Two monofluoride-bridged Dy~Ⅲdimers with different magnetization dynamics

As a monoatomic bridge,fluoride ion can transmit efficient magnetic interaction between lanthanide ions but its effect on tuning the magnetization dynamics has not been well understood.Herein,two monofluoride-bridged dinuclear dysprosium complexes[Dy_(2)F(bbpen)_(2)(Et OH)_(2)]Br·Et OH(1)and[Dy_(2)F(bbppy)_(2)]Br·2Et OH(2)with Dy-F-Dy angles of~178°and their diamagnetic-ion diluted analogues 1'and 2'were synthesized.Magnetic studies reveal that 1 and 1'barely show any magnetization dynamics,but 2 and 2'exhibit strong magnetization dynamics.Systematical experimental analysis combined with ab initio calculations reveals that the different magnetization dynamics between 1 and 2 mainly originate from the effect of magnetic anisotropy by terminal ligand and bridging group of the chelating ligand,and the fluoride bridge can effectively suppress the quantum tunneling of the magnetization and turn on Orbach process in 2.

Antiferromagnetic spin dynamics in exchanged-coupled Fe/GdFeO_(3) heterostructure

We investigate the ultrafast spin dynamics of an antiferromagnet in a ferromagnet/antiferromagnet heterostructure Fe/GdFeO_(3) via an all-optical method.After laser irradiation,the terahertz spin precession is hard to be excited in a bare GdFeO_(3) without spin reorientation phase but efficiently in Fe/GdFeO_(3).Both quasi-ferromagnetic and impurity modes,as well as a phonon mode,are observed.We attribute it to the optical modification of interfacial exchange coupling between Fe and GdFeO3.Moreover,the excitation efficiency of dynamics can be modified significantly via the pump laser influence.Our results elucidate that the interfacial exchange coupling is a feasible stimulation to efficiently excite terahertz spin dynamics in antiferromagnets.It will expand the exploration of terahertz spin dynamics for antiferromagnet-based opto-spintronic devices.

Evaluating pediatric ureteropelvic junction obstruction:Dynamic magnetic resonance urography vs renal scintigraphy 99mtechnetium mercaptoacetyltriglycine

BACKGROUND Ureteropelvic junction obstruction(UPJO)is a common congenital urinary tract disorder in children.It can be diagnosed as early as in utero due to the presence of hydronephrosis or later in life due to symptomatic occurrence.AIM To evaluate the discrepancy between dynamic contrast-enhanced magnetic resonance urography(dMRU)and scintigraphy 99m-technetium mercaptoacetyltriglycine(MAG-3)for the functional evaluation of UPJO.METHODS Between 2016 and 2020,126 patients with UPJO underwent surgery at Robert DebréHospital.Of these,83 received a prenatal diagnosis,and 43 were diagnosed during childhood.Four of the 126 patients underwent surgery based on the clinical situation and postnatal ultrasound findings without undergoing functional imaging evaluation.Split renal function was evaluated preoperatively using scintigraphy MAG-3(n=28),dMRU(n=53),or both(n=40).In this study,we included patients who underwent surgery for UPJO and scintigraphy MAG-3+dMRU but excluded those who underwent only scintigraphy MAG-3 or dMRU.The patients were divided into groups A(<10%discrepancy)and B(>10%discrepancy).We examined the discrepancy in split renal function between the two modalities and investigated the possible risk factors.RESULTS The split renal function between the two kidneys was compared in 40 patients(28 boys and 12 girls)using scintigraphy MAG-3 and dMRU.Differential renal function,as determined using both modalities,showed a difference of<10%in 31 children and>10%in 9 children.Calculation of the relative renal function using dMRU revealed an excellent correlation coefficient with renal scintigraphy MAG-3 for both kidneys.CONCLUSION Our findings demonstrated that dMRU is equivalent to scintigraphy MAG-3 for evaluating split renal function in patients with UPJO.

Conformational dynamics in GPCR signaling by NMR

G-protein-coupled receptors(GPCRs)mediate a wide range of cellular responses to various ligands or stimuli,and are the most important drug targets associated with human diseases.While major advances in GPCR structural biology have greatly deepened our understanding of its activation mechanism,the highly complex changes in the structural dynamics of GPCRs during activation remain underdetermined and their links to physiological functions largely unknown.Solution nuclear magnetic resonance(NMR)spectroscopy is an essential technique that allows the characterization of protein structural dynamics at atomic level,and has been applied in the studies of GPCR structural-function relationship in the past decade.Herein,we summarize a few specific studies in which solution NMR methods were employed and provided novel insights into questions difficult to be addressed by other methods.

Role of pulmonary perfusion magnetic resonance imaging for the diagnosis of pulmonary hypertension:A review

Among five types of pulmonary hypertension,chronic thromboembolic pulmonary hypertension(CTEPH)is the only curable form,but prompt and accurate diagnosis can be challenging.Computed tomography and nuclear medicine-based techniques are standard imaging modalities to non-invasively diagnose CTEPH,however these are limited by radiation exposure,subjective qualitative bias,and lack of cardiac functional assessment.This review aims to assess the methodology,diagnostic accuracy of pulmonary perfusion imaging in the current literature and discuss its advantages,limitations and future research scope.

Perfusion magnetic resonance imaging of the liver

Perfusion magnetic resonance imaging (MRI) studies quantify the microcirculatory status of liver parenchyma and liver lesions, and can be used for the detection of liver metastases, assessing the effectiveness of antiangiogenic therapy, evaluating tumor viability after anticancer therapy or ablation, and diagnosis of liver cirrhosis and its severity. In this review, we discuss the basic concepts of perfusion MRI using tracer kinetic modeling, the common kinetic models applied for analyses, the MR scanning techniques, methods of data processing, and evidence that supports its use from published clinical and research studies. Technical standardization and further studies will help to establish and validate perfusion MRI as a clinical imaging modality.

Dynamic contrast-enhanced magnetic resonance imaging of prostate cancer: A review of current methods and applications

In many areas of oncology, dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI) has proven to be a clinically useful, non-invasive functional imaging technique to quantify tumor vasculature and tumor perfusion characteristics. Tumor angiogenesis is an essential process for tumor growth, proliferation, and metastasis. Malignant lesions demonstrate rapid extravasation of contrast from the intravascular space to the capillary bed due to leaky capillaries associated with tumor neovascularity. DCE-MRI has the potential to provide information regarding blood flow, areas of hypoperfusion, and variations in endothelial permeability and microvessel density to aid treatment selection, enable frequent monitoring during treatment and assess response to targeted therapy following treatment. This review will discuss the current status of DCE-MRI in cancer imaging, with a focus on its use in imaging prostate malignancies as well as weaknesses that limit its widespread clinical use. The latest techniques for quantification of DCE-MRI parameters will be reviewed and compared.

Dynamic Analysis of Axial Magnetic Forces for DVD Spindle Motors

The axial magnetic force, induced by the complicated flux linkage distribution from rotor magnet and stator slotted, is constructed by different relative heights and calculated by 3D finite element method (FEM) to analyze the dynamic characteristics for a DVD spindle motor. The axial magnetic force is designed to provide an axial stiffness and govern the natural frequency of the dynamic performance. According to the simulation results and experimental measurements, the dynamic behaviors are significantly improved with a variation of relative height of rotor magnet and stator slotted on a DVD spindle motor.

Diagnostic Value of Quantitative Parameters of DCE-MRI in Endometrial Carcinoma and Its Correlation with Clinicopathological Factors

In the study,108 patients with endometrial cancer were selected as the observation group,and 105 patients with benign endometrial lesions were selected as the control group.After DCE-MRI examination,it was found that the volume transfer constant(K^(trans)),rate constant(K_(e))and extracellular space volume ratio(V_(e))in the observation group were higher than those in the control group(P<0.05).The area under curve(AUC)of combined K^(trans),K_(e) and V_(e) values in the diagnosis of endometrial cancer was 0.841.The values of K^(trans),K_(e )and V_(e) were positively correlated with the clinical stage and the degree of muscular invasion,but negatively correlated with the degree of differentiation(P<0.05).The results of the study suggested that DCE-MRI quantitative parameters have a certain value in the differential diagnosis of endometrial cancer,which helped to further distinguish the degree of muscular invasion,clinical stage,and differentiation of endometrial cancer patients.

Relationship between treatment types and blood–brain barrier disruption in patients with acute ischemic stroke:Two case reports

BACKGROUND Blood-brain barrier(BBB)disruption plays an important role in the development of neurological dysfunction in ischemic stroke.However,diagnostic modalities that can clearly diagnose the degree of BBB disruption in ischemic stroke are limited.Here,we describe two cases in which the usefulness of dynamic contrastenhanced magnetic resonance imaging(DCE-MRI)in detecting BBB disruption was evaluated after treatment of acute ischemic stroke using two different methods.CASE SUMMARY The two patients of similar age and relatively similar cerebral infarction locations were treated conservatively or with thrombectomy,although their sex was different.As a result of analysis by performing DCE-MRI,it was confirmed that BBB disruption was significantly less severe in the patient who underwent thrombectomy(P=3.3×10^(-7)),whereas the average Ktrans of the contralateral hemisphere in both patients was similar(2.4×10^(-5)min^(-1) and 2.0×10^(-5)min^(-1)).If reperfusion is achieved through thrombectomy,it may indicate that the penumbra can be saved and BBB recovery can be promoted.CONCLUSION Our cases suggest that BBB disruption could be important if BBB permeability is used to guide clinical treatment.

Experimental observation of interlayer perpendicular standing spin wave mode with low damping in skyrmion-hosting[Pt/Co/Ta]_(10)multilayer

An interlayer perpendicular standing spin wave mode is observed in the skyrmion-hosting[Pt/Co/Ta]_(10) multilayer by measuring the time-resolved magneto-optical Kerr effect.The observed interlayer mode depends on the interlayer spin-pumping and spin transfer torque among the neighboring Co layers.This mode shows monotonically increasing frequency-field dependence which is similar to the ferromagnetic resonance mode,but within higher frequency range.Besides,the damping of the interlayer mode is found to be a relatively low constant value of 0.027 which is independent of the external field.This work expounds the potential application of the[heavy-metal/ferromagnetic-metal]_(n) multilayers to skyrmion-based magnonic devices which can provide multiple magnon modes,relatively low damping,and skyrmion states,simultaneously.

Dynamic Comparison of the Two Models to Enhance the Application Value of MRI in Cervical Cancer Case Classification

Objective:To explore the application of dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)with Extended Tofts Linear(ETL)model and extended tofts(ET)model in pathological grading of cervical cancer.Method:Retrospective analysis was performed on 31 cases of patients admitted to Shaoxing People's Hospital from January 2016 to October 2019 who were pathologically confirmed to have cervical cancer.They underwent preoperative multistage pelvic DCE-MRI examination.Extended Tofts Linear and Extended Tofts hemodynamic model of cervical cancer were calculated separately,and the quantitative perfusion parameters including transport capacity constant(K^(trans)),the rate constant(K_(ep)),blood vessels,extracellular clearance volume fraction(V_(e)),blood vessels,and clearance volume fraction(V_(p)).According to the postoperative pathologic stage can be divided into low,medium and high differentiate cervical cancer group,the difference contrast of three groups of cervical cancer perfusion parameter were analyzed.The parameters with statistical significance were screened out,and the ROC curves for the differentiation of cervical cancer with different degrees were drawn.Result:The diagnostic efficacy of the quantitative parameters obtained by the two models in the pathological grading of cervical cancer was compared.The Ktrans values of the Exte Nded Tofts Linear model highly differentiated(0.518±0.180)min^(-1),poorly differentiated(1.032±0.408)min^(-1)and the Extended Tofts model highly differentiated(0.525±0.283)min^(-1),poorly differentiated(1.487±0.991)min^(-1)were significantly different between the highly differentiated and poorly differentiated groups(P<0.05).There were no significant differences in Kep,Ve and Vp between high and low differentiated cervical cancer groups(all P>0.05).There were no significant differences in Ktrans,Kep,Ve and Vp between the two models(all P>0.05).The AUC of Ktrans in the Exte Nded Tofts Linear model was greater than that of Ktrans in the Extended Tofts model for the identification of highly and poorly differentiated cervical cancers.Joint diagnosis:Logistic regression analysis was used to calculate the joint diagnostic probability values of Ktrans of the Extended Tofts Linear and Extended Tofts models,and the results showed that the AUC of the two models was greater than that of the single model.Conclusion:The Ktrans obtained by the Extended Tofts Linear model and the Extended Tofts DCE-MRI model had certain value for the pathological grading of high and low differentiated cervical cancer,and the overall efficacy of the former was better than the latter.Meanwhile,the differential value of the two models combined for the pathological grading of cervical cancer was better than that of the single model perfusion parameter,and the differential diagnosis sensitivity and specificity of the two models combined with Ktrans were the highest.

Local Pulse Wave Velocity Estimation in the Carotids Using Dynamic MR Sequences

The current study presents a new protocol for local pulse wave velocity (PWV) measurement using dynamic MR sequences, which have a high temporal resolution (TR < 6 ms). MR images were obtained at two positions along the common carotid artery, separated by a distance of 5 cm. In each phase of a MR series, carotid region was automatically extracted and then its area distension waveform could be obtained. Sixteen volunteers with no symptoms of cardiovascular diseases were studied. For local PWV estimation, three delay estimation principles were tested and produced the following values: intersecting tangents method (M1): 4.72 ± 1.40 m/s, second derivative method (M2): 4.94 ± 1.68 m/s and cross-correlation method (M3): 5.03 ± 1.17 m/s. The cross-correlation method showed a relative high reliability as its least standard deviation.

Renal functional MRI in mice evaluated with a dual bolus of intravascular and diffusible contrast agents

Background: The aim of this study was to evaluate the feasibility of a dualbolus protocol, where a first bolus of an intravascular tracer is used to measure perfusion, followed by a second bolus of a freely filtered gadolinium-containing agent to measure filtration capacity. Methods: The study was conducted in mice subjected to complete unilateral ureteral obstruction (UUO), and sham operated mice were used as controls. Dynamic contrast- en-hanced MRI was performed 2 days after surgery. Results and discussions: Mean signal-time curves of the renal cortex, renal medulla and abdominal aorta were used to calculate the relative renal blood flow (rRBF), relative renal blood volume (rRBV), mean transit time (MTT) and the glomerular transfer rate Ktrans. We demonstrated that kidneys suffering from two days of UUO showed a decrease in cortical as well as medullary rRBF compared to kidneys from sham-operated mice. Further, we found no changes in rRBV and MTT among groups, neither in the cortex nor in the medulla. The renal functional parameter Ktrans showed a tendency (but statistically insignificant) to be reduced in the ob-structed kidney compared to the sham-operated mice. Conclusions: We showed our first experiences with the consecutive use of intra- and extra-vascularly distributed agents in a renal-diseased mouse model, allowing analysis of both functional haemo- dyamics and filtration capacity in kidneys.

二维拓扑反铁磁材料MnBi_(2)Te_(4)中超快磁化率和磁振子动力学的实时观测

原子级薄的范德华磁性材料不仅为探索二维极限下的基本物理学提供了肥沃的土壤,也为新型超快功能器件创造了巨大的机会.本文系统研究了少层拓扑反铁磁MnBi_(2)Te_(4)晶体在不同层厚、温度和磁场下的超快磁化率和自旋波动力学.作者发现激光诱导的(退)磁化过程可用于精确地跟踪不同磁场区域中的不同磁状态,包括显示出明显的奇偶层数效应.此外,频率为数十千兆赫兹的反铁磁磁振子模式可以被光脉冲激发并在时域中直接被观察到,其频率强烈地依赖于磁场.值得注意的是,磁化率和磁振子动力学不仅可以在时间分辨的磁光克尔效应中观察到,而且在时间分辨的反射率中也可以观察到,这表明磁态和电子结构之间存在很强的相关性.本工作研究了这种新型二维反铁磁体中的超快自旋动力学,为二维反铁磁自旋电子学和磁振子学的潜在应用以及磁态和拓扑量子态的超快调控研究铺平了道路.

Bioactive superparamagnetic iron oxide-gold nanoparticles regulated by a dynamic magnetic field induce neuronal Ca^(2+)influx and differentiation

Treating neurodegenerative diseases,e.g.,Alzheimer’s Disease,remains a significant challenge due to the limited neuroregeneration rate in the brain.The objective of this study is to evaluate the hypothesis that external magnetic field(MF)stimulation of nerve growth factor functionalized superparamagnetic iron oxide-gold(NGF-SPIO-Au)nanoparticles(NPs)can induce Ca^(2+)influx,membrane depolarization,and enhance neuron differentiation with dynamic MF(DMF)outperforming static MF(SMF)regulation.We showed the that total intracellular Ca^(2+)influx of PC-12 cells was improved by 300%and 535%by the stimulation of DMF(1 Hz,0.5 T,30min)with NGF-SPIO-Au NPs compared to DMF alone and SMF with NGF-SPIO-Au NPs,respectively,which was attributed to successive membrane depolarization.Cellular uptake performed with the application of sodium azide proved that DMF enhanced cellular uptake of NGF-SPIO-Au NPs via endocytosis.In addition,DMF upregulated both the neural differentiation marker(β3-tubulin)and the cell adhesive molecule(integrin-β1)with the existence of NGF-SPIO-Au NPs,while SMF did not show these effects.The results imply that noninvasive DMF-stimulated NPs can regulate intracellular Ca^(2+)influx and enhance neuron differentiation and neuroregeneration rate.

正弦激励下三磁铁磁悬浮动力吸振器的被动减振性能研究

本本文设计了一种新型的三磁铁磁悬浮动力吸振器(TMSDVA),并进行了建模和测试首先建立了TMSDVA悬臂梁减振系统的等效动力学模型.基于等效磁化电流理论,建立了非线性磁悬浮力的计算模型,并分析了非线性磁悬浮力的特征.然后用Runge-Kutta方法求解系统在正弦激励下的动力学响应.通过对仿真结果的分析发现,适当调整TMSDVA的阻尼系数不仅可以降低TMSDVA的减振效果对激励幅值的敏感性,还可以整体提高TMSDVA的减振效果.最后通过实验验证了理论分析的正确性.综合来看,TMSDVA在工程结构的被动减振方面具有潜在应用价值.

Diagnostic accuracy of dynamic contrast-enhanced magnetic resonance imaging for distinguishing pseudoprogression from glioma recurrence:a meta-analysis

Background:It is crucial to differentiate accurately glioma recurrence and pseudoprogression which have entirely different prognosis and require different treatment strategies.This study aimed to assess the diagnostic accuracy of dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)as a tool for distinguishing glioma recurrence and pseudoprogression.Methods:According to particular criteria of inclusion and exclusion,related studies up to May 1,2019,were thoroughly searched from several databases including PubMed,Embase,Cochrane Library,and Chinese biomedical databases.The quality assessment of diagnostic accuracy studies was applied to evaluate the quality of the included studies.By using the"mada"package in R,the heterogeneity,overall sensitivity,specificity,and diagnostic odds ratio were calculated.Moreover,funnel plots were used to visualize and estimate the publication bias in this study.The area under the summary receiver operating characteristic(SROC)curve was computed to display the diagnostic efficiency of DCE-MRI.Results:In the present meta-analysis,a total of 11 studies covering 616 patients were included.The results showed that the pooled sensitivity,specificity,and diagnostic odds ratio were 0.792(95%confidence interval[CI]0.707-0.857),0.779(95%CI 0.715-0.832),and 16.219(97.5%CI 9.123-28.833),respectively.The value of the area under the SROC curve was 0.846.In addition,the SROC curve showed high sensitivities(>0.6)and low false positive rates(<0.5)from most of the included studies,which suggest that the results of our study were reliable.Furthermore,the funnel plot suggested the existence of publication bias.Conclusions:While the DCE-MRI is not the perfect diagnostic tool for distinguishing glioma recurrence and pseudoprogression,it was capable of improving diagnostic accuracy.Hence,further investigations combining DCE-MRI with other imaging modalities are required to establish an efficient diagnostic method for glioma patients.

A 10-miRNA risk score-based prediction model for pathological complete response to neoadjuvant chemotherapy in hormone receptor-positive breast cancer

Patients with hormone receptor(HR)-positive tumors breast cancer usually experience a relatively low pathological complete response(p CR)to neoadjuvant chemotherapy(NAC).Here,we derived a 10-micro RNA risk score(10-mi RNA RS)-based model with better performance in the prediction of p CR and validated its relation with the disease-free survival(DFS)in 755 HRpositive breast cancer patients(273,265,and 217 in the training,internal,and external validation sets,respectively).This model,presented as a nomogram,included four parameters:the 10-mi RNA RS found in our previous study,progesterone receptor(PR),human epidermal growth factor receptor 2(HER2)status,and volume transfer constant(K).Favorable calibration and discrimination of 10-mi RNA RS-based model with areas under the curve(AUC)of 0.865,0.811,and 0.804 were shown in the training,internal,and external validation sets,respectively.Patients who have higher nomogram score(>92.2)with NAC treatment would have longer DFS(hazard ratio=0.57;95%CI:0.39–0.83;P=0.004).In summary,our data showed the 10-mi RNA RS-based model could precisely identify more patients who can attain p CR to NAC,which may help clinicians formulate the personalized initial treatment strategy and consequently achieves better clinical prognosis for patients with HRpositive breast cancer.

Design of the magnets for the HEPS injector

Purpose The high energy photon source(HEPS)is a diffraction-limited storage ring light source being built in Beijing,China.The HEPS accelerators consist of the storage ring and its injector which includes the linac,booster and beam transport lines.The magnet system is one of the most important systems for the accelerators.In this paper,the field design,mechanical design and some special issues of the main magnets for the injector are presented.Methods The magnets for the linac and transport lines work at DC mode,whereas the magnets for the booster work at dynamic mode.So the module of OPERA/TOSCA is used to design the DC magnetic field and the module of OPERA/ELLEKTRA is used to design the dynamic magnetic field.The CAD programs are used to design the mechanical structures of the magnets.Results The magnetic field simulation results of all the magnets for the injector can meet the physical requirements,the mechanical designs of all magnets are reasonable,and engineering drawings of the magnets for production are finished.Conclusions Both the magnetic field design and mechanical design of all magnets are satisfied with the physical requirements of the HEPS injector;the production of all magnets has been started up.