Adsorption microcalorimetric studies of the interaction between oxygen and an industrial ammonia synthesis catalyst

Heats of oxygen adsorption on an industrial Ca-IB type catalyst for ammonia synthesis have been measured at 20°C. Participation of various forms of adsorbed oxygen (adsorption heats of 420 kJ/mol and below 84 kJ/mol) in the formation of a passivating (stabilizing) catalyst layer has been found.

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CA-IB 20°C. ( 100 / 20 /) () .

     

Complexation and Pd-Catalyzed Asymmetric Allylation with Participation of Chiral Ferrocenyliminophosphites

Chiral ferrocene-containing iminoarylphosphite ligands based on 4,4-dimethoxy-6,6-di-tert-butyl-biphenyldiol-2,2 and their chelate complexes with Rh(I) and Pd(II) were synthesized for the first time. They were shown to be perspective reagents in the reactions of asymmetric allyl substitution. The Pd-catalyzed alkylation of 1,3-diphenylallylacetate with dimethyl malonate results in a 87% enantiomer excess (ee), while in sulfonylation of 1,3-diphenylallylacetate with sodium para-toluenesulfinite, this figure amounts to 67%. The results obtained were compared with coordination and catalytic efficiency of a less sterically hindered ferro-cenyliminophosphite based on pyrocatechol. The compositions and structures of new compounds were determined by the ¹H, ¹³C, ³¹P NMR, IR, mass spectrometry (EI, FAB, and electrospray techniques), and elemental analysis.     

Critical review of theoretical models for anomalous effects in deuterated metals

We briefly summarize the reported anomalous effects in deuterated metals at ambient temperature commonly known as cold fusion (CF) with an emphasis on the latest experiments, as well as the theoretical basis for the opposition to interpreting them as cold fusion. Then we critically examine more than 25 theoretical models for CF, including unusual nuclear and exotic chemical hypotheses. We conclude that they do not explain the data.     

Complexing and catalytic properties of easily available chiral iminophosphite based on biphenyl-2,2"-diol

A chiral iminophosphite ligand based on biphenyl-2,2"-diol and its chelates with rhodium(i) and palladium(ii) were synthesized for the first time. Successful use of these compounds in asymmetric allylic substitution was demonstrated. The enantioselectivity of palladium-catalyzed alkylation of methyl pent-3-en-2-yl carbonate with dimethyl malonate reached 70%, that in the alkylation of 1,3-diphenylallyl acetate with dimethyl malonate was 88%. In the rhodium-catalyzed sulfonylation of 1,3-diphenylallyl acetate with sodium p-toluenesulfinite, the enantioselectivity was 56%.     

A new type of small size acousto-optic tunable filter with super narrow optical linewidth

The new concept of the creation of an acousto-optic tunable filter (AOTF) with super-resolution and small size is discussed. The advantage of the device is based on the use of a novel type of multi reflector beam expander that produces a highly collimated optical beam (angular spread about 100 ppm), tilted with a change in optical wavelength. The proposed AOTF, 1 cm in length, can have an optical linewidth about 0.1 nm and up to 400 tunable channels at a wavelength of 1540 nm. It can be utilized as a tunable filter for dense wavelength-division multiplexing (DWDM) in fiber optic networks and as a small-sized tunable optical spectrometer, for example, in sensors of gases, liquids and solids. The acousto-optic tunable filter can be developed by known technology developed for the creation of integrated optics and microelectronics devices. Received: 28 April 2001 / Revised version: 22 August 2001 / Published online: 2 November 2001     

On the modularity of a lattice of τ-closed <Emphasis Type="Italic">n</Emphasis>-multiply ω-composite formations

Let n ≥ 0, let ω be a nonempty set of prime numbers and let τ be a subgroup functor (in Skiba’s sense) such that all subgroups of any finite group G contained in τ (G) are subnormal in G. It is shown that the lattice of all τ-closed n-multiply ω-composite formations is algebraic and modular.     

A comparison of acoustooptic interaction in LiNbO3 and GaAlAs waveguides

A comparison of acoustooptic efficiency in both Ti:LiNbO₃ and GaAlAs waveguides is made with the help of known results and additional experiments. It is shown that the acoustooptic figure of merit for the frequency of 100 MHz in a GaAlAs waveguide is one order of magnitude higher than in Ti:LiNbO₃ waveguide.