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A cheap, comparatively simple and effective method is proposed for the large quantity production of the sheets of graphenic carbon materials (GCM) by annealing the mixture of nickel powder with a suitable carbon amount at the temperatures close to 1000 ºC. The number of graphene layers in the sheets of GCM may be varied by altering the amount of carbon in the mixture and parameters of annealing and drying of the obtained products. Samples of GCM were prepared in the form of heat-dried GCM paper and in the form of graphene sponge with freeze-drying. The appearance of GCM on the surface of Ni particles was identified using a scanning electron microscope (SEM) at a low accelerating voltage of 5 kV. The thickness and properties of the layers were investigated by electron microscopy and X-ray diffraction. The fabrication processes were carried out at the concentrations of added carbon from 0 to 1 at%. The results obtained are fully consistent with the well-known solid phase reactions of carbon dissolution in Ni at 1000 °C and graphene or graphite precipitation on the surface with cooling down to the room temperatures.

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Abstract.The article presents the results of experimental work in the first waste mechanical Pre-treatment Centre in Latvia. The goal -to detect the main parameters for separated waste parts and to compare them with parameters stated for alternative fuels in cement plant in Latvia. Samples were taken in three fractions -coarse, medium, and fine. 132 samples have been taken. The parameters -upper, lower heating values, moisture, ash content, S, Cl, metals were determined. Resultscoarse fraction has greater potential of the production of the alternative fuel.

The authors propose methods for estimation of the potential of riverflows for electricity production at hydrokinetic power plants. The methods can be applied to any river or its span where it is possible to move using a floating means. The methodical part includes validation of the flow velocity and bed depth measurement data using the available statistics as well as a case study. Analysis of the in-river measurement results for the selected spans of river Daugava shows that the flow rate variations exert only a minor influence on the flow velocity at particular sites. This testifies the hydrokinetic power plants as stable and predictable sources of electrical energy, both in a long term and, especially, in a short one. The proposed estimation methods could be useful in explorations of rivers, making them simpler and cheaper.