Influence of synthesis method on the properties of mixed Aurivillius phase Bi5TiNbWO15

The ceramic material Bi₅TiNbWO₁₅ (BTNW) was obtained and is characterized by a layered, Aurivillus type structure (MBLPO—mixed bismuth oxide layered perovskites) with m = 1.5. In order to optimize the production, BTNW was synthesized by two methods: synthesis of a mixture of simple oxides Bi₂O₃, Nb₂O₅, WO₃, TiO₂ and synthesis of a mixture of appropriate, layered Aurivillus type structures Bi₂WO₆ (m = 1) and Bi₃TiNbO₉ (m = 2). Synthesized solid solutions were consolidated with a conventional method. The crystal structure of Bi₂WO₆ and Bi₃TiNbO₉ Bi₅TiNbWO₁₅ was examined at room temperature with an X-ray diffraction method. Microstructure and chemical composition were analyzed. The authors analyzed the temperature—permittivity ɛ relationship for the ceramic with m = 1,5, which was obtained with two methods, as well as for m = 1 and m = 2.     

Structural analysis of tars from fluidized-bed pyrolysis of coal. 1. Gas-liquid chromatography of aliphatic and aromatic subfractions

The effect of pyrolysing gas composition on the low-molecular-weight aliphatic and aromatic components of fluidized-bed tars has been investigated. Two tars from the rapid pyrolysis of coal in a fluidized-bed were solvent-fractionated into oils, asphaltenes and benzene-insoluble materials. The aliphatic and low-molecular-weight aromatic subfractions of the oils were then analysed by glass-capillary column gas-liquid chromatography. The results show that pyrolysis in a more active atmosphere of char gasification gases is ‘deeper’, and, to some extent, similar to hydrogen-assisted pyrolysis; the yield of tar is higher, and the product has higher aromaticity and average molecular weight compared with pyrolysis in nitrogen-rich flue gases.     

Microstructural and optical characterization of TiO2 doped with ytterbium synthesized by sol-gel and Solar physical vapor deposition process

Pure and ytterbium doped TiO2 nanopowders in anatase phase have been prepared by sol-gel method (SGM) and Solar Physical Vapour Deposition process (SPVD). The physico-chemical parameters of the nanopowders have been described based on the results of micro-structural characterization performed by X-ray diffractometry, scanning electron microscopy, atomic force microscopy, and nitrogen sorption measurements. Thus, final micro-structural properties of SGM and SPVD titania nanopowders have been compared in detail revealing significant changes in the structure and morphology of these two types of materials. Addition of ytterbium had no significant effect on above-mentioned properties, although it modifies significantly the optical properties of the investigated materials. The luminescent properties of developed material were found to be comparable to bulk oxide materials and better than these reported earlier for ytterbium doped titania. In particular it has been shown that the luminescence of SPVD nanopowders is significantly stronger than this of SGM samples.     

Demand re‐registration for PCS database restoration

In a Personal Communications Services (PCS) network, mobility databases such as Home Location Register (HLR) and Visitor Location Register (VLR) are utilized to support mobility management for Mobile Stations (MSs). If the location databases fail, the location information loss or corruption will seriously degrade the service offered to the subscribers. In this paper, we propose a new VLR failure recovery scheme called demand reregistration. In this scheme, the VLR broadcasts a reregistration request to all MSs after the VLR failure. When an MS receives the reregistration request, it sends a registration message to the VLR to recover the location record. Since all MSs will reregister after receiving the broadcasting request, traffic jam (and thus collisions) may occur. If a collision occurs, then the involved MSs must resend the registration messages. This paper studies the performance of demand reregistration by investigating how effectively the reregistration can recover the location record for an MS before the first MS call termination occurs. Our results indicate that demand reregistration can effectively recover VLR failure.     

Dynamical cooling of semiconductor by contact layer

The subject of this paper is the presentation of a simple theoretical model of cooling of a semiconductor. The problem of the unsteady behaviour both of the semiconductor and of the cold plate that are in touch by the contact layer was studied analytically. The influence of the parameters of the materials and the cooling conditions was investigated. The results in the form of an analytical formula and graphs are presented and the heat stream is compared with the experimental results.     

Synthesis of 5-nitro- and 5-aminobenzimidazolone-2

The pure mononitro derivative of benzimidazolone-2 can be obtained only when the nitration reaction is carried out in mild conditions, otherwise di-, tri- and tetranitro derivatives are also formed. The results of our studies derived optimum conditions for the nitration process necessary to obtain pure 5-nitrobenzimidazolone-2.     

Role of the contact layer between liquid and solid on a solidification process

The object of this paper is the presentation of a theoretical solidification model of heat-conducting liquid metal flowing near of a cold plate. The problem of the unsteady behaviour both of the frozen metal layer and of the cold plate is studied analytically. Influence of the contact layer between the frozen layer and the cold plate on the solidification process is also studied. The results in the form of the analytical formula and the graphs are presented and compared with the other results.     

Biomass productivity and phytoremediation potential of Salix alba and Salix viminalis

The aim of this work was to determine selected Salix clones’ capacities for biomass production and accumulation of heavy metal ions. Determination of the relationship between sorption of metals and biomass productivity was a further purpose of this study. Eight Salix viminalis cultivars and one Salix alba cultivar were analyzed. The taxa characterized by greatest biomass production were S. alba var. Chermesina and S. viminalis ‘1056’ (respectively 6.8 and 4.3 kg of fresh mass per shrub per year).The results have revealed significant differences among clones. The clones most effective in accumulating all five metals were S. viminalis ‘1154’ and ‘1054’. The studied Salix population was significantly diverse as regards accumulation efficiency. The differences between the highest and lowest heavy metal content in extreme clones were for: Cd 84%, Cu 90%, Hg 167%, Pb 190% and Zn 36%. At the same time, significant differences were observed in Salix structure. The greatest cellulose content was observed in S. viminalis ‘Sprint’ (49.69%) and the lowest in S. viminalis ‘1059’ (42.09%).     

The use of the Synthes 7.3-mm. cannulated screw in rearfoot and ankle surgery: a preliminary prospective study

The authors present a preliminary prospective study of the Synthes 7.3 mm. cannulated screw used in 31 rearfoot and ankle surgeries on 29 patients. The patients had a variety of rearfoot and ankle procedures performed, in which a total of 75 screws were placed across 47 arthrodesis or osteotomy sites. The percentage of union or healing was 95.74% for the joints or sites involved. The average healing time was 2.71 months. The techniques for placement of the screw are described.