电子探针定量分析的标准样品——几种多元氧化物单晶

在很高的温度和适宜的生长条件下,分别采用熔盐籽晶法和高温引上法生长了高质量的YAP、NAB、KTP、LN、BBO、SBN等多元氧化物单晶,它们具有优良的物理化学性能,严格的化学比,固定的组成与结构以及较好的化学均匀性和电子束轰击下的稳定性。广泛地用于激光和非线性光学领域。我们选用这些晶体为原材料研制电子探针定量分析的标准样品。经过测量和标定,这些单晶标样符合中华人民共和国国家标准GB 4930-85(电子探针显微分析标准样品通用技术条件)的规定。含有稀土元素的标样如NAB和YAP能发出绿色荧光,是电子显微术中理想的阴极发光材料。     

On the second eigenfunctions of the Laplacian in R2

A conjecture about the nodal line of a second eigenfunction states that the nodal line of a second eigenfunction divides the domain by intersecting with the boundary of transversely, where is a bounded convex domain ofR ². We prove this conjecture provided has a symmetry. Also, we prove the multiplicity of the second eigenvalue is two at most provided is a bounded convex domain ofR ².Supported in part by NSF DMS 84-09447Home Institution: Department of Mathematics, University of California, San Diego, La Jolla, CA 92093, USA     

Mixing properties of mim diodes in the infrared

Point contact MIM diodes of different materials have been tested as harmonic mixers at 29 THz and 88 THz. From the analysis of the I-V static characteristic quantitative informations have been obtained about the effectiveness of the diodes as high order mixers.     

Al2O3-supported Fe?Ni catalysts for CO hydrogenation, I. Catalytic properties

CO conversion to hydrocarbons at various reaction temperatures and atmospheric pressure has been investigated on alumina-supported Fe, Ni and Fe–Ni catalysts. Maxima of activity and selectivity were obtained in hydrocarbon formation as a function of Fe content in the samples, which corresponds to a certain stoichiometry of metallic components.     

The significance of Kekulé structures for the stability of aromatic systems—II

Dihydroheptazethrene (V) and 1:14,11:12-dibenzo-5,7-dihydro-pentacene (VI) were synthesized. The former gave heptazethrene (VII) on dehydrogenation, whilst the latter polymerized immediately. This difference is explained by the fact that heptazethrene (VII) can be formulated with a Kekulé structure and the dehydrogenation product of VI cannot. Heptazethrene is a basis hydrocarbon and is closely related to dibenzoheptazethrene (VIII). Heptazethrenequinone (II) is a true quinone giving a blue vat, whilst the isomer (IV) is a diketone and does not give a vat.     

2.6 Foods

Abstracts2 Particular products and fields of application

2.6 Foods     

An investigation of the structure of butadiene by high resolution infra-red and raman spectroscopy

The rotational Raman spectra of butadiene and butadiene-d₆ are found to consist of discrete lines having small ≈0·4 cm⁻¹) yet almost constant spacings, as would be expected for symmetric or nearly symmetric top molecules. An infra-red absorption band (Type C) of butadiene at 908 cm⁻¹ is observed to have a spacing of about 2·5 cm⁻¹. Both the Raman and infra-red spectra provide evidence for the trans structure of the butadiene molecule. From the rotational constants A″ and ″ the following structural parameters were obtained: C=C---C) = 122·9 ± 0·5° rC---C) = 1·47₆ ± 0·010 Å dy]somewhat shorter than recently determined from electron-diffraction experiments).