Magneto-Orientated Graphite Double-Layer Homo-Structure with Broadband Microwave Absorption

We utilized magnetic fields as an efficient tool to manipulate the orientation and electromagnetic properties of graphite micro-flakes(GMFs).As a result,we successfully developed a GMF double-layer homo-structure,which shows excellent electromagnetic absorption properties.By tuning the direction of a small magnetic field(850 G),vertical and horizontal aligned GMFs are produced.Their electromagnetic parameters are effectively tailored by this magneto-orientation effect,and the vertical and horizontal aligned GMFs achieve good results in terms of impedance matching and microwave absorption.With the combination of these two magneto-orientated layers,vertically oriented as the surficial impedance matching layer and horizontally oriented as the inner loss layer,we design a GMF-based double-layer homo-structure.After thickness optimization,-38.2 d B minimum reflection loss and 6.4 GHz(11.6–18.0 GHz)absorption bandwidth are achieved.Our findings further emphasize the importance of material orientation freedom and provide a magneto-strategy to design multiple-layer structures and to produce high-performance microwave devices.

Effect of thermal treatment and ball milling on microstructure and phase transformation of Ni-Mn-Ga-Nb alloys

To clarify phase transformation evolution of Nb-doped Ni-Mn-Ga bulk alloys after aging and ball milling, the microstructure and phase transformation of the aged and ball-milled dual-phase Nb-doped Ni-Mn-Ga alloys were investigated by SEM, EDS, XRD, DSC and susceptibility measurements. The as-cast alloys were mainly composed of the second phase with layer-shape and presented a reduced martensitic transformation with increasing the second phase content. The second phase transformed from layer-shape to dense bar-shape and the martensitic transformation was enhanced after being quenched at 1173 K. After aging at 673 and 873 K, the 3% Nb alloy with less second phase exhibited a single-step phase transformation, whereas the 6% Nb and 9% Nb alloys with more second phase exhibited a two-step martensitic transformation and Curie transition. The martensitic transformation and Curie transition of the as-milled dual-phase particles disappeared and were retrieved after annealing at 1073 K due to the recovery of high ordered structure of the matrix.

Generating mechanism of pathological beta oscillations in STN-GPe circuit model: A bifurcation study

Parkinson’s disease(PD)is characterized by pathological spontaneous beta oscillations(13 Hz-35 Hz)often observed in basal ganglia(BG)composed of subthalamic nucleus(STN)and globus pallidus(GPe)populations.From the viewpoint of dynamics,the spontaneous oscillations are related to limit cycle oscillations in a nonlinear system;here we employ the bifurcation analysis method to elucidate the generating mechanism of the pathological spontaneous beta oscillations underlined by coupling strengths and intrinsic properties of the STN-GPe circuit model.The results reveal that the increase of inter-coupling strength between STN and GPe populations induces the beta oscillations to be generated spontaneously,and causes the oscillation frequency to decrease.However,the increase of intra-coupling(self-feedback)strength of GPe can prevent the model from generating the oscillations,and dramatically increase the oscillation frequency.We further provide a theoretical explanation for the role played by the inter-coupling strength of GPe population in the generation and regulation of the oscillations.Furthermore,our study reveals that the intra-coupling strength of the GPe population provides a switching mechanism on the generation of the abnormal beta oscillations:for small value of the intra-coupling strength,STN population plays a dominant role in inducing the beta oscillations;while for its large value,the GPe population mainly determines the generation of this oscillation.

Analytically determining frequency and amplitude of spontaneous alpha oscillation in Jansen's neural mass model using the describing function method

Spontaneous alpha oscillations are a ubiquitous phenomenon in the brain and play a key role in neural information processing and various cognitive functions.Jansen＇s neural mass model（NMM） was initially proposed to study the origin of alpha oscillations.Most of previous studies of the spontaneous alpha oscillations in the NMM were conducted using numerical methods.In this study,we aim to propose an analytical approach using the describing function method to elucidate the spontaneous alpha oscillation mechanism in the NMM.First,the sigmoid nonlinear function in the NMM is approximated by its describing function,allowing us to reformulate the NMM and derive its standard form composed of one nonlinear part and one linear part.Second,by conducting a theoretical analysis,we can assess whether or not the spontaneous alpha oscillation would occur in the NMM and,furthermore,accurately determine its amplitude and frequency.The results reveal analytically that the interaction between linearity and nonlinearity of the NMM plays a key role in generating the spontaneous alpha oscillations.Furthermore,strong nonlinearity and large linear strength are required to generate the spontaneous alpha oscillations.

~1H nuclear magnetic resonance-based metabolomics reveals sex-specific metabolic changes of gastrodin intervention in rats

Objective:To explore^1H nuclear magnetic resonance-based metabolomics on sex-specific metabolic changes of gastrodin intervention in rats.Methods:In this research,~1H NMR-based metabolomics was used for the first time to investigate metabolic changes following chronic intervention with gastrodin in rats.Results:24 endogenous metabolites were identified.Body weight.daily diet and the total volume of urine in in each day of each rat were measured synchronously.Modifications in 12 metabolites were observsd following gastrodin intervention,indicating gastrodin-induced alterations in carbohydrate and energy metabolism.Interestingly,these metabolic changes were not totally identical in female and male rats.Some metabolic changes arising from gastrodin intervention showed sexual dimorphism including LDL/VLDL and lactate which were on the decrease in the female but on the increase in the male,together with arginine/ornithine,creatine,and glycerol which were on the increase in the female but on the decrease in the male.While the decrease in pyruvate,succinate and glutamate was only shown in the male and the increase in valine,α-ketoglutarate and glucose was only in the female.Conclusions:This resesrch shows the sex-specific metabolic response to GAS intervention,weather GAS is a healthy dietary supplement for the male merits further

Pharmacokinetic and NMR metabolomics approach to evaluate therapeutic effect of berberine and Coptidis Rhizoma for sepsis

Objective: Sepsis, a systemic response to infection, often leads to end-organ dysfunction. Despite its high rates of mortality and morbidity, its pathophysiology is still poorly understood. Coptidis Rhizoma and its main active alkaloid compound, berberine, have been as anti-bacterial and anti-inflammatory drugs used in clinic. The objective of this study was to gain more insights towards understanding the sepsis associated with drug absorption and disposition and treatments of berberine and Coptidis Rhizoma dynamically.Methods: Pharmacokinetic and metabolomic studies of Coptidis Rhizoma and its main active component berberine have been performed.Results: Cecal ligation and puncture(CLP) induced sepsis showed marked changes of metabolites concerning energy metabolism and amino acids metabolisms, which could be reversed towards the normal state by Coptidis Rhizoma and berberine.Conclusion: Berberine exhibited an equivalent and even better therapeutic effect than Coptidis Rhizoma.

Effect of Heat Treatment on Microstructure and Stress Rupture Properties of a Ni–Mo–Cr–Fe Base Corrosion-Resistant Superalloy

The influences of heat treatment and test condition on the microstructure and stress rupture properties of a Ni–Mo–Cr–Fe base corrosion-resistant superalloy have been investigated in this paper. Optical microscope and scanning electron microscope were employed for the microstructure observation, and X-ray diffraction, electron probe micro-analyzer, and transmission electron microscope were used for phase determination. It was found that the grain size increased and the volume fractions of initial M_6C carbides decreased along with the increase in solution treatment temperature. When tested at 650 °C/320 MPa, the stress rupture lives decreased with the increase in solution treatment temperature, but the stress rupture lives increased slightly at first and then decreased for the samples solution heat treated at 1220 °C when tested at 700 °C/240 MPa. The elongations showed the descendent trends under these two conditions. The stress rupture life and elongation for the aged samples all showed a noticeable improvement at 650 °C/320 MPa, but there was no noticeable improvement at 700 °C/240 MPa. The reasons can be attributed to the grain size, test conditions, and the initial and secondary carbides.