Developmental gametophyte morphology of seven species of Thelypteris subg. Cyclosorus (Thelypteridaceae)

The morphogenesis of the sexual phase of seven species of Thelypteris subg. Cyclosorus (Thelypteridaceae) is described and compared. Spores of all species are monolete, ellipsoid and have positive photoblastism. They have Vittaria-type germination, germinal filaments are short and uniseriate, and Aspidium-type development. Adult gametophytes are spatulate-cordiform, and have wide wings with numerous glandular, marginal and superficial hairs. Antheridia have a narrow or widened basal cell, an undivided annular cell, and an opercular cell; antherozoids are liberated through three mechanisms. Archegonia have short necks and four triangular cells on the neck's mouth. The sporophyte's first leaf is lobed, with open dichotomous veins, glandular hairs similar to those of the gametophyte, and anomocytic stomata. Differences observed between the studied species are: spore size; ornamentation of the perispore; germination and emergence periods; size of hairs; developmental period of gametangia; and antherozoid liberation mechanisms through total detachment of the operculum, partial detachment of the operculum, and development of an apical pore through tearing of the operculum. These taxonomically valuable characters, combined with the sporophyte characteristics, can be useful tools in the identification of the species studied to the subg. Cyclosorus.     

Study on the Crystal Structure of RS-1-(2-methoxyphenyl)-4-〔3-(1-naphthyloxy)-2-hydroxypropyl〕-piperazine

ＩＮＴＲＯＤＵＣＴＩＯＮＮａｆｔｏｐｉｄｉｌ,ＲＳ １ （２ ｍｅｔｈｏｘｙｐｈｅｎｙｌ） ４ 〔３ （１ ｎａｐｈｔｈｙｌｏｘｙ） ２ ｈｙｄｒｏｘｙｐｒｏｐｙｌ〕 ｐｉｐｅｒａｚｉｎｅ,ｉｓａｎｏｖｅｌａｎｔｉｈｙｐｅｒｔｅｎｓｉｖｅｄｒｕｇｃｕ...     

卢瑟福散射实验装置的研制

研制了一种鼎瑟福散的实验装置,并介绍了其实验结果,由于要用了步进电机和半导体探测器,该装置具有结构紧凑,操作简便等优点。     

σ-Aromaticity-Induced Stabilization of Heterometallic Supertetrahedral Clusters [Zn6Ge16]4− and [Cd6Ge16]4−

In this work, the largest heterometallic supertetrahedral clusters, [Zn₆Ge₁₆]⁴⁻ and [Cd₆Ge₁₆]⁴⁻, were directly self-assembled through highly-charged [Ge₄]⁴⁻ units and transition metal cations, in which 3-center–2-electron σ bonding in Ge₂Zn or Ge₂Cd triangles plays a vital role in the stabilization of the whole structure. The cluster structures have an open framework with a large central cavity of diameter 4.6 Å for Zn and 5.0 Å for Cd, respectively. Time-dependent HRESI-MS spectra show that the larger clusters grow from smaller components with a single [Ge₄]⁴⁻ and ZnMes₂ units. Calculations performed at the DFT level indicate a very large HOMO–LUMO energy gap in [M₆Ge₁₆]⁴⁻ (2.22 eV), suggesting high kinetic stability that may offer opportunities in materials science. These observations offer a new strategy for the assembly of heterometallic clusters with high symmetry.     

A Systematic Quantum Chemistry Study on Cyclodextrins

Summary.  AM1 and PM3 modeling of β-hydroxyethyl ether and α-(1→4)-glucobiose indicated that PM3 is advantageous to AM1 in cyclodextrin (CD) chemistry. The conclusion was supported by direct structure optimization of α- and β-CD with AM1 and PM3, in which AM1 gave badly distorted geometries due to unreasonable hydrogen bonding, whereas PM3 reproduced the crystalline structures rather well. Ab initio calculation was for the first time performed on CD, demonstrating the feasibility of this method for future studies concerning CD chemistry. The results also provided valuable insights into the driving forces in CD molecular recognition. Received January 7, 2000. Accepted (revised) March 22, 2000     

Zirconium oxide films: deposition techniques and their applications in dye-sensitized solar cells

Zirconium oxide (ZrO₂) is acquiring considerable attention of most of the research groups and leading to a large number of publications due to its unique properties, especially in the context of emerging trends in the third generation of solar cell research. ZrO₂ films offer magnificent aspects related to physicochemical properties, and the properties are found to be dependent on synthesis methods. In the present review, various deposition techniques used to grow zirconium oxide thin films and their application to enhance the quantum efficiency of titanium oxide (TiO₂) based dye-sensitized solar cells (DSSCs) are discussed. Also, the modulated performances of DSSCs fabricated by growing the conformal ZrO₂ insulating films to retard interfacial recombination dynamics on preformed TiO₂ films are discussed.

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Solvent effects on substitution reactions at complexes of the [Fe(CN)5L]3- type in binary aqueous mixtures

Summary The kinetics of replacement of 4,4-bipyridine, (4,4-bipy), and 4-cyanopyridine, (4-CNpy), by cyanide in [Fe(CN)₅-(4,4-bipy)]^3-. at 298 K have been studied in binary aqueous mixtures containing different amounts of t-butanol, methanol, glycerol, ethyleneglycol and sucrose. The plots of logarithms of the limiting rate constantsversus the mole fraction of water are linear over the entire composition range studied, showing the importance of solvation phenomena. A different straight line of log (k_L/s^–1)versus X_H2O is obtained for each mixture, indicating the influence of other solvent parameters on the reaction rate. A multiparameter regression of G _exp with A (acidity vector), B (basicity vector) and G^E is used for both reactions; plots of G _calc versus G _exp are linear with slopes of near unity.