Improvement of diamond X-ray mask membrane: Optical transmittance, surface roughness and irradiation durability

A viable method for the improvement of the polycrystalline diamond X-ray mask membrane is proposed. The use of an ionized cluster beam yields the smoothest surface. Sol-gel planarization film coating with indium tin oxide is the most effective method for obtaining high optical transmittance without sacrificing high synchrotron irradiation durability.     

Electron Spin Resonance of High-Spin Co2+ in Alkali Borate and Alkali Germanate Glasses

Electron spin resonance spectra of high-spin Co²⁺ doped in alkali borate and alkali germanate glasses have been measured at 4.2 K. For comparison, the corresponding spectrum in a 33K₂O·67SiO₂ glass has also been measured. On the basis of the spectral line shape, the observed spectra, together with those in the literature, seem to be classified into four spectral types that represent Co²⁺ ions in octahedral coordination, a mixture of some types of coordination, tetrahedral coordination with nearly axial symmetry, and distorted tetrahedral coordination.     

纺丝及纤维成形的机理(V)

本文以等规聚丙烯为例,继上期学报对熔体纺丝过程的讨论之后,对熔体纺丝纤维的拉伸加工过程中,纤维结构和性能的变化进行了深入的阐述和分析,并根据纺丝的基础方程式介绍了数学模拟的方法。     

1.6 Gbit/s optical receiver at 1.3 ?m with SAW timing retrieval circuit

The performance of a 1.6 Gbit/s optical receiver employing a s.a.w. filter as a timing tank is reported. The error-rate characteristics in a p.c.m. transmission system using a 1.3 ?m In-GaAsP laser and single-mode fibres were studied. The average received optical power at a 10?9 error rate was ?28 dBm. In a 15 km transmission experiment, the receiving level was degraded by 2 dB owing to fibre dispersion. Timing phase margin of 75 degrees after 12 km transmission was confined with the self-timed receiver.     

Magnetic properties of CeC2 and its solid solutions,CeXDy1−XC2

Magnetic properties of CeC₂ and its solid solutions, Ce_XDy_1?XC₂, were investigated. Cerium dicarbide has the highest Neel temperature, 30 K, of the cerium compounds with non-magnetic elements and a positive paramagnetic Curie temperature, +12 K. This Nèel temperature is greatly higher than that expected on the basis of the de Gennes factor. In order to explain this high Nèel temperature we propose an idea that a super exchange interaction via acetylide ion, C₂^2?, contributes much to the total magnetic exchange for CeC₂. The positive paramagnetic Curie temperature observed for CeC₂ are also discussed in terms of the crystal field effects. The Nèel temperature (T_N) for Ce_XDy_1?XC₂ has a minimum on the T_N vs. the de Gennes factor curve, while the paramagnetic Curie temperature (θ_p) varies almost linearly with the de Gennes factor. These behaviors of T_N and θ_p are understood based on a difference in the magnetic exchange between CeC₂ and DyC₂.     

Determination of the cooperativity parameter σ from viscometric data of poly-L-glutamic acid-Na

Summary Viscometry of PLGNa solutions was performed for various degrees of neutralization . The cooperativity parameter in the helix-coil transition was estimated using Ptitsyn's method with some modifications. The increase of thus obtained with decreasing is explained in terms of the a dependence of short-range interactions of PLGNa segments.     

Electrical properties of sintered EuZrO3  EuNbO3 and EuNbO3

Electrical resistivity of two-phase products [yEuZrO₃ + (1 ? y) EuNbO₃] increased continuously with y, and a transition from a metallic to semiconducting characteristic occured at y = 0.14. The resistivity varied almost linearly with temperaure in the range y = 0 to y = 0.24, and thermal coefficients of resistivity at 300 K for the products decreased from +5.9 × 10^?4 K^?1 to ?7.4 × 10^?4 K^?1 according to the value of y. At y = 0.14, the thermal coefficient was almost zero. Thermal coefficients of electrical resistivity for the niobates with various oxygen contents were all positive in the range $\text{2.55 <}\text{O}\text{Nb}\text{< 3.24}$ and exhibited a sharp minimum at $\text{O}\text{Nb}\text{= 2.92}$. In all these niobates, Eu_xNbO₃ was a major phase and Eu₃NbO₆ or EuNbO₂ was detected as a second phase in the range $\text{O}\text{Nb}\text{> 3}$ or $\text{O}\text{Nb}\text{< 3}$ respectively. Peaks in the resistivity curves were correlated with a magnetic ordering temperature for samples with an overall ratio $\text{O}\text{Nb}\text{> 3}$.     

Electrical properties of sintered EuTiO3  EuNbO3

Two-phase sintered products [yEuTiO₃ + (1?y)EuNbO₃] were investigated as electrical-resistor materials. Electrical resistivities of the products did not depend on y in the range 0 < y < 0.96, and rapidly increased with increasing y over y = 0.96. The sintered products were metallic conductors from y = 0 to y = 0.96, and were semiconductors at y > 0.96. Thermal coefficients of resistivity for sintered products varied continuously with y, and became a maximum of 2.8 × 10^?3 K^?1 at y = 0.75 and a minimum around y = 1.00. The coefficient was positive at y < 0.96 and negative at y > 0.96. The absolute value of the thermal coefficient of resistivity minimized, namely ($\text{1}\text{?}$) ($\text{d}\text{?}\text{dT}\text{) = 0}$, at y = 0.96.     

循环荷载下砂质混合土孔隙水压力特性研究

通过对各种细颗粒含量的土实施从小到大应变水平的动力循环荷载试验,采用累积损失能量的观点,分别考察了土的细颗粒成分含量、围压、加载频率、加载形式及荷载的不规则性对孔压的影响,提出了孔隙水压力和累积损失能量的归一化方法,建立了砂质混合土的孔隙水压力上升模型,并探讨了模型参数和土的细颗粒成分含量的关系。     

Unusual Fatty Acids in the Fat Body of the Early Nesting Bumblebee, <Emphasis Type="Italic">Bombus pratorum</Emphasis>

Unusual fatty acids with 24, 26, and 28 carbon atoms were found in triacylglycerols (TAGs) isolated from fat body tissue of bumblebee Bombus pratorum. The most abundant one was (Z,Z)-9,19-hexacosadienoic acid. Its structure was determined by mass spectrometry after derivatization with dimethyl disulfide and by infrared spectroscopy. ECL (equivalent chain length) values of its methyl ester were determined on both DB-1 and DB-WAX capillary columns. (Z,Z)-9,19-Hexacosadienoic acid is quite rare in nature. So far it has been identified only in marine sponges, and this work is the first evidence of its occurrence in a terrestrial organism. HPLC/MS analysis of the bumblebee TAGs showed that (Z,Z)-9,19-hexacosadienoic acid is present in one third of all TAG molecular species. As it was found in all sn-TAG positions, it is likely that (Z,Z)-9,19-hexacosadienoic acid is transported to tissues. Interestingly, labial gland secretion of B. pratorum was found to contain (Z,Z)-7,17-pentacosadiene, a hydrocarbon with markedly similar double bond positions and geometry. Possible biosynthetic relationships between these two compounds are discussed.