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431.
Gong-Yi Li Xiao-Dong Li Hao Wang Zhong-Quan Li 《Applied Physics A: Materials Science & Processing》2008,93(2):471-475
Long silicon nitride (Si3N4) nanowires with high purity were synthesized by heating mixtures of SiO2 powders and short carbon fibers at 1430°C for 2 h in a flowing N2 atmosphere. The nanowires had the length of 1–2 millimeters and the diameters of 70–300 nm, and were mainly composed of ⍺-Si3N4, growing along the [001] direction. The vapor–solid (VS) mechanism was employed to interpret the nanowires growth. 相似文献
432.
ZHANG Jian-Fu RUAN Xi-Chao HOU Long LI Xia BAO Jie ZHANG Guo-Guang HUANG Han-Xiong SONG Chao-Hong 《中国物理C(英文版)》2010,34(7)
The light output functions for protons of ST-401 and BC-408 plastic scintillators were measured using white neutron source produced by the 9Be(d,n)10B reaction at the HI-13 Tandem Accelerator at China Institute of Atomic Energy(CIAE).The LOFs of plastic scintillators for protons in the energy range of 0.516.5 MeV were obtained by the time-of-flight(TOF)technique and an iterative procedure.Two parameters(kB and C)were deduced by fitting the experimental data. 相似文献
433.
计算了在太阳核心从R=0到R=0.125R⊙处,7Be存在1个或2个K壳层束缚电子的概率约为4.54%.这表明7Be原子俘获的电子95.46%是自由电子.假定太阳中微子自产生后没有发生任何改变,并且太阳的其他参量不改变,那么7Be和8B太阳中微子流量的理论计算值分别约为4.04×109和6.12×106cm-2s-1.这将进一步扩大8B太阳中微子与superKamiokande太阳中微子实验测量值之间的差距
关键词:
K壳层束缚电子 电子俘获概率 7Be太阳中微子流量 8B太阳中微子流量 相似文献
434.
From the results of first principles tight-binding linear muffin-tin orbital (TB-LMTO) calculations, half-metallic ferromagnetism is proposed in Zn(TM)O2 with a chalcopyrite structure. The calculated electronic and magnetic property shows that consistent with the integer value for the total magnetic moment, half metallicity is obtained for ZnCrO2, ZnMnO2, ZnFeO2, ZnCoO2 and ZnNiO2. A careful analysis of the spin density reveals the ferromagnetic coupling between the p–d states and the cation dangling-bond p states, which is believed to be responsible for the stabilization of the ferromagnetic phase. The calculated heat of formation, bulk modulus and cohesive energy are reported. 相似文献
435.
U.S. Taralkar 《Journal of Non》2007,353(2):194-199
The hydrothermal synthesis of Si-MCM-48 mesoporous molecular sieves was carried out using a ternary SiO2:CTAOH:H2O system wherein differently manufactured amorphous silica powders such as fumed silica (FMDS), spray dried precipitated silica (SDPS) and flash dried precipitated silica (FDPS) were used as silica source materials. The changes in structural/textural properties were evaluated using powder XRD, N2 adsorption-desorption and scanning electron microscopy techniques. Studies on the progressive development of MCM-48 mesophases revealed that, the reactivity of the silica source follow the trend: FMDS > SDPS > FDPS. MCM-48 synthesized using low cost FDPS has exhibited thicker pore walls but poorer orderness, while MCM-48 prepared from relatively expensive FMDS has thinner pore walls and more ordered structure. Moreover, the extent of contraction caused by calcinations, agglomerate size and structural stability were found to depend on the reactivity of the silica source used. 相似文献
436.
G. De Lellis S. Buontempo F. Di Capua A. Di Crescenzo P. Migliozzi Y. Petukhov C. Pistillo A. Russo P. Strolin V. Tioukov M. Durante Y. Furusawa T. Toshito N. Yasuda A. Ariga N. Naganawa 《Nuclear Physics A》2011
The increasing use of Carbon nuclei in cancer therapy centres is motivated by their potential advantages as a very precise high LET radiation. The knowledge of the fragmentation of Carbon nuclei when they interact with the human body is important to evaluate the spatial profile of their energy deposition in the tissues, hence the damage to the tissues neighbouring the tumour. We report here a study of the fragmentation with the nuclear emulsion experimental technique. We have designed, built and exposed to a Carbon nuclei beam a chamber made of Lexan plates alternated with nuclear emulsion films. Lexan plates acted as passive material simulating human body tissues while nuclear emulsion films were used as both tracking devices with micrometric accuracy and ionisation detectors. Such a detector allowed the detection of Carbon interactions produced along their path, the identification of the fragments produced and the measurement of their scattering angle. We have measured the Carbon ion survival probability and studied their interactions. We report on the secondary particle multiplicity and the electrical charge distribution. We give results of the scattering angle of final state fragments as well as the range for H and He. Finally we give the total and partial charge-changing cross-sections for Δz=1,2,3,4 which are compared with previous results when available. The present work aims at providing data required as input to Monte Carlo simulations of Carbon ion interactions in the human body and ultimately of their therapeutic effectiveness. 相似文献
437.
Alexander A. Kaminskii Oliver Lux Hanjo Rhee Hans‐Joachim Eichler Hitoki Yoneda Akita Shirakawa Petra Becker Ladislav Bohatý 《Laser \u0026amp; Photonics Reviews》2014,8(2):324-331
In single crystals of the beryllium silicate Be2SiO4 with trigonal symmetry , known also as the mineral phenakite, χ(3)‐nonlinear lasing by stimulated Raman scattering (SRS) is investigated. All observed Stokes and anti‐Stokes lasing components are identified and ascribed to a single SRS‐promoting vibration mode with ωSRS ≈876 cm−1. With picosecond single‐wavelength pumping at one micrometer the generation of an octave‐spanning Stokes and anti‐Stokes comb is observed. 相似文献
438.
Qiong Luo 《中国科学B辑(英文版)》2008,51(11):1030-1035
The smallest molecules up to date containing a D5h pentacoordinate planar carbon (PPC) atom, CBe5 and CBe54-, are presented by means of ab initio calculations. To gain a better understanding about which electronic factors contribute to their stabilization, natural bond orbital (NBO) analysis and the nucleus independent chemical shifts (NICS) were calculated. The data reported here suggest that D5h CBe5 is σ aromaticity in nature, while in D5h CBe54- π aromaticity is dominating. The classical octet rule is well satisfied in both molecules, and is one of the fundamental reasons to understand the stability of the pentagon structures. The Be5 ring serves as σ donor in D5h CBe5, and π-acceptor in D5h CBe54-. The D5h CBe54- possessing 18 valence electrons with a closed-shell electron configuration is the most plau-sible candidate for experimental detection. 相似文献
439.
T. Sugibayashi 《Solid State Communications》2004,132(1):43-47
Optical conductivity in NaxCoO2 is calculated with tight binding approximation. The calculated gross features agree with the experimental findings. Interband transitions between nearly degenerate t2g bands bring about absorption in the mid-infrared and near infrared regions. Structures observed at higher energies are also quite well reproduced with the present calculation. Possible effects of electron correlation are also briefly discussed. 相似文献
440.
Effects of Annealing on Microstructure and Optical Properties of TiO2 Sculptured Thin Films 下载免费PDF全文
The evolution of microstructure and optical properties of TiO2 sculptured thin films under thermal annealing is reported. XRD, field emission SEM, UV-Vis-NIR spectra are employed to characterize the microstructural and optical properties. It is found that the optimum annealing temperature for linear birefringence is 500℃. The maximum of transmission difference for linear birefringence is up to 18%, which is more than twice of that in as-deposited thin films. In addition, the sample annealed at 500℃ has a minimum of column angle about 12℃. The competitive process between the microstructural and optical properties is discussed in detail. Post-annealing is a useful method to improve the linear birefringence in sculptured thin films for practical applications. 相似文献