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41.
Yasushi MIYASHITA 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2022,98(3):93
The cerebral cortex performs its computations with many six-layered fundamental units, collectively spreading along the cortical sheet. What is the local network structure and the operating dynamics of such a fundamental unit? Previous investigations of primary sensory areas revealed a classic “canonical” circuit model, leading to an expectation of similar circuit organization and dynamics throughout the cortex. This review clarifies the different circuit dynamics at play in the higher association cortex of primates that implements computation for high-level cognition such as memory and attention. Instead of feedforward processing of response selectivity through Layers 4 to 2/3 that the classic canonical circuit stipulates, memory recall in primates occurs in Layer 5/6 with local backward projection to Layer 2/3, after which the retrieved information is sent back from Layer 6 to lower-level cortical areas for further retrieval of nested associations of target attributes. In this review, a novel “dynamic multimode module (D3M)” in the primate association cortex is proposed, as a new “canonical” circuit model performing this operation. 相似文献
42.
To understand the behaviour of nuclear waste glass in groundwater, borosilicate glasses were placed in simulated groundwater for more than 200 days. The composition of the simulated groundwater was similar to that of the groundwater in Beishan (a potential nuclear waste site). The pH value of groundwater was adjusted to 7.5, and the ratio of the surface area of glass to the volume of the solution (SA/V) was set to 10?m?1. Solutions and bulk glasses were characterised to obtain the elemental behaviour and surface morphology of the glass/solution interface, which was named the alteration layer. The mean thicknesses of the alteration layer were 5.16?±?0.11?µm and 11.67?±?0.28?µm at 70°C and 90°C, respectively. A thicker alteration layer was attributed to the lower surface activation energy of the glass and a high ion exchange between K+ and Na+ in the interface between the glass surface and the solution. For the elemental behaviour, mobile species B and Na were depleted, while K and Ca from the solution were enriched in the alteration layer due to ion exchange. Network species Si decreased in the layer, leading to the corrosion of the backbone of the glass; however, species Al increased, which implied that some [SiO4] units were partially replaced by [AlO4] units. In this work, glass in groundwater suffered much more intense corrosion than that in de-ionised water. 相似文献
43.
Chengyun Cui Zuoxing Guo Yuhua Liu Qiongqiong Xie Zheng Wang Jiandong Hu Yuan Yao 《Optics & Laser Technology》2007,39(8):1544-1550
Co-based alloy coating was deposited on tool steel by powder feeding laser cladding. Sections of such coatings were examined to reveal their microstructures and phases using scanning electron microscope (SEM) and X-ray diffractometer (XRD). The results showed that the prime phase (γ-Co dendrite) and other phases, including Cr23C6, Co7W6, and CrNi existed in the coatings. Some different solidification morphologies, such as planar (at the interface), cellular and dendrite formed, varying from the interface to the surface. Fine microstructures of γ-Co dendrite and lamellar eutectic in dendritical regions strengthened the coatings. Besides, the effects of aged treatment on the microstructure and microhardness of the surface coating were studied. Aged treatment led to the precipitations of some carbide particles (Cr7C3 and Co3C) and boride particles (Co4B) from the cladded coating, causing an increase in microhardness in the laser-cladded coating. 相似文献
44.
Seok-Jun Won 《Applied Surface Science》2011,257(23):10311-10313
The reaction of Bis(ethyl-methyl-amino)silane (BEMAS) and water in atomic layer deposition (ALD) became possible when Zr-containing species were adsorbed on the vacant sites of the surface after a pulse and purge of BEMAS. The growth rates of the Si(Zr)Ox films were 0.8-0.9 nm/cycle in the temperature range of 185-325 °C. This phenomenon probably originates from the highly reactive hydroxyl species generated by Zr atoms. From this point of view, transition metals make reactant gas molecules to be highly activated in the ALD processes of transition metal oxides and nitrides, which might be an important factor that determines the ALD characteristics. 相似文献
45.
46.
Inspired by the promising potential of re-configurable intelligent surface (RIS)-aided transmission in achieving the vision of 6th Generation (6G) network, we analyze the security model for a vehicular-to-infrastructure (V2I) network by considering multiple RISs (M-RIS) on buildings to act as passive relays at fixed distances from a source. In addition, multiple eavesdroppers are presented in the vicinity of the intended destination. Our aim is to enhance the secrecy capacity (SC) and to minimize secrecy outage probability (SOP) in presence of multiple eavesdroppers with the help of M-RIS in V2I communications. We propose a key-less physical layer security using beam-forming by exploiting M-RIS. The proposed approach assumes the concept of detecting eavesdroppers before the information can be transmitted via beam-forming by utilizing M-RIS. The results reveal that with consideration of M-RIS and beam-forming, the achievable SC and SOP performance is significantly improved while imposing minimum power consumption and fewer RIS reflectors. 相似文献
47.
The distinctive features of the atomic and electronic structure of thin surface layers of substances in the process of formation
of epitaxial silicon films on silicon are studied using the procedures of reflection and scattering of ultrasoft x-ray radiation.
The angular distribution of the scattered x-ray radiation (the scattering indicatrices) and the near fine structure of SiL2,3 spectra of reflection are investigated. The assumption of the sensitivity of the observed peak of anomalous scattering (the
Yoneda peak) of x-ray radiation to the presence, in the surface regions of the materials, of extended double-boundary defects,
the defects of packing, grain boundaries, dislocations, etc. is made. It is shown that the experimental procedure used makes
it possible to obtain information on the surface layers of substances.
Translated from Zhurnal Priklaldnoi Spektroskopii, Vol. 67, No. 4, pp. 496–498, July–August, 2000. 相似文献
48.
M. Schöck C. Sürgers H. v. Löhneysen 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,14(1):1-10
The superconducting and magnetic properties of Nb/Pd1-xFex/Nb triple layers with constant Nb layer thickness dNb=200 ? and different interlayer thicknesses 3 ?≤ dPdFe ≤ ? are investigated. The thickness dependence of the magnetization and of the superconducting transition temperature shows
that for small iron concentration x the Pd1-xFex layer is likely to be in the paramagnetic state for very thin films whereas ferromagnetic order is established for x ≥ 0.13.
The parallel critical field Bc2||(T){B_{c2||}}(T) exhibits a transition from two-dimensional (2D) behavior where the Nb films are coupled across the interlayer, towards a
2D behavior of decoupled Nb films with increasing dPdFeand/or x. This transition allows a determination of the penetration depth xF{\xi _F} of Cooper pairs into the Pd1-xFex layer as a function of x. For samples with a ferromagnetic interlayer xF{\xi _F} is found to be independent of x. 相似文献
49.
Zhongwei Jiang Wenxin Wang Hanchao Gao Linshen Liu Hong Chen Junming Zhou 《Applied Surface Science》2008,254(16):5241-5246
Low-temperature step-graded high indium content InAlAs (In% = 0.75) metamorphic buffer layers with reverse step layer grown on GaAs substrate by molecular beam epitaxy are investigated in this paper. The composition and the strain relaxation of the top InAlAs layer are determined by high-resolution triple-axis X-ray diffraction measurements, which show that the top InAlAs layer is nearly fully relaxed and the growth parameters for these samples have little influence on the strain relaxation ratio. Surface morphology is observed by reflection high-energy electron diffraction pattern and atomic force microscopy. The surface morphology is found to depend strongly on both the growth temperature and the As flux. Compared with other samples, the sample growth under the optimized conditions has the smallest value of root mean square surface roughness. Furthermore, the ω − 2θ and ω scans of the triple-axis X-ray diffraction and transmission electron microscopy result also show the sample grown under the optimized conditions has good crystalline quality. 相似文献
50.
《Journal of separation science》2018,41(18):3553-3560
The combination of sofosbuvir and daclatasvir or sofosbuvir and ledipasvir is now widely used as an ideal treatment for hepatitis C virus infection. For this purpose, a simple, sensitive, accurate, economic, and precise high‐performance thin‐layer chromatography was developed and validated for the determination of sofosbuvir, daclatasvir, and ledipasvir in their pure form as well as their different pharmaceutical products. The method used Merck high‐performance thin‐layer chromatography aluminum plates precoated with silica gel 60 F254 as a stationary phase and mobile phase consisting of methylene chloride/methanol/ethyl acetate/ammonia (25%) (6:1:4:1, v/v/v/v). This system was found to give compact symmetric peaks of sofosbuvir, daclatasvir, and ledipasvir with retardation factors of 0.27 ± 0.01, 0.50 ± 0.007, and 0.68 ± 0.008, respectively. The densitometric scanner was set at 275 nm using a deuterium lamp. The calibration curves were linear over the range of 100–3000 ng/spot for sofosbuvir, and daclatasvir, and range of 50–3000 ng/spot for ledipasvir. The detection limits were 22.5, 31.90, and 15.80 for sofosbuvir, daclatasvir, and ledipasvir. The quantitation limits were 67.50, 95.60, and 47.50 for sofosbuvir, daclatasvir, and ledipasvir. The proposed method was validated according to International Conference on Harmonization (ICH) guidelines and the results were acceptable. 相似文献