We focus on the ferromagnetic thin films and review progress in understanding the magnetization dynamic of coherent precession, its application in seeking better high frequency magnetic properties for magnetic materia...We focus on the ferromagnetic thin films and review progress in understanding the magnetization dynamic of coherent precession, its application in seeking better high frequency magnetic properties for magnetic materials at GHz frequency, as well as new approaches to these materials＇ characterization. High frequency magnetic properties of magnetic materials determined by the magnetization dynamics of coherent precession are described by the Landau-Lifshitz-Gitbert equation. However, the complexity of the equation results in a lack of analytically universal information between the high frequency magnetic properties and the magnetization dynamics of coherent precession. Consequently, searching for magnetic materials with higher permeability at higher working frequency is still done case by case.展开更多
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 ...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.展开更多
Magnetization orientation of a nanoscale ferromagnet can be manipulated by an electric current via spin-transfer torque(STT) effect,which holds great promise in the applications of non-volatile magnetic random access ...Magnetization orientation of a nanoscale ferromagnet can be manipulated by an electric current via spin-transfer torque(STT) effect,which holds great promise in the applications of non-volatile magnetic random access memory(MRAM) and spintorque oscillators.We review the fundamental mechanism and experimental progress of the STT effect.Then,different formula of STT torque has been classified,which can be added to the conventional Landau-Lifshitz-Gilbert equation.After that,we show some simulation results that mainly concern the STT-driven vortex dynamics,magnetization oscillations excited by a perpendicular polarizer,and the detail dynamics by in-plane and out-of-plane dual spin polarizers.展开更多
We investigate the carrier, phonon, and spin dynamics in the ferromagnetic semiconductor(In,Fe)Sb using ultrafast optical pump-probe spectroscopy. We discover two anomalies near T^(*)(~40 K) and T^(†)(~200 K) in the p...We investigate the carrier, phonon, and spin dynamics in the ferromagnetic semiconductor(In,Fe)Sb using ultrafast optical pump-probe spectroscopy. We discover two anomalies near T^(*)(~40 K) and T^(†)(~200 K) in the photoexcited carrier dynamics, which can be attributed to the electron-spin and spin-lattice scattering processes influenced by the magnetic phase transition and modifications in magnetic anisotropy. The magnetization change can be revealed by the dynamics of coherent acoustic phonon. We also observe abrupt changes in the photoinduced spin dynamics near T^(*)and T^(†), which not only illustrate the spin-related scatterings closely related to the long-range magnetic order, but also reveal the D'yakonov–Perel and Elliott–Yafet mechanisms dominating at temperatures below and above T^(†), respectively. Our findings provide important insights into the nonequilibrium properties of the photoexcited(In,Fe)Sb.展开更多
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...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.展开更多
In a rapid cycling synchrotron(RCS),the magnetic field is synchronized with the beam energy,creating a highly dynamic magnetic environment.A ceramic chamber with a shielding layer(RF shield),composed of a series of co...In a rapid cycling synchrotron(RCS),the magnetic field is synchronized with the beam energy,creating a highly dynamic magnetic environment.A ceramic chamber with a shielding layer(RF shield),composed of a series of copper strips connected to a capacitor at either end,is typically employed as a vacuum chamber to mitigate eddy current effects and beam coupling impedance.Consequently,the ceramic chamber exhibits a thin-walled multilayered complex structure.Previous theoretical studies have suggested that the impedance of such a structure has a negligible impact on the beam.However,recent impedance measurements of the ceramic chamber in the China Spallation Neutron Source(CSNS)RCS revealed a resonance in the low-frequency range,which was confirmed by further theoretical analysis as a source of beam instability in the RCS.Currently,the magnitude of this impedance cannot be accurately assessed using theoretical calculations.In this study,we used the CST Microwave Studio to confirm the impedance of the ceramic chamber.Further simulations covering six different types of ceramic chambers were conducted to develop an impedance model in the RCS.Additionally,this study investigates the resonant characteristics of the ceramic chamber impedance,finding that the resonant frequency is closely related to the capacitance of the capacitors.This finding provides clear directions for further impedance optimization and is crucial for achieving a beam power of 500 kW for the CSNS Phase-Ⅱ project(CSNS-Ⅱ).However,careful attention must be paid to the voltage across the capacitors.展开更多
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...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.展开更多
We investigate bias and different barrier thicknesses effects on quantities related to spin and charge currents in MgO-based magnetic tunnel junctions. Using the non-Equilibrium Green＇s function formalism, we demonst...We investigate bias and different barrier thicknesses effects on quantities related to spin and charge currents in MgO-based magnetic tunnel junctions. Using the non-Equilibrium Green＇s function formalism, we demonstrate that the in-plane and out-of-plane components of the spin-transfer torque have asymmetric and symmetric behaviors respectively. Magneto-resistance also decreases with increasing barrier thickness. The Landau–Lifshits–Gilbert equation describes the dynamics of the magnetization made by spin transfer torque. Increasing in spin current above its critical value or smaller the magnet reduces the switching time which is major result for making of new memory devices.展开更多
The magnetization dynamics of lanthanide coordination compounds are fundamentals governing their potential applications such as information storage or molecular switches.Herein,two two-dimensional coordination polymer...The magnetization dynamics of lanthanide coordination compounds are fundamentals governing their potential applications such as information storage or molecular switches.Herein,two two-dimensional coordination polymers[Er(CA)_(1.5)(bpy)(DMF)]_(n)(1)and[Er(CA)_(1.5)(phen)(DMF)]_(n)(2)(H_(2)CA=2,5-dichloro-3,6-dihydroxy-p-quinone,bpy=2,2'-bipyridine,phen=1,10-phenanthroline)were synthesized and fully characterized.By the irradiation of ultraviolet light,1 and 2 were converted to la and 2a which contain light-generated radicals,inducing an increase ofχ_(MT)at room temperature.A detailed study of the dynamic magnetic property shows that the magnetization dynamics observed for 1 and la are dominated by Raman process,but Orbach and Raman processes are observed in 2 and 2a.The structural factors influencing the magnetic properties of this photomagnetic system are discussed.展开更多
Magnetic solitons are nonlinear,local excitations in magnetic systems.In this study,we theoretically and numerically investigate the properties and generation of one-dimensional(1D)topologically trivial magnetic solit...Magnetic solitons are nonlinear,local excitations in magnetic systems.In this study,we theoretically and numerically investigate the properties and generation of one-dimensional(1D)topologically trivial magnetic solitons in ferromagnetic nanowires.An approximate analytical soliton solution described by two free parameters is validated by comparison with the micromagnetic simulation.Across an interface between two media of different anisotropy,the reflection and refraction of a soliton are highly nonlinear,which differ from linear spin waves.A pair of magnetic solitons that propagate in opposite directions can be generated by alternately applying magnetic-field or spin-polarized-current pulses of opposite directions to at least two successive regions.Each soliton corresponds to a soliton solution that can be controlled by the generation process.These magnetic solitons can be used to drive domain wall motion over a distance determined by the soliton magnitude,allowing for discrete manipulation of domain walls compatible with the digital nature of information technology.Our findings pave the way for the application of topologically trivial solitons in spintronics.展开更多
BACKGROUND Colorectal cancer stands among the most prevalent digestive system malignancies.The microsatellite instability(MSI)profile plays a crucial role in determining patient outcomes and therapy responsiveness.Tra...BACKGROUND Colorectal cancer stands among the most prevalent digestive system malignancies.The microsatellite instability(MSI)profile plays a crucial role in determining patient outcomes and therapy responsiveness.Traditional MSI evaluation methods require invasive tissue sampling,are lengthy,and can be compromised by intratumoral heterogeneity.AIM To establish a non-invasive technique utilizing dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)radiomics and machine learning algorithms to determine MSI status in patients with intermediate-stage rectal cancer.METHODS This retrospective analysis examined 120 individuals diagnosed with stage II/III rectal cancer[30 MSI-high(MSI-H)and 90 microsatellite stability(MSS)/MSI-low(MSI-L)cases].We extracted comprehensive radiomics signatures from DCE-MRI scans,encompassing textural parameters that reflect tumor heterogeneity,shapebased metrics,and histogram-derived statistical values.Least absolute shrinkage and selection operator regression facilitated feature selection,while predictive frameworks were developed using various classification algorithms(logistic regression,support vector machine,and random forest).Performance assessment utilized separate training and validation cohorts.RESULTS Our investigation uncovered distinctive imaging characteristics between MSI-H and MSS/MSI-L neoplasms.MSIH tumors exhibited significantly elevated entropy values(7.84±0.92 vs 6.39±0.83,P=0.004),enhanced surface-tovolume proportions(0.72±0.14 vs 0.58±0.11,P=0.008),and heightened signal intensity variation(3642±782 vs 2815±645,P=0.007).The random forest model demonstrated superior classification capability with area under the curves(AUCs)of 0.891 and 0.896 across training and validation datasets,respectively.An integrated approach combining radiomics with clinical parameters further enhanced performance metrics(AUC 0.923 and 0.914),achieving 88.5%sensitivity alongside 87.2%specificity.CONCLUSION DCE-MRI radiomics features interpreted through machine learning frameworks offer an effective strategy for MSI status assessment in intermediate-stage rectal cancer.展开更多
BACKGROUND Rectal cancer requires accurate preoperative assessment of T stage and differentiation grade for treatment planning.Traditional imaging and serum markers have limitations in diagnostic accuracy.AIM To evalu...BACKGROUND Rectal cancer requires accurate preoperative assessment of T stage and differentiation grade for treatment planning.Traditional imaging and serum markers have limitations in diagnostic accuracy.AIM To evaluate the predictive value of dynamic contrast-enhanced-magnetic resonance imaging(DCE-MRI)parameters and serum biomarkers[carbohydrate antigen(CA)19-9,CA125]for determining T stage and differentiation grade in rectal cancer.METHODS We conducted a retrospective review of clinical data from 126 patients who were pathologically diagnosed with rectal cancer between January 2021 to June 2024.Each patient underwent DCE-MRI scans and serum tests for CA19-9 and CA125.Receiver operating characteristic curves were utilized to assess the diagnostic value of DCE-MRI parameters,including volume transfer constant(Ktrans),rate constant(Kep),and volume fraction of extravascular extracellular space(Ve),as well as serum biomarkers for staging and grading rectal cancer.The DeLong test algorithm was employed to evaluate differences in diagnostic performance among the various indicators.RESULTS There were statistically higher levels of Ktrans,Ve,CA19-9,and CA125 serum concentrations of patients with advanced T stages and on poorly differentiated tumors than that in patients with low stages and moderate to high differentiation(P<0.05).Combined use of Ktrans and Ve for T stage diagnosis showed an area under the curve(AUC)of 0.892[95%confidence interval(CI):0.832-0.952],which increased to 0.923(95%CI:0.865-0.981)when combined with serum biomarkers.For grades differentiation,the combined DCE-MRI parameters had an AUC of 0.883(95%CI:0.821-0.945),which rose to 0.912(95%CI:0.855-0.969)when combined with serum markers.According to the Delong test,the combined diagnostic method performed better than a single diagnostic method(P<0.05).CONCLUSION The combined application of DCE-MRI functional parameters and serum tumor markers can significantly improve the diagnostic accuracy of T staging and differentiation degree of rectal cancer,providing a new approach to improve the preoperative assessment system of rectal cancer.This combined diagnostic model has important clinical application value,but further validation is needed through large-scale multicenter studies.展开更多
BACKGROUND Underdiagnosis of peripheral arterial disease results in inadequate treatment and more serious consequences.Hence,clinicians have focused on early diagnosis and treatment.AIM To investigate the effectivenes...BACKGROUND Underdiagnosis of peripheral arterial disease results in inadequate treatment and more serious consequences.Hence,clinicians have focused on early diagnosis and treatment.AIM To investigate the effectiveness of the combination of doppler ultrasonography(DUS),three-dimensional dynamic contrast-enhanced magnetic resonance an-giography(CE-MRA),and CT angiography(CTA)in assessing lower extremity arterial disease in diabetes mellitus(DM).METHODS This study retrospectively analyzed the imaging and clinical data of 116 patients diagnosed with DM complicated with lower extremity vascular diseases from January 2021 to June 2023.All patients underwent unilateral or bilateral DUS,CTA,and CE-MRA as well as invasive digital subtraction angiography(DSA).The application values of DUS,CE-MRA,and CTA were compared.RESULTS A total of 152 lower extremity arteries in the 116 patients were graded following the classification of vascular branches.The Kappa values between DUS and DSA were 0.780,0.755,and 0.806 for diagnosing moderate stenosis and 0.484,0.699,and 0.449 for severe stenosis of grade 1 arteries,grade 2 arteries,and grade 3 arteries,respectively.The Kappa values between CE-MRA and DSA were 0.784,0.814,and 0.835 for diagnosing moderate stenosis and 0.694,0.748,and 0.606 for severe stenosis of grade 1 arteries,grade 2 arteries,and grade 3 arteries,respectively.The Kappa values between CTA and DSA were 0.900,0.858,and 0.878 for diagnosing moderate stenosis and 0.882,0.823,and 0.756 for severe stenosis of grade 1 arteries,grade 2 arteries,and grade 3 arteries,respectively.CONCLUSION DUS,CE-MRA,and CTA demonstrated comparable accuracy in diagnosing lower extremity arterial disease in DM,and the consistency between CTA and DSA diagnoses was higher than the other two imaging methods.展开更多
The management of patients with colorectal cancer(CRC)mainly lies on the use of magnetic resonance imaging(MRI)technique as a diagnostic tool for both staging and restaging.AIM To explore the preoperative value of qua...The management of patients with colorectal cancer(CRC)mainly lies on the use of magnetic resonance imaging(MRI)technique as a diagnostic tool for both staging and restaging.AIM To explore the preoperative value of quantitative parameters of dynamic contrastenhanced MRI(DCE-MRI)in evaluating clinical stages of CRC.METHODS A total of 86 CRC patients undergoing DCE-MRI examinations were included and then classified into CRC group(n=46)and benign tumor group(n=40)according to surgical and pathological results.Quantitative parameters of DCE-MRI,including volume transfer constant(Ktrans),rate constant(Kep)and extravascular extracellular volume fraction(Ve),were analyzed between two groups and among CRC at different stages.Receiver operating characteristic(ROC)curves with of quantitative parameters of DCE-MRI for clinical diagnosis and preoperative staging of CRC were plotted.RESULTS The CRC group had 9 cases with tumor in the upper segment,21 cases in the middle segment,16 in the low segment,10 cases with well differentiation,27 cases with moderate differentiation,and 9 cases with poor differentiation.The Ktrans,Kep,and Ve in the CRC group were higher than those in the benign tumor group(P<0.05).The ROC curves indicated that the optimal cutoff values of Ktrans,Kep and Ve for diagnosing CRC were 0.905 minute-1,0.225 minute-1 and 0.585%,respectively.The Ktrans,Kep and Ve as a combined tool to diagnose CRC yielded 0.863 of area under the curve and 82.60%of sensitivity,and both values were higher than those yielded by Ktrans,Kep,or Ve alone(P<0.05).The Ktrans,Kep and Ve in CRC patients at T3-T4 stage or N1-N2 stage were higher than those at T1-T2 stage or N0 stage(P<0.05).Results of Spearman correlation analysis showed that the Ktrans,Kep and Ve were correlated with advanced T and N stages in CRC patients(P<0.05).The ROC results indicated that the Ktrans produced a higher specificity(81.48%)and sensitivity(94.70%)in evaluating preoperative T stage of CRC.The Kep generated a higher specificity(96.00%)and sensitivity(81.00%)in evaluating preoperative N stage of CRC.CONCLUSION The study suggests that the values of Ktrans,Kep and Ve of DCE-MRI exhibit good performance in diagnosing CRC and preoperative assessment of clinical stages.However,relatively small sample size should be considered for data interpretation.展开更多
BACKGROUND The role of cerebral microvascular dysfunction in early cognitive impairment and dementia has become increasingly recognized.Furthermore,pathological changes in both Alzheimer’s disease and vascular dement...BACKGROUND The role of cerebral microvascular dysfunction in early cognitive impairment and dementia has become increasingly recognized.Furthermore,pathological changes in both Alzheimer’s disease and vascular dementia are almost always associated with cerebral hemodynamic deficits.AIM To investigate the diagnostic performance of dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)assessment of the blood-brain barrier(BBB)in combination with relevant plasma biomarkers for mild cognitive impairment(MCI).METHODS This study selected 50 patients with non-amnestic MCI(na-MCI group),52 patients with amnestic MCI(a-MCI group),and 55 healthy elderly controls(control group).The Chinese version of the Montreal cognitive assessment(MoCA),auditory verbal learning test(AVLT),Hamilton anxiety/depression scale(HAMA/HAMD),and activity of daily living(ADL)scales were used to analyze the characteristics of mental and behavioral symptoms of patients with MCI.The DCE-MRI technique was used to assess the contrast enhancement kinetics.The Patlak model was utilized to analyze the BBB permeability(volume transfer constants).Further,fasting blood was was used to quantify plasma homocysteine(Hcy),β-amyloid protein(Aβ)40,Aβ42,human phosphorylated tau-181 protein(p-tau181),intercellular adhesion molecule-1(ICAM-1),vascular cell adhesion molecule-1(VCAM-1),and plasminogen activator inhibitor-1(PAI-1)levels,as well as serum neurofilament light chain(NFL)and glial fibrillary acidic protein(GFAP)concentrations.RESULTS The na-MCI and a-MCI groups demonstrated significantly lower MoCA and AVLT-Huashan version scores,and statistically higher HAMA,HAMD,and ADL scores compared to the control group.Moreover,the a-MCI group showed notably higher HAMA,HAMD,and ADL scores compared to the na-MCI group.Cranial MRI results revealed significant disparities in cerebral blood flow in the left and right frontal lobes,temporal lobes,hippocampi,cuneus,precuneus,parietal lobes,basal ganglia,and occipital lobes between the a-MCI and na-MCI groups.Compared to healthy controls,patients with MCI demonstrated a smaller amplitude of hippocampal contrast enhancement kinetics and a slower decay rate,indicating smaller vascular volume and increased BBB permeability.Further,Hcy,p-tau181,ICAM-1,VCAM-1,PAI-1,and NFL levels were substantially higher in the a-MCI group than in the na-MCI group,whereas the Aβ42 level was significantly lower.We did not observe any significant differences in Aβ40 and GFAP levels.CONCLUSION Patients with MCI may have experienced cerebrovascular system changes in the hippocampal region.Disorders associated with changes in cerebral blood supply may begin before pathophysiological changes are visible by imaging,which provides references for the assessment and treatment of patients with cognitive disorders.Further,DCE-MRI provides a noninvasive approach to diagnose subtle BBB leakage associated with cerebrovascular pathology.展开更多
In this study, micromagnetism simulation by using timte dltterence method is cameo out on the Ncl21-el415/a-Fe nanocomposite magnet with soft phase imbedded in hard phase. The effects of soft magnetic phase size （S）...In this study, micromagnetism simulation by using timte dltterence method is cameo out on the Ncl21-el415/a-Fe nanocomposite magnet with soft phase imbedded in hard phase. The effects of soft magnetic phase size （S） on the magnetic properties and magnetic reversal modes are systematically analyzed. As S increases from 1 nm to 48 nm, the remanence （Jr） increases, while the coercivity （Hci） decreases, leading to the result that the magnetic energy prod- uct [（BH）max] first increases slowly, and then decreases rapidly, peaking at S = 24 nm with the （BH）max of 72.9 MGOe （1 MGOe = 7.95775 kJ.m-3）. Besides, with the increase of S, the coercivity mechanism of the nanocomposite magnet changes from nucleation to pinning. Furthermore, by observing the magnetic moment evolution in demagnetization pro- cess, the magnetic reversal of the soft phase in the nanocomposite magnet can be divided into three modes with the increase of S： coherent rotation （S 〈 3 nm）, quasi-coherent rotation （3 nm≤S 〈 36 nm）, and the vortex-like rotation （S ≥36 nm）.展开更多
AIM: To evaluate the ability of the time-signal intensity curve (TIC) of the pancreas obtained from dynamic contrast-enhanced magnetic resonance imaging (MRI) for differentiation of focal pancreatic masses, especially...AIM: To evaluate the ability of the time-signal intensity curve (TIC) of the pancreas obtained from dynamic contrast-enhanced magnetic resonance imaging (MRI) for differentiation of focal pancreatic masses, especially pancreatic carcinoma coexisting with chronic pancreatitis and tumor-forming pancreatitis. METHODS: Forty-eight consecutive patients who underwent surgery for a focal pancreatic mass, including pancreatic ductal carcinoma (n = 33), tumor-forming pancreatitis (n = 8), and islet cell tumor (n = 7), were reviewed. Five pancreatic carcinomas coexisted with longstanding chronic pancreatitis. The pancreatic TICs were obtained from the pancreatic mass and the pancreatic parenchyma both proximal and distal to the mass lesion in each patient, prior to surgery, and were classified into 4 types according to the time to a peak: 25 s and 1, 2, and 3 min after the bolus injection of contrast material, namely, type-Ⅰ, Ⅱ, Ⅲ, and Ⅳ, respectively, and were then compared to the corresponding histological pancreatic conditions. RESULTS: Pancreatic carcinomas demonstrated type-Ⅲ (n = 13) or Ⅳ (n = 20) TIC. Tumor-forming pancreatitis showed type-Ⅱ (n = 5) or Ⅲ (n = 3) TIC. All islet cell tumors revealed type-Ⅰ. The type-Ⅳ TIC was only recognized in pancreatic carcinoma, and the TIC of carcinoma always depicted the slowest rise to a peak among the 3 pancreatic TICs measured in each patient, even in patients with chronic pancreatitis.CONCLUSION: Pancreatic TIC from dynamic MRI provides reliable information for distinguishing pancreatic carcinoma from other pancreatic masses, and may enable us to avoid unnecessary pancreatic surgery and delays in making a correct diagnosis of pancreatic carcinoma, especially, in patients with longstanding chronic pancreatitis.展开更多
Light-induced transformation from diamagnetic ligand to paramagnetic radical offers a unique approach to modulating the magnetization dynamics of magnetic compounds.In this study,we present a two-dimensional Yb(III)co...Light-induced transformation from diamagnetic ligand to paramagnetic radical offers a unique approach to modulating the magnetization dynamics of magnetic compounds.In this study,we present a two-dimensional Yb(III)coordination polymer 1 and its Y(III)-diluted analog 1@Y,along with their lightinduced radical forms,1a and 1a@Y.Due to the presence of light-induced radicals,the magnetic susceptibility properties(_(χM)T values)of 1a and 1a@Y featured remarkable 82.3%and 88.9%enhancements,respectively,at room temperature,compared with those of 1 and 1@Y,and were accompanied by an unexpected increase in the effective energy barrier for magnetization dynamics.The magnetization dynamics of 1 and 1a involved both Orbach and Raman processes,while 1@Y and 1a@Y exhibited two Raman processes,indicating that the Orbach process that occurred in 1 and 1a was mainly attributed to the magnetic coupling between Yb(III)ions.This work showcases the potential of light-induced radical transformation for tuning both the static and dynamic magnetic properties of lanthanide coordination polymers.展开更多
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 anti...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.展开更多
Dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)enables tumor vascular physiology to be assessed.Within the tumor tissue,contrast agents(gadolinium chelates)extravasate from intravascular into the extrava...Dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)enables tumor vascular physiology to be assessed.Within the tumor tissue,contrast agents(gadolinium chelates)extravasate from intravascular into the extravascular extracellular space(EES),which results in a signal increase on T1-weighted MRI.The rate of contrast agents extravasation to EES in the tumor tissue is determined by vessel leakiness and blood flow.Thus,the signal measured on DCE-MRI represents a combination of permeability and perfusion.The semi-quantitative analysis is based on the calculation of heuristic parameters that can be extracted from signal intensity-time curves.These enhancing curves can also be deconvoluted by mathematical modeling to extract quantitative parameters that may reflect tumor perfusion,vascular volume,vessel permeability and angiogenesis.Because hepatocellular carcinoma(HCC)is a hypervascular tumor,many emerging therapies focused on the inhibition of angiogenesis.DCE-MRI combined with a pharmacokinetic model allows us to produce highly reproducible and reliable parametric maps of quantitative parameters in HCC.Successful therapies change quantitative parameters of DCE-MRI,which may be used as early indicators of tumor response to anti-angiogenesis agents that modulate tumor vasculature.In the setting of clinical trials,DCE-MRI may provide relevant clinical information on the pharmacodynamic and biologic effects of novel drugs,monitor treatment response and predict survival outcome in HCC patients.展开更多
基金supported by the National Basic Research Program of China(Grant No.2012CB933101)the National Natural Science Foundation of China(Grant Nos.11034004 and 51371093)+1 种基金the Program for Changjiang Scholars and Innovative Research Team in University,China(Grant No.IRT1251)the Specialized Research Fund for the Doctoral Program of Higher Education,China(Grant No.20130211130003)
文摘We focus on the ferromagnetic thin films and review progress in understanding the magnetization dynamic of coherent precession, its application in seeking better high frequency magnetic properties for magnetic materials at GHz frequency, as well as new approaches to these materials＇ characterization. High frequency magnetic properties of magnetic materials determined by the magnetization dynamics of coherent precession are described by the Landau-Lifshitz-Gitbert equation. However, the complexity of the equation results in a lack of analytically universal information between the high frequency magnetic properties and the magnetization dynamics of coherent precession. Consequently, searching for magnetic materials with higher permeability at higher working frequency is still done case by case.
基金supported by the National Key R&D Program of China(No.2018YFA0306002)the National Natural Science Foundation of China(Nos.21971123 and 21973046)the Natural Science Foundation of Tianjin(No.18JCJQJC47200)。
文摘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.
基金support by the National Natural Science Foundation of China(Grant Nos.11074046,11274241,51171047 and 51222103)the Shuguang Program of Shanghai Education Commission(Grant No.09SG22)the New Century Educational Talents Plan of Chinese Education Ministry(Grant No.NCET-10-0603)
文摘Magnetization orientation of a nanoscale ferromagnet can be manipulated by an electric current via spin-transfer torque(STT) effect,which holds great promise in the applications of non-volatile magnetic random access memory(MRAM) and spintorque oscillators.We review the fundamental mechanism and experimental progress of the STT effect.Then,different formula of STT torque has been classified,which can be added to the conventional Landau-Lifshitz-Gilbert equation.After that,we show some simulation results that mainly concern the STT-driven vortex dynamics,magnetization oscillations excited by a perpendicular polarizer,and the detail dynamics by in-plane and out-of-plane dual spin polarizers.
基金supported by the National Key R&D Program of China (Grant No. 2024YFA1408502)the National Natural Science Foundation of China (Grant Nos. 92365102, 62027807, 12474107, and 12174383)+1 种基金the Chinese Academy of Sciences project for Yong Scientists in Basic Research (Grant No. YSBR-030)the Guangdong Basic and Applied Basic Research Foundation (Grant No. 2024A1515011600)。
文摘We investigate the carrier, phonon, and spin dynamics in the ferromagnetic semiconductor(In,Fe)Sb using ultrafast optical pump-probe spectroscopy. We discover two anomalies near T^(*)(~40 K) and T^(†)(~200 K) in the photoexcited carrier dynamics, which can be attributed to the electron-spin and spin-lattice scattering processes influenced by the magnetic phase transition and modifications in magnetic anisotropy. The magnetization change can be revealed by the dynamics of coherent acoustic phonon. We also observe abrupt changes in the photoinduced spin dynamics near T^(*)and T^(†), which not only illustrate the spin-related scatterings closely related to the long-range magnetic order, but also reveal the D'yakonov–Perel and Elliott–Yafet mechanisms dominating at temperatures below and above T^(†), respectively. Our findings provide important insights into the nonequilibrium properties of the photoexcited(In,Fe)Sb.
基金Project supported by the National Key Research Program of China(Grant Nos.2018YFF01010303,2017YFB0702702,and 2016YFA0300701)the National Natural Sciences Foundation of China(Grant Nos.52031015,1187411,51427801,and 51871235)the Key Research Program of Frontier Sciences,Chinese Academy of Sciences(Grant Nos.QYZDJ-SSW-JSC023,KJZD-SW-M01,and ZDYZ2012-2).
文摘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.
基金supported by the Guangdong Basic and Applied Basic Research Foundation,China(No.2021B1515140007).
文摘In a rapid cycling synchrotron(RCS),the magnetic field is synchronized with the beam energy,creating a highly dynamic magnetic environment.A ceramic chamber with a shielding layer(RF shield),composed of a series of copper strips connected to a capacitor at either end,is typically employed as a vacuum chamber to mitigate eddy current effects and beam coupling impedance.Consequently,the ceramic chamber exhibits a thin-walled multilayered complex structure.Previous theoretical studies have suggested that the impedance of such a structure has a negligible impact on the beam.However,recent impedance measurements of the ceramic chamber in the China Spallation Neutron Source(CSNS)RCS revealed a resonance in the low-frequency range,which was confirmed by further theoretical analysis as a source of beam instability in the RCS.Currently,the magnitude of this impedance cannot be accurately assessed using theoretical calculations.In this study,we used the CST Microwave Studio to confirm the impedance of the ceramic chamber.Further simulations covering six different types of ceramic chambers were conducted to develop an impedance model in the RCS.Additionally,this study investigates the resonant characteristics of the ceramic chamber impedance,finding that the resonant frequency is closely related to the capacitance of the capacitors.This finding provides clear directions for further impedance optimization and is crucial for achieving a beam power of 500 kW for the CSNS Phase-Ⅱ project(CSNS-Ⅱ).However,careful attention must be paid to the voltage across the capacitors.
文摘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.
文摘We investigate bias and different barrier thicknesses effects on quantities related to spin and charge currents in MgO-based magnetic tunnel junctions. Using the non-Equilibrium Green＇s function formalism, we demonstrate that the in-plane and out-of-plane components of the spin-transfer torque have asymmetric and symmetric behaviors respectively. Magneto-resistance also decreases with increasing barrier thickness. The Landau–Lifshits–Gilbert equation describes the dynamics of the magnetization made by spin transfer torque. Increasing in spin current above its critical value or smaller the magnet reduces the switching time which is major result for making of new memory devices.
基金Project supported by the National Natural Science Foundation of China(21971123,21931004,92156002)。
文摘The magnetization dynamics of lanthanide coordination compounds are fundamentals governing their potential applications such as information storage or molecular switches.Herein,two two-dimensional coordination polymers[Er(CA)_(1.5)(bpy)(DMF)]_(n)(1)and[Er(CA)_(1.5)(phen)(DMF)]_(n)(2)(H_(2)CA=2,5-dichloro-3,6-dihydroxy-p-quinone,bpy=2,2'-bipyridine,phen=1,10-phenanthroline)were synthesized and fully characterized.By the irradiation of ultraviolet light,1 and 2 were converted to la and 2a which contain light-generated radicals,inducing an increase ofχ_(MT)at room temperature.A detailed study of the dynamic magnetic property shows that the magnetization dynamics observed for 1 and la are dominated by Raman process,but Orbach and Raman processes are observed in 2 and 2a.The structural factors influencing the magnetic properties of this photomagnetic system are discussed.
基金supported by the National Natural Science Foundation of China(Grants Nos.11804045 and 12174093)the Natural Science Foundation of Hunan Province of China(Grant No.2025JJ60001)the Fundamental Research Funds for the Central Universities。
文摘Magnetic solitons are nonlinear,local excitations in magnetic systems.In this study,we theoretically and numerically investigate the properties and generation of one-dimensional(1D)topologically trivial magnetic solitons in ferromagnetic nanowires.An approximate analytical soliton solution described by two free parameters is validated by comparison with the micromagnetic simulation.Across an interface between two media of different anisotropy,the reflection and refraction of a soliton are highly nonlinear,which differ from linear spin waves.A pair of magnetic solitons that propagate in opposite directions can be generated by alternately applying magnetic-field or spin-polarized-current pulses of opposite directions to at least two successive regions.Each soliton corresponds to a soliton solution that can be controlled by the generation process.These magnetic solitons can be used to drive domain wall motion over a distance determined by the soliton magnitude,allowing for discrete manipulation of domain walls compatible with the digital nature of information technology.Our findings pave the way for the application of topologically trivial solitons in spintronics.
基金Supported by the Natural Science Foundation of Fujian Province,China,No.2022J011460。
文摘BACKGROUND Colorectal cancer stands among the most prevalent digestive system malignancies.The microsatellite instability(MSI)profile plays a crucial role in determining patient outcomes and therapy responsiveness.Traditional MSI evaluation methods require invasive tissue sampling,are lengthy,and can be compromised by intratumoral heterogeneity.AIM To establish a non-invasive technique utilizing dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)radiomics and machine learning algorithms to determine MSI status in patients with intermediate-stage rectal cancer.METHODS This retrospective analysis examined 120 individuals diagnosed with stage II/III rectal cancer[30 MSI-high(MSI-H)and 90 microsatellite stability(MSS)/MSI-low(MSI-L)cases].We extracted comprehensive radiomics signatures from DCE-MRI scans,encompassing textural parameters that reflect tumor heterogeneity,shapebased metrics,and histogram-derived statistical values.Least absolute shrinkage and selection operator regression facilitated feature selection,while predictive frameworks were developed using various classification algorithms(logistic regression,support vector machine,and random forest).Performance assessment utilized separate training and validation cohorts.RESULTS Our investigation uncovered distinctive imaging characteristics between MSI-H and MSS/MSI-L neoplasms.MSIH tumors exhibited significantly elevated entropy values(7.84±0.92 vs 6.39±0.83,P=0.004),enhanced surface-tovolume proportions(0.72±0.14 vs 0.58±0.11,P=0.008),and heightened signal intensity variation(3642±782 vs 2815±645,P=0.007).The random forest model demonstrated superior classification capability with area under the curves(AUCs)of 0.891 and 0.896 across training and validation datasets,respectively.An integrated approach combining radiomics with clinical parameters further enhanced performance metrics(AUC 0.923 and 0.914),achieving 88.5%sensitivity alongside 87.2%specificity.CONCLUSION DCE-MRI radiomics features interpreted through machine learning frameworks offer an effective strategy for MSI status assessment in intermediate-stage rectal cancer.
文摘BACKGROUND Rectal cancer requires accurate preoperative assessment of T stage and differentiation grade for treatment planning.Traditional imaging and serum markers have limitations in diagnostic accuracy.AIM To evaluate the predictive value of dynamic contrast-enhanced-magnetic resonance imaging(DCE-MRI)parameters and serum biomarkers[carbohydrate antigen(CA)19-9,CA125]for determining T stage and differentiation grade in rectal cancer.METHODS We conducted a retrospective review of clinical data from 126 patients who were pathologically diagnosed with rectal cancer between January 2021 to June 2024.Each patient underwent DCE-MRI scans and serum tests for CA19-9 and CA125.Receiver operating characteristic curves were utilized to assess the diagnostic value of DCE-MRI parameters,including volume transfer constant(Ktrans),rate constant(Kep),and volume fraction of extravascular extracellular space(Ve),as well as serum biomarkers for staging and grading rectal cancer.The DeLong test algorithm was employed to evaluate differences in diagnostic performance among the various indicators.RESULTS There were statistically higher levels of Ktrans,Ve,CA19-9,and CA125 serum concentrations of patients with advanced T stages and on poorly differentiated tumors than that in patients with low stages and moderate to high differentiation(P<0.05).Combined use of Ktrans and Ve for T stage diagnosis showed an area under the curve(AUC)of 0.892[95%confidence interval(CI):0.832-0.952],which increased to 0.923(95%CI:0.865-0.981)when combined with serum biomarkers.For grades differentiation,the combined DCE-MRI parameters had an AUC of 0.883(95%CI:0.821-0.945),which rose to 0.912(95%CI:0.855-0.969)when combined with serum markers.According to the Delong test,the combined diagnostic method performed better than a single diagnostic method(P<0.05).CONCLUSION The combined application of DCE-MRI functional parameters and serum tumor markers can significantly improve the diagnostic accuracy of T staging and differentiation degree of rectal cancer,providing a new approach to improve the preoperative assessment system of rectal cancer.This combined diagnostic model has important clinical application value,but further validation is needed through large-scale multicenter studies.
文摘BACKGROUND Underdiagnosis of peripheral arterial disease results in inadequate treatment and more serious consequences.Hence,clinicians have focused on early diagnosis and treatment.AIM To investigate the effectiveness of the combination of doppler ultrasonography(DUS),three-dimensional dynamic contrast-enhanced magnetic resonance an-giography(CE-MRA),and CT angiography(CTA)in assessing lower extremity arterial disease in diabetes mellitus(DM).METHODS This study retrospectively analyzed the imaging and clinical data of 116 patients diagnosed with DM complicated with lower extremity vascular diseases from January 2021 to June 2023.All patients underwent unilateral or bilateral DUS,CTA,and CE-MRA as well as invasive digital subtraction angiography(DSA).The application values of DUS,CE-MRA,and CTA were compared.RESULTS A total of 152 lower extremity arteries in the 116 patients were graded following the classification of vascular branches.The Kappa values between DUS and DSA were 0.780,0.755,and 0.806 for diagnosing moderate stenosis and 0.484,0.699,and 0.449 for severe stenosis of grade 1 arteries,grade 2 arteries,and grade 3 arteries,respectively.The Kappa values between CE-MRA and DSA were 0.784,0.814,and 0.835 for diagnosing moderate stenosis and 0.694,0.748,and 0.606 for severe stenosis of grade 1 arteries,grade 2 arteries,and grade 3 arteries,respectively.The Kappa values between CTA and DSA were 0.900,0.858,and 0.878 for diagnosing moderate stenosis and 0.882,0.823,and 0.756 for severe stenosis of grade 1 arteries,grade 2 arteries,and grade 3 arteries,respectively.CONCLUSION DUS,CE-MRA,and CTA demonstrated comparable accuracy in diagnosing lower extremity arterial disease in DM,and the consistency between CTA and DSA diagnoses was higher than the other two imaging methods.
文摘The management of patients with colorectal cancer(CRC)mainly lies on the use of magnetic resonance imaging(MRI)technique as a diagnostic tool for both staging and restaging.AIM To explore the preoperative value of quantitative parameters of dynamic contrastenhanced MRI(DCE-MRI)in evaluating clinical stages of CRC.METHODS A total of 86 CRC patients undergoing DCE-MRI examinations were included and then classified into CRC group(n=46)and benign tumor group(n=40)according to surgical and pathological results.Quantitative parameters of DCE-MRI,including volume transfer constant(Ktrans),rate constant(Kep)and extravascular extracellular volume fraction(Ve),were analyzed between two groups and among CRC at different stages.Receiver operating characteristic(ROC)curves with of quantitative parameters of DCE-MRI for clinical diagnosis and preoperative staging of CRC were plotted.RESULTS The CRC group had 9 cases with tumor in the upper segment,21 cases in the middle segment,16 in the low segment,10 cases with well differentiation,27 cases with moderate differentiation,and 9 cases with poor differentiation.The Ktrans,Kep,and Ve in the CRC group were higher than those in the benign tumor group(P<0.05).The ROC curves indicated that the optimal cutoff values of Ktrans,Kep and Ve for diagnosing CRC were 0.905 minute-1,0.225 minute-1 and 0.585%,respectively.The Ktrans,Kep and Ve as a combined tool to diagnose CRC yielded 0.863 of area under the curve and 82.60%of sensitivity,and both values were higher than those yielded by Ktrans,Kep,or Ve alone(P<0.05).The Ktrans,Kep and Ve in CRC patients at T3-T4 stage or N1-N2 stage were higher than those at T1-T2 stage or N0 stage(P<0.05).Results of Spearman correlation analysis showed that the Ktrans,Kep and Ve were correlated with advanced T and N stages in CRC patients(P<0.05).The ROC results indicated that the Ktrans produced a higher specificity(81.48%)and sensitivity(94.70%)in evaluating preoperative T stage of CRC.The Kep generated a higher specificity(96.00%)and sensitivity(81.00%)in evaluating preoperative N stage of CRC.CONCLUSION The study suggests that the values of Ktrans,Kep and Ve of DCE-MRI exhibit good performance in diagnosing CRC and preoperative assessment of clinical stages.However,relatively small sample size should be considered for data interpretation.
文摘BACKGROUND The role of cerebral microvascular dysfunction in early cognitive impairment and dementia has become increasingly recognized.Furthermore,pathological changes in both Alzheimer’s disease and vascular dementia are almost always associated with cerebral hemodynamic deficits.AIM To investigate the diagnostic performance of dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)assessment of the blood-brain barrier(BBB)in combination with relevant plasma biomarkers for mild cognitive impairment(MCI).METHODS This study selected 50 patients with non-amnestic MCI(na-MCI group),52 patients with amnestic MCI(a-MCI group),and 55 healthy elderly controls(control group).The Chinese version of the Montreal cognitive assessment(MoCA),auditory verbal learning test(AVLT),Hamilton anxiety/depression scale(HAMA/HAMD),and activity of daily living(ADL)scales were used to analyze the characteristics of mental and behavioral symptoms of patients with MCI.The DCE-MRI technique was used to assess the contrast enhancement kinetics.The Patlak model was utilized to analyze the BBB permeability(volume transfer constants).Further,fasting blood was was used to quantify plasma homocysteine(Hcy),β-amyloid protein(Aβ)40,Aβ42,human phosphorylated tau-181 protein(p-tau181),intercellular adhesion molecule-1(ICAM-1),vascular cell adhesion molecule-1(VCAM-1),and plasminogen activator inhibitor-1(PAI-1)levels,as well as serum neurofilament light chain(NFL)and glial fibrillary acidic protein(GFAP)concentrations.RESULTS The na-MCI and a-MCI groups demonstrated significantly lower MoCA and AVLT-Huashan version scores,and statistically higher HAMA,HAMD,and ADL scores compared to the control group.Moreover,the a-MCI group showed notably higher HAMA,HAMD,and ADL scores compared to the na-MCI group.Cranial MRI results revealed significant disparities in cerebral blood flow in the left and right frontal lobes,temporal lobes,hippocampi,cuneus,precuneus,parietal lobes,basal ganglia,and occipital lobes between the a-MCI and na-MCI groups.Compared to healthy controls,patients with MCI demonstrated a smaller amplitude of hippocampal contrast enhancement kinetics and a slower decay rate,indicating smaller vascular volume and increased BBB permeability.Further,Hcy,p-tau181,ICAM-1,VCAM-1,PAI-1,and NFL levels were substantially higher in the a-MCI group than in the na-MCI group,whereas the Aβ42 level was significantly lower.We did not observe any significant differences in Aβ40 and GFAP levels.CONCLUSION Patients with MCI may have experienced cerebrovascular system changes in the hippocampal region.Disorders associated with changes in cerebral blood supply may begin before pathophysiological changes are visible by imaging,which provides references for the assessment and treatment of patients with cognitive disorders.Further,DCE-MRI provides a noninvasive approach to diagnose subtle BBB leakage associated with cerebrovascular pathology.
基金Project supported by the Key Program of the National Natural Science Foundation of China(Grant No.51331003)the International S&T Cooperation Program of China(Grant No.2015DFG52020)+1 种基金the General Program of Science and Technology Development Project of Beijing Municipal Education Commission,China(Grant No.KM201710005006)the State Key Laboratory of Advanced Metals and Materials,China(Grant No.2015-ZD02)
文摘In this study, micromagnetism simulation by using timte dltterence method is cameo out on the Ncl21-el415/a-Fe nanocomposite magnet with soft phase imbedded in hard phase. The effects of soft magnetic phase size （S） on the magnetic properties and magnetic reversal modes are systematically analyzed. As S increases from 1 nm to 48 nm, the remanence （Jr） increases, while the coercivity （Hci） decreases, leading to the result that the magnetic energy prod- uct [（BH）max] first increases slowly, and then decreases rapidly, peaking at S = 24 nm with the （BH）max of 72.9 MGOe （1 MGOe = 7.95775 kJ.m-3）. Besides, with the increase of S, the coercivity mechanism of the nanocomposite magnet changes from nucleation to pinning. Furthermore, by observing the magnetic moment evolution in demagnetization pro- cess, the magnetic reversal of the soft phase in the nanocomposite magnet can be divided into three modes with the increase of S： coherent rotation （S 〈 3 nm）, quasi-coherent rotation （3 nm≤S 〈 36 nm）, and the vortex-like rotation （S ≥36 nm）.
文摘AIM: To evaluate the ability of the time-signal intensity curve (TIC) of the pancreas obtained from dynamic contrast-enhanced magnetic resonance imaging (MRI) for differentiation of focal pancreatic masses, especially pancreatic carcinoma coexisting with chronic pancreatitis and tumor-forming pancreatitis. METHODS: Forty-eight consecutive patients who underwent surgery for a focal pancreatic mass, including pancreatic ductal carcinoma (n = 33), tumor-forming pancreatitis (n = 8), and islet cell tumor (n = 7), were reviewed. Five pancreatic carcinomas coexisted with longstanding chronic pancreatitis. The pancreatic TICs were obtained from the pancreatic mass and the pancreatic parenchyma both proximal and distal to the mass lesion in each patient, prior to surgery, and were classified into 4 types according to the time to a peak: 25 s and 1, 2, and 3 min after the bolus injection of contrast material, namely, type-Ⅰ, Ⅱ, Ⅲ, and Ⅳ, respectively, and were then compared to the corresponding histological pancreatic conditions. RESULTS: Pancreatic carcinomas demonstrated type-Ⅲ (n = 13) or Ⅳ (n = 20) TIC. Tumor-forming pancreatitis showed type-Ⅱ (n = 5) or Ⅲ (n = 3) TIC. All islet cell tumors revealed type-Ⅰ. The type-Ⅳ TIC was only recognized in pancreatic carcinoma, and the TIC of carcinoma always depicted the slowest rise to a peak among the 3 pancreatic TICs measured in each patient, even in patients with chronic pancreatitis.CONCLUSION: Pancreatic TIC from dynamic MRI provides reliable information for distinguishing pancreatic carcinoma from other pancreatic masses, and may enable us to avoid unnecessary pancreatic surgery and delays in making a correct diagnosis of pancreatic carcinoma, especially, in patients with longstanding chronic pancreatitis.
基金supported by the National Natural Science Foundation of China(grant nos.22435002a,92156002,21971123,and 62401563)L.U.acknowledges the financial support of the research projects A-800079-00-00,A-8000017-00-00,and A-8001894-00-00 of the National University of Singapore(NUS)+1 种基金Ab initio calculations were done on the Advanced Supercomputer for Petascale Innovation,Research and Enterprise 2A(ASPIRE-2A)cluster of the Singapore National Supercomputing Centre(NSCCwww.nscc.sg)under project 11001278.The highperformance computational(HPC)resources of NUS(HPC-NUS)are gratefully acknowledged.The NUS Research Scholarship program supported W.H.
文摘Light-induced transformation from diamagnetic ligand to paramagnetic radical offers a unique approach to modulating the magnetization dynamics of magnetic compounds.In this study,we present a two-dimensional Yb(III)coordination polymer 1 and its Y(III)-diluted analog 1@Y,along with their lightinduced radical forms,1a and 1a@Y.Due to the presence of light-induced radicals,the magnetic susceptibility properties(_(χM)T values)of 1a and 1a@Y featured remarkable 82.3%and 88.9%enhancements,respectively,at room temperature,compared with those of 1 and 1@Y,and were accompanied by an unexpected increase in the effective energy barrier for magnetization dynamics.The magnetization dynamics of 1 and 1a involved both Orbach and Raman processes,while 1@Y and 1a@Y exhibited two Raman processes,indicating that the Orbach process that occurred in 1 and 1a was mainly attributed to the magnetic coupling between Yb(III)ions.This work showcases the potential of light-induced radical transformation for tuning both the static and dynamic magnetic properties of lanthanide coordination polymers.
基金Supported by Singapore Cancer Syndicate (SCS_CS-0072)Biomedical Research Council (BMRC 08/1/31/19/577)+1 种基金CRUK and EPSRC Cancer Imaging Centre in association with the MRC and Department of Health (England) grant C1060/A10334NHS funding to the NIHR
文摘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.
文摘Dynamic contrast-enhanced magnetic resonance imaging(DCE-MRI)enables tumor vascular physiology to be assessed.Within the tumor tissue,contrast agents(gadolinium chelates)extravasate from intravascular into the extravascular extracellular space(EES),which results in a signal increase on T1-weighted MRI.The rate of contrast agents extravasation to EES in the tumor tissue is determined by vessel leakiness and blood flow.Thus,the signal measured on DCE-MRI represents a combination of permeability and perfusion.The semi-quantitative analysis is based on the calculation of heuristic parameters that can be extracted from signal intensity-time curves.These enhancing curves can also be deconvoluted by mathematical modeling to extract quantitative parameters that may reflect tumor perfusion,vascular volume,vessel permeability and angiogenesis.Because hepatocellular carcinoma(HCC)is a hypervascular tumor,many emerging therapies focused on the inhibition of angiogenesis.DCE-MRI combined with a pharmacokinetic model allows us to produce highly reproducible and reliable parametric maps of quantitative parameters in HCC.Successful therapies change quantitative parameters of DCE-MRI,which may be used as early indicators of tumor response to anti-angiogenesis agents that modulate tumor vasculature.In the setting of clinical trials,DCE-MRI may provide relevant clinical information on the pharmacodynamic and biologic effects of novel drugs,monitor treatment response and predict survival outcome in HCC patients.
