Demonstrating close-packing of atoms using spherical bubble gums

In this paper, the use of spherical bubble gums (Gum Balls) to demonstrate the close-packing of atoms and ions is presented. Spherical bubble gums having distinctive colours were used to illustrate the different layers in variety of crystalline packing and the formation of tetrahedral and octahedral holes. Students with hands-on experience of building the different packing models could better understood the close-packing of atoms

Vegetables for building molecular models

An exciting classroom activity involving the construction of molecular models and building hybrid orbitals is presented in this paper. Basic molecular geometries were built by connecting different types of vegetables using bamboo skewers. Vegetable of different shapes were used to describe the hybridization of atomic orbitals. This exercise is suitable for high school and undergraduate chemistry students. The activity helps students to apply Valence Shell Electron Pair Repulsion (VSEPR) theory to envisage the basic shapes of molecules and to conceptualize the hybridization of the atomic orbital

Prevalence and associated factors of neonatal mortality in North Gondar Zone, Northwest Ethiopia

Background: Childhood mortality is often used as a broad indicator of the social development and health conditions of a country. Updated information on neonatal mortality does thus influence policy, improve services and lead to better health for newborns.Objective: To assess the prevalence of neonatal mortality and associated factors in North Gondar Zone, Ethiopia.Methods: Community based cross-sectional study was carried out from November 2009 to January 2010 in North Gondar Zone. Multi-stage sampling was adopted to get respondents and data was collected using structured questionnaires from 3600 mothers who gave live birth during the year 2005 to 2009.Results: Neonatal mortality was found to be 214 out of 4888 live births with the rate of 43.8 per 1000 live births. The number of pregnancies the women, had (AOR =3.76: 95% CI, 2.73- 5.20), maternal morbidity (AOR =5.43: 95% CI, 2.90-10.17) and neonatal illness (AOR = 3.68: 95% CI, 2.41-5.62) were strongly associated with neonatal mortality. Small size neonates at birth were 2 times more likely to die compared with medium sized ones. Compared with illiterate mothers, secondary and above secondary educated mothers reduced the risk of neonatal deaths by 85% (0.04, 0.51) and 90% (0.01, 0.94), respectively.Conclusion: Neonatal mortality was very high when compared with the national data of Ethiopia. Strategies to improve female education, reducing maternal morbidity, limiting the number of pregnancies, early intervention for neonatal illness, prevention and intervention in low birth weight neonates are recommended to reduce neonatal mortality

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

Incidence of common opportunistic infections among HIV-infected children on ART at Debre Markos referral hospital, Northwest Ethiopia: a retrospective cohort study.

BACKGROUND:Opportunistic infections (OIs) are the leading cause of morbidity and mortality among children living with human immunodeficiency virus (HIV). For better treatments and interventions, current and up-to-date information concerning occurrence of opportunistic infections in HIV-infected children is crucial. However, studies regarding the incidence of common opportunistic infections in HIV-infected children in Ethiopia are very limited. Hence, this study aimed to determine the incidence of opportunistic infections among HIV-infected children on antiretroviral therapy (ART) at Debre Markos Referral Hospital. METHODS:A facility-based retrospective cohort study was undertaken at Debre Markos Referral Hospital for the period of January 1, 2005 to March 31, 2019. A total of 408 HIV-infected children receiving ART were included. Data from HIV-infected children charts were extracted using a data extraction form adapted from ART entry and follow-up forms. Data were entered using Epi-data™ Version 3.1 and analyzed using Stata™ Version 14. The Kaplan Meier survival curve was used to estimate the opportunistic infections free survival time. Both bi-variable and multivariable Cox proportional hazard models were fitted to identify the predictors of opportunistic infections. RESULTS:This study included the records of 408 HIV-infected children-initiated ART between the periods of January 1, 2005 to March 31, 2019. The overall incidence rate of opportunistic infections during the follow-up time was 9.7 (95% CI: 8.13, 11.48) per 100 child-years of observation. Tuberculosis at 29.8% was the most commonly encountered OI at follow-up. Children presenting with advanced disease stage (III and IV) (AHR: 1.8, 95% CI: 1.2, 2.7), having "fair" or "poor" ART adherence (AHR: 2.6, 95% CI: 1.8, 3.8), not taking OI prophylaxis (AHR:1.6, 95% CI: 1.1, 2.4), and CD4 count or % below the threshold (AHR:1.7, 95% CI: 1.1, 2.6) were at a higher risk of developing opportunistic infections. CONCLUSIONS:In this study, the incidence rate of opportunistic infections among HIV-infected children remained high. Concerning predictors, such as advanced disease stage (III and IV), CD4 count or % below the threshold, "fair" or "poor" ART adherence, and not taking past OI prophylaxis were found to be significantly associated with OIs

Tuberculous lesions not detected by routine abattoir inspection: the experience of the Hossana municipal abattoir, southern Ethiopia

Summary The efficacy of the meat inspection procedures implemented for the detection of tuberculous cattle was evaluated by testing for bovine tuberculosis in 751 animals. The study involved routine inspection at slaughter, collection of tissues for detailed examination in the laboratory, and bacteriological investigation to identify Mycobacterium bovis. Of the 751 carcasses examined, 34 (4.5%) were found to have tuberculous lesions. Routine abattoir inspection detected only 29.4% of the carcasses with visible lesions. Eighty-four percent of the tuberculous lesions were found in the lungs and thoracic lymph nodes, 11.5% in the lymph nodes of the head, and the remaining 4.5% in the mesenteric and other lymph nodes of the carcasses. In addition, M. bovis was isolated from a carcass that presented no gross tuberculosis lesions. The low sensitivity of routine abattoir inspection demonstrates that existing necropsy procedures should be improved

Dokaz protutijela protiv velikog metilja Fasciola hepatica u goveda na otoku Ulleung, Koreja.

We performed a cross-sectional study to estimate the seroprevalence of Fasciola hepatica in herds of cattle on Ulleung island, Korea. Blood samples were collected from randomly selected cattle and the sera were separated and analysed with an ELISA to detect antibodies against F. hepatica. The positive samples were classified as mildly, moderately or strongly positive. Out of 405 cattle sera assessed, 38 (9.4%) were seropositive for antibodies against F. hepatica. From these, 2.5% each were moderately or strongly positive and 4.4% were mildly positive. A significantly higher seroprevalence (P<0.05) was observed in young animals (<2 y old, 15.3%) compared to adults (≥2 y old, 5.4%), while no significant difference in seropositivity was found between male and female animals. This is the the first report of F. hepatica seroprevalence in cattle herds in Korea. These findings may be used to establish a base-line of information for future investigations focused on the significance of F. hepatica in Korea.Provedeno je presječno istraživanje radi procjene seroprevalencije invadiranosti velikim metiljem Fasciola hepatica u stadima goveda na otoku Ulleung u Koreji. Uzorci krvi bili su uzeti od nasumce odabranih goveda, a odvojeni uzorci seruma bili su pretraženi imunoenzimnim testom na prisutnost protutijela specifičnih za velikog metilja. Pozitivni uzorci bili su svrstani u skupine: slabo, umjereno i jako pozitivni. Od 405 pretraženih uzoraka seruma, 38 (9,4%) je bilo pozitivnih na protutijela specifična za metilj F. hepatica. Od toga je 2,5% uzoraka bilo umjereno ili jako pozitivno, a 4,4% slabo pozitivno. Značajno veća seroprevalencija (P<0,05) ustanovljena je u mladih životinja (u dobi manjoj od dvije godine, 15,3%) u usporedbi s odraslima (≥2 godine, 5,4%), dok nije ustanovljena značajna razlika u seropozitivnosti između mužjaka i ženki. Ovo je prvo izvješće o seroprevalenciji velikog metilja u stadima goveda u Koreji. Nalazi mogu biti od koristi za buduća istraživanja o značenju velikog metilja F. hepatica u Koreji

Dokaz protutijela protiv velikog metilja Fasciola hepatica u goveda na otoku Ulleung, Koreja.

We performed a cross-sectional study to estimate the seroprevalence of Fasciola hepatica in herds of cattle on Ulleung island, Korea. Blood samples were collected from randomly selected cattle and the sera were separated and analysed with an ELISA to detect antibodies against F. hepatica. The positive samples were classified as mildly, moderately or strongly positive. Out of 405 cattle sera assessed, 38 (9.4%) were seropositive for antibodies against F. hepatica. From these, 2.5% each were moderately or strongly positive and 4.4% were mildly positive. A significantly higher seroprevalence (P<0.05) was observed in young animals (<2 y old, 15.3%) compared to adults (≥2 y old, 5.4%), while no significant difference in seropositivity was found between male and female animals. This is the the first report of F. hepatica seroprevalence in cattle herds in Korea. These findings may be used to establish a base-line of information for future investigations focused on the significance of F. hepatica in Korea.Provedeno je presječno istraživanje radi procjene seroprevalencije invadiranosti velikim metiljem Fasciola hepatica u stadima goveda na otoku Ulleung u Koreji. Uzorci krvi bili su uzeti od nasumce odabranih goveda, a odvojeni uzorci seruma bili su pretraženi imunoenzimnim testom na prisutnost protutijela specifičnih za velikog metilja. Pozitivni uzorci bili su svrstani u skupine: slabo, umjereno i jako pozitivni. Od 405 pretraženih uzoraka seruma, 38 (9,4%) je bilo pozitivnih na protutijela specifična za metilj F. hepatica. Od toga je 2,5% uzoraka bilo umjereno ili jako pozitivno, a 4,4% slabo pozitivno. Značajno veća seroprevalencija (P<0,05) ustanovljena je u mladih životinja (u dobi manjoj od dvije godine, 15,3%) u usporedbi s odraslima (≥2 godine, 5,4%), dok nije ustanovljena značajna razlika u seropozitivnosti između mužjaka i ženki. Ovo je prvo izvješće o seroprevalenciji velikog metilja u stadima goveda u Koreji. Nalazi mogu biti od koristi za buduća istraživanja o značenju velikog metilja F. hepatica u Koreji

A systems and partnership approach to agricultural research for development: Lessons from Ethiopia

In spite of the availability of several improved agricultural technologies generated by the research system in Ethiopia over the last four decades, adoption of these innovations by smallholder farmers has been very low. This has led to stagnation of agricultural productivity and low crop yields, exposing the country to recurrent food shortfalls and national food insecurity. The old approach to agricultural research emphasized developing new technologies mainly through onstation research that were then supposed to reach farmers through the public-sector extension system. The Ethiopian Institute of Agricultural Research (EIAR) has in recent years introduced a shift in agricultural research for development, which is based on the innovation systems approach that involved cultivating partnerships with several actors along the value chain, especially farmers, farmers’ cooperatives and input suppliers. This paper presents the methodology used to facilitate agricultural innovations and the diffusion of new technologies and illustrates the outcomes of this initiative with regard to technology adoption, productivity growth and the market orientation of production. The authors use examples from experiences in scaling up three grain legumes. Compared to the three-year baseline average (2003–05), crop output increased nationally by 89%, 85% and 97% in 2008 for common bean, chickpea and lentil respectively. Nationally, 53–59% of the output growth is attributable to yield growth due to technological change, while the balance is due to area expansion. These results affirm that the new approach has led to accelerated adoption of new and high-yielding or low-risk varieties

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