Synchronized Bursting Induced by Network Connectivity in Cortical Neuronal Cultures

L.C. Jia,P.-Y. Lai,C. K. Chan,C.H. Chang,C.R. Han,M.T. Tsai,Y.S. Chou 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.1I

Synchronization of cortical neural cultures is studied as a function of the effective network connectivity in the phenomenon of synchronized firing (SF). The synchronized bursting frequency (during SF) of the network is found to be much slower than the characteristic time scale of a neuron and increases with the network connectivity. Using fluorescence imaging techniques, we found that SF occurs only when the incubation time is longer than some critical age tc and the synchronized bursting frequency f increases with time as f = fc + fo log( t tc ). Furthermore, tc is found to scale with the cell plating density as tc 1 p . Based on the result of photolysis of neurons, the synchronized bursting frequency is shown to be related to the network connectivity, hence, the growth behavior can be inferred from the measured SF frequencies. We further build a network growth model with the characteristics of an early stage active growth followed by a late-stage retarded growth, which can account for the experimental data quantitatively. Electrophysiological measurements using double-patch techniques reveal that even though the bursting frequencies are synchronized, the intra-burst spikes are not. We also present a mean-field model of the neural network that enables the neuron firing to be inhibited and generates inter-spike intervals with long time scales resulting in bursting.

Observation of a vector charmoniumlike state in e+e−→Ds+Ds1(2536)−+c.c.

Jia, S.,Shen, C. P.,Yuan, C. Z.,Wang, X. L.,Adachi, I.,Aihara, H.,Asner, D. M.,Atmacan, H.,Aulchenko, V.,Ayad, R.,Babu, V.,Badhrees, I.,Bakich, A. M.,Behera, P.,Bhuyan, B.,Bilka, T.,Biswal, J.,Bobrov, American Physical Society 2019 Physical review. D Vol.100 No.11

Feasibility of UHPC shields in spent fuel vertical concrete cask to resist accidental drop impact

Jia P.C.,Wu H.,Ma L.L.,Peng Q. 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.11

Ultra-high performance concrete (UHPC) has been widely utilized in military and civil protective structures to resist intensive loadings attributed to its excellent properties, e.g., high tensile/compressive strength, high dynamic toughness and impact resistance. At present, aiming to improve the defects of the traditional vertical concrete cask (VCC), i.e., the external storage facility of spent fuel, with normal strength concrete (NSC) shield, e.g., heavy weight and difficult to fabricate/transform, the feasibility of UHPC applied in the shield of VCC is numerically examined considering its high radiation and corrosion resistance. Firstly, the finite element (FE) analyses approach and material model parameters of NSC and UHPC are verified based on the 1/3 scaled VCC tip-over test and drop hammer test on UHPC members, respectively. Then, the refined FE model of prototypical VCC is established and utilized to examine its dynamic behaviors and damage distribution in accidental tip-over and end-drop events, in which the various influential factors, e.g., UHPC shield thickness, concrete ground thickness, and sealing methods of steel container are considered. In conclusion, by quantitatively evaluating the safety of VCC in terms of the shield damage and vibrations, it is found that adopting the 300 mm-thick UHPC shield instead of the conventional 650 mm-thick NSC shield can reduce about 1/3 of the total weight of VCC, i.e., about 50 t, and 37% floor space, as well as guarantee the structural integrity of VCC during the accidental drop simultaneously. Besides, based on the parametric analyses, the thickness of concrete ground in the VCC storage site is recommended as less than 500 mm, and the welded connection is recommended for the sealing method of steel containers

Observation of e+e−→γχc1 and search for e+e−→γχc0 , γχc2 , and γηc at s near 10.6 GeV at Belle

Jia, S.,Wang, X. L.,Shen, C. P.,Yuan, C. Z.,Adachi, I.,Aihara, H.,Al Said, S.,Asner, D. M.,Atmacan, H.,Aulchenko, V.,Aushev, T.,Ayad, R.,Babu, V.,Bansal, V.,Behera, P.,Beleñ,o, C.,Berger, M.,Bhu American Physical Society 2018 Physical Review D Vol.98 No.9

Evolution of asexual and sexual reproduction in the aspergilli

Ojeda-Ló,pez, M.,Chen, W.,Eagle, C.E.,Gutié,rrez, G.,Jia, W.L.,Swilaiman, S.S.,Huang, Z.,Park, H.-S.,Yu, J.-H.,Cá,novas, D.,Dyer, P.S. CBS Fungal Biodiversity Centre 2018 Studies in mycology Vol.91 No.-

<P><I>Aspergillus nidulans</I> has long-been used as a model organism to gain insights into the genetic basis of asexual and sexual developmental processes both in other members of the genus <I>Aspergillus</I>, and filamentous fungi in general. Paradigms have been established concerning the regulatory mechanisms of conidial development. However, recent studies have shown considerable genome divergence in the fungal kingdom, questioning the general applicability of findings from <I>Aspergillus</I>, and certain longstanding evolutionary theories have been questioned. The phylogenetic distribution of key regulatory elements of asexual reproduction in <I>A. nidulans</I> was investigated in a broad taxonomic range of fungi. This revealed that some proteins were well conserved in the <I>Pezizomycotina</I> (<I>e.g.</I> AbaA, FlbA, FluG, NsdD, MedA, and some velvet proteins), suggesting similar developmental roles. However, other elements (<I>e.g.</I> BrlA) had a more restricted distribution solely in the <I>Eurotiomycetes</I>, and it appears that the genetic control of sporulation seems to be more complex in the aspergilli than in some other taxonomic groups of the <I>Pezizomycotina</I>. The evolution of the velvet protein family is discussed based on the history of expansion and contraction events in the early divergent fungi. Heterologous expression of the <I>A. nidulans abaA</I> gene in <I>Monascus ruber</I> failed to induce development of complete conidiophores as seen in the aspergilli, but did result in increased conidial production. The absence of many components of the asexual developmental pathway from members of the <I>Saccharomycotina</I> supports the hypothesis that differences in the complexity of their spore formation is due in part to the increased diversity of the sporulation machinery evident in the <I>Pezizomycotina</I>. Investigations were also made into the evolution of sex and sexuality in the aspergilli. <I>MAT</I> loci were identified from the heterothallic <I>Aspergillus</I> (<I>Emericella</I>) <I>heterothallicus</I> and <I>Aspergillus</I> (<I>Neosartorya</I>) <I>fennelliae</I> and the homothallic <I>Aspergillus pseudoglaucus</I> (=<I>Eurotium repens</I>). A consistent architecture of the <I>MAT</I> locus was seen in these and other heterothallic aspergilli whereas much variation was seen in the arrangement of <I>MAT</I> loci in homothallic aspergilli. This suggested that it is most likely that the common ancestor of the aspergilli exhibited a heterothallic breeding system. Finally, the supposed prevalence of asexuality in the aspergilli was examined. Investigations were made using <I>A. clavatus</I> as a representative ‘asexual’ species. It was possible to induce a sexual cycle in <I>A. clavatus</I> given the correct <I>MAT1-1</I> and <I>MAT1-2</I> partners and environmental conditions, with recombination confirmed utilising molecular markers. This indicated that sexual reproduction might be possible in many supposedly asexual aspergilli and beyond, providing general insights into the nature of asexuality in fungi.</P>

A fractional approach to the time-temperature dependence of dynamic viscoelastic behavior

Z. L. Li,Y. Qin,B. Sun,C. L. Jia,W. J. Zhang,B. J. Yan,Q. L. Shi 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.1

Fractional derivative and WLF equation are effective in describing the dynamic behavior and time-temperature effect of viscoelastic damping materials, respectively. These approaches have essentially evolved from the viscoelastic constitutive behavior. Based on such intrinsic relation, a fractional time-temperature superposition principle model (FTTSPM) that integrates the fractional constitutive relation and WLF equation was proposed. The parameters of this model were determined by performing tensile and DMA tests, and the master curves at 5 °C constructed by FTTSPM and WLF equation were compared. The theoretical prediction over the extended frequency span as the master curves was made by using the fractional standard linear solid model (FSLSM) to validate FTTSPM. The numerical results show that FTTSPM conforms to the time-temperature superposition principle. The parameters α and B¢ in this model denote the impact of the material and environment on the shifted factor, respectively. For the storage and loss modulus, the extended frequency obtained by FTTSPM is broader than that obtained by the WLF equation. Moreover, the evaluation of the storage and loss modulus by FTTSPM is much closer to the theoretical prediction compared with that by the WLF equation. Therefore, FTTSPM is a concise and experiment-based approach with a higher precision and greater frequency-extended capacity compared with the WLF equation. However, FTTSPM inevitably faces a vertical shift when non-thermo-rheologically simple materials are considered. The physical mechanism and practical application of FTTSPM will be examined in further research.

Impact-resistant design of RC slabs in nuclear power plant buildings

Li Z.C.,Jia P.C.,Jia J.Y.,Wu H.,Ma L.L. 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.10

The concrete structures related to nuclear safety are threatened by accidental impact loadings, mainly including the low-velocity drop-weight impact (e.g., spent fuel cask and assembly, etc. with the velocity less than 20 m/s) and high-speed projectile impact (e.g., steel pipe, valve, turbine bucket, etc. with the velocity higher than 20 m/s), while the existing studies are still limited in the impact resistant design of nuclear power plant (NPP), especially the primary RC slab. This paper aims to propose the numerical simulation and theoretical approaches to assist the impact-resistant design of RC slab in NPP. Firstly, the continuous surface cap (CSC) model parameters for concrete with the compressive strength of 20 e70 MPa are fully calibrated and verified, and the refined numerical simulation approach is proposed. Secondly, the two-degree freedom (TDOF) model with considering the mutual effect of flexural and shear resistance of RC slab are developed. Furthermore, based on the low-velocity drop hammer tests and high-speed soft/hard projectile impact tests on RC slabs, the adopted numerical simulation and TDOF model approaches are fully validated by the flexural and punching shear damage, deflection, and impact force time-histories of RC slabs. Finally, as for the two low-velocity impact scenarios, the design procedure of RC slab based on TDOF model is validated and recommended. Meanwhile, as for the four actual high-speed impact scenarios, the impact-resistant design specification in Chinese code NB/T 20012-2019 is evaluated, the over conservation of which is found, and the proposed numerical approach is recommended. The present work could beneficially guide the impact-resistant design and safety assessment of NPPs against the accidental impact loadings.

Improvement of lower hybrid current drive systems for high-power and long-pulse operation on EAST

Wang M.,Liu L.,Zhao L.M.,Li M.H.,Ma W.D.,Hu H.C.,Wu Z.G.,Feng J.Q.,Yang Y.,Zhu L.,Chen M.,Zhou T.A.,Jia H.,Zhang J.,Cao L.,Zhang L.,Liang R.R.,Ding B.J.,Zhang X.J.,Shan J.F.,Liu F.K.,Ekedahl A.,Gonich 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.11

Aiming at high-power and long-pulse operation up to 1000 s, some improvements have been made for both 2.45 GHz and 4.6 GHz lower hybrid (LH) systems during the recent 5 years. At first, the guard limiters of the LH antennas with graphite tiles were upgraded to tungsten, the most promising material for plasma facing components in nuclear fusion devices. These new guard limiters can operate at a peak power density of 12.9 MW/m2 . Strong hot spots were usually observed on the old graphite limiters when 4.6 GHz system operated with power >2.0 MW [B. N. Wan et al., Nucl. Fusion 57 (2017) 102019], leading to a reduction of the maximum power capability. With the new limiters, 4.6 GHz LH system, the main current drive (CD) and electron heating tool for EAST, can be operated with power >2.5 MW routinely. Long-pulse operation up to 100 s with 4.6 GHz LH power of 2.4 MW was achieved in 2021 and the maximal temperature on the guard limiters measured by an infrared (IR) camera was about 540 C, much below the permissible value of tungsten material (~1200 C). A discharge with a duration of 1056 s was achieved and the 4.6 GHz LH energy injected into the plasma was up to 1.05 GJ. Secondly, the fully-activemultijunction (FAM) launcher of 2.45 GHz system was upgraded to a passive-active-multijunction (PAM), for which the density of optimum coupling was relatively low (below the cut-off value). Good coupling with reflection coefficient ~3% has been achieved with plasma-antenna distance up to 11 cm for the new PAM. Finally, in order to eliminate the effect of ion cyclotron range of frequencies (ICRF) wave on 4.6 GHz LH wave coupling, the location of the ICRF launcher was changed to a port that is located 157.5 toroidally from the 4.6 GHz LH system and is not magnetically connected

Femtosecond electron-phonon lock-in by photoemission and x-ray free-electron laser

Gerber, S.,Yang, S.-L.,Zhu, D.,Soifer, H.,Sobota, J. A.,Rebec, S.,Lee, J. J.,Jia, T.,Moritz, B.,Jia, C.,Gauthier, A.,Li, Y.,Leuenberger, D.,Zhang, Y.,Chaix, L.,Li, W.,Jang, H.,Lee, J.-S.,Yi, M.,Dakovs American Association for the Advancement of Scienc 2017 Science Vol.357 No.6346

<P><B>A deeper look into iron selenide</B></P><P>In the past 10 years, iron-based superconductors have created more puzzles than they have helped resolve. Some of the most fundamental outstanding questions are how strong the interactions are and what the electron pairing mechanism is. Now two groups have made contributions toward resolving these questions in the intriguing compound iron selenide (FeSe) (see the Perspective by Lee). Gerber <I>et al.</I> used photoemission spectroscopy coupled with x-ray diffraction to find that FeSe has a very sizable electron-phonon interaction. Quasiparticle interference imaging helped Sprau <I>et al.</I> determine the shape of the superconducting gap and find that the electron pairing in FeSe is orbital-selective.</P><P><I>Science</I>, this issue p. 71, p. 75; see also p. 32</P><P>The interactions that lead to the emergence of superconductivity in iron-based materials remain a subject of debate. It has been suggested that electron-electron correlations enhance electron-phonon coupling in iron selenide (FeSe) and related pnictides, but direct experimental verification has been lacking. Here we show that the electron-phonon coupling strength in FeSe can be quantified by combining two time-domain experiments into a “coherent lock-in” measurement in the terahertz regime. X-ray diffraction tracks the light-induced femtosecond coherent lattice motion at a single phonon frequency, and photoemission monitors the subsequent coherent changes in the electronic band structure. Comparison with theory reveals a strong enhancement of the coupling strength in FeSe owing to correlation effects. Given that the electron-phonon coupling affects superconductivity exponentially, this enhancement highlights the importance of the cooperative interplay between electron-electron and electron-phonon interactions.</P>

Dependence of infrared radiation on microstructure of polymer derived ceramic coating on steel

H. Tian,Y.M. Wang,Y. Liu,L.X. Guo,J.H. Ouyang,Y. Zhou,D.C. Jia 한국물리학회 2013 Current Applied Physics Vol.13 No.1

High infrared emissivity ceramic coatings were prepared on 304 steel by pyrolyzing reactions with poly(hydridomethylsiloxane) (PHMS) and Al/Cr2O3 based mixing powders. The effects of pyrolysis temperature, testing temperature and surface roughness on infrared radiation of polymer derived ceramic coating were systematically investigated. The results indicated that the coating pyrolyzed at 800 C exhibited a slightly higher infrared emissivity value than that of the coating pyrolyzed at 600 C, which was attributed to the enhancing photon emission caused by the complete conversion of Al to Al2O3 and PHMS pyrolysis into SiO2, together with the introduction of Cr2O3 based mixing powders. The emissivity value in 3e8 mm waveband of the coating was lower about 0.03 at 600 C compared with 800 C testing temperature, while the emissivity value was almost the same in 8e20 mm waveband. The high surface roughness of the coating led to a slightly increasing emissivity due to the enhancing infrared absorbance.