Rebar properties in sand-substitute mortars after exposure to high temperatures

U ovom se radu istražuje utjecaj zagrijavanja, metoda hlađenja i debljine zaštitnog sloja na ponašanje (čvrstoću i duktilnost) rebraste armature promjera 12 mm ugrađene u mort u kojem je riječni pijesak zamijenjen granitnim prahom i proizvedenim pijeskom, pri čemu debljina zaštitnog sloja iznosi 30 i 50 mm. Na temperaturama iznad 500 °C, toplinsko naprezanje uzrokovalo je nasumično ljuskanje zaštitnog sloja, a vlačna ispitivanja upozorila su na smanjenje čvrstoće i povećanje duktilnosti armature pri hlađenju na zraku, dok je suprotna pojava uočena pri gašenju vodom.This study investigates the effects of fire, cooling methods, and cover thickness, on the behaviour (strength and ductility) of 12-mm diameter rebars embedded in mortars with river sand (RS) substitutes such as granite powder and manufactured sand, with 30 and 50 mm cover thickness. Beyond 500°C, thermal stress induced random spalling of mortar cover, and tension test results showed strength decrement and ductility increment of rebars for air cooling, while the vice versa was observed for water quenching

Performance of electrical energy monitoring data acquisition system for plant-based microbial fuel cell

Plant microbial fuel cell (Plant-MFC) is an emerging technology that uses the metabolic activity of electrochemically active bacteria (EABs) to continue the production of bioelectricity. Since its invention and to date, great efforts have been made for its application both in real-time and large-scale. However, the construction of platforms or systems for automatic voltage monitoring has been insufficiently studied. Therefore, this study aimed to develop an automatic real-time voltage data acquisition system, which was coupled with an ATMEGA2560 connected to a personal computer. Before the system operation started it was calibrated to obtain accurate data. During this experiment, the power generation performance of two types of reactors i.e. (i) Plant-MFC and (ii) control microbial fuel cell (C-MFC), was evaluated for 15 days. The Plant-MFC was planted with an herbaceous perennial plant (Stevia rebaudiana), electrode system was placed close to the plant roots at the depth of 20 cm. The results of the study have indicated that the Plant-MFC, was more effective and achieved higher bioelectricity generation than C-MFC. The maximum voltage reached with Plant-MFC was 850 mV (0.85 V), whereas C-MFC achieved a maximum voltage of 762 mV (0.772 V). Furthermore, the same reactor demonstrated a maximum power generation of 66 mW m¯2 on 10 min of polarization, while a power density with C-MFC was equal to 13.64 mW m¯2. S.rebaudiana showed a great alternative for power generation. In addition, the monitoring acquisition system was suitable for obtaining data in real-time. However, more studies are recommended to enhance this type of system

Build your own closed loop: Graph-based proof of concept in closed loop for autonomous networks

Next Generation Networks (NGNs) are expected to handle heterogeneous technologies, services, verticals and devices of increasing complexity. It is essential to fathom an innovative approach to automatically and efficiently manage NGNs to deliver an adequate end-to-end Quality of Experience (QoE) while reducing operational expenses. An Autonomous Network (AN) using a closed loop can self-monitor, self-evaluate and self-heal, making it a potential solution for managing the NGN dynamically. This study describes the major results of building a closed-loop Proof of Concept (PoC) for various AN use cases organized by the International Telecommunication Union Focus Group on Autonomous Networks (ITU FG-AN). The scope of this PoC includes the representation of closed-loop use cases in a graph format, the development of evolution/exploration mechanisms to create new closed loops based on the graph representations, and the implementation of a reference orchestrator to demonstrate the parsing and validation of the closed loops. The main conclusions and future directions are summarized here, including observations and limitations of the PoC

Interaction of nucleobases with silicon doped and defective silicon doped graphene and optical properties

The interaction of nucleobases (NBs) with the surface of silicon doped graphene (SiGr) and defective silicon doped graphene (dSiGr) has been studied using electronic structure methods. A systematic comparison of the calculated interaction energies (adsorption strength) of NBs with the surface of SiGr and dSiGr with those of pristine graphene (Gr) has also been made. The doping of graphene with silicon increases the adsorption strength of NBs. The introduction of defects in SiGr further enhances the strength of interaction with NBs. The appreciable stability of complexes (SiGr-NBs and dSiGr-NBs) arises due to the partial electrostatic and covalent (Si⋯O(N)) interaction in addition to π–π stacking. The interaction energy increases with the size of graphene models. The strong interaction between dSiGr-NBs and concomitant charge transfer causes significant changes in the electronic structure of dSiGr in contrast to Gr and SiGr. Further, the calculated optical properties of all the model systems using time dependent density functional theory (TD-DFT) reveal that absorption spectra of SiGr and dSiGr undergo appreciable changes after adsorption of NBs. Thus, the significant variations in the HOMO–LUMO gap and absorption spectra of dSiGr after interaction with the NBs can be exploited for possible applications in the sensing of DNA nucleobases

Functional assessment of subtilosin A against <em>Aeromonas</em> spp. causing gastroenteritis and hemorrhagic septicaemia

27-32Anti-Aeromonas and cell membrane lytic bacteriocin substance, subtilosin A producing Bacillus subtilis VT03 was explored. Strain VT03 was isolated from freshwater fish (Tilapia) intestine and screened for its antimicrobial activity against four pathogenic strains of Aeromonas spp. causing gastroenteritis and hemorrhagic septicaemia. Isolate (VT03) was identified showing inhibition in agar spot assay. The strain VT03 was the one exhibiting strong inhibition and identified as Bacillus subtilis using 16S rRNA sequencing. Cell free supernatant (CFS) of the strain VT03 was active against pathogenic strains of Aeromonas spp, subsequently CFS was partially purified and designated as PPB-VT03 showing inhibition against A. hydrophila ATCC 49140. PPB-VT03 completely lost its activity upon treating with proteinase K revealing that the defense molecule could be proteinaceous in nature. Based on polymerase chain reaction (PCR), functional gene coding for subtilosin A (sboA) was found to be present whereas subtilin (spaS) was absent. The role of partially purified bacteriocin of isolate VT03 (PPB-VT03) through FTIR and SEM analysis revealed the activity of cell lysis. The study demonstrated the potential use of subtilosin A producing Bacillus subtilis as a potent source for antibacterial peptide

Use of Novel Reinforced Cation Exchange Membranes for Microbial Fuel Cells

This work has been focused on the synthesis and characterization of different blended membranes SPEEK-35PVA (Water), SPEEK-35PVA (DMAc) prepared by casting and nanofiber-reinforced proton exchange membranes Nafion-PVA-15, Nafion-PVA-23 and SPEEK/PVA-PVB. The two first reinforced membranes were made up of Nafion (R) polymer deposited between polyvinyl alcohol (PVA) nanofibers. The last composite membrane is considered because the PVA is a hydrophilic polymer which forms homogeneous blends with SPEEK suitable to obtain high proton conductivity, while the hydrophobic PVB can produce blends in a phase separation morphology in which very low water uptake can be found. The synthesized membranes showed an outstanding stability, high proton conductivity, and enhanced mechanical and barrier properties. The membranes were characterized in single chamber microbial fuel cells (SCMFCs) using electrochemically enriched high sodic saline hybrid H-inocula (Geobacter metallireducen, Desulfurivibrio alkaliphilus, and Marinobacter adhaerens) as biocatalyst. The best performance was obtained with Nafion-PVA-15 membrane, which achieved a maximum power density of 1053 mW/m(3) at a cell voltage of 340 mV and displayed the lowest total internal resistance (Rint approximate to 522 Omega). This result is in agreement with the low oxygen permeability and the moderate conductivity found in this kind of membranes. These results are encouraging towards obtaining high concentrated sodic saline model wastewater exploiting MFCs.The authors wish to thank SEP and CINVESTAV-IPN for granting a PhD fellowship to one of the authors (KSK). We gratefully acknowledge the financial support of the National Council of Science and Technology, CONACYT, under grant FOINS 75/2012 and the Ministry of Science and Innovation of Spain through the project SP-ENE-20120718 and Support Programme for Research and Development of the Polytechnic University of Valencia through the project ref. 24761. Dr O. Solorza thanks Plan de Movilidad e Internalizacion Academica VLC/CAMPUS fellowship at the Universidad Politecnica de Valencia.Kamaraj, S.; Mollá Romano, S.; Compañ Moreno, V.; Poggi-Varaldo, HM.; Solorza-Feria, O. (2015). Use of Novel Reinforced Cation Exchange Membranes for Microbial Fuel Cells. Electrochimica Acta. 176:555-566. doi:10.1016/j.electacta.2015.07.042S55556617

Nanomaterials for Electrochemical Energy Conversion and Storage Technologies

In this modern era, our society faces a serious energy crisis due to increasing human population. Energy consumption starts from small-scale electronic gadgets to high power consuming electric vehicles. To supply power on demand, researchers focus on alternative renewable energy resources including solar energy, wind energy, hydropower, geothermal energy, and bioenergy. Effectively, energy conversion and storage technologies such as solar cells, fuel cells, secondary batteries, supercapacitors, and other self-powered systems are under rigorous investigation. The efficient energy conversion and storage performance of those technologies rely on material properties of their electrode, electrolyte, and other device components. It is recently known that nanostructuring of device components leads to enhanced efficiency in terms of robustness and reliability of the energy conversion and storage systems. Moreover, the nanostructured materials have attracted great interest due to their unique physicochemical and electrochemical properties. Hence, the utilization of such materials in nanodimensions will create enormous impact on the efficiency of various energy conversion and storage devices. The main objective of this special issues is to identify the significant research paradigms of nanomaterials and their potential impacts on applications. In particular, focus of this issue is on the synthesis and characterization of nanostructured materials for various applications such as supercapacitors, batteries, photoelectrochemical, and thermal enhancement systems. The highlights of the published articles are summarized as follows. In this special issue, Y. Yuan et al. synthesized the porous activated carbon materials from Pleurotus eryngii-based biomass material via carbonization, followed by KOH activation and utilized it for supercapacitor applications. The as-prepared activated carbon presented a large specific area with high porosity which exhibited a maximum specific capacitance of 195 F g-1 with 93% capacitance retention after 15000 cycles. It is known that Pleurotus eryngii is one of the readily available sources of carbon materials, potentially suitable for supercapacitor applications. Also, this biomass can be the resource for development of porous activated carbon for other energy conversion and storage devices in the future. Further, B.-X. Zou et al. synthesized hierarchical porous N, O-doped carbon composites by combining low molecular weight phenol resin and silk fibers in various combinations using a hydrothermal method and carbonization process. The as-prepared electroactive materials showed a low resistance and good surface area with hierarchical porosity. The low molecular phenol resin and silk fiber combination increases the surface area and enhanced the electron transport within the active materials. The fabricated symmetric device delivered a maximum energy density of 7.4 Wh kg-1 and power density of 90.1 W kg−1 using aqueous electrolyte

Nanomaterials for Electrochemical Energy Conversion and Storage Technologies

In this modern era, our society faces a serious energy crisis due to increasing human population. Energy consumption starts from small-scale electronic gadgets to high power consuming electric vehicles. To supply power on demand, researchers focus on alternative renewable energy resources including solar energy, wind energy, hydropower, geothermal energy, and bioenergy. Effectively, energy conversion and storage technologies such as solar cells, fuel cells, secondary batteries, supercapacitors, and other self-powered systems are under rigorous investigation. The efficient energy conversion and storage performance of those technologies rely on material properties of their electrode, electrolyte, and other device components. It is recently known that nanostructuring of device components leads to enhanced efficiency in terms of robustness and reliability of the energy conversion and storage systems. Moreover, the nanostructured materials have attracted great interest due to their unique physicochemical and electrochemical properties. Hence, the utilization of such materials in nanodimensions will create enormous impact on the efficiency of various energy conversion and storage devices. The main objective of this special issues is to identify the significant research paradigms of nanomaterials and their potential impacts on applications. In particular, focus of this issue is on the synthesis and characterization of nanostructured materials for various applications such as supercapacitors, batteries, photoelectrochemical, and thermal enhancement systems. The highlights of the published articles are summarized as follows. In this special issue, Y. Yuan et al. synthesized the porous activated carbon materials from Pleurotus eryngii-based biomass material via carbonization, followed by KOH activation and utilized it for supercapacitor applications. The as-prepared activated carbon presented a large specific area with high porosity which exhibited a maximum specific capacitance of 195 F g-1 with 93% capacitance retention after 15000 cycles. It is known that Pleurotus eryngii is one of the readily available sources of carbon materials, potentially suitable for supercapacitor applications. Also, this biomass can be the resource for development of porous activated carbon for other energy conversion and storage devices in the future. Further, B.-X. Zou et al. synthesized hierarchical porous N, O-doped carbon composites by combining low molecular weight phenol resin and silk fibers in various combinations using a hydrothermal method and carbonization process. The as-prepared electroactive materials showed a low resistance and good surface area with hierarchical porosity. The low molecular phenol resin and silk fiber combination increases the surface area and enhanced the electron transport within the active materials. The fabricated symmetric device delivered a maximum energy density of 7.4 Wh kg-1 and power density of 90.1 W kg−1 using aqueous electrolyte

Magnetic Nanomaterials as Catalysts for Syngas Production and Conversion

The conversion of diverse non-petroleum carbon elements, such as coal, biomass, natural/shale gas, and even CO2, into cleaner hydrocarbon fuels and useful chemicals relies heavily on syngas, which is a combination of CO and H2. Syngas conversions, which have been around for almost a century, will probably become even more important in the production of energy and chemicals due to the rising need for liquid fuels and chemical components derived from sources of carbon other than crude oil. Although a number of syngas-based technologies, including the production of methanol, Fischer–Tropsch (FT) synthesis, and carbonylation, have been industrialized, there is still a great need for new catalysts with enhanced activity and adjustable product selectivity. New novel materials or different combinations of materials have been investigated to utilize the synergistic effect of these materials in an effective way. Magnetic materials are among the materials with magnetic properties, which provide them with extra physical characteristics compared to other carbon-based or conventional materials. Moreover, the separation of magnetic materials after the completion of a specific application could be easily performed with a magnetic separation process. In this review, we discuss the synthesis processes of various magnetic nanomaterials and their composites, which could be utilized as catalysts for syngas production and conversion. It is reported that applying an external magnetic field could influence the outcomes of any applications of magnetic nanomaterials. Here, the possible influence of the magnetic characteristics of magnetic nanomaterials with an external magnetic field is also discussed