Femtochemistry of Guest Molecules Hosted in Colloidal Zeolites

The ultrafast deprotonation of 2‐(2′‐hydroxyphenyl)benzothiazole (HBT) hosted in nanometer‐sized FAU and MFI zeolites is reported. Samples are prepared via in‐situ incorporation of HBT in the precursor colloidal solutions resulting in the formation of nanometer‐sized zeolites under hydrothermal treatment. The diameter of the zeolite particles formed in the crystalline suspensions is determined by dynamic light scattering and high‐resolution transmission microscopy to lie in the range 40–100 nm. It is shown that the HBT loading does not influence the degree of the zeolite crystallinity but does change the size and the morphology of the individual zeolite nanoparticles. Colloidal suspensions containing the crystalline nanoparticles are well suited for optical investigations since they are sufficiently transparent and clear. The photochemical properties of the HBT guest in the zeolite‐host systems are studied with femtosecond transient transmission spectroscopy. Depending on the acid–base properties either the enol or the keto tautomer of HBT is found to be hosted in the internal voids of the zeolites; upon UV excitation, the HBT‐keto tautomer is converted to the enol form in both MFI‐ and FAU‐type hosts. The HBT photoconversion takes place via an ultrafast deprotonation within 1.5 ps as detected by femtosecond transient absorption spectroscopy.     

Defect detection in analog and mixed circuits by neural networks using wavelet analysis

An efficient defect-oriented parametric test method for analog & mixed-signal integrated circuits based on neural network classification of a selected circuit's parameter using wavelet decomposition preprocessing is proposed in this paper. The neural network has been used for detecting catastrophic defects in two experimental analog & mixed-signal CMOS circuits by sensing the abnormalities in selected parameters, observed under defective conditions and by their consequent classification into a proper category. To reduce complexity of the neural network, wavelet decomposition is used to perform preprocessing of the analyzed parameter. Moreover, we show that wavelet analysis brings significant enhancement in the correct classification, and makes the neural network-based test method extremely efficient & versatile for detecting hard-detectable catastrophic defects in analog & mixed-signal circuits.     

Catalytic reduction of N2O with CH4 and C3H6 over Ag–Rh/Al2O3 bimetallic catalyst in the presence of oxygen

A study of nitrous oxide (N₂O) reduction with methane (CH₄) and propene (C₃H₆) in the presence of oxygen (5%) over Ag/Al₂O₃, Rh/Al₂O₃ and Ag–Rh/Al₂O₃ catalysts, with Ag and Rh loadings of 5 wt% and 0.05 wt% respectively, has been performed. From the results, it was observed that the Ag–Rh bimetallic catalyst was the most active for both nitrous oxide removal (more than 95%) and hydrocarbon oxidation. This high activity seems to be connected with a synergistic effect between Ag and Rh. The findings from X‐ray diffraction and X‐ray photoelectron spectroscopy studies showed also, that there were no strong interactions (eg alloying) between Ag and Rh. Copyright © 2005 Society of Chemical Industry     

Effect of Nontraditional Additives on the Processes of Silicate and Glass Formation

The results of studying the effect of nontraditional additives, namely, metallic aluminum and zinc powders on the process of silicate and glass formation using polythermal and thermogravimetric analysis, are described. The specifics of the glass-melting process for decorative glasses using the nontraditional additives are considered. __________ Translated from Steklo i Keramika, No. 5, pp. 7 – 10, May, 2005.     

Use of the Precipitation Method in the Synthesis of Ceramic Pigments

The results of the synthesis of ceramic pigments using coprecipitation of hydroxides and difficultly soluble salts of multivalent metal ions are described. The specifics of the coprecipitation process and the effect of various factors on the production of the initial precipitates for subsequent synthesis of ceramic pigments are analyzed. The technology of pigment production is described. __________ Translated from Steklo i Keramika, No. 6, pp. 37 – 39, June, 2005.     

The Metaflow architecture

The Metaflow architecture, a unified approach to maximizing the performance of superscalar microprocessors, is introduced. The Metaflow architecture exploits inherent instruction-level parallelism in conventional sequential programs by hardware means, without relying on optimizing compilers. It is based on a unified structure, the DRIS (deferred-scheduling, register-renaming instruction shelf), that manages out-of-order execution and most of the attendant problems. Coupling the DRIS with a speculative-execution mechanism that avoids conditional branch stalls results in performance limited only be inherent instruction-level parallelism and available execution resources. Although presented in the context of superscalar machines, the technique is equally applicable to a superpipelined implementation. Lightning, the first implementation of the Metaflow architecture, which executes the Sparc RISC instruction set is described     

Transformational approach to program concretization

This paper focuses on the problem of program concretization by applying correctness-preserving transformations of annotated programs. According to the approach presented, a general-purpose program can be annotated by known information about a specific context of its applications and correctly transformed into a specialized program which is equivalent to the original one on the context-defined ranges of inputs and outputs and is better than it by quality criteria given by the context. Tools for program concretizations via annotated program transformations are considered.