuropsychiatric disorders.Neuromodulation techniques,such as transcranial magnetic stimulation and deep brain stimulation,have revolutionized clinical therapies for neuropsychiatric disorders.However,the lack of fine-scale brain atlases limits the precision and effectiveness of these techniques.Advances in neuroimaging and machine learning techniques have led to the emergence of stereotactic-assisted neurosurgery and navigation systems.Still,the individual variability among patients and the diversity of brain diseases make it necessary to develop personalized solutions.The article provides an overview of recent advances in individualized brain mapping and navigated neuromodulation and discusses the methodological profiles,advantages,disadvantages,and future trends of these techniques.The article concludes by posing open questions about the future development of individualized brain mapping and navigated neuromodulation.

The differential effects of integrase strand transfer inhibitors and efavirenz on neuropsychiatric conditions and brain imaging in HIV-positive men who have sex with men

Integrase strand transfer inhibitors(INSTIs)have emerged as the first‐line choice for treating human immunodeficiency virus(HIV)infection due to their superior efficacy and safety.However,the impact of INSTIs on the development of neuropsychiatric conditions in people living with HIV(PLWH)is not fully understood due to limited data.In this study,we conducted a cross‐sectional examination of PLWH receiving antiretroviral therapy,with a specific focus on HIV‐positive men who have sex with men(MSM)on INSTI‐based regimens(n=61)and efavirenz(EFV)‐based regimens(n=28).Participants underwent comprehensive neuropsychiatric evaluations and multimodal magnetic resonance imaging(MRI)scans,including T1‐weighted images and resting‐state functional MRI.Compared to the EFV group,the INSTI group exhibited primarily reduced gray matter volume(GMV)in the right superior parietal gyrus,higher regional homogeneity(ReHo)in the left postcentral gyrus,lower ReHo in the right orbital part of the inferior frontal gyrus,and increased voxel‐wise functional connectivity for the seed region in the left inferior temporal gyrus with clusters in the right cuneus.Furthermore,the analysis revealed a main effect of antiretroviral drugs on GMV changes,but no main effect of neuropsychiatric disorders or their interaction.The repeated analysis of participants who did not switch regimens confirmed the GMV changes in the INSTI group,validating the initial findings.Our study demonstrated gray matter atrophy and functional brain changes in PLWH on INSTI‐based regimens compared to those on EFV‐based regimens.These neuroimaging results provide valuable insights into the characteristics of brain network modifications in PLWH receiving INSTI‐based regimens。

Generalized Odd-Even Mode Theory and Mode Synthesis Antenna Design Approach

In this article,studies on the multimode excitation problem of waveguides and antennas,the balance/unbalance mech-anism and the balanced feeding techniques in dipole antenna systems are first briefly historically reviewed.In this context,general-ized odd-even mode theory is advanced to quantitatively and approximately describe the mutual coupling effect between a feed line and an antenna.As is mathematically deduced and demonstrated,the modal parity mismatch between the feed line and the antenna should ultimately dominate the unbalance phenomenon in antenna systems.Thus,an elegant,closed-form formula is derived to ap-proximately calculate the“unbalance degree”of a straight dipole off-center fed by a symmetric twin-wire line.Design approaches for the simplest,linear,1-D multimode resonant antennas are introduced.Moreover,the“falling tone excitation”law gauged based on prototype dipoles is revealed and used to develop a mode synthesis design approach for microstrip patch antennas(MPAs)and 2-D sectorial electric dipole antennas.Design examples with distinctive radiation performance are presented and discussed.Finally,possible development trends of multimode resonant antennas are prospected.

Application Value of Multimodal Magnetic Resonance Imaging in the Diagnosis of Atypical Hepatocellular Carcinoma

Objective This study aims to explore the application value of multimodal magnetic resonance imaging(MRI)in the diagnosis of atypical hepatocellular carcinoma(HCC).Methods 80 patients with atypical HCC who were admitted to our hospital from August 2018 to February 2020 were selected as the research subjects.All patients underwent dynamic computed tomography(CT)enhancement scans,and then multimodal MRI scans,including an MRI plain scan,dynamic contrastenhancement(DCE),and diffusion-weighted imaging(DWI).Then,the image data were analyzed.Results The diagnostic accuracy of the observation group(95.00%)was significantly higher than that of the control group(75.00%).This difference was statistically significant(χ2=6.128,P<0.05).With the increase of the b value,the apparent diffusion coefficient(ADC)values of the liver tissue and liver cancer tissue gradually decreased.Compared with normal liver tissue,the ADC value of liver cancer tissue was significantly lower than that of normal liver tissue(P<0.05).A plain MRI scan of 89 lesions,DCE examination of 93 lesions,(1)7 lesions were slow-rising and fast-falling;(2)72 lesions were fast-rising and fast-falling;(3)10 were platform-type lesions;(4)4 lesions had no enhancement.Conclusion The diagnostic efficiency of a multimodal MRI in the diagnosis of atypical HCC is high,and it has particular clinical application value.