和县猿人及其动物群年代测定的初步研究

用电子自旋共振法对和县猿人头骨化石共生动物牙齿测年结果为距今３０（２９．９８）万年，印证了古人类学家对和县直立猿人相当于北京猿人（直立人）的晚期与ＨⅢ头骨年代相似的估计，另一动物牙齿测年数据与铀系封闭性的测年结果近似，表明和县猿人动物群生存于距今１５－３０万年。     

Techniques and applications of electron spin resonance

A broad-spectrum review of the applications of electron spin resonance to advanced materials is presented. Starting with basic concepts the reader is taken through a quick tour of techniques including continuous-wave and pulse ESR, microscopy and imaging, as well as a few emerging techniques. Applications of spin identification, spin counting, spin mapping and spin imaging of a variety of advanced solid state materials including metals and alloys, semiconductors, inorganics, electroceramics, catalysts, intercalates, polymers, glasses, and organic charge-transfer complexes besides superionic conductors and high-temperature superconductors are included. It is thus demonstrated that the technique is at once specific, sensitive to composition, phase and texture yet accurate enough to be a quantitative but non-invasive tool that promises to be useful in the study of newer and newer materials including multilayers, ferrofluids and nanomaterials. Dedicated to my teacher, the Late Prof. C Ramasastry (1923–1989)     

A study of intramolecular electron exchange in copper-radical complexes involved in catalysis using ESR spectroscopy

ESR simulation and experimental results have been presented to show that transition metal-radical complexes can engage in intramolecular electron exchange and that the exchange gives rise to ESR asymmetric line broadening effect. Depending on the relative concentration of the redox-exchange pair, metal or radical-like spectrum can be obtained. Simulation results show that a metal-radical complex can be masked by its redox counterpart upto a relative concentration of 1:2 at a modest exchange rate of 3 x 10⁸/s. Asymmetric line broadening was predicted to occur upon such metal-radical complexation. Experimentally, a pronounced ESR asymmetric line broadening was observed for Cu(II) complexes of various redox-active ligands. Cu(II) complex with redox-inert ammonia, however, showed no such evidence. Ligand displacement experiments established the reversibility of metalradical complexation and the associated ESR line broadening.     

An electron spin resonance study of Mn2+ doped calcium hydrazine carboxylate monohydrate

Single crystals of calcium hydrazine carboxylate, monohydrate have been studied by ESR of Mn²⁺ doped in the calcium sites. X-band ESR indicated a large crystal field splitting necessitating experiments at Q band. The analysis shows two magnetically inequivalent (but chemically equivalent) sites withg _xx = 2.0042±0.0038,g _yy=2.0076 ±0.0029,g _zz=2.0314±0.001,A _zz=0.0099±0.0002 cm⁻¹,A _xx=0.0092±0.0002 cm⁻¹,A _yy=0.0082±0.0002 cm⁻¹,D=3/2D _zz=0.0558±0.0006 cm⁻¹, andE=1/2 (D _yy−D _yy)=0.0127±0.0002 cm⁻¹. One of the principal components of the crystal field, (D _zz), is found to be along the Ca ↔ Ca direction in the structure and a second one, (D _xx), along the perpendicular to the plane of the triangle formed by three neighbouring calciums. TheA tensor is found to have an orientation different from that of theg andD tensors reflecting the low symmetry of the Ca²⁺ sites.     

电渣熔铸过程电流大小对金属熔池影响的数值模拟研究

电渣熔铸过程中,金属熔池深度直接影响熔铸件的结晶,从而影响钢锭的质量。本文借助大型通用有限元软件AN-SYS,对不同电流大小时的金属熔池进行了模拟研究,得出金属熔池深度与电流大小之间存在一次线性函数关系的结论。模拟结果与实验值吻合较好。运用此模型可预报金属熔池状况,指导实际生产。     

Microwave power absorption and nonresonant signals due to viscous fluxon motion

To account for low field microwave absorption in high-T _c superconducting cuprates situated in the electron spin resonance configuration, an elegant model based on viscous fluxon motion has been proposed by Portiset al. [11–13]. In view of this model, however, derivations of neither the explicit expression of the power absorption nor the signal had been addressed. In this publication, the stated expressions are derived by fusing the idea of Portiset al. [11–13] and that of Kessleret al. and Duliet al. [20,21].     

铁镍基耐蚀合金凝固组织控制研究

采用固定式电渣重熔工艺、单电极导电结晶器抽锭电渣重熔工艺和双极串联抽锭电渣重熔工艺以不同的熔化速度生产出UNS N08825合金电渣锭,分析了电渣锭的结晶组织、热加工性能以及三种冶炼工艺的电极熔化速度、冷却条件和温度场差别。结果表明,当UNS N08825合金电渣锭凝固组织的柱状晶方向与纵轴方向夹角θ不大于54°时,钢锭具有良好的热加工塑性。     

用于RFID阅读器的低噪声高电源抑制比LDO

基于0.18 μm CMOS工艺,提出了一种为UHF RFID阅读器中VCO供电的低噪声、高电源抑制比LDO。根据LDO的基本结构,对噪声和电源抑制比进行了分析。采用两级结构,通过预调制级和低通滤波器来降低输出噪声,采用电源负反馈结构为带隙基准电路提供独立电源,并在功率输出级增加减法电路来提高电源抑制比。仿真结果表明,该LDO在100 kHz和1 MHz处的输出噪声分别为26 nV/Hz1/2和6.7 nV/Hz1/2,10 kHz和1 MHz处的PSRR分别为-82 dB和-71.6 dB。在3.3 V电源电压供电时,LDO消耗的静态电流为300 μA。     

Alkane oxidation on isolated Cu2+ ions in zeolitic matrix: a relation between catalytic activity and Cu2+-site local topography

Catalytic ethane oxidation, with O₂, using H-ZSM-5 and H-mordenite containing different discrete types of isolated Cu(II) cations was studied. An ESR spectroscopic study was carried out on copper ion coordination in zeolites. It was shown that the intrinsic activity of Cu(II) ion depends strongly on the Cu²⁺-site local topography. Covalent-bonded Cu(II) cations in the most coordinatively unsaturated square-planar coordination in H-ZSM-5 demonstrated the highest activity in C₂H₆ complete oxidation.     

电熔刚玉和锆刚玉中变价态氧化物存在价态的ESR分析

对影响刚玉、电熔锆刚玉 (FCAZS)中变价态氧化物存在价态的因素之一的熔炼气氛 ,以及变价态氧化物存在价态的测定方法进行了研究。研究结果证实 ,致密电熔刚玉和还原法生产的FCAZS制品中 ,变价态氧化物确实是以低价态存在的 ,而电子自旋共振法 (ESR)是定性或半定量分析变价态氧化物杂质存在价态的有效手段。