Abstract— This work was done to investigate the effect of heating rate and sintering temperature on the structure and mechanical properties of W-50Cu (wt.%) composites using spark plasma sintering technique. For investigate the effect of sintering temperature, the W-50Cu composites were sintered at temperature in the range of 900 to 975oC for 30 min using the heating rate of 50 oC/min meanwhile in order to see the effect of heating rate, the composites were sintered at 950 oC for 30 min at different heating rate from 25 to 200oC/min. The results show that all the sintered composites have a good distribution of W particles in Cu matrix. The increase of sintering temperature led to higher density, larger W average particle size and better strain at break (by compressive test), however, the hardness has a tendency to decrease at higher sintering temperature. The heating rate how an opposite effect in comparison with sintered temperature. The increase of heating rate led to the lower density, smaller W particles and lower strain at break of sintered sample but higher Vickers hardness.
2. Design of the Two-Wheeled Vehicle using Metal Hydride Vessels
Authors: Filip Duda, Natalia Jasminska, Ivan Mihalik, Romana Dobakova
Abstract— Article describes the issue of hydrogen storage in the structure of metal alloys, solves design of metal hydride pressure vessel and solves the design of the concept of prototype two-wheeled vehicle powered by fuel cell with designed metalhydride pressure vessels.
3. Suitability of using Silica Gel in Powder Form as an Adsorbent in the Drying Process
Authors: Romana Dobakova, Filip Duda, Ivan Mihalik, Tomas Brestovic
Abstract— Gases used in industry must meet the required parameters such as the content of gas impurities, moisture content and mechanical impurities, which have a significant impact on its subsequent use. Various industrial drying methods are used to remove moisture. Among the most used drying methods are methods based on subcooling the gas below the condensation temperature, adsorption drying methods or special methods. The article primarily deals with the drying of gases in a fluid layer of ground silica gel. It describes the issue of the suitability of silica gel as an adsorbent in any form of its structure, the advantages and disadvantages of its use.
4. Yeast Strains from Burukutu and Fura, as an Alternative for Commercial Baker’s Yeast
Authors: Umeh, S.O.; Igwilo, I.O.; Okafor, U.C.; Agbara, A.C; Ezeh F. N.
Abstract— Baker’s yeast has been employed in the manufacturing of bread for at least 6,000 years ago. They are responsible for dough leavening and without them sugar in the dough will not be reduced and the substrate will be left unleavened. They have been identified by Scientists as Saccharomyces cerevisiae and are easily obtainable from fermenting fruits and beverages of high carbohydrate content. This work was carried out to determine the possibility of isolating baker’s yeast from two local drinks, Burukutu and Fura. The drinks were prepared and allowed to ferment for 72hrs and cultured on Sabouraud Dextrose Agar (SDA) plates incorporated with chloramphenicol for 48hrs. Colonies that grow were counted and sub-cultured on Yeast Peptone Dextrose (YPD) Medium for 72hrs. Discrete colonies were sub-cultured, stored, identified and characterized. Their attributes as baker’s yeast such as ethanol and stress tolerance, flocculation, hydrogen sulphide production, temperature tolerance and fermentative ability were determined. Results showed that two isolates were selected and identified as ‘Isolated yeast from burukutu (IYB), Isolated yeast from fura (IYF)’. They showed similar microscopic appearance with reconstituted conventional commercial baker’s yeast (CCY) such as the presence of ellipsoidal to oval cells with multipolar buds and ascospores. The multipolar buds were highest in IYB and lowest in CCY. Yeast count ranges from 3.7X103 to 2.8X103 colony forming unit per millilitre (cfu/ml). All the isolates were able to tolerate different concentrations of ethanol and temperature regimes at varying intensities. None of the isolates produced hydrogen sulphide but show intense to moderate response to stress, flocculation and fermentative ability. Local beverages (Burukutu and Fura) are therefore recommended to be good sources of baker’s yeast which can compare favourably with the conventional commercial baker’s yeast.
5. Indoor Environment of Buildings – Quality and Basic Ventilation Air Parameters: Part I
Authors: Lubomira Kmetova, Romana Dobakova, Lukas Toth
Abstract— A series of articles focused on the indoor environment of buildings. Articles discuss the importance of a quality indoor environment and the implementation of the measurement of the parameters of the outgoing air from the indoor environment in the ventilation shaft of an apartment building. The content of the first article is a description of pathogens disrupting the indoor environment, manifestations of sick building syndrome, the need for ventilation.
6. Comparison of Different Natural Gas Flow Rates in Pipelines and their Effect on Odorant Concentration
Authors: Ivan Mihalik, Tomas Brestovic, Romana Dobakova, Lukas Toth
Abstract— The article deals with the problem of adding and spreading an odorant in a high-pressure pipeline. Briefly describes the basic properties of odorants added to natural gas. Furthermore, it mainly focuses on the odorant concentration in natural gas at different natural gas flow rates. By using the ANSYS CFX software, simulations were carried out on the pipeline models representing the selected section of the distribution network at the maximum, minimum and zero flow of natural gas.
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Agriculture Journal IJOEAR
International Journal of Environmental and Agriculture Research