Magnetic ground state of plutonium dioxide: DFT+U calculations

The magnetic states of the strongly correlated system plutonium dioxide(PuO_(2)) are studied based on the density functional theory(DFT) plus Hubbard U(DFT +U) method with spin–orbit coupling(SOC) included. A series of typical magnetic structures including the multiple-k types are simulated and compared in the aspect of atomic structure and total energy. We test LDA, PBE, and SCAN exchange–correlation functionals on PuO_(2) and a longitudinal 3k antiferromagnetic(AFM) ground state is theoretically determined. This magnetic structure has been identified to be the most stable one by the former computational work using the hybrid functional. Our DFT +U + SOC calculations for the longitudinal 3k AFM ground state suggest a direct gap which is in good agreement with the experimental value. In addition, a genetic algorithm is employed and proved to be effective in predicting magnetic ground state of PuO2. Finally, a comparison between the results of two extensively used DFT +U approaches to this system is made.

CALCULATION OF THE MAGNETIZATION AND MAGNETOCALORIC EFFECT IN THE MnFeP_(0.45)As_(0.55) COMPOUND

A magnetic state equation of the MnFeP0.45As0.55 compound has been obtained by minimizing the Gibbs free energy with respect to the volume and the magnetization based on the Bean-Rodbell model. The isothermal magnetization of the compound has been calculated using this equation. The magnetic entropy change of the compound was determined from the surface area between the two adjacent isothermal magnetization curves divided by the average temperature. A comparison and an error analysis of the calculated magnetic entropy change and the one determined from the experimental data were given.

Combined Effect of Uniaxial Strain and Magnetic Field on the Exciton States in Semiconducting Single-Walled Carbon Nanotubes

The exciton states of semiconducting carbon nanotubes are calculated by a tight-binding model supplemented by Coulomb interactions under the combined effect of uniaxial strain and magnetic field. It is found that the excitation energies and absorption spectra of zigzag tubes（11,0） and（10,0） show opposite trends with the strain under the action of the magnetic field. For the（11,0） tube, the excitation energy decreases with the increasing uniaxial strain, with a splitting appearing in the absorption spectra. For the（10,0） tube, the variation trend firstly increases and then decreases, with a reversal point appearing in the absorption spectra. More interesting,at the reversal point the intensity of optical absorption is the largest because of the degeneracy of the two bands nearest to the Fermi Level, which is expected to be observed in the future experiment. The similar variation trend is also exhibited in the binding energy for the two kinds of semiconducting tubes.

Magnetic Field Measurement with Heisenberg Limit Based on Solid Spin NOON State

The maximum entangled number state （NOON state） can improve the sensitivity of physical quantity measure- ment to the Heisenberg limit 1/N. In this work, the magnetic field measurement based on the individual solid spin NOON state is investigated. Based on the tunable effective coupling coefficient, we propose a generation scheme of the three-spin NOON state, i.e, the Creenberger-Horne-Zeilinger （CHZ） state, and discussed the mea- surement resolution reduction due to decoherence. It is unnecessary to entangle spins as many as possible when decoherence exists. In practice, defect spins in diamond and alp donors with long coherence time can be applied with current techniques in the nano-scaled high resolution magnetic measurement.

Study on magnetic memory signals of medium carbon steel specimens with surface crack precut during loading process

Static tensile test and tensile-tensile fatigue test of medium carbon steel sheet specimens with surface crack precut were performed on MTS810 hydraulic testing machine to clear the meaning of the point of Hp(y) value zero. Magnetic memory signals were measured during the test process. The results show that only one point of Hp(y) zero value exists in all measured magnetic signal curves during the loading process, which should be a sign of intersection of positive-negative magnetic poles after magnetic ordered state appears and does not indicate the position of surface crack precut. The analysis shows that the surface crack precut can not interrupt the magnetic ordered state occurred during the test completely, hence its Hp(y) value is not zero. However, the crack extending to a penetrated defect at the instant of specimen′s fracture leads to the discontinuance of magnetic ordered state.

Efficacy of acupuncture at ghost points combined with fluoxetine in treating depression:A randomized study

BACKGROUND Depression affects more than 350 million people worldwide.In China,4.2%(54 million people)of the total population suffers from depression.Psychotherapy has been shown to change cognition,improve personality,and enhance the ability to cope with difficulties and setbacks.While pharmacotherapy can reduce symptoms,it is also associated with adverse reactions and relapse after drug withdrawal.Therefore,there has been an increasing emphasis placed on the use of non-pharmacological therapies for depression.The hypothesis of this study was that acupuncture at ghost points combined with fluoxetine would be more effective than fluoxetine alone for the treatment of depression.AIM To investigate the efficacy of acupuncture at ghost points combined with fluoxetine for the treatment of patients with depression.METHODS This randomized controlled trial included patients with mild to moderate depression(n=160).Patients received either acupuncture at ghost points combined with fluoxetine(n=80)or fluoxetine alone(control group,n=80).Needles were retained in place for 30 min,5 times a week;three treatment cycles were administered.The Mann–Whitney U test was used to compare functional magnet resonance imaging parameters,Hamilton depression rating scale(HAMD)scores,and self-rating depression scale(SDS)scores between the acupuncture group and control group.RESULTS There were no significant differences in HAMD or SDS scores between the acupuncture group and control group,before or after 4 wk of treatment.The acupuncture group exhibited significantly lower HAMD and SDS scores than the control group after 8 wk of treatment(P<0.05).The acupuncture group had significantly lower fractional Amplitude of Low Frequency Fluctuations values for the left anterior wedge leaf,left posterior cingulate gyrus,left middle occipital gyrus,and left inferior occipital gyrus after 8 wk.The acupuncture group also had significantly higher values for the right inferior frontal gyrus,right insula,and right hippocampus(P<0.05).After 8 wk of treatment,the effective rates of the acupuncture and control groups were 51.25%and 36.25%,respectively(P<0.05).CONCLUSION The study results suggest that acupuncture at ghost points combined with fluoxetine is more effective than fluoxetine alone for the treatment of patients with mild to moderate depression.

Computation of the structure of a magnetized strange quark star

We have calculated some properties of spin polarized strange quark matter（SQM） in a strong magnetic field at zero temperature using the MIT bag model.We showed that the equation of state of spin polarized SQM is stiffer than that for unpolarized cases.We have also computed the structural properties of a spin polarized strange quark star（SQS） and found that the presence of a magnetic field leads to a more stable SQS when compared to the structural properties of an unpolarized SQS.

Pancreatic imaging:Current status of clinical practices and small animal studies

Different causative factors acting on the pancreas can result in diseases such as pancreatitis, diabetes and pancreatic tumors. The high incidence and mortality of pancreatic diseases have placed diagnostic imaging in a crucial position in daily clinical practice. In this minireview article different pancreatic imaging techniques are discussed, from the standard clinical imaging modalities and state of the art clinical magnetic resonance imaging techniques to current situations in pre-clinical pancreatic imaging studies. In particular, the challenges of pre-clinical rodent pancreatic imaging are addressed, with both the image acquisition techniques and the post-processing methods for rodent pancreatic imaging elaborated.

Thermochromic and Magnetic Properties of a Copper(Ⅱ)Coordination Compound

Copper complexes that can experience reversible heat-induced dehydration and rehydration in the solid state were rarely reported although thermochromic copper complexes have been widely reported, and their heat-induced magnetic properties have not been studied. We firstly observed the reversible thermochromic phenomena of the known copper（II） complex [Cu（bpy）（OOCCH3）2]n·xn H2O（x = 2.5 or 3; bpy = 4,4＇-bipyridine） in the solid state, which is associated with the dehydration and rehydration processes, and found that heat-induced coloration clearly enhanced the magnetic susceptibility.

Quark stars with strong magnetic fields: considering different magnetic field geometries

We calculate the mass-radius relationship of quark stars with the magnetized density- dependent quark mass model in this work, considering two magnetic field geometries： a statistically isotropic, tangled field and a force-free configuration. In both cases, magnetic field production decreases in the case of maximum quark star mass. Furthermore, a tangled, isotropic magnetic field has a relatively smaller impact on the mass and radius, compared to the force-free configuration, which implies that the geometry of the interior magnetic field is at least as important as the field strength itself when the influ- ence of the strong magnetic field on the mass and radius is assessed.

Maximum mass of magnetic white dwarfs

We revisit the problem of the maximum masses of magnetized white dwarfs （WDs）. The impact of a strong magnetic field on the structure equations is addressed. The pressures become anisotropic due to the presence of the magnetic field and split into parallel and perpendicular components. We first construct stable solutions of the Tolman-Oppenheimer-Volkoff equations for parallel pressures and find that physical solutions vanish for the perpendicular pressure whenB ≥ 10^13 G. This fact estab- lishes an upper bound for a magnetic field and the stability of the configurations in the （quasi） spherical approximation. Our findings also indicate that it is not possible to obtain stable magnetized WDs with super-Chandrasekhar masses because the val- ues of the magnetic field needed for them are higher than this bound. To proceed into the anisotropic regime, we can apply results for structure equations appropriate for a cylindrical metric with anisotropic pressures that were derived in our previous work. From the solutions of the structure equations in cylindrical symmetry we have con- firmed the same bound for B- 10^13 G, since beyond this value no physical solutions are possible. Our tentative conclusion is that massive WDs with masses well beyond the Chandrasekhar limit do not constitute stable solutions and should not exist.

Anisotropic stellar structure equations for magnetized strange stars

The fact that a fermion system in an external magnetic field breaks the spherical symmetry suggests that its intrinsic geometry is axisymmetric rather than spherical. In this work we analyze the impact of anisotropic pressures, due to the presence of a magnetic field, in the structure equations of a magnetized quark star.We assume a cylindrical metric and an anisotropic energy momentum tensor for the source. We found that there is a maximum magnetic field that a strange star can sustain, closely related to the violation of the virial relations.

Theoretical study on anomalous thermal expansion of two AB_(2)-type compounds

Anomalous thermal expansion,or other words,negative thermal expansion(NTE),resulting from the lattice contraction upon temperature increasing,has been an enduring topic for material science and engineering.The variation of a lattice go with the temperature is straightly originated from its electronic structures and is inseparable from those physical properties.In the past several decades,many efforts have been made to searching new series of NTE compounds or control the thermal expansion performance in order to supply various demands of different extreme applications.These development of new NTE systems also dependences on the theoretical studies.Here,we carried out theoretical calculation on CrB_(2) and FeZr_(2) with anisotropic negative thermal expansion.Intriguingly,theoretical calculations reveal that the binding of either Cr-Cr pair or Fe-Fe pair is relatively small.The results reveal that the origin of NTE is the ordered magnetic state during the increasing of temperature.The localized electrons would prevent the lattice parameters increase with heating,which shows macroscopic NTE phenomenon.

Local synchronization and amplitude of the fluctuation of spontaneous brain activity in attention-deficit/hyperactivity disorder:a resting-state fMRI study

Regional homogeneity（ReHo）and the amplitude of low-frequency fluctuation（ALFF）are two approaches to depicting different regional characteristics of resting-state functional magnetic resonance imaging（RS-fMRI）data.Whether they can complementarily reveal brain regional functional abnormalities in attention-deficit/hyperactivity disorder（ADHD）remains unknown.In this study,we applied ReHo and ALFF to 23 medication-na ve boys diagnosed with ADHD and 25 age-matched healthy male controls using whole-brain voxel-wise analysis.Correlation analyses were conducted in the ADHD group to investigate the relationship between the regional spontaneous brain activity measured by the two approaches and the clinical symptoms of ADHD.We found that the ReHo method showed widely-distributed differences between the two groups in the fronto-cingulo-occipitocerebellar circuitry,while the ALFF method showed a difference only in the right occipital area.When a larger smoothing kernel and a more lenient threshold were used for ALFF,more overlapped regions were found between ALFF and ReHo,and ALFF even found some new regions with group differences.The ADHD symptom scores were correlated with the ReHo values in the right cerebellum,dorsal anterior cingulate cortex and left lingual gyrus in the ADHD group,while no correlation was detected between ALFF and ADHD symptoms.In conclusion,ReHo may be more sensitive to regional abnormalities,at least in boys with ADHD,than ALFF.And ALFF may be complementary to ReHo in measuring local spontaneous activity.Combination of the two may yield a more comprehensive pathophy-siological framework for ADHD.

Glassy magnetic ground state in layered compound MnSb_(2)Te_(4)

As a sister compound of MnBi_(2)Te_(4),the highquality MnSb_(2)Te_(4) single crystals are grown via solid-state reaction where prolonged annealing and narrow temperature window play critical roles on account of its thermal metastability.Single-crystal X-ray diffraction(SCXRD)analysis on MnSb_(2)Te_(4) illustrates a crystal model that is isostructural to MnBi_(2)Te_(4),consisting of Te-Sb-Te-Mn-Te-Sb-Te septuple layers(SLs)stacking in an ABC sequence.However,MnSb_(2)Te_(4) reveals a more pronounced cation intermixing in comparison with MnBi_(2)Te_(4),comprising 28.9(7)%Sb antisite defects on the Mn(3a)site and 19.3(6)%Mn antisite defects on the Sb(6c)site,which may give rise to novel magnetic properties in emerging layered MnBi_(2)Te_(4)-family materials.Unlike the antiferromagnetic(AFM)nature in MnBi_(2)Te_(4),MnSb_(2)Te_(4) exhibits a glassy magnetic ground state below 24 K and can be easily tuned to a ferromagnetic state under a weak applied magnetic field.Its magnetic hysteresis,anisotropy,and relaxation process are investigated in detail via static and dynamic magnetization measurements.Moreover,anomalous Hall effect as a p-type conductor is demonstrated with transport measurements.This work grants MnSb_(2)Te_(4) a possible access to the future exploration of exotic quantum physics by removing the odd/even layer number restraint in realizing quantum transport phenomena in intrinsic AFM MnBi_(2)Te_(4)-family materials,as a result of the crossover between its magnetism and potential topology arising from the Sb-Te layer.

Quantum state and process tomography via adaptive measurements

We investigate quantum state tomography(QST) for pure states and quantum process tomography(QPT) for unitary channels via adaptive measurements. For a quantum system with a d-dimensional Hilbert space, we first propose an adaptive protocol where only 2d. 1 measurement outcomes are used to accomplish the QST for all pure states. This idea is then extended to study QPT for unitary channels, where an adaptive unitary process tomography(AUPT) protocol of d2+d.1measurement outcomes is constructed for any unitary channel. We experimentally implement the AUPT protocol in a 2-qubit nuclear magnetic resonance system. We examine the performance of the AUPT protocol when applied to Hadamard gate, T gate(/8 phase gate), and controlled-NOT gate,respectively, as these gates form the universal gate set for quantum information processing purpose. As a comparison, standard QPT is also implemented for each gate. Our experimental results show that the AUPT protocol that reconstructing unitary channels via adaptive measurements significantly reduce the number of experiments required by standard QPT without considerable loss of fidelity.

The magnetic states and Labyrinth ordering in 2D lattices of ising spins with RKKY Interaction

The numerical simulation of 2D simple square lattice of Ising superspins,that interact via the Ruderman–Kittel–Kasuya–Yosida(RKKY)exchange interaction is performed.It is found,that at low temperatures in the researched systems predominantly realized labyrinth domain structure.The modeled image of magnetization distribution does not coincide with the image of energy distribution.Hysteresis loops of the samples and labyrinth domain structures similarly obtained by Monte Carlo method,are also observed in physical experiments.

Intrinsic exchange bias effect in strain-engineered single antiferromagnetic LaMnO3 films

In this work, epitaxial growth of LaMnO3 thin films on different substrates using pulsed laser deposition under tensile and compressive strain was studied. The intrinsic exchange bias effect was observed in the single A-type antiferromagnetic LaMnO3 films no matter whether the tensile or compressive strain was supplied by the substrates. Due to the lattice mismatch between the film and different substrates, the intense strain can induce MnO6 octahedral rotation in the bottom region of the film neighboring the substrate, which leads to the distortion of MnO6 octahedron and the net magnetic behavior. However, the upper part maintains the original A-type antiferromagnetic order due to strain relaxation. The exchange bias effect in single films is attributed to the coupling between the bottom canted magnetic part and the upper antiferromagnetic region. The observation of exchange bias in single films on different substrates enables the emergence of a new class of biasing components in spintronics, which are based on strain-engineering.

Tuning the magnetic and electronic properties of strontium titanate by carbon doping

The magnetic and electronic properties of strontium titanate with different carbon dopant configurations are explored using first-principles calculations with a generalized gradient approximation(GGA)and the GGA+U approach.Our results show that the structural stability,electronic properties and magnetic properties of C-doped SrTiO3 strongly depend on the distance between carbon dopants.In both GGA and GGA+U calculations,the doping structure is mostly stable with a nonmagnetic feature when the carbon dopants are nearest neighbors,which can be ascribed to the formation of a C–C dimer pair accompanied by stronger C–C and weaker C–Ti hybridizations as the C–C distance becomes smaller.As the C–C distance increases,C-doped SrTiO3 changes from an n-type nonmagnetic metal to ferromagnetic/antiferromagnetic half-metal and to an antiferromagnetic/ferromagnetic semiconductor in GGA calculations,while it changes from a nonmagnetic semiconductor to ferromagnetic half-metal and to an antiferromagnetic semiconductor using the GGA+U method.Our work demonstrates the possibility of tailoring the magnetic and electronic properties of C-doped SrTiO3,which might provide some guidance to extend the applications of strontium titanate as a magnetic or optoelectronic material.

Observational connection between local high-temperature phenomena within magnetic clouds and the Sun

Magnetic clouds(MCs) frequently show abnormal high-ionization states of heavy ions. The abnormal high-charge distributions are related to the coronal temperature of their source regions. We examined the plasma and magnetic field data of 74 MCs observed by the Advanced Composition Explorer from February 1998 to December 2008. We determined that 14 of the 74 events showed local high-temperature phenomena. We analyzed the correlation between proton temperature and O7/O6ratio(or high mean Fe charge state ?Fe?) within the local high-temperature regions in the 14 MCs. Results show that proton temperature and O7/O6 ratio(or high mean Fe charge state) had good correlations in nine MCs, but had no evident correlation in the other five MCs. The local high-temperature phenomena within the nine MCs have resulted from the Sun.