Experimental observation of current-driven antiskyrmion sliding in stripe domains.

Magnetic skyrmions are promising as next-generation information units. Their antiparticle-the antiskyrmion-has also been discovered in chiral magnets. Here we experimentally demonstrate antiskyrmion sliding in response to a pulsed electric current at room temperature without the requirement of an external magnetic field. This is realized by embedding antiskyrmions in helical stripe domains, which naturally provide one-dimensional straight tracks along which antiskyrmion sliding can be easily launched with low current density and without transverse deflection from the antiskyrmion Hall effect. The higher mobility of the antiskyrmions in the background of helical stripes in contrast to the typical ferromagnetic state is a result of intrinsic material parameters and elastic energy of the stripe domain, thereby smearing out the random pinning potential, as supported by micromagnetic simulations. The demonstration and comprehensive understanding of antiskyrmion movement along naturally straight tracks offers a new perspective for (anti)skyrmion application in spintronics.

Electron-Assisted Generation and Straight Movement of Skyrmion Bubble in Kagome TbMn6 Sn6.

Topological magnetic textures are promising candidates as binary data units for the next-generation memory device. The precise generation and convenient control of nontrivial spin topology at zero field near room temperature endows the critical advantages in skyrmionic devices but is not simultaneously integrated into one material. Here, in the Kagome plane of quantum TbMn6 Sn6 , the expedient generation of the skyrmion bubbles in versatile forms of lattice, chain, and isolated one by converging the electron beam, where the electron intensity gradient contributes to the dynamic generation from local anisotropy variation near spin reorientation transition (SRT) is reported. Encouragingly, by utilizing the dynamic shift of the SRT domain interface, the straight movement is actualized with the skyrmion bubble slave to the SRT domain interface forming an elastic composite object, avoiding the usual deflection from the skyrmion Hall effect. The critical contribution of the SRT domain interface via conveniently electron-assisted heating is further theoretically validated in micromagnetic simulation, highlighting the compatible application possibility in advanced devices.

Light-driven nanoscale vectorial currents.

Controlled charge flows are fundamental to many areas of science and technology, serving as carriers of energy and information, as probes of material properties and dynamics1 and as a means of revealing2,3 or even inducing4,5 broken symmetries. Emerging methods for light-based current control5-16 offer particularly promising routes beyond the speed and adaptability limitations of conventional voltage-driven systems. However, optical generation and manipulation of currents at nanometre spatial scales remains a basic challenge and a crucial step towards scalable optoelectronic systems for microelectronics and information science. Here we introduce vectorial optoelectronic metasurfaces in which ultrafast light pulses induce local directional charge flows around symmetry-broken plasmonic nanostructures, with tunable responses and arbitrary patterning down to subdiffractive nanometre scales. Local symmetries and vectorial currents are revealed by polarization-dependent and wavelength-sensitive electrical readout and terahertz (THz) emission, whereas spatially tailored global currents are demonstrated in the direct generation of elusive broadband THz vector beams17. We show that, in graphene, a detailed interplay between electrodynamic, thermodynamic and hydrodynamic degrees of freedom gives rise to rapidly evolving nanoscale driving forces and charge flows under the extremely spatially and temporally localized excitation. These results set the stage for versatile patterning and optical control over nanoscale currents in materials diagnostics, THz spectroscopies, nanomagnetism and ultrafast information processing.

Prenatal diagnosis: Hypoplastic left heart syndrome in combination with ventriculo-coronary communication.

BACKGROUND: Both hypoplastic left heart syndrome and ventriculo-coronary communication are extremely rare congenital cardiac conditions. CASE: The diagnosis of hypoplastic left heart syndrome combined with endocardial fibroelastosis and ventriculo-coronary communication was made in a pregnant woman at 24 weeks of gestation. Interestingly, unlike diastolic flow from the coronary artery to the left ventricle in typical ventriculo-coronary communication, this fetus showed a systolic flow from the left ventricle to the coronary artery. CONCLUSION: To the best of our knowledge, this is the first study to present only a systolic flow signal in hypoplastic left heart syndrome combined with ventriculo-coronary communication in prenatal ultrasonography.

Topological Exact Flat Bands in Two-Dimensional Materials under Periodic Strain.

We study flat bands and their topology in 2D materials with quadratic band crossing points under periodic strain. In contrast to Dirac points in graphene, where strain acts as a vector potential, strain for quadratic band crossing points serves as a director potential with angular momentum ℓ=2. We prove that when the strengths of the strain fields hit certain "magic" values, exact flat bands with C=±1 emerge at charge neutrality point in the chiral limit, in strong analogy to magic angle twisted-bilayer graphene. These flat bands have ideal quantum geometry for the realization of fractional Chern insulators, and they are always fragile topological. The number of flat bands can be doubled for certain point group, and the interacting Hamiltonian is exactly solvable at integer fillings. We further demonstrate the stability of these flat bands against deviations from the chiral limit, and discuss possible realization in 2D materials.

Discovery of Topological Magnetic Textures near Room Temperature in Quantum Magnet TbMn6 Sn6.

The study of topology in quantum materials has fundamentally advanced the understanding in condensed matter physics and potential applications in next-generation quantum information technology. Recently, the discovery of a topological Chern phase in the spin-orbit-coupled Kagome lattice TbMn6 Sn6 has attracted considerable interest. Whereas these phenomena highlight the contribution of momentum space Berry curvature and Chern gap on the electronic transport properties, less is known about the intrinsic real space magnetic texture, which is crucial for understanding the electronic properties and further exploring the unique quantum behavior. Here, the stabilization of topological magnetic skyrmions in TbMn6 Sn6 using Lorentz transmission electron microscopy near room temperature, where the spins experience full spin reorientation transition between the a- and c-axes, is directly observed. An effective spin Hamiltonian based on the Ginzburg-Landau theory is constructed and micromagnetic simulation is performed to clarify the critical role of Ruderman-Kittel-Kasuya-Yosida interaction on the stabilization of skyrmion lattice. These results not only uncover nontrivial spin topological texture in TbMn6 Sn6 , but also provide a solid basis to study its interplay with electronic topology.

Application of the fetal adrenal volume evaluated by three-dimensional ultrasound in fetuses with intrauterine growth restriction and its correlation with adverse perinatal outcomes / 中华超声影像学杂志

Objective:To evaluate the fetal adrenal gland volume (AGV) and corrected adrenal gland volume (cAGV) in intrauterine growth restriction (IUGR) fetuses and observe their associations with the adverse perinatal outcomes.Methods:From February 2021 to August 2022, 32 IUGR fetuses who underwent fetal ultrasound examination in the Second Xiangya Hospital of Central South University were prospectively selected as the IUGR group, and 32 normal fetuses matched for gestational age during the same period were selected as the control group. Three-dimensional ultrasound was used to obtain fetal adrenal volume images, and the virtual organ computer-aided analysis (VOCAL) was used to measure AGV, then the cAGV was calculated. The values of AGV and cAGV were appropriately compared between the IUGR and the control groups. The pregnancy outcomes were noted. Multiple logistic regression analysis was employed to evaluate the relationship between the cAGV and adverse perinatal outcomes in IUGR fetus, with maternal age and the CPR included as covariates to control for confounding factors.Results:A total of 32 fetuses with IUGR and 32 controls were involved in this prospective study. There was no significant difference in the AGV between these two groups ( P=0.417). The cAGV of the IUGR fetus was substantially larger than that of the normal fetus ( P=0.034). In the multivariate logistic regression analysis, after adjusting for maternal age and fetal CPR, the fetal cAGV was noticeably associated with the fetal distress (adjusted OR=0.005, 95% CI=0.000-0.587, P=0.029) and the total adverse perinatal outcomes (adjusted OR=0.014, 95% CI=0.000-0.475, P=0.018). Conclusions:The value of cAGV is increased in the IUGR fetuses and associated with adverse perinatal outcomes. The evaluation of fetal AGV could be beneficial to monitoring and managing IUGR fetuses.

Analysis of Structure and Antioxidant Activity of Polysaccharides from Aralia continentalis.

We extracted, purified, and characterized three neutral and three acidic polysaccharides from the roots, stems, and leaves of Aralia continentalis Kitigawa. The results of the analysis of monosaccharide composition indicated that the polysaccharides from the roots and stems were more similar to each other than they were to the polysaccharides from the leaves. The in vitro antioxidant results demonstrated that the acidic polysaccharides had stronger antioxidant activity than the neutral fractions. Therefore, we investigated the primary purified acidic polysaccharide fractions (WACP(R)-A-c, WACP(S)-A-c, and WACP(L)-A-d) by NMR and enzymatic analysis. The structural analytical results indicated that WACP(R)-A-c contained homogalacturonan (HG); WACP(S)-A-c contained HG and rhamnogalacturonan II (RG-II), and WACP(L)-A-d contained HG, RG-II, and rhamnogalacturonan I (RG-I) domains. Our findings offer insights into the screening of natural polysaccharide-based antioxidants and provide a theoretical basis for the application of A. continentalis.

Current-Induced Magnetic Skyrmions with Controllable Polarities in the Helical Phase.

We report the current-induced creation of magnetic skyrmions in a chiral magnet FeGe nanostructure by using in situ Lorentz transmission electron microscopy. We show that magnetic skyrmions with controllable polarity can be transferred from the helical ground state simply by controlling the direction of the current flow at zero magnetic fields. The force analysis and symmetry consideration, backed up by micromagnetic simulations, well explain the experimental results, where magnetic skyrmions are created because of the edge instability of the helical state in the presence of spin-transfer torque. The on-demand generation of skyrmions and control of their polarity by electric current without the need for a magnetic field will enable novel purely electric-controlled skyrmion devices.

Field-free topological behavior in the magnetic domain wall of ferrimagnetic GdFeCo.

Exploring and controlling topological textures such as merons and skyrmions has attracted enormous interests from the perspective of fundamental research and spintronic applications. It has been predicted theoretically and proved experimentally that the lattice form of topological meron-skyrmion transformation can be realized with the requirement of external magnetic fields in chiral ferromagnets. However, such topological transition behavior has yet to be verified in other materials. Here, we report real-space observation of magnetic topology transformation between meron pairs and skyrmions in the localized domain wall of ferrimagnetic GdFeCo films without the need of magnetic fields. The topological transformation in the domain wall of ferrimagnet is introduced by temperature-induced spin reorientation transition (SRT) and the underlying mechanism is revealed by micromagnetic simulations. The convenient electric-controlling topology transformation and driving motion along the confined domain wall is further anticipated, which will enable advanced application in magnetic devices.

Study on renal artery blood flow parameters of fetuses with isolated borderline oligohydramnios and maternal and infant pregnancy outcomes / 中华超声影像学杂志

Objective:To evaluate the changes of fetal renal artery blood flow parameters in fetuses with isolated borderline oligohydramnios (IBO) in the middle and third trimesters by Doppler ultrasound, and to assess its correlations with maternal and infant pregnancy outcomes.Methods:Twenty-seven IBO fetuses (IBO group) and 27 gestational age-matched normal fetuses (control group) from April to October 2019 in the Second Xiangya Hospital of Central South University underwent prenatal ultrasound examination during the middle and third trimesters. Renal artery blood flow parameters, including renal artery pulsatility index (RAPI), volume corrected renal artery pulsatility index (vcRAPI) and pregnancy outcomes were measured and compared between the two groups. Once diagnosed IBO, patients were recommended to the obstetric clinic for consultation and intervention. The correlation between RAPI, vcRAPI measured before intervention and prepartum amniotic fluid volume and pregnancy outcomes was analyzed, the ROC curve was plotted to find the better predictor.Results:The vcRAPI of the IBO group was higher than that of the control group ( P=0.015). In the IBO group, the vcRAPI measured before intervention was higer in those fetuses who were still IBO before delivery( P=0.048). In the IBO group, the correlation of the vcRAPI measured before intervention and IBO before delivery was statistically significant ( OR=2.41, 95% CI=1.06-5.43, P=0.035). The ROC curve showed that the sensitivity of vcRAPI to IBO was 0.67, the specificity was 0.75( P=0.002). Conclusions:Compared with RAPI, The vcRAPI may reflect the increase in fetal renal artery perfusion resistance of IBO group more timely. The higher vcRAPI before intervention in the IBO group have difficulty in recovering amniotic fluid volume before delivery.Increased vcRAPI is a better predictor of IBO before delivery.

Diagnosis and treatment for incarceration of retroverted uterus during pregnancy: a report of four cases / 中华围产医学杂志

Objective:To investigate the diagnosis and treatment for incarceration of retroverted uterus in pregnant women.Methods:This study retrospectively recruited four gravidas with incarcerated retroverted uterus indicated by prenatal ultrasonography in Hunan Provincial Maternal and Child Health Care Hospital from August 2016 to February 2020. Clinical features, diagnosis, and treatment of these cases were described.Results:Vaginal bleeding or discharge were the main symptoms of the four cases and prenatal ultrasound suggested incarcerated retroverted uterus. Obstetric examination was performed for all cases, except one due to small gestational age, and bulging posterior fornix was found in one case. Three cases were diagnosed in the third trimester and one at 14 gestational weeks. In light of gestations, symptoms, and anterior uterine muscle thickness, three patients underwent planned cesarean sections with a median abdominal incision and a superior transverse uterine incision after fetal lung maturation acceleration. Uterus involution was good, and the incisions healed well in these three cases, with all neonates in good condition. Following a two-week knee-chest position treatment, the position of her uterus and bladder turned normal in case 4.Conclusions:Considering the atypical clinical presentations, clinicians should be aware of incarceration of retroverted uterus when related symptoms or signs were presented. Placenta previa might be the comorbidity and should be differentially diagnosed. The timing of a cesarean section is supposed to be determined based on multiple factors. Moreover, a median abdominal incision and a superior transverse uterine incision are recommended, and an anatomic landmark is often required for the latter's accurate position.

Current-Induced Reversal of Anomalous Hall Conductance in Twisted Bilayer Graphene.

It is observed experimentally that the sign of the Hall resistance can be flipped by a dc electric current in the twisted bilayer graphene (TBG) at 3/4 filling of the fourfold degenerate conduction flat bands. The experiment implies a switching of the valley polarization (VP) and topology in TBG. Here we present a theory on the current-induced switching of VP and topology. The presence of current in the bulk causes the redistribution of electron occupation in bands near the Fermi energy, which then deforms and shifts the band dispersion due to the Coulomb interaction. Above a critical current, the original occupied and empty bands can be swapped, resulting in the switching of VP and topology.

Interplay of the Spin Density Wave and a Possible Fulde-Ferrell-Larkin-Ovchinnikov State in CeCoIn_{5} in Rotating Magnetic Field.

The d-wave superconductor CeCoIn_{5} has been proposed as a strong candidate for supporting the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state near the low-temperature boundary of its upper critical field. Neutron diffraction, however, finds spin-density-wave (SDW) order in this part of the phase diagram for field in the a-b plane, and evidence for the SDW disappears as the applied field is rotated toward the tetragonal c axis. It is important to understand the interplay between the SDW and a possible FFLO state in CeCoIn_{5}, as the mere existence of an SDW does not necessarily exclude an FFLO state. Here, based on a model constructed on the basis of available experiments, we show that an FFLO state competes with an SDW phase. The SDW state in CeCoIn_{5} is stabilized when the field is directed close to the a-b plane. When the field is rotated toward the c axis, the FFLO state emerges, and the SDW phase disappears. In the FFLO state, the nodal planes with extra quasiparticles (where the superconducting order parameter is zero) are perpendicular to the field, and in the SDW phase, the quasiparticle density of states is reduced. We test this model prediction by measuring heat transported by normal quasiparticles in the superconducting state. As a function of field, we observe a reduction of thermal conductivity for field close to the a-b plane and an enhancement of thermal conductivity when field is close to the c axis, consistent with theoretical expectations. Our modeling and experiments, therefore, indicate the existence of the FFLO state when field is parallel to the c axis.

Skyrmion Crystal from RKKY Interaction Mediated by 2D Electron Gas.

We consider a C_{6} invariant lattice of magnetic moments coupled via a Kondo exchange J with a 2D electron gas (2DEG). The effective Ruderman-Kittel-Kasuya-Yosida interaction between the moments stabilizes a magnetic skyrmion crystal in the presence of magnetic field and easy-axis anisotropy. An attractive aspect of this mechanism is that the magnitude of the magnetic ordering wave vectors, Q_{ν} (ν=1, 2, 3), is dictated by the Fermi wave number k_{F}: |Q_{ν}|=2k_{F}. Consequently, the topological contribution to the Hall conductivity of the 2DEG becomes of the order of the quantized value, e^{2}/h, when J is comparable to the Fermi energy ε_{F}.

Z-scores analysis of kidney volume in normal fetuses in second and third trimester / 中华超声影像学杂志

Objective:To explore the variation of renal volume with gestational age(GA), biparietal diameter(BPD), abdominal circumference(AC), femur length (FL) and the Z value calculation formula.Methods:Five hundred and eighty singleton pregnancy women from 20th to 38th gestational weeks in Second Xiangya Hospital of Central South University were enrolled. Two dimensional ultrasound was performed to record fetal growth parameters and renal longitudinal, transverse, anteroposterior diameters. Renal volume was calculated using ellipsoid volume equation: Volume =6/π×length×width×thickness. Using GA, BPD, AC, FL as independent variables and renal volume as dependent variables, the regression analyses of the mean and the standard deviation(SD) for each parameter were calculated separately. The Z-scores were calculated by the formula: Z-scores=(actual measurements of renal volume-predictive value of renal volume)/SD of predictive value.Results:Five hundred and forty-three cases of normal singleton fetuses were involved.The left and right renal volume were increased along with GA, BPD, AC, FL. Quadratic polynomial regression equations were each fitted to the models( r=0.775, 0.771, 0.811, 0.738, P<0.001; r=0.747, 0.735, 0.754, 0.745, P<0.001, respectively). The SD increased with the increases of independent variables and could be modeled with a simple linear regression( r=0.146, 0.225, 0.071, 0.155, P<0.001; r=0.091, 0.157, 0.091, 0.123, P<0.001, respectively). Z-scores were calculated and proved normally distributed after Shapiro-Wilk test( P>0.05). Conclusions:The normal Z-score reference range of fetal renal volume is established to help assess the normal renal growth and identify fetal renal abnormalities.

Volume-corrected renal artery pulsatility index in normal fetuses during the second and third trimester of gestation / 中华超声影像学杂志

Objective:To measure the normal single fetal volume-corrected renal artery pulsatility index (vcRAPI) in the middle and late pregnancy, and to determine the normal reference range of vcRAPI and to observe its correlation with gestational age.Methods:The sagittal and transverse sections of the kidneys of normal single pregnant fetuses at 22 to 36 gestational weeks in the Second Xiangya Hospital from January to July 2019 were prospectively obtained by two-dimensional ultrasound. Estimated renal volume was calculated as length× transverse × antero-posterior×π/6. Pulse Doppler was used to detect the renal artery pulsatility index (RAPI) at the renal hilum in coronary section. The vcRAPI was obtained by dividing the RAPI by the ipsilateral estimated renal volume. The normal reference range of vcRAPI was established, and the scatter diagram of its relationship with gestational age was drawn. Multiple regression models were fitted to select the best fitting curve and to obtain the relevant formulas.Results:A total of 540 normal fetuses were enrolled and the normal reference value range of vcRAPI was established. The vcRAPI of both kidneys was negatively correlated with gestational age ( r=-0.793, -0.780; all P<0.001). The left kidney parameters and gestational age were best fitted with S-curve, and the right kidney parameters were best fitted with power curve. There was no difference between the right and left kidney vcRAPI values( P>0.05). Conclusions:The vcRAPI of normal fetuses decreases with gestational age, indicating that renal perfusion increases with gestational age. In this study, normal reference range of vcRAPI is established to provide reference basis for prediction and monitoring of complicated pregnancy.

The clinical research of Z-scores in assessing fetal coarctation of aorta / 中华超声影像学杂志

Objective:To develop Z-scores for the aortic arch in normal fetuses as a reference for fetuses with suspected coarctation of aorta(CoA).Methods:The aortic arch inner diameters of 610 normal fetuses and 59 CoA fetuses from May 2010 to March 2015 in the Second Xiangya Hospital of Central South University were measured at the long axis of the aortic arch view. Gestational age(GA), femur length(FL) as the independent variable, the aortic arch inner diameters as the dependent variable, Z-scores were created relating the aortic arch inner diameters to the GA and FL. Z-score=[ln(measured diameter)-ln(predicted diameter)]/root MSE. Z-scores of the CoA fetuses were calculated with the above regression, and compared with the Z-scores of the control group.Results:A simple linear regression model was the best description of the data in each case and correlations between FL and the aortic arch inner diameters were excellent ( P<0.001). There was no significant difference in Z-scores calculated with FL or GA as independent variables ( P>0.05). Z-scores of the control group was between -2 and + 2, Z-scores of the CoA group was significantly lower and below -2( P<0.001). Conclusions:Z-scores of fetal aortic arch are sensitive indicators of fetal coarctation, and are of clinical importance for the diagnosis and follow-up study of CoA.

Maternal oxygen therapy for fetus with congenital heart disease / 中华围产医学杂志

Intrauterine hypoxia occurs in the fetus with congenital heart disease (CHD) due to abnormal cardiovascular anatomy and hemodynamic changes, which could affect fetal growth and development. Maternal oxygen therapy has been used in various perinatal cardiovascular diseases, including hypoplastic left heart syndrome, atrial septum aneurysm, coarctation of the aorta, and others. Maternal oxygen therapy may improve the prognosis of the fetus with CHD and predict the neonatal outcomes by dilating the fetal pulmonary vessels, increasing pulmonary blood flow to affect abnormal cardiovascular anatomy and hemodynamic changes.

Z-score analysis of brain fissure depth in normal fetuses / 中华超声影像学杂志

Objective@#To construct the Z-score models for normal fetal brain fissures.@*Methods@#Four hundred and eighty-seven pregnant woman who underwent prenatal ultrasonography from January to August 2018 in the Second Xiangya Hospital of Central South University were collected randomly for analysis, and all the fetuses(18-38 weeks) were healthy. The calacarine fissure, pariet-ooccipital fissure, sylvian fissure of the fetuses were measured and they were chosed as the dependent variables, while the independent variable were the gestational age and biparietal diamete, as well as femur length. The regression analyses of the mean(M) and the standard deviation(SD) for each parameter were performed separately. Two observers randomly measured the brain fissures depth two hours apart to evaluate the interobserver repeatability.@*Results@#The brain fissure depth in normal fetuses during geatational age between 18 to 38 weeks can be evaluated by Z-score model.Positive correlations were found between the depth of calacarine fissure, pariet-ooccipital fissure, sylvian fissure and gestational age, biparietal diameter and femur length.@*Conclusions@#Z-score can intuitively reflect the development of brain fissure more accurate, and is valuable, and can be used as a powerful supplement to the traditional method.