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Gebeyehu, Getaneh,Soromessa, Teshome,Bekele, Tesfaye,Teketay, Demel The Ecological Society of Korea 2019 Journal of Ecology and Environment Vol.43 No.1
Background: Tropical montane forests played an important role in the provision of ecosystem services. The intense degradation and deforestation for the need of agricultural land expansion result in a significant decline of forest cover. However, the expansion of agricultural land did not completely destruct natural forests. There remain forests inaccessible for agricultural and grazing purpose. Studies on these forests remained scant, motivating to investigate biomass and soil carbon stocks. Data of biomass and soils were collected in 80 quadrats ($400m^2$) systematically in 5 forests. Biomass and disturbance gradients were determined using allometric equation and disturbance index, respectively. The regression modeling is employed to explore the spatial distribution of carbon stock along disturbance and environmental gradients. Correlation analysis is also employed to identify the relation between site factors and carbon stocks. Results: The result revealed that a total of 1655 individuals with a diameter of ${\geq}5cm$, representing 38 species, were measured in 5 forests. The mean aboveground biomass carbon stocks (AGB CS) and soil organic carbon (SOC) stocks at 5 forests were $191.6{\pm}19.7$ and $149.32{\pm}6.8Mg\;C\;ha^{-1}$, respectively. The AGB CS exhibited significant (P < 0.05) positive correlation with SOC and total nitrogen (TN) stocks, reflecting that biomass seems to be a general predictor of SOCs. AGB CS between highly and least-disturbed forests was significantly different (P < 0.05). This disturbance level equates to a decrease in AGB CS of 36.8% in the highly disturbed compared with the least-disturbed forest. In all forests, dominant species sequestrated more than 58% of carbon. The AGB CS in response to elevation and disturbance index and SOC stocks in response to soil pH attained unimodal pattern. The stand structures, such as canopy cover and basal area, had significant positive relation with AGB CS. Conclusions: Study results confirmed that carbon stocks of studied forests were comparable to carbon stocks of protected forests. The biotic, edaphic, topographic, and disturbance factors played a significant variation in carbon stocks of forests. Further study should be conducted to quantify carbon stocks of herbaceous, litter, and soil microbes to account the role of the whole forest ecosystem.
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Getaneh Gebeyehu,Teshome Soromessa,Tesfaye Bekele,Demel Teketay 한국생태학회 2019 Journal of Ecology and Environment Vol.43 No.1
Background: Tropical montane forests played an important role in the provision of ecosystem services. The intense degradation and deforestation for the need of agricultural land expansion result in a significant decline of forest cover. However, the expansion of agricultural land did not completely destruct natural forests. There remain forests inaccessible for agricultural and grazing purpose. Studies on these forests remained scant, motivating to investigate biomass and soil carbon stocks. Data of biomass and soils were collected in 80 quadrats (400m2) systematically in 5 forests. Biomass and disturbance gradients were determined using allometric equation and disturbance index, respectively. The regression modeling is employed to explore the spatial distribution of carbon stock along disturbance and environmental gradients. Correlation analysis is also employed to identify the relation between site factors and carbon stocks. Results: The result revealed that a total of 1655 individuals with a diameter of ≥ 5 cm, representing 38 species, were measured in 5 forests. The mean aboveground biomass carbon stocks (AGB CS) and soil organic carbon (SOC) stocks at 5 forests were 191.6 ± 19.7 and 149.32 ± 6.8 Mg C ha−1, respectively. The AGB CS exhibited significant (P < 0.05) positive correlation with SOC and total nitrogen (TN) stocks, reflecting that biomass seems to be a general predictor of SOCs. AGB CS between highly and least-disturbed forests was significantly different (P < 0.05). This disturbance level equates to a decrease in AGB CS of 36.8% in the highly disturbed compared with the least-disturbed forest. In all forests, dominant species sequestrated more than 58% of carbon. The AGB CS in response to elevation and disturbance index and SOC stocks in response to soil pH attained unimodal pattern. The stand structures, such as canopy cover and basal area, had significant positive relation with AGB CS. Conclusions: Study results confirmed that carbon stocks of studied forests were comparable to carbon stocks of protected forests. The biotic, edaphic, topographic, and disturbance factors played a significant variation in carbon stocks of forests. Further study should be conducted to quantify carbon stocks of herbaceous, litter, and soil microbes to account the role of the whole forest ecosystem.
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Kebena Gebeyehu Motora,Chang-Mou Wu,Saba Naseem 한국공업화학회 2021 Journal of Industrial and Engineering Chemistry Vol.102 No.-
For environmental scientists, developing an efficient, stable, and recyclable solar light photocatalyst is achallenging issue. Even though powder photocatalysts have excellent photocatalytic activity, their recyclabilityand reusability is a noteworthy problem. Therefore, it is very crucial to develop a new photocatalysissystem that possesses efficient photocatalytic activity, excellent stability, and ease ofrecyclability, and is free of secondary pollution. Herein, a solar light active WO2.72/Fe3O4 nanocompositephotocatalyst was immobilized in hydrophobic porous recycled triacetate cellulose (rTAC) to solve thereusability problem and was electrospun on hydrophilic nonwoven polyvinyl alcohol (PVA) to fabricatea self-floatable recyclable Janus membrane. TAC possesses very important properties such as high moisturepermeability and high light transmittance, which helps all the light irradiated to be utilized by thephotocatalyst and hydrophobicity, which increases the ease of floating. The recyclable Janus membranewas purposefully designed so that the contaminated water can be attracted by PVA due to its hydrophilicityand pass to porous rTAC, where the pollutant and the photocatalyst come into contact and photocatalysistakes place, while the hydrophobicity of the rTAC makes the Janus membrane float on the surface ofpolluted water. The photocatalytic property of the synthesized recyclable Janus membrane was studiedfor the photodegradation of rhodamine B (Rh B) and methylene blue (MB) as well as the photoreductionof the carcinogenic pollutant Cr(VI) under solar light irradiation. The recyclable Janus membrane presentedan outstanding photocatalytic property for the photodegradation of Rh B and MB dyes and thephotoreduction of Cr(VI). It also displayed excellent cyclic stability and ease of recyclability for bothorganic and inorganic pollutants after multiple experimental cycles. The Janus membrane also presentedbetter photocatalytic activity than previously reported photocatalysts for MB photodegradation. Therefore, the developed interfacial photocatalysis system and the recyclable Janus membrane arepromising candidates for environmental remediation under solar light irradiation. This study paves theway for the design of an environmentally friendly, effective, and stable photocatalyst for wastewatertreatment.
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Does satellite television programing satisfy ethiopian secondary school students?
SungWan Kim,Gebeyehu Bogale APEC국제교육협력원 2015 Asia-Pacific Cybereducation Journal Vol.11 No.1
The Ethiopian development plans have dealt with the education sector as a key strategic pillar. There have been a lot of educational efforts. In particular, to cope with a lack of qualified teachers, lack of good teaching models, and remote rural regions separated from educational benefits, the Ethiopian Ministry of Education has made efforts to utilize educational media, such as satellite TV programing, to improve the quality of secondary education for last decade. However, there was lack of national investigation in the aspect of systemic evaluation to measure the effectiveness of the satellite TV programing. This study aims to investigate the actual practice and effectiveness of the satellite TV programing in Ethiopian secondary schools. To achieve the goal, one questionnaire was developed based on the CIPP model. Two secondary schools were selected and 228 students (Grade 9-12) participated in the survey. Data collected from them were utilized for descriptive & frequencies analysis, chi-square test, and multiple regression analysis. The results indicated that Ethiopian students utilizing satellite TV programing scored highly in the evaluation areas of context, input, process, and product of the program. It was also found that learning demand, learning content, and class management were factors affecting the satisfaction in the satellite TV programing. These findings suggested that satellite TV programing could play an important role in improving the quality of Ethiopian secondary education. As a conclusion, several educational and administrative strategies to improve the TV program were recommended.
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마찰대전 기반의 에너지 하베스팅에서 다층박막적층법의 응용
합타무게베예후멩게 ( Habtamu Gebeyehu Menge ),박용태 ( Yong Tae Park ) 한국복합재료학회 2022 Composites research Vol.35 No.6
마찰대전 나노발전기(triboelectric nanogenerator, TENG) 장치는 최근 몇 십여년 동안 많은 관심을 불러일으켰다. 주변에서 버려지는 에너지 중 기계적 에너지를 수확하는 기술 중 하나인 TENG 기술은 정전기 유도 및 마찰 대전의 이중 효과로 얻어진다. 특히, 나노 로봇이나 마이크로 전자기계 장치와 같은 초소형 전자 장치의 급속한 발전으로 초박막 장치에 대한 수요가 크게 증가했다. TENG 기술의 급속한 성장과 함께 높은 전기 출력 성능과 저렴한 제조 기술을 갖춘 적절한 마찰대전 재료를 선택하는 것은 지속 가능한 나노발전기 작동에 필수적이다. 최근 이러한 문제를 극복하기 위한 하나의 방법으로 다층박막적층법 (혹은 층상자기조립법, layer-by-layer (LbL) self-assembly technique)이 고려되고 있다. 이 LbL 자기조립 기술은 TENG의 성능 향상 및 응용 분야에서 두께 문제를 성공적으로 극복할 뿐만 아니라 저비용, 친환경 공정을 제시했으며 대규모 생산에 사용할 수 있다. 본 리뷰에서는 TENG 장치를 위한 LbL 기반의 소재 개발에 있어 최근의 연구들을 검토하였으며, 현재까지 검토된 에너지 수확 장치 분야에서의 잠재력을 살펴보았다. LbL 기술을 적용하여 제작한 TENG 장치의 이점에 대해 논의하고, 마지막으로 다양한 초박형 TENG 구현을 위한 본 제작 기술의 방향과 관점을 간략하게 제시하였다. Triboelectric nanogenerator (TENG) devices have generated a lot of interest in recent decades. TENG technology, which is one of the technologies for harvesting mechanical energy among the energy wasted in the environment, is obtained by the dual effect of electrostatic induction and triboelectric charging. Recently, a multilayer thin film stacking method (or layer-by-layer (LbL) self-assembly technique) is being considered as a method to improve the performance of TENG and apply it to new fields. This LbL assembly technology can not only improve the performance of TENG and successfully overcome the thickness problem in applications, but also present an inexpensive, environmentally friendly process and be used for large-scale and mass production. In this review, recent studies in the accomplishment of LbL-based materials for TENG devices are reviewed, and the potential for energy harvesting devices reviewed so far is checked. The advantages of the TENG device fabricated by applying the LbL technology are discussed, and finally, the direction and perspective of this fabrication technology for the implementation of various ultra-thin TENGs are briefly presented.
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안성희,Kebede Gebeyehu Mekete,김병주 사단법인 한국질량분석학회 2023 Mass spectrometry letters Vol.14 No.4
QuEChERS is used worldwide as a universal sample preparation method with many benefits, such as being quick, easy, cheap, effective, rugged and safe. This study examined whether QuEChERS can be employed in isotope dilution mass spectrometry (ID-MS) for accurate analysis of pesticides in food. The ratios of fortified values and measured values of malathion and fenitrothion using the QuEChERS method were compared with those using the solid phase extract (SPE) method which was previously used in this laboratory. The separations of the two pesticides on DB-5MS and VF-1701MS columns were compared. Malathion and fenitrothion were fortified into kimchi cabbage and pretreated with the QuEChERS method and the SPE method. The results obtained using the DB-5MS column varied according to the sample preparation method, column and pesticide level. Using the VF-1701 column, ratios were 98–102% by both QuEChERS and Carb/NH 2 SPE method for all fortification level. Malathion and fenitrothion were fortified into strawberry samples for comparison with kimchi cabbage. The results for the strawberry samples indicated that the ratios were not influenced by the sample preparation methods or GC column. The QuECh- ERS method could be acceptable in the ID-MS method for pesticide residue analysis in food, however other conditions should be carefully considered for accurate determination, such as the column, amount of analyte and food matrix.
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( Tadesse Amare ),( Gebeyehu Goshu ),( Berhan Tamir ) 한국축산학회(구 한국동물자원과학회) 2018 한국축산학회지 Vol.60 No.5
Background: Sheep production is a major component of the livestock sector in Ethiopia. The country owing to the large population of 30.70 million estimated numbers of sheep in the country and out of which about 72.14% are females, and 27.86% are males with diverse genetic resources. The real value of indigenous breeds was often under-estimated mostly due to their poor appearance and relatively low productivity. Developing countries in most cases opt for exotic breeds to increase animal productivity through crossbreeding or breed substitution without properly investigating the production potential of the indigenous breeds. The main objective of the research was to identify sheep flock composition and structure, farmers’ traits of interest and breeding objective of Wollo highland sheep, and their F<sub>1</sub> crossbreed progenies. Results: Smallholder farmers’ flock synthesized from breeding ewes, breeding rams, pre-weaned ewe lambs, pre-weaned ram lambs, unproductive ewes, castrated and fattened rams, with the percentage coverage of 29.2, 13.3, 15.5, 16.5, 12.4, and 12.5%, respectively. The maximum number of flock size was 289.0 sheep per flock and higher in the third stratum. The off-take rate percentage of the three strata presented as 21.9% in 1st stratum, 12% in the 2nd stratum, and 16.4% in the 3rd stratum and higher off-take rate recorded in the first stratum. Sheep producer’s traits of interest ranked by growth rate (first), body size (second) and marketing value was third rank. Communal breeding (random mating), village based controlled breeding, mixed type and private ram controlled breeding practice were comprised of 39.7, 61.7, 52 and 71.3%, respectively. The percentages of ewes per flock composition were presented as 36.5, 27.1 and 25.5%, respectively in the 3rd stratum, 2nd stratum and 3rd stratum in the order of their importance’s. Conclusion: Genetic improvement practices at smallholder sheep producers situation was showing promising outcome with indigenous Washera F<sub>1</sub> crossbred lambs and which designated for weaning rate, body size, marketing age, age at first lambing, good temperament and large litter size in the order of their rank. The contemporary breeding practice tendency indicated that, reduced flock size to improve flock productivity via crossbreeding practices.
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