Highly Efficient p-i-n Type Organic Light-emitting Diodes Using Doping of the Transport and Emission Layers

We demonstrate high-efficiency organic light-emitting diodes (OLEDs) by incorporating a double as well as triple emission layers into p-i-n-type device structures based on vacuum deposition technique. The term p-i-n means here a layer sequence in the form p-doped layer, intrinsic layer and n-doped layer. Both predominantly hole transporting material (TCTA) and an exclusively electron transporting host material (TAZ) are doped with the green phosphorescent dye tris(phenylpyridine)iridium [Ir(ppy)3]. The intrinsic and doped transport and emission layers are formed using a high vacuum controlled co-evaporation deposition technique. As results, high efficient light emission is obtained in double emission system. For double emission system, a power efficiency of 68 lm/W and peak external quantum efficiency of 20 % are achieved at 100 cd/m2 and at an operating voltage of 3.0 V. In addition, impressive characteristics of white OLED has been achieved in doped red and green phosphorescent dopants {NPB:Ir(MDQ)2(acac) and TCTA:Ir(ppy)3} and blue-fluorescent dye (Spiro-DPVBi). As a result, a power efficiency of 14.4 lm/W is obtained at a driving voltage of 3 volt and a luminance of 1000 cd/m2 in stacked white OLEDs.Key words: p-i-n structure, doped charge transport layers, doped emission layers, phosphorescent OLED

Influence of doped-charge transport layers on the photovoltaic performance of donor-acceptor blend p-i-n type organic solar cells

This report demonstrates external power conversion efficiencies of 2% under 100 mW/cm2 simulated AM1.5 illumination for organic thin-film photovoltaic cells using a phthalocyanine-fullerene (ZnPc/C60) bulk heterojunction as an active layer, embedded into a p-i-n type architecture with doped wide-gap charge transport layers. For an optically optimized device, we found internal quantum efficiency (IQE) of above 80% under short circuit conditions. Such optically thin cells with high internal quantum efficiency are an important step towards high efficiency tandem cells. The p-i-n architecture allows for the design of solar cells with high internal quantum efficiency where only the photoactive region absorbs visible light and recombination losses at contacts are avoided. The I-V characteristics, power conversion efficiencies, the dependence of short circuit current on incident white light intensity, incident photon to collected electron efficiency (IPCE) and absorption spectra of the active layer system are discussed. KEY WORDS: Doped-charge transport layers, Organic solar cells, Photovoltaic cells,Phthalocyanine-fullerene  Bull. Chem. Soc. Ethiop. 2004, 18(1), 101-109

Market Access, Intensification and Productivity of Common Bean in Ethopia: A microeconomic analysis

This work analyses on-farm adjustments in land allocation and intensification in a commercial crop following the increases in market demand in a developing economy. Drawing from the survey conducted among common bean producers in Ethiopia in 2008, a two stage econometric method was used to investigate the contribution of market access and other micro-level factors in facilitating crop intensification and productivity. Ethiopia is the leading commercial producer and exporter of common bean in Africa but also one of the countries in Africa with high levels of soil nutrient depletion. Understanding factors that influence input use and productivity is critical for food security and agricultural sustainability in the country. Based on farm survey data, it was shown that most farmers had expanded their area under common bean but the use of fertilizer and improved varieties was still low. Increase in the intensity of fertilizer and seed use produces an increase in yield and so is market access. Market access has intensification as well as specialization effects on common bean yield. Access to credit, extension and household wealth are other factors that facilitate common bean intensification while risk increasing factors constrain it

Importance of Ethnicity, CYP2B6 and ABCB1 Genotype for Efavirenz Pharmacokinetics and Treatment Outcomes: A Parallel-group Prospective Cohort Study in two sub-Saharan Africa Populations.

We evaluated the importance of ethnicity and pharmacogenetic variations in determining efavirenz pharmacokinetics, auto-induction and immunological outcomes in two African populations. ART naïve HIV patients from Ethiopia (n = 285) and Tanzania (n = 209) were prospectively enrolled in parallel to start efavirenz based HAART. CD4+ cell counts were determined at baseline, 12, 24 and 48 weeks. Plasma and intracellular efavirenz and 8-hydroxyefvairenz concentrations were determined at week 4 and 16. Genotyping for common functional CYP2B6, CYP3A5, ABCB1, UGT2B7 and SLCO1B1 variant alleles were done. Patient country, CYP2B6*6 and ABCB1 c.4036A>G (rs3842A>G) genotype were significant predictors of plasma and intracellular efavirenz concentration. CYP2B6*6 and ABCB1 c.4036A>G (rs3842) genotype were significantly associated with higher plasma efavirenz concentration and their allele frequencies were significantly higher in Tanzanians than Ethiopians. Tanzanians displayed significantly higher efavirenz plasma concentration at week 4 (p<0.0002) and week 16 (p = 0.006) compared to Ethiopians. Efavirenz plasma concentrations remained significantly higher in Tanzanians even after controlling for the effect of CYP2B6*6 and ABCB1 c.4036A>G genotype. Within country analyses indicated a significant decrease in the mean plasma efavirenz concentration by week 16 compared to week 4 in Tanzanians (p = 0.006), whereas no significant differences in plasma concentration over time was observed in Ethiopians (p = 0.84). Intracellular efavirenz concentration and patient country were significant predictors of CD4 gain during HAART. We report substantial differences in efavirenz pharmacokinetics, extent of auto-induction and immunologic recovery between Ethiopian and Tanzanian HIV patients, partly but not solely, due to pharmacogenetic variations. The observed inter-ethnic variations in efavirenz plasma exposure may possibly result in varying clinical treatment outcome or adverse event profiles between populations

Investigating the impact of poverty on colonization and infection with drug-resistant organisms in humans: a systematic review

Background Poverty increases the risk of contracting infectious diseases and therefore exposure to antibiotics. Yet there is lacking evidence on the relationship between income and non-income dimensions of poverty and antimicrobial resistance. Investigating such relationship would strengthen antimicrobial stewardship interventions. Methods A systematic review was conducted following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. PubMed, Ovid, MEDLINE, EMBASE, Scopus, CINAHL, PsychINFO, EBSCO, HMIC, and Web of Science databases were searched in October 2016. Prospective and retrospective studies reporting on income or non-income dimensions of poverty and their influence on colonisation or infection with antimicrobial-resistant organisms were retrieved. Study quality was assessed with the Integrated quality criteria for review of multiple study designs (ICROMS) tool. Results Nineteen articles were reviewed. Crowding and homelessness were associated with antimicrobial resistance in community and hospital patients. In high-income countries, low income was associated with Streptococcus pneumoniae and Acinetobacter baumannii resistance and a seven-fold higher infection rate. In low-income countries the findings on this relation were contradictory. Lack of education was linked to resistant S. pneumoniae and Escherichia coli. Two papers explored the relation between water and sanitation and antimicrobial resistance in low-income settings. Conclusions Despite methodological limitations, the results suggest that addressing social determinants of poverty worldwide remains a crucial yet neglected step towards preventing antimicrobial resistance

Breeding schemes: what are they, how to formalize them, and how to improve them?

Open Access Journal; Published online: 21 Jan 2022Formalized breeding schemes are a key component of breeding program design and a gateway to conducting plant breeding as a quantitative process. Unfortunately, breeding schemes are rarely defined, expressed in a quantifiable format, or stored in a database. Furthermore, the continuous review and improvement of breeding schemes is not routinely conducted in many breeding programs. Given the rapid development of novel breeding methodologies, it is important to adopt a philosophy of continuous improvement regarding breeding scheme design. Here, we discuss terms and definitions that are relevant to formalizing breeding pipelines, market segments and breeding schemes, and we present a software tool, Breeding Pipeline Manager, that can be used to formalize and continuously improve breeding schemes. In addition, we detail the use of continuous improvement methods and tools such as genetic simulation through a case study in the International Institute of Tropical Agriculture (IITA) Cassava east-Africa pipeline. We successfully deploy these tools and methods to optimize the program size as well as allocation of resources to the number of parents used, number of crosses made, and number of progeny produced. We propose a structured approach to improve breeding schemes which will help to sustain the rates of response to selection and help to deliver better products to farmers and consumers

Rapid production of large-area, transparent and stretchable electrodes using metal nanofibers as wirelessly operated wearable heaters

A rapidly growing interest in wearable electronics has led to the development of stretchable and transparent heating films that can replace the conventional brittle and opaque heaters. Herein, we describe the rapid production of large-area, stretchable and transparent electrodes using electrospun ultra-long metal nanofibers (mNFs) and demonstrate their potential use as wirelessly operated wearable heaters. These mNF networks provide excellent optoelectronic properties (sheet resistance of similar to 1.3 O per sq with an optical transmittance of similar to 90%) and mechanical reliability (90% stretchability). The optoelectronic properties can be controlled by adjusting the area fraction of the mNF networks, which also enables the modulation of the power consumption of the heater. For example, the low sheet resistance of the heater presents an outstanding power efficiency of 0.65 W cm(-2) (with the temperature reaching 250 degrees C at a low DC voltage of 4.5 V), which is similar to 10 times better than the properties of conventional indium tin oxide-based heaters. Furthermore, we demonstrate the wireless fine control of the temperature of the heating film using Bluetooth smart devices, which suggests substantial promise for the application of this heating film in next-generation wearable electronics