Copper (I) oxide (Cu2) based solar cells - a review

Copper (I) oxide (Cu2O) is a potential material for the fabrication of low cost solar cells for terrestrial application. A detailed survey on the previous work so far carried out on Cu2O based solar cells has been presented. The aspects discussed include the fabrication of Schottky (metal/semiconductor) barrier Cu2O solar cells, where different low work function metals are used to form the Schottky barrier solar cells. The problems associated with the Cu2O Schottky barrier solar cells and efforts made at improving the performance of these solar cells are highlighted. Discussions on heterojunction solar cells with Cu2O have also been presented. Various transparent conducting oxides (TCOs) used in forming the heterojunction cells are mentioned, and successes and failures of using them highlighted. The technological developments of these cells are still in their infancy and the performance remains very poor. The root causes of this poor performance are analyzed and possible areas for future research in the field are outlined. Keyword: Copper (I) oxide, Solar cells, Solar cells, Schottky barrier sola cell

Effects of Interfacial Bonding on Friction and Wear at Silica/Silica Interfaces

Static friction between amorphous silica surfaces with a varying number of interfacial siloxane (Si–O–Si) bridges was studied using molecular dynamic simulations. Static friction was found to increase linearly with the applied normal pressure, which can be explained in the framework of Prandlt–Tomlinson’s model. Friction force was found to increase with concentration of siloxane bridges, but with a decreasing gradient, with the latter being due to interactions between neighboring siloxane bridges. In addition, we identified atomic-level wear mechanisms of silica. These mechanisms include both transfer of individual atoms accompanied by breaking interfacial siloxane bridges and transfer of atomic cluster initialized by rupturing of surface Si–O bonds. Our simulations showed that small clusters are continually formed and dissolved at the sliding interface, which plays an important role in wear at silica/silica interface.National Science Foundation (U.S.) (Grant EAR-0910779)United States. Army Research Office (Grant W911NF-12-1-0548

Electroless deposition and electrical characterization of N- Cu2O layer

This work describes the preparation of n-Cu2O layer by the electroless methods of boiling and immersion of copper plates in 0.001M  CuSO4Electron Microscopy (SEM) have been used to characterize the oxide films deposited. XRD studies show, for the first time, that cuprous oxide (Cu2O) and cupric oxide (CuO) were deposited by the two methods. The dissolution of the oxide layer for boiling above the 60 minutes time was found to be due to the turbulent nature of the boiling solution. There was no dissolution of the oxide layer in the case of the immersion method. The thickness of the films deposited for 60 minutes boiling andthat obtained by the immersion method at the solution pH of 9.83 are approximately 4.8 ìm and 3.8ìm, respectively. The resistivities of the oxide layers were found to be 75.64 Ùcm and 61.32 Ùcm, respectively. Annealing of the sample for 60 minutes by boiling, changes the mixed oxides(Cu2O-CuO) into the single phase Cu2O.Keywords: n-Cu2O deposition, boiling and immersion methods

Curtailing Fertilizer Scarcity and Climate Change; An Appraisal of Factors Affecting Organic Materials Use Option in Nigeria’s Agriculture

Global trends nowadays towards long term sustainable crop production is hinged on either supplementing the use of chemical fertilizers with organic materials or a complete use of organic materials. This is more so since substituting chemical fertilizers with organic materials reduces the risks of exposure to ailments that arise on account of synthetic compounds and increases farmers’ gains via reduced soil erosion and carbon emissions and increased bio-diversity. The current study investigated organic materials use in Nigeria’s agriculture. Specifically, the study examined availability and use of chemical fertilizers and organic materials substitutes and investigated factors affecting the use of organic materials in the Nigerian food sector. The study data were drawn from a survey of sixty-one farm households that used organic materials as major nutrients inputs or as supplement with chemical fertilizers for their cropping activities. The study area is Shira in Nigeria. Farmers in this area usually incorporate the use of organic materials in their agriculture. The descriptive statistics and regression analyses were used to analyse the study data. Results indicate that farmers in the study area source their chemical fertilizer inputs from the open market at an exorbitant price of N2000 (US dollar $13.8) per bag on average thereby using very low rates of chemical fertilizers. Organic materials used by farmers were sourced from cattle, goats, sheep and poultry droppings. The quantity of organic material used was 12,513.0 kg per hectare at a cost of N15,015.6 (US dollar$103.5). Major constraints in the use of organic materials by farmers include poor transport facilities and cutworm infestations of the organic materials. Factors revealed to influence the quantity of organic materials used by farmers were the cost of organic materials and the quantity of chemical fertilizers used by the farmers. The study therefore calls for stake-holders involvement in the establishment of blending plants for the production of organic materials, burning of organic materials before usage, and the need to enhance researches aimed at establishing optimal material mixtures and application rates for organic materials used in the Nigerian farming systems.Keywords: farming systems, bio-diversity, carbon emissions, cut-worm infestation, sheep, goat, poultr

Tunneling of a Quantized Vortex: Roles of Pinning and Dissipation

We have performed a theoretical study of the effects of pinning potential and dissipation on vortex tunneling in superconductors. Analytical results are obtained in various limits relevant to experiment. In general we have found that pinning and dissipation tend to suppress the effect of the vortex velocity dependent part of the Magnus force on vortex tunneling.Comment: Latex, 12 page

PEPPI: a peptidomic database of human protein isoforms for proteomics experiments

Background Protein isoform generation, which may derive from alternative splicing, genetic polymorphism, and posttranslational modification, is an essential source of achieving molecular diversity by eukaryotic cells. Previous studies have shown that protein isoforms play critical roles in disease diagnosis, risk assessment, sub-typing, prognosis, and treatment outcome predictions. Understanding the types, presence, and abundance of different protein isoforms in different cellular and physiological conditions is a major task in functional proteomics, and may pave ways to molecular biomarker discovery of human diseases. In tandem mass spectrometry (MS/MS) based proteomics analysis, peptide peaks with exact matches to protein sequence records in the proteomics database may be identified with mass spectrometry (MS) search software. However, due to limited annotation and poor coverage of protein isoforms in proteomics databases, high throughput protein isoform identifications, particularly those arising from alternative splicing and genetic polymorphism, have not been possible. Results Therefore, we present the PEPtidomics Protein Isoform Database (PEPPI, http://bio.informatics.iupui.edu/peppi), a comprehensive database of computationally-synthesized human peptides that can identify protein isoforms derived from either alternatively spliced mRNA transcripts or SNP variations. We collected genome, pre-mRNA alternative splicing and SNP information from Ensembl. We synthesized in silico isoform transcripts that cover all exons and theoretically possible junctions of exons and introns, as well as all their variations derived from known SNPs. With three case studies, we further demonstrated that the database can help researchers discover and characterize new protein isoform biomarkers from experimental proteomics data. Conclusions We developed a new tool for the proteomics community to characterize protein isoforms from MS-based proteomics experiments. By cataloguing each peptide configurations in the PEPPI database, users can study genetic variations and alternative splicing events at the proteome level. They can also batch-download peptide sequences in FASTA format to search for MS/MS spectra derived from human samples. The database can help generate novel hypotheses on molecular risk factors and molecular mechanisms of complex diseases, leading to identification of potentially highly specific protein isoform biomarkers

The Food Habits of Ctenopoma pethereci, Gunther (Pisces: Anabantidae) in River Oluwa, Ondo State, Nigeria

The natural foods of Ctenopoma pethereci from River Oluwa in Ondo State, South-west Nigeria, were urrence and points methods of analysis. The quantity of food in the full stomach constituted 0.83% of the body weight while food in the intestine formed 1.54%, thus, giving the quantity of food in the entire gut as 2.37% of the body weight. There was little or no qualitative difference in the food items found in the stomachs and intestines. The food items encountered in the gut covered a wide spectrum, and the species is shown to utilize a wider variety of plant materials than animals. The dominant plant source included diatoms, blue-green algae, green algae and higher plants, while the range of animals included rotifers, copepods and insects. Organic detritus also formed a substantial portion of its food which amounted to 98.94%. The study revealed that C. pethereci is an omnivore with herbivorous tendency in River Oluwa