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931.
L.J. Chang Y. SuY.-J. Kao Y.Z. ChouK. Kakurai R. Mittal H. SchneiderTh. Brückel G. BalakrishnanM.R. Lees 《Physica B: Condensed Matter》2011,406(12):2393-2396
Diffuse polarized neutron scattering studies have been carried out on single crystals of pyrochlore spin ice Ho2−xYxTi2O7 (x=0, 0.3, and 1) to investigate the effects of doping and anisotropy on spin correlations in the system. The crystals were aligned with the (1 −1 0) orientation coincident with the direction of neutron polarization. For all the samples studied the spin flip (SF) diffuse scattering (i.e. the in-plane component) reveals that the spin correlations can be described using a nearest-neighbour spin ice model (NNSM) at higher temperatures (T=3.6 K) and a dipolar spin ice model (DSM) as the temperature is reduced (T=30 mK). In the non-spin flip (NSF) channel (i.e. the out-of-plane component), the signature of strong antiferromagnetic correlations is observed for all the samples at the same temperature as the dipolar spin ice behaviour appears in the SF channel. Our studies show that the non-magnetic dopant Y does not significantly alter SF or NSF scattering for the spin ice state, even when Y doping is as high as 50%. In this paper, we focus on the experimental results of the highly doped spin ice HoYTi2O7 and compare our results with pure spin ice Ho2Ti2O7. The crossover from a dipolar to a nearest-neighbour spin ice behaviour and the doping insensitivity in spin ices are briefly discussed. 相似文献
932.
H. Kira Y. Sakaguchi T. Oku J. Suzuki M. Nakamura M. Arai K. Kakurai Y. Endo Y. Arimoto T. Ino H.M. Shimizu T. Kamiyama K. Tsutsumi K. Ohoyama H. Hiraka K. Yamada L.-J. Chang 《Physica B: Condensed Matter》2011,406(12):2433-2435
We have begun the development of an in-situ spin-exchange optical pumping (SEOP) system aiming to use it as a neutron spin filter for incident beam polarization at the Japan Proton Accelerator Research Complex (J-PARC). To use it, it is recommended that the optics be adjusted easily, have high stability, and have a small size. In this paper we improved our previous SEOP system aiming to use it in J-PARC and performed a neutron beam test at the JRR-3 NOP beamline to see the performance of the neutron spin filter (NSF). The polarization of the 3He gas reached 73%. This paper gives the present status of the development of in-situ SEOP system in J-PARC. 相似文献
933.
Objectives
The present study was performed to examine which factors among self-rated scales, perceptual evaluations, and acoustic parameters, calculated from sustained vowels, are reliable indicators of physical and mental fatigues.Methods
A total of 73 volunteers (male:female, 52:21), aged 19–24 years, were enrolled in this study. We defined the high- and low-fatigue groups using the Chalder Fatigue Scale score. For assessment of self-rated symptoms, each subject was asked to complete Voice Handicap Index (VHI) and Voice Rating Scale (VRS). For perceptual evaluations, three clinicians assessed each subject’s vocal quality on the Grade, Roughness, Breathiness, Asthenia, Strain Scale. For acoustic analysis, each subject was asked to produce sustained vowels /a/, /e/, /i/, /o/, and /u/ for 3 seconds. Then, the habitual fundamental frequency (F0), jitter, shimmer, F0 tremor, mean F0, standard deviation of F0, maximum F0, minimum F0, normalized noise energy, harmonic-to-noise ratio (HNR), signal-to-noise ratio (SNR), amplitude tremor, and ratio within 2–4 kHz were calculated using Dr. Speech software.Results
In men, VHI, VRS, F0 tremor, shimmer, HNR, SNR, and amplitude tremor were related to mental fatigue. In women, only VHI was related to physical fatigue, and none of the acoustic parameters was related to the fatigue score. Perceptual evaluations were not related to fatigue in men or women.Conclusions
These findings suggest that self-rated symptoms and acoustic parameters related to voice quality are indicative of mental fatigue, and these features are prominent in men. 相似文献934.
Abstract
The photoinduced electron transfer from chlorophyll a through the interface of positively charged dioctadecyltrimethylammonium chloride (DODAC), neutral dipalmitoylphosphatidylcholine (DPPC) and negatively charged dihexadecylphosphate (DHP) headgroup of the lipid bilayers was studied. The photoinduced radicals were identified by electron spin resonance (ESR) and radical yields of chlorophyll a were determined by double integration of the ESR spectra. The formation of vesicles was identified indirectly by measuring change of the λ max value of optical absorption spectrophotometer from diethyl ether solution to vesicle solutions, and observed directly with scanning and transmission electron microscopic images. The interaction distance between chlorophyll a and interface water (D2O) determined by deuterium modulation depth with electron spin echo modulation (ESEM) showed a decreasing order DODAC > DPPC > DHP. The interface charge of each vesicle was determined with zeta potential measurement. The interface charge of the lipid bilayers affected the radical yields of chlorophyll a more critically than the interaction distance between chlorophyll a and interface water. 相似文献935.
In the present paper, we describe utilization of cathode active material as anode active material, for example, Li2MnSiO4. The lithium manganese silicate has been successfully synthesized by solid-state reaction method. The X-ray diffraction pattern
confirms the orthorhombic structure with Pmn2
1 space group. The Li/Li2MnSiO4 cell delivered the initial discharge capacity of 420 mA h g−1, which is 110 mA h g−1 higher than graphitic anodes. The electrochemical reversibility and solid electrolyte interface formation of the Li2MnSiO4 electrode was emphasized by cyclic voltammetry. 相似文献
936.
M. Y. Song W. C. Chen Daniel Hsu C. R. Chang J. G. Lin 《Applied Physics A: Materials Science & Processing》2011,104(3):811-813
In this study, the spacer-thickness-dependent room-temperature magnetoresistance (RTMR) is investigated in ferromagnetic/antiferromagnetic
(FM/AFM) superlattices composed of 10 repetitions of La0.7Sr0.3MnO3/Nd0.6Ca0.4MnO3 [LSMO/NCMO]10. A series of superlattice samples with the thickness of the LSMO layer being fixed at 5 nm while that of the NCMO layer varied
from 0 to 5 nm were fabricated using pulsed laser deposition. RTMR is measured at the fields from zero to 10 kOe with two
different configurations, in plane (IP) and out-of-plane (OOP). At 10 kOe, RTMR varies with increasing spacer thickness of
NCMO at both IP and OOP configurations. A maximum IP MR ratio of 16% at 10 kOe is found in the sample of [LSMO(5 nm)/NCMO(0.45 nm)]10, which is three times that for the pure LSMO film. Therefore, it is concluded that the inserting of the NCMO layer between
LSMO layers can effectively tune the RTMR ratio, which might be related to the magnetic coupling between FM and AFM domains. 相似文献
937.
Wang Tzyy-Jiann Tsou Yueh-Hsun Chang Wen-Che Niu Huan 《Applied Physics A: Materials Science & Processing》2011,102(2):463-467
We present a new fabrication technique to produce three-dimensional (3D) microstructures on crystalline substrate using selective
ion implantation and chemical etching. Localized lattice-damage layers at the specified depth beneath the substrate surface
are formed by selective ion implantation. After etching out the partial surface regions and the buried lattice-damage layers
by chemical etching, the 3D crystalline microstructures are produced. This technique is demonstrated on LiNbO3 crystal to produce undercutting and free-standing microstructures, including microwire, microring, and microdisk. The measurement
results of micro-Raman spectra show that the used fabrication process does not affect the original crystalline structure.
The features of this technique include smooth structure surface, large undercutting range, and auto-etching stop. By using
multiple implantations or repeating the proposed process several times, versatile 3D crystalline microstructures can be produced. 相似文献
938.
磁性碳纳米管吸附去除水中甲基橙的研究 总被引:1,自引:0,他引:1
采用高温催化裂解法制备碳纳米管,对其用浓硝酸氧化法进行纯化处理,并用化学共沉淀方法制备了磁性碳纳米管(简称磁性管)。利用场发射扫描电子显微镜对磁性管进行了表征。将磁分离技术应用于碳纳米管吸附性能研究,探索碳纳米管负载磁性颗粒后对甲基橙的吸附性能,寻找最佳实验条件,对吸附质溶液进行紫外-可见吸收光谱分析。同时,进行了磁性管的脱附和再吸附性能研究。 相似文献
939.
利用在线多信息紫外光电阴极激活评估系统,测试了真空室内两个GaN 光电阴极Cs,O激活后及衰减6 h和18 h后补Cs的光谱响应特性曲线和量子效率曲线;并绘制了光纤光源波长为300 nm的光电阴极响应电流衰减变化曲线.实验结果证明,GaN 光电阴极较GaAs阴极具有更好的稳定性,量子效率可保持相对稳定达10 h,然后缓慢衰减,衰减速率较窄禁带半导体材料低得多.补Cs后光电流最大值较刚激活完有16.8%的增长,这充分证明阴极表面量子效率衰减的原因是Cs的脱附,而不是O的吸附.这些现象可由双偶极层模型来解释,
关键词:
光学
光电阴极
量子效率
稳定性 相似文献
940.
大气压空气放电由于脱离了真空装置,易于实现流水线生产,因而在工业上具有广泛的应用. 采用等离子体针装置在空气中产生了稳定的大气压均匀放电. 利用光谱法对等离子体的相关参数进行了空间分辨率测量,并通过光学方法对放电机理进行了研究. 结果表明,等离子体针产生的放电存在电晕放电和等离子体羽放电两种模式. 在稳定的等离子体羽放电模式中,发光分为强光区和弱光区. 弱光区放电的发展速度远大于强光区的发展速度,电子能量和电子密度均是弱光区比强光区大. 对均匀放电的气体温度和振动温度的研究表明,强光区放电遵循汤生击穿机理而弱光区为流光放电. 这些结果对大气压空气放电的工业应用具有重要意义.
关键词:
大气压均匀放电
等离子体针
发射光谱
放电机理 相似文献