The preparation of TiO2–nitrogen doped by calcination of TiO2·xH2O under ammonia atmosphere for visible light photocatalysis

The investigation on incorporating nitrogen group into titanium dioxide in order to obtain powdered visible light-active photocatalysts is presented. The industrial hydrated amorphous titanium dioxide (TiO₂·xH₂O) obtained directly from sulphate technology installation was modified by heat treatment at temperatures of 100–800 °C for 4 h in an ammonia atmosphere. The photocatalysts were characterized by UV–VIS–DR and XRD techniques. The UV–VIS–DR spectra of the modified catalysts exhibited an additional maximum in the VIS region (, ) which may be due to the presence of nitrogen in TiO₂ structure. On the basis of XRD analysis it can be supposed that the presence of nitrogen does not have any influence on the transformation temperature of anatase to rutile. The photocatalytic activity of the modified photocatalysts was determined on the basis of decomposition rate of phenol and azo-dye (Reactive Red 198) under visible light irradiation. The highest rate of phenol degradation was obtained for catalysts calcinated at 700 °C (6.55%), and the highest rate of dye decomposition was found for catalysts calcinated at 500 and 600 °C (ca. 40–45%). The nitrogen doping during calcination under ammonia atmosphere is a very promising way of preparation of photocatalysts which could have a practical application in water treatment system under broader solar light spectrum.     

Aspects of dSpace in contemporary design

Computer dependent design space is illustrated with the recent international competition project for Kowloon Arts Center. The spatial condition of design resulted from the deployment of Euclidian geometry and use of the nonrational, complex surfaces. Another aspect of computer dependent space was rooted in the contemporary work situation where architects located on the three different continents collaborated in distributed mode over the internet. The resulting project confirms the creative potential of the above aspects of the digital space in contemporary design.     

Experimental analysis of post-buckling and collapse behaviour of thin-walled box-section beam

This paper contains the results and analysis of tests carried out on a large-scale model of the thin-walled box-section beam subject to pure bending. The whole range of loading was analysed — up to the collapse of the beam. The stress and deflection distribution in selected beam cross-sections is presented by means of diagrams. The magnitudes of buckling load and ultimate load obtained on the basis of the tests results are compared with the results of the theoretical analysis.     

Anthocyanins,total polyphenols and antioxidant activity in amaranth and quinoa seeds and sprouts during their growth

Total antioxidant capacity, total phenolic contents (TP) and anthocyanins contents (ANT) were determined in Amaranthus cruentus and Chenopodium quinoa seeds and sprouts. Antioxidant activity of the investigated seeds decreased in the following order: quinoa, amaranth v. Rawa, amaranth v. Aztek for FRAP and quinoa, amaranth v. Aztek, amaranth v. Rawa for both ABTS and DPPH. Sprouts activity depended on the length of their growth, and the peak values were reached on the fourth day in the case of amaranth and on the sixth day in the case of quinoa. The data obtained by the three methods showed significant correlation between TP content in seeds and sprouts. In sprouts grown in the daylight and in the darkness we observed some significant changes of TP, ANT and antioxidant activity. Amaranth and quinoa seeds and sprouts can be used in food, because it is a good source of ANT and TP with high antioxidant activity.     

The secand method in banach spaces

The paper concerns to solutions of the operator equationf(x)=0. Using the quotient operator the equation is solved with the iteration method. Points from a given sphere are arbitrarily chosen for quotients creating.     

Effect of reduction parameters on the particle size of tungsten monocarbide obtained from the blue tungsten oxide

Conclusions A study was made, using the methods of particle size analysis and metallographic examination, of the effects of temperature and bed thickness in the reduction of the blue tungsten oxide upon some properties of tungsten and tungsten monocarbide powders and sintered 6 wt.% Co hard alloys produced from the monocarbide powders. Quantitative results were obtained showing the relationship between these reduction parameters on the one hand and the particle size of the resultant powders and the physicomechanical properties of hard alloys on the other. It was established that the particle size grows with rise in reduction temperature and with increase in the thickness of the blue oxide bed.Translated from Poroshkovaya Metallurgiya, No. 11(143), pp. 102–107, November, 1974.     

A study of the electrical conductivity processes in amorphous semiconductors using the computer simulation method I. One-dimensional case

In this paper we present a computational model of electrical conductivity processes via variable range hopping of electrons between localized states (‘sites’) in quasi one-dimensional disordered systems. For two, slightly different models, the temperature dependence of the conductivity of parallel connected systems of filaments and of quasi-infinite, single filaments are discussed and compared with theoretical and experimental results.     

Method for the synthesis of semitransparent wide band dielectric mirrors

A general method for the numerical design of wide band dielectric mirrors with non-zero transmission is given. The values of the optical parameters for twenty mirrors designed by this method are presented and discussed.