Key Engineering Materials Vol. 1025

Abstract: The present work reports an approach of hydrothermal growth of ZnO nanorods, which simplifies the production of low cost films with controlled morphology for H₂S gas sensor application. The prepared ZnO nanorods exhibit a hexagonal wurtzite phase analyzed by the X-ray diffraction analysis. The FTIR spectra provide information that the band located between 465-570 cm^-1 corresponds to the stretching bond of Zn-O, which confirms the creation of ZnO. PL spectroscopic studies showed that the doping of Ag NPs and f-MWCNT in the ZnO matrix leads to the tuning of the bandgap. The SEM analysis showed the morphology of ZnO was the nanorods. The nanocomposites Ag/ZnO and F-MWCNT/ZnO which prepared, separately were tested for H₂S gas at low (2 ppm) and high (50 ppm) concentrations. ZnO nanorods films showed a sensitivity of 14.71% for pure ZnO with a fast response time of 25.2 sec and recovery time of 33.3 sec towards 2 ppm H₂S. For Ag NPs/ZnO and f-MWCNTs/ZnO, sensors showed a significant sensitivity of 27.95 and 42.39 % at ~150 °C with a response time and recovery time less than pure ZnO. The ZnO sensor showed a higher sensitivity at ~150 °C for both Ag NPs and F-MWCNTs at high gas concentration, where it was 35.085 and 58.89% respectively.

Abstract: In this study biowaste-derived carbon electrode materials with improved physical properties for supercapacitor application are synthesized. The chosen biomass is Desmostachya bipinnata, which was activated using a chemical method to improve previous results. The morphological and structural study of the synthesized activated carbon material is carried out using a multi-technique experimental approach revealing the presence of a micro-and nanoporosity and their effects on the physico-chemical performance of the electrode. In order to check the applicability of the process of synthesis, the activated carbon has been tested as electrode material working in a supercapacitor device subjected to cyclic voltammetry analysis. The synthesized material is able to deliver maximum specific capacitance of ~ 167.2 Fg-1, quite one order of magnitude higher than the same material characterized without activation. The results show that Desmostachya bipinnata is an important precursor for electrode materials for energy devices and deserves further studies to make possible its possible use in industrial production routes.

Abstract: Elastomer-cable ropes (ECR) can be used as tractive and transporting elements in mine hoisting installations, powerful conveyors, or as stay ropes in permanent structures. The operating conditions and design of such ropes may differ in various conditions; however, the composite structure of ropes has its unique advantages in industrial applications. Article purpose is determining the influence of cable design on a stress state of elastic shell in a elastomer-cable rope. Article methodology is in numerical calculation using CAD and an analytical method used in strength of materials. Dependency of a stress-strain state is established for a elastomer-cable rope (belt) shell, which is loaded by a force evenly distributed among the cables, considering helical strand shape and periodical placement of cables with opposite twisting directions in a rope (belt). Energy loss values due to cable and elastomer-cable rope design are established. The scientific novelty of the article is in establishing that a helical strand shape of cables causes a twisting moment (torque) that is proportional to a part of an internal loading force on cables, which is transmitted by strands, a sine of inclination angle of helical strands and a distance between centers of strands cross-sections and cable axis. Stresses in the elastic shell decrease when cable placement spacing increases and does not exceed 1.7 cable diameters. Practical significance of the article is in establishing the dependency of a stress state of elastic shell in a elastomer-cable rope on rope and cable design, which allows taking into account this phenomenon during the rope design phase, increase of accuracy of determining its stress-strain state and reliability during operation in mine hoisting installations, powerful conveyors or permanent structures.