Recent Trends in Plasmonic Nanowire Solar Cells

Light trapping is crucial for low-cost and highly efficient nanowire (NW) solar cells (SCs). In order to increase the light absorption through the NWSCs, plasmonic materials can be incorporated inside or above the NW design. In this regard, two novel designs of plasmonic NWSCs are reported and analyzed using 3D finite difference time domain method. The geometrical parameters of the reported designs are studied to improve their electrical and optical efficiencies. The ultimate and power conversion efficiencies (PCE) are used to quantify the conversion efficiency of the light into electricity. The first design relies on funnel shaped SiNWs with plasmonic core while the cylindrical NWs of the second design are decorated by Ag diamond shaped. The calculated ultimate efficiency and PCE of the plasmonic funnel design are equal to 44% and 18.9%, respectively with an enhancement of 43.3 % over its cylindrical NWs counterpart. This enhancement can be explained by the coupling between the three optical modes, supported by the upper cylinder, lower cone and plasmonic material. Moreover, the cylindrical SiNWs decorated by Ag diamond offer an ultimate efficiency and short-circuit current density of 25.7%, and 21.03 mA∕cm2, respectively with an improvement of 63% over the conventional cylindrical SiNWs

A new degree six modified chordal ring network topology

The performance of a parallel or distributed network depends on the design of its interconnection topology. One good network interconnection topology that has been the focus of various researchers is the chordal ring. In this paper, a new degree six modified chordal ring is presented, the optimised degree six 3-modified chordal ring (CHR6o3), with the aim of comparing its performance parameters in terms of optimal diameter and optimal average path length to existing degree six chordal rings. Formulae to generate the data for each different chordal ring were derived from its corresponding tree visualisation or used from previous work. Network sizes tested were from 1200 to 12000 nodes. Large networks of CHR6o3 were shown to perform better than those of previous degree six chordal rings. This gives CHR6o3 an added advantage for its implementation in large distributive networks, such as Fibre to the Home (FTTH) networks, since it offers redundancies at higher network layers

High speed internet development in Africa using 4G-LTE technology-a review

The African continent is ranked second most populated region and has a huge amount of natural resources to be locally transformed or outsourced overseas. The traditional telecommunications system has helped connect people and enabled them to manage their businesses and trading in Africa for a long-time; many African countries have embarked early in changing their network and technology systems during the first years of the information age. Over a few decades ago, the introduction of new telecommunication methods and techniques have influenced much of African countries’ growth via different perspectives. The situation has triggered an enormous interest in people. They analyzed the factors supporting such changes, which in the case of this paper is all about the advent and adoption of LTE/4G-LTE technologies including its service commercialization in Africa. This review article attempts to provide an overview of 4G-LTE networks technologies and the internet; it includes the current evolution of telecommunication networks within and even beyond the African continent, assisted by the 4G-LTE expansion. An extended view is provided throughout this article’s development with respect to what could be expected (or is missing) for the sake of this continent’s telecommunication infrastructure enhancement and a better QoS to Africa’s dwellers

Cellular transcripts regulated during infections with Highly Pathogenic H5N1 Avian Influenza virus in 3 host systems

<p>Abstract</p> <p>Background</p> <p>Highly pathogenic Avian Influenza (HPAI) virus is able to infect many hosts and the virus replicates in high levels in the respiratory tract inducing severe lung lesions. The pathogenesis of the disease is actually the outcome of the infection as determined by complex host-virus interactions involving the functional kinetics of large numbers of participating genes. Understanding the genes and proteins involved in host cellular responses are therefore, critical for the elucidation of the mechanisms of infection.</p> <p>Methods</p> <p>Differentially expressed transcripts regulated in a H5N1 infections of whole lung organ of chicken, <it>in-vitro </it>chick embryo lung primary cell culture (CeLu) and a continuous Madin Darby Canine Kidney cell line was undertaken. An improved mRNA differential display technique (Gene Fishing™) using annealing control primers that generates reproducible, authentic and long PCR products that are detectable on agarose gels was used for the identification of differentially expressed genes (DEGs). Seven of the genes have been selected for validation using a TaqMan^®based real time quantitative PCR assay.</p> <p>Results</p> <p>Thirty seven known and unique differentially expressed genes from lungs of chickens, CeLu and MDCK cells were isolated. Among the genes isolated and identified include heat shock proteins, Cyclin D2, Prenyl (decaprenyl) diphosphate synthase, IL-8 and many other unknown genes. The quantitative real time RT-PCR assay data showed that the transcription kinetics of the selected genes were clearly altered during infection by the Highly Pathogenic Avian Influenza virus.</p> <p>Conclusion</p> <p>The Gene Fishing™ technique has allowed for the first time, the isolation and identification of sequences of host cellular genes regulated during H5N1 virus infection. In this limited study, the differentially expressed genes in the three host systems were not identical, thus suggesting that their responses to the H5N1 infection may not share similar mechanisms and pathways.</p

A survey of routing MAC techniques for wireless sensor networks routing protocol

A Wireless Sensor Network (WSN) contains a random number of sensors distributed in the environment to monitor physical conditions. In the following, a survey of MAC routing mechanisms in WSN is presented and discussed. One of the most important issues in WSN is the issue of energy efficiency of the routing protocols. The importance of this issue stems from the fact that the nodes have usually a life time and this life time can be extended by saving more energy by using efficient routing techniques. In the following, we present a survey of the MAC routing mechanisms in WSN. Firstly, an outline of the architecture challenges for routing protocols in WSN is given according to the system tradeoffs between the power and communication overhead savings in different routing techniques. Secondly, advantages and disadvantages for each routing protocol are presented and discussed. In this survey, we will concentrate only on some protocols like Data Centric, Hierarchal and other related energy saving protocols. In addition, we will discuss some of the surveyed protocols results, comparisons and conclusions

Reduced graphene oxide-multiwalled carbon nanotubes hybrid film with low Pt loading as counter electrode for improved photovoltaic performance of dye-sensitised solar cells

In this work, the role of reduced graphene oxide (rGO) with hyperbranched surfactant and its hybridisation with multiwalled carbon nanotubes (MWCNTs) and platinum (Pt) nanoparticles (NPs) as counter electrode (CE) were investigated to determine the photovoltaic performance of dye-sensitised solar cells (DSSCs). Sodium 1,4-is(neopentyloxy)-3-(neopentyloxycarbonyl)- 1,4-dioxobutane-2-sulphonate (TC14) surfactant was utilised as dispersing and stabilising agent in electrochemical exfoliation to synthesise graphene oxide (GO) as initial solution for rGO production prior to its further hybridisation and fabrication as thin film. A chemical reduction process utilising hydrazine hydrate was conducted to produce rGO due to the low temperature process and water-based GO solution. Subsequently, hybrid solution was prepared by mixing 1 wt% MWCNTs into the produced rGO solution. TC14-rGO and TC14-rGO_MWCNTs hybrid solution were transferred into fluorine-doped tin oxide substrate to fabricate thin film by spraying deposition method. Finally, the CE films were prepared by coating with thin Pt NPs. Photoanode film was prepared by a two-step process: hydrothermal growth method to synthesise titanium dioxide nanowires (TiO2 NWs) and subsequent squeegee method to apply TiO2 NPs. According to solar simulator measurement, the highest energy conversion efficiency (η) was achieved by using CE-based TC14-rGO_MWCNTs/Pt (1.553%), with the highest short current density of 4.424 mA/cm2. The highest η was due to the high conductivity of CE hybrid film and the morphology of fabricated TiO2 NWs/TiO2 NPs. Consequently, the dye adsorption was high, and the photovoltaic performance of DSSCs was increased. This result also showed that rGO and rGO_MWCNTs hybrid can be used as considerable potential candidate materials to replace Pt gradually

Agronomical, physiological and molecular evaluation reveals superior salt-tolerance in bread wheat through salt-induced priming approach

Salt stress significantly limit wheat crop productivity worldwide. Exposure to non-lethal levels of salt stress, referred to as "salt-priming", allows plants to persist subsequent lethal conditions; the priming effect continues even after an extended salt stress-free period. This study attempted to evaluate the effectiveness of the salt-induced priming approach to cope with the toxic effects of long-term salinity stress in wheat. After 22 days of gradual salt acclamation to reach 250 mM NaCl, plants were recovered for eight days and finally shocked with 250 mM NaCl (priming+shock) for 7 days. After that, physiological parameters and gene expression of six salt-responsive genes were assessed. Additionally, 120 days after germination (at the end of the season), agronomic traits were recorded. Analysis of the agronomical traits revealed higher productivity in the salt-pretreated group (priming+shock) plants than the non-pretreated (shock only). Consistently, salt-pretreated plants maintained higher photosynthetic pigments level and decreased proline and MDA content than non-pretreated, suggesting enhanced salt tolerance. Moreover, salt-pretreated plants sustained high expressional levels of salt-responsive genes (TaNHX1, TaSOS1, TaSOS4, TaHKT1, TaHKT2, and TaAKT1) comparing with non-pretreated, indicating a vital role in ion homeostasis and conferring salt tolerance. Ultimately, this finding could facilitate novel smart approaches to improve wheat productivity under salt stress

Application of organic fertilisers on natural stand bamboos for sustainable management in Peninsular Malaysia

This paper highlights research on the influence of three organic fertilisers (chicken dung, palm oil mill effluent and peat materials specially made for fertilisers) on the number of new shoots, the diameter at breast height, the height of the culms and the number of culms. Especially the number of new shoots and the diameter at breast height are positively influenced, which is promising for commercial purposes