50 research outputs found
Excitation Intensity Dependent Carrier Dynamics of Chalcogen Heteroatoms in Medium-Bandgap Polymer Solar Cells
No full text11Nsciescopu
Synergistic effects of an alkylthieno 3,2-b thiophene pi-bridging backbone extension on the photovoltaic performances of donor-acceptor copolymers
No full textThe synergistic effects of a thiophene-based pi-bridging backbone extension on the intrinsic and photovoltaic properties of electron donor-acceptor (D-A) copolymers were systematically investigated. A series of alternating D-A copolymers (PBTs) based on 4,8-bis(5-ethylhexylselenophen-2-yl)benzo[1,2-b:4,5-b']dithiophene (EHSeBDT) and 5-(2-butyloctyl)-4H-thieno[3,4-c]pyrrole-4,6(5H)-dione (BOTPD), which featured thiophene-based pi-bridges, were synthesized: PBT without a pi-bridge, PBT with a 3-octylthiophene (OT) pi-bridge (PBT-OT), and PBT with a 3-octylthieno[3,2-b]thiophene (OTT) pi-bridge (PBT-OTT). The light absorption and charge transport properties were significantly enhanced upon incorporation of the OTT pi-bridge. The enhancements resulted from the strong pi-pi intermolecular interactions using the OTT pi-bridging backbone extension between neighboring polymer chains. PBT-OTT was most miscible in PC71BM. As a result, the photoactive layers prepared using PBT-OTT and PC71BM formed a well-mixed bulk-heterojunction morphology and yielded organic solar cells (OSCs) with a high power conversion efficiency of 7.21%. Transient absorption analysis suggested that the mu-electrons were further delocalized along the copolymer after incorporation of the OTT pi-bridge, and the charge separation efficiency increased. These results suggested that incorporating OTT pi-bridges into D-A copolymers provides a useful strategy for developing highly efficient OSCs.118Nsciescopu
Identification of the 3' and 5' terminal sequences of the 8 rna genome segments of european and north american genotypes of infectious salmon anemia virus (an orthomyxovirus) and evidence for quasispecies based on the non-coding sequences of transcripts
No full textAbstract Background Infectious salmon anemia (ISA) virus (ISAV) is a pathogen of marine-farmed Atlantic salmon (Salmo salar); a disease first diagnosed in Norway in 1984. This virus, which was first characterized following its isolation in cell culture in 1995, belongs to the family Orthomyxoviridae, genus, Isavirus. The Isavirus genome consists of eight single-stranded RNA segments of negative sense, each with one to three open reading frames flanked by 3' and 5' non-coding regions (NCRs). Although the terminal sequences of other members of the family Orthomyxoviridae such as Influenzavirus A have been extensively analyzed, those of Isavirus remain largely unknown, and the few reported are from different ISAV strains and on different ends of the different RNA segments. This paper describes a comprehensive analysis of the 3' and 5' end sequences of the eight RNA segments of ISAV of both European and North American genotypes, and evidence of quasispecies of ISAV based on sequence variation in the untranslated regions (UTRs) of transcripts. Results Two different ISAV strains and two different RNA preparations were used in this study. ISAV strain ADL-PM 3205 ISAV-07 (ADL-ISAV-07) of European genotype was the source of total RNA extracted from ISAV-infected TO cells, which contained both viral mRNA and cRNA. ISAV strain NBISA01 of North American genotype was the source of vRNA extracted from purified virus. The NCRs of each segment were identified by sequencing cDNA prepared by three different methods, 5' RACE (Rapid amplification of cDNA ends), 3' RACE, and RNA ligation mediated PCR. Sequence analysis of five clones each derived from one RT-PCR product from each NCR of ISAV transcripts of segments 1 to 8 revealed significant heterogeneity among the clones of the same segment end, providing unequivocal evidence for presence of intra-segment ISAV quasispecies. Both RNA preparations (mRNA/cRNA and vRNA) yielded complementary sequence information, allowing the simultaneous identification and confirmation of the 3' and 5' NCR sequences of the 8 RNA genome segments of both genotypes of ISAV. The 3' sequences of the mRNA transcripts of ADL-ISAV-07 terminated 13-18 nucleotides from the full 3' terminus of cRNA, continuing as a poly(A) tail, which corresponded with the location of the polyadenylation signal. The lengths of the 3' and 5' NCRs of the vRNA were variable in the different genome segments, but the terminal 7 and 11 nucleotides of the 3' and 5' ends, respectively, were highly conserved among the eight genomic segments of ISAV. The first three nucleotides at the 3' end are GCU-3' (except in segment 5 with ACU-3'), whereas at the 5' end are 5'-AGU with the polyadenylation signal of 3-5 uridines 13-15 nucleotides downstream of the 5' end terminus of the vRNA. Exactly the same features were found in the respective complementary 5' and 3' end NCR sequences of the cRNA transcripts of ADL-ISAV-07, indicating that the terminal sequences of the 8 RNA genome segments are highly conserved among the two ISAV genotypes. The 5' NCR sequences of segments 1, 2, 3, 5, and 7, and the 3' NCR sequences of segments 3 and 4 cRNA were 100% identical in the two genotypes, and the 3' NCR sequences of segment 5 cRNA was the most divergent, with a sequence identity of 77.2%. Conclusions We report for the first time, the presence of intra-segment ISAV quasispecies, based on sequence variation in the NCR sequences of transcripts. In addition, this is the first report of a comprehensive unambiguous analysis of the 3' and 5' NCR sequences of all 8 RNA genome segments from two strains of ISAV representing the two genotypes of ISAV. Because most ISAV sequences are of cDNA to mRNA, they do not contain the 3' end sequences, which are removed during polyadenylation of the mRNA transcripts. We report for the first time the ISAV consensus sequence CAT/ATTTTTACT-3' (in the message sense 5'-3') in all segments of both ISAV genotypes.</p
Leucine residues in conserved region of 33K protein of bovine adenovirus – 3 are important for binding to major late promoter and activation of late gene expression
No full textThe L6 region of bovine adenovirus 3 (BAdV-3) encode 33K (spliced) and 22K (unspliced) proteins. Earlier, anti-33K serum detected five major and three minor proteins in BAdV-3 infected cells. Here, we demonstrate that anti-sera raised against L6-22K protein detected two proteins of 42 and 37 kDa in BAdV-3 infected cells and one protein of 42 kDa in transfected cells expressing splice-site variant 22K protein (pC.22K containing substituted splice acceptor/donor sequence). Unlike 22K, 33K stimulated the transcription from the major late promoter (MLP) by binding to the downstream sequence elements (DE). Analysis of the variant proteins demonstrated that amino acids 201–240 of the conserved C-terminus of 33K containing the potential leucine zipper and RS repeat are required for the activation of MLP. Furthermore, amino acid substitution analysis demonstrated that unlike arginine residues of RS repeat, the leucine residues (217, 224, 232 and 240) of the conserved leucine zipper appear required for the binding of 33K to the MLP.Natural Sciences and Engineering Research Council of Canada to SK
CoRncrete: A bio-based construction material
No full textCoRncrete is a corn starch based bio-material formed by mixing corn starch with water and sand, and heating the mix in a microwave or oven. This heating process results in the formation of a hardened material. A constant corn starch to sand proportion of 1:5 has been adopted in this study. The transformation of CoRncrete from a semi-solid to a hardened material is caused by modification of corn starch that occur through a ‘gelatinization’ process. Heating of corn starch in the presence of water results in the formation of a gel that binds with sand grains and hardens. The temperature at which gel formation or gelatinization in CoRncrete occurs, was studied by DSC (Differential Scanning Calorimetry). To understand the microstructure of CoRncrete, ESEM (Environmental Scanning Electron Microscope) tests were carried out. ESEM scans revealed the effect of water content, heating source and heating duration on the gelatinization process that affects the development of microstructure of CoRncrete. The physical properties of CoRncrete was studied by analysing consistency behaviour of fresh CoRncrete and compressive strength of hardened CoRncrete. It was found that the corn starch in fresh CoRncrete changes its phase from solid to plastic/liquid at a specific water content. This water content was determined by cone penetrometer and proctor tests. This change in phase of corn starch was observed at an optimum water content. At optimum water content, the maximum dry density of fresh CoRncrete and maximum density and strength of hardened CoRncrete is also achieved. The fresh CoRncrete was heated to form hardened CoRncrete with the compressive strength found to be comparable to that of red clay bricks. The factors influencing the strength of hardened CoRncrete such as water content, size of the sand particle and heating duration (in a microwave) has been studied and discussed. A strong positive correlation between density and strength of hardened CoRncrete has been observed. Degradation of CoRncrete was studied by immersing specimens in water. Specimens were degraded partially to fully within a day, raising durability issues. The sustainability of CoRncrete was studied by carrying out LCA (Life Cycle Assessment) and compared with LCA results of Portland cement concrete and fired clay brick. The analysis indicated that the CoRncrete has comparatively higher environmental impact. Finally, the limiting factors in application of a CoRncrete and their remedial measures have been discussed. This research work addresses CoRncrete as a potential precursor to a new class of construction materials which gain strength rapidly by heating at relatively low temperature (~100oC).Geo-engineering, Materials and EnvironmentGeoscience & EngineeringCivil Engineering and Geoscience
Building Affordable, Durable and Desirable Earthen Houses: Construction with Materials Derived from Locally Available Natural and Biological Resources
No full textBuilding with unfired earth (mud) is an ancient practice that is regaining popularity due to the rising concern about the impact of the construction sector on climate. However, the low image of earthen materials is a major barrier to its acceptance in India, and is caused due to its poor water resistance performance. This research focuses on developing a low-cost, water resistant and desirable earthen building material for rural housing in India. This thesis contributes toward a better understanding of water ingress and water resistance in unstabilised and biologically stabilised earthen materials, especially cow-dung stabilised earthen blocks. Moreover, it addresses the three key aspects identified for rural earthen housing in India; 1. Affordability, by using inexpensive techniques and binder; 2. Durability, by enhancing the water resistance in both unstabilised and cow-dung stabilised earthen material, and 3. Desirability, by producing Compressed Earth Blocks of a good finish and aesthetic and using a widely acceptable stabiliser. The research work is expected not only to provide scientific insights that facilitate understanding and adoption of earthen materials but also the knowledge that can be directly applied in the construction of earthen houses.Materials and Environmen
Regional computable general equilibrium models: A review
No full textComputable General Equilibrium (CGE) models are very popular for analyzing a wide range of policy issues. CGE applications vary from estimating the welfare impact of tax reform and alternative energy policies to the effect of foreign trade reforms, labour markets and employment. CGE models are commonly developed at the country level; however, modified versions of CGE, so called Regional CGE (RCGE) models, can be used at subnational disaggregation to examine impacts studied at the national counterparts on a specific region. RCGE models have grown in popularity as an alternative to the Input-Output (I-O) models, which are regularly used for regional analysis. RCGE models can provide comprehensive information, which make them more desirable analytical models for many researchers. Yet, RCGE models have not yet become a “go-to” for governmental policy practitioners when they are developing regional public policies. This paper reviews the current state of regional CGE models, describes their features, contributions and limitations and surveys some applications of the main three classes of RCGE models: region-specific, bottom-up, and top-down models. This paper concludes that the applications of RCGE are quite variable and flexible, with a new and more complex type of application to be developed with the advancement of computation economics. The paper offers recommendations on the micro, meso and macro conditions that are necessary to increase policy practitioners’ utilization of RCGE models
The state of earthen housing worldwide: how development affects attitudes and adoption
No full textHousing is a cross-cutting issue that is crucial to achieving several of the Sustainable Development Goals. Earthen housing is found across the globe, particularly in developing countries, but there is a lack of up-to-date information about its distribution and trends. This knowledge gap is a barrier to developing more effective research and policy for earthen housing. In this study, national demographic datasets were used to investigate the distribution, trends and attitudes towards earthen housing worldwide. Data was collected and analysed for the most populous 26 countries, which make up >75% of the global population. Globally, earthen housing is in decline relative to non-earthen housing, driven by demographic changes and negative perceptions of earthen materials in developing countries. The proportion of households living in earthen dwellings worldwide is estimated to be 8–10%, and the average across developing countries to be 20–25%. There is a negative correlation between countries’ level of development and prevalence of earthen housing. Whilst data is more sparse for highly developed countries, the development of standards and commercial interest suggests more favourable attitudes to earthen housing. A focus is encouraged on high-quality earthen dwellings which can help meet housing needs in both developing and developed countries
Compressed Stabilized Earthen Blocks and Their Use in Low-Cost Social Housing
No full textEarthen techniques have been historically used in construction of housing in Africa, Asia and Latin America. In the past two decades the interest in earthen material has grown considerably, leading to the development of sustainable materials such as compressed earth blocks (CEB), compressed stabilized earth blocks (CSEB) and interlocking stabilized soil blocks (ISSB). Scientific publications from various countries and context have examined the physical aspects of these earthen building materials, but so far, the results are not well connected to housing practices for and by low-income households with their self-organizing skills. This research sought to close this gap by documenting the housing projects where earth blocks are applied in participatory social housing. The study provides an overview of relevant practical examples from the three world regions (Africa, Asia and Latin America), with their cultural and climatic differences, and an analysis of similarities and possibilities. Based on the lessons learned from these examples, recommendations are made on further research on sustainable building materials within social housing practices, which can benefit the scientific community. We propose to set up a worldwide database of housing projects where earthen techniques have been applied responsibly. We conclude and recommend that more high-quality pilot projects with CSEB and ISSB are needed to get a broader picture on the potential of these materials for social housing, and the necessary support for local communities wishing to be involved in these sustainable housing practices
