Mimic Drug Dosage Modulation for Neuroplasticity Based on Charge-Trap Layered Electronics

The human brain is often likened to an incredibly complex and intricate computer, rather than electrical devices, consisting of billions of neuronal cells connected by synapses. Different brain circuits are responsible for coordinating and performing specific functions. The reward pathway of the synaptic plasticity in the brain is strongly related to the features of both drug addiction and relief. In the current study, a synaptic device based on layered hafnium disulfide (HfS₂) is developed for the first time, to emulate the behavioral mechanisms of drug dosage modulation for neuroplasticity. A strong gate-dependent persistent photocurrent is observed, arising from the modulation of substrate-trapping events. By controlling the polarity of gate voltage, the basic functions of biological synapses are realized under a range of light spiking conditions. Furthermore, under the control of detrapping/trapping events at the HfS₂/SiO₂ interface, positive/negative correlations of the A_n/A₁ index, which significantly reflected the weight change of synaptic plasticity, are realized under the same stimulation conditions for the emulation of the drug-related addition/relief behaviors in the brain. The findings provide a new advance for mimicking human brain plasticity.     

A cathode support structure for use in a magnetron oscillator experiment

A low temperature co-fired ceramic (LTCC) material system has been used to develop a protype field emission cathode structure for use in an experimental magnetron oscillator. The structure is designed for used with 30 gated field emission array (GFEA) die electrically connected through silver metal traces and electrical vias. To approximate a cylinder, the cathode structure (48 mm long and 13.7 mm in diameter) is comprised of 10 faceted plates which cover the GFEA dies. Slits in the facet plates allow electron injection. The GFEA die (3 mm × 8 mm) are placed in axial columns of 3 and spaced azimuthally around a cylindrical support structure in a staggered configuration resulting in 10 azimuthal locations. LTCC manufacturing techniques were developed in order to fabricate the newly designed cathode with seven layers wrapped to form the cylinder with electrical traces and vias. Two different cathode wrapping techniques and two different via filling techniques were studied and compared. Two different facet plate manufacturing techniques were studied. Finally, four different support stand configurations for firing the cylindrical structure were also compared with a square post stand having the best circularity and linearity measurements of the fired structure.     

A new ternary phase in the system CaO–Al2O3–Cr2O3: Crystal structure and thermal expansion of CaAl2Cr2O7

Polycrystalline material of a novel phase in the system CaO–Al₂O₃–Cr₂O₃ has been obtained by solid-state reactions. Chemical analysis indicated the composition CaAl₂Cr₂O₇. Single-crystal growth of the new compound using borax as a mineralizer was successful. Diffraction experiments at ambient conditions on a crystal with composition CaAl_2.13Cr_1.87O₇ yielded the following basic crystallographic data: space group P 3, a = 7.7690(5) Å, c = 7.6463(5) Å, V = 399.68(6) ų, Z = 3. Structure determination and subsequent least-squares refinements resulted in a residual of R(|F|) = 2.3% for 1440 independent observed reflections and 113 parameters. To the best of our knowledge, the structure of CaAl_2.13Cr_1.87O₇ or CaAl₂Cr₂O₇ represents a new structure type. It belongs to the group of double layer structures where individual double layers contain octahedrally and tetrahedrally coordinated cation positions. Linkage between neighboring sheet packages is provided by additional calcium cations. Furthermore, thermal expansion has been studied in the interval between 29 and 790°C using in situ high-temperature single-crystal diffraction. No indications for a structural phase transition were observed. From the evolution of the lattice parameters the thermal expansion tensor has been obtained. A pronounced anisotropy is evident. The response of structural building units to variable temperature has been discussed.     

Structural Aspects of P2-Type Na0.67Mn0.6Ni0.2Li0.2O2 (MNL) Stabilization by Lithium Defects as a Cathode Material for Sodium-Ion Batteries

A known strategy for improving the properties of layered oxide electrodes in sodium-ion batteries is the partial substitution of transition metals by Li. Herein, the role of Li as a defect and its impact on sodium storage in P2-Na_0.67Mn_0.6Ni_0.2Li_0.2O₂ is discussed. In tandem with electrochemical studies, the electronic and atomic structure are studied using solid-state NMR, operando XRD, and density functional theory (DFT). For the as-synthesized material, Li is located in comparable amounts within the sodium and the transition metal oxide (TMO) layers. Desodiation leads to a redistribution of Li ions within the crystal lattice. During charging, Li ions from the Na layer first migrate to the TMO layer before reversing their course at low Na contents. There is little change in the lattice parameters during charging/discharging, indicating stabilization of the P2 structure. This leads to a solid-solution type storage mechanism (sloping voltage profile) and hence excellent cycle life with a capacity of 110 mAh g^-1 after 100 cycles. In contrast, the Li-free compositions Na_0.67Mn_0.6Ni_0.4O₂ and Na_0.67Mn_0.8Ni_0.2O₂ show phase transitions and a stair-case voltage profile. The capacity is found to originate from mainly Ni³⁺/Ni⁴⁺ and O^2-/O^2-δ redox processes by DFT, although a small contribution from Mn⁴⁺/Mn⁵⁺ to the capacity cannot be excluded.     

基于边图的线性流重叠社区发现算法

重叠网络的社区发现是复杂网络研究中的重要问题。为了提高网络中重叠社区发现的时间效率，提出一种基于边图的线性流重叠社区发现算法LBSA。算法首先对于边图网络中的边进行随机的依次处理，完成节点的初步社区划分，再将其中重叠小社区合并到相似度最大的其他大社区中得到最终的社区。通过以上步骤，算法能够以接近线性的时间复杂度得到网络的重叠结构。从最终的实验结果来看，与其他算法相比，该算法能够在更短的时间有质量地发现网络中的重叠社区。     

浓香型白酒新老窖池分层池底窖泥钙含量差异及其影响因素

该研究分析了浓香型白酒新、老窖池分层池底窖泥中钙离子、相对钙含量分别与pH值、乳酸之间的皮尔森相关性和线性回归关系。通过统计分析发现：与新窖泥相比，老窖泥中钙离子和相对钙含量与pH值的相关性（-0.808 1，0.750 2）以及与乳酸的相关性（0.717 6，-0.637 9）较强，线性回归拟合度较高；受表层0～3 cm新窖泥钙盐过度解离的影响，新窖泥中相应的相关性较弱。结果表明，pH值和乳酸含量差异对新、老窖泥钙离子和相对钙含量差异有较大影响。推测新、老窖泥表层0～3 cm钙离子和相对钙含量的显著差异与两者乳酸含量差异引起的钙盐解离差异有直接关系，与其菌群乳酸降解差异有间接关系。该研究为“退化”和“钙化”窖泥的形成提供了新的理论依据。     

Effect of phytic acid–modified layered double hydroxide on flammability and mechanical properties of intumescent flame retardant polypropylene system

Phytic acid–modified layered double hydroxide (Ph‐LDH) was synthesized via coprecipitation method and subsequently was used in polypropylene (PP) by combining with an ammonium polyphosphate (APP) via melt compounding method. The synergistic effect between APP and Ph‐LDH on the thermal stability, flammability, and mechanical properties of the resultant PP composites was investigated by thermogravimetric analysis, limiting oxygen index, vertical burning test (UL‐94), cone calorimeter tests, tensile test, and impact test. Morphologies of the chars obtained from the samples after the cone calorimeter tests were studied by scanning electron microscopy. The combination of APP and Ph‐LDH slightly influenced the impact and tensile properties of PP. Also, the synergistic effect between APP and Ph‐LDH occurred in the cone calorimeter test. Moreover, the combination of APP and Ph‐LDH produced better quality char that effectively suppressed the spread of the flame and volatile and finally extinguished the fire.     

Reversible Flat to Rippling Phase Transition in Fe Containing Layered Battery Electrode Materials

Layered sodium transition metal oxides of NaTMO₂ (TM = 3d transition metal) show unique capability to mix different compositions of Fe to the TM layer, a phenomenon that does not exist in LiTMO₂. Here, a novel spontaneous TM layer rippling in the sodium ion battery cathode materials is reported, revealed by in situ X‐ray diffraction, Cs‐corrected scanning transmission electron microscopy, and density functional theory simulation, where the softening and distortion of FeO₆ octahedra collectively drives the flat TM planes into rippled ones with inhomogeneous interlayer distance at high voltage. In such a rippling phase, charge and discharge of Na ions take different evolution pathways, resulting in an unusual hysteresis voltage loop. Importantly, upon discharge beyond a certain Na composition, the rippling TM layer will go back to flat, giving the reversibility of such structural evolution in the following cycles.