检索结果-内蒙古大学图书馆

Provenance and paleotectonic setting of the triassic to lower jurassic adigrat sandstone around Yejube, Blue Nile Basin, Central Ethiopia

引用

Arabian Journal of Geosciences 2025年第6期18卷 1-19页

作者： Kassahun, Muluken Zemene, Demeke Haileslassie, Teame Meshesha, Daniel Department of Geology College of Natural and Computational Science Woldia University Woldia Ethiopia Department of Geology College of Applied Science Addis Ababa Science and Technology University Addis Ababa Ethiopia Mineral Exploration Extraction and Processing Center of Excellence Addis Ababa Science and Technology University Addis Ababa Ethiopia

Mineralogical and geochemical (major and trace element) data are presented for the Adigrat Sandstone exposed around Yejube, located in the Blue Nile Basin of central Ethiopia, to determine its provenance and tectonic setting. On the Q-F-L diagram, the Yejube Adigrat Sandstone falls within the sublitharenite to quartzarenite fields, consistent with its chemical classification. The Yejube Adigrat Sandstone comprises a higher amount of sub-rounded to rounded quartz grains (~ 89.98%), with subordinate amounts of rock fragments and feldspars associated with higher SiO₂/Al₂O₃ and K₂O/Na₂O ratios, which suggest that it is highly reworked, recycled, and matured. Mineralogical and major element analyses of the Yejube Adigrat Sandstone demonstrate a quartzose sedimentary provenance. However, the immobile trace elemental ratios (La/Sc, Th/Co, La/Co, Cr/Th, and Th/Sc), high LREE/HREE ratios, and low Eu/Eu* values (Eu/Eu* = 0.5) strongly support a felsic (granitic and gneissic) source. Furthermore, a comparison of provenance studies for the Adigrat Sandstone in the Yejube and Dejen–Gohatsion areas of the Blue Nile Basin and the Mekelle outlier indicates that the sediments of the former were primarily derived from felsic source rocks, similar to those of the Mekelle outlier, in contrast to the mafic to intermediate sources identified at Dejen–Gohatsion in the Blue Nile Basin. The higher quartz content (~ 89.98%), SiO₂/Al₂O₃, and K₂O/Na₂O ratios, the enrichment in immobile trace elements (e.g., La, Th, Zr, Co, Sc, Hf), the negative Eu anomaly, and the rare earth element (REE) pattern, which are almost like that of the typical average upper continental crust, infer that the Yejube Adigrat Sandstone was deposited in a passive margin tectonic setting. Moreover, the tectonic discrimination diagram for Yejube Adigrat sandstone indicates a passive margin tectonic setting.

关键词：

来源：评论

学校读者我要写书评

暂无评论

In vitro Anti-Leishmanial Activities of Methanol Extract of Brucea antidysenterica J.F. Mill Seeds and Its Solvent Fractions

引用

Journal of Experimental Pharmacology 2023年 15卷 123-135页

作者： Ketema, Tasisa Tadele, Markos Gebrie, Zewdie Makonnen, Eyasu Hailu, Asrat Abay, Solomon M. Department of Pharmacology and Clinical Pharmacy School of Pharmacy College of Health Science Addis Ababa University Addis Ababa Ethiopia Animal Health Research Program Ethiopian Institute of Agricultural Research Holetta Ethiopia Center for Innovative Drug Development and Therapeutic Trials for Africa (CDT Africa) College of Health Sciences Addis Ababa University Addis Ababa Ethiopia Department of Microbiology Immunology and Parasitology College of Health Sciences Addis Ababa University Addis Ababa Ethiopia

Introduction: Leishmaniasis is one of the neglected tropical diseases, threatening lives of about 350 million people globally. Brucea antidysenterica seeds are used for the treatment of cutaneous leishmaniasis in the traditional medicine in Ethiopia. Objective: This study aimed to evaluate Brucea antidysenterica seeds’ anti-leishmanial activity in vitro. Methods: The crude (80% methanol) extract of Brucea antidysenterica seeds and its fractions were evaluated for their anti-leishmanial activities against promastigotes and intracellular amastigotes of Leishmania donovani and Leishmania aethiopica, and for their cytotoxic effects against mammalian cells. The quantitative estimations of total phenolic compounds (TPCs), flavonoids (TFCs) and alkaloids (TACs) were determined, spectrophotometrically. Median inhibitory concentration (IC₅₀) and median cytotoxic concentration (CC₅₀) of the extract and its solvent fractions were calculated using GraphPad Prism 9.1.0 computer software. Data was presented as mean ± standard error of the mean (SEM). Results: The crude extract and its hexane, ethyl acetate and butanol fractions showed anti-leishmanial activities, with IC₅₀ values of 4.14–60.12 µg/mL against promastigotes, and 6.16–40.12 µg/mL against amastigotes of both Leishmania species. They showed moderate cytotoxicity against Vero cell lines and peritoneal mice macrophages, with CC₅₀ values of 100–500 µg/mL, but >1600 µg/mL against red blood cells. Selectivity indices ranged from 7.97 to 30.97. The crude extract, and its ethyl acetate and hexane fractions possessed 54.78–127.72 mg of gallic acid equivalent TPC, 18.30–79.21 mg of quercetin equivalent TFC, and 27.62–97.22 mg of atropine equivalent TAC per gram of extracts. Conclusion: The seeds of the plant possessed anti-leishmanial activities against L. aethiopica and L. donovani that might provide a scientific justification for its use in the treatment of leishmaniasis by traditio

关键词： amastigote anti-leishmanial activity Brucea antidysenterica seeds Leishmania aethiopica Leishmania donovani promastigote

来源：评论

学校读者我要写书评

暂无评论

Site characterization using active and passive surface wave analysis: a case study for some representative sites in addis ababa, Ethiopia

引用

Arabian Journal of Geosciences 2024年第11期17卷 1-20页

作者： Wolde, Biruk Ayele, Atalay Hailmariam, Turfat Geremew, Zemenu School of Earth Science College of Natural and Computational Sciences Addis Ababa University Addis Ababa Ethiopia Department of Geology College of Engineering Debre Berhan University Debre Berhan Ethiopia Institute of Geophysics Space Science and Astronomy Addis Ababa University Addis Ababa Ethiopia

The subsurface condition of addis ababa City is heterogeneous and distinctly varies from place to place, ranging from very soft soil formation to competent rock mass units. This study characterized subsurface variations and estimated site-specific average shear wave velocity changes within the upmost 30 m (Vs30) geological medium at representative sites. We implemented combined active-source Multichannel Analysis of Surface Waves (MASW) and passive-source Microtremor Array Measurements (MAM) surface wave methods to effectively characterize and estimate the shear wave velocity (Vs) of shallow and deep subsurface materials at nine selected sites in the city. The Vs30 of geological profile at the selected sites was attained by joint dispersion inversion analysis of active and passive surface wave data. The result shows that the Vs30 calculated at the selected sites in the city ranges from 256 to 1787 m/s. The study results were used for site classification of near-surface geological materials according to the Vs30 classification guideline proposed by the National Earthquake Hazards Reduction program (NERHP) and Eurocode-8 (EC-8) classification. Based on Vs30 results, the near-surface materials at the representative sites of the study area are categorized as site types C and D as per NEHRP and as site types B and C as per EC-8. Exceptionally, the rocky Arat Killo site is classified as a site type A in accordance with both NEHRP and EC-8. In addition, we validated acquired shear wave velocity profiles with local geological and engineering geological mapping and geotechnical boreholes proximate to measured sites to control the final inversion quality of Vs values to the corresponding layers. Since this study is the first in addis ababa City, the findings will be used for preliminary local site characterization and site specific seismic response analysis.

关键词：

来源：评论

学校读者我要写书评

暂无评论

Multi-channel Convolutional Neural Network for Hate Speech Detection in Social Media 9th

Multi-channel Convolutional Neural Network for Hate Speech D...

引用

9th EAI International Conference on Advancement of science and Technology, ICAST 2021

作者： Abebaw, Zeleke Rauber, Andreas Atnafu, Solomon IT Doctoral Program Addis Ababa University Addis Ababa Ethiopia Institute of Information Systems Engineering Technical University of Vienna Vienna Austria Department of Computer Science Addis Ababa University Addis Ababa Ethiopia

ISBN: (纸本)9783030937089

As online social media content continues to grow, so does the spread of hate speech. Hate speech has devastating consequences unless it is detected and monitored early. Recently, deep neural network-based hate speech detection models, particularly conventional single-channel Convolutional Neural Network (CNN), have achieved remarkable performance. However, the effectiveness of the models depends on the type of language they are trained on and the training data size. We argue that the effectiveness of the models could further be enhanced if we use multi-channel CNN models even for under-resourced languages that have limited training data size. This is because the single-channel CNN might fail to consider the potential effect of multiple channels to generate better features, which is not well investigated for hate speech detection. Therefore, in this work, we explore the use of multi-channel CNN to extract better features from different channels in an end-to-end manner on top of a word2vec embedding layer. Tested on a new small-scale Amharic hate speech dataset containing 2000 annotated social media comments, the experimental results show that the proposed multi-channel CNN model outperforms the single-channel CNN models but underperform from the baseline Support Vector Machine (SVM) with an average F-score of 81.3%, 78.2%, and 92.5% respectively. The finding of the study implies that the proposed MC-CNN model can be used as an alternative solution for hate speech detection using a deep learning approach when dataset scarcity is an issue. © 2022, ICST Institute for Computer sciences, Social Informatics and Telecommunications Engineering.

关键词： Embeddings

来源：评论

学校读者我要写书评

暂无评论

Enhancing cement mechanical properties with cellulose nanocrystals as supplementary cementitious materials

引用

Discover Civil Engineering 2025年第1期2卷 1-17页

作者： Firdissa, Benti Degefa, Sileshi Mulugeta, Eyobel Sithole, Dingane Environmental Protection Authority Addis Ababa Ethiopia Center for Environmental Science Collage of Natural and Computational Sciences Addis Ababa University Addis Ababa Ethiopia Ministry of Innovation and Technology Bio and Emerging Technology Institute Addis Ababa Ethiopia University of Zimbabwe Harare Zimbabwe

Cement production is a major contributor to global CO₂ emissions, responsible for approximately 5–10% of total emissions, with the challenges being even more pronounced in developing nations like Ethiopia. This study investigates the potential of cellulose nanocrystals (CNCs), derived from sugarcane bagasse, as supplementary cementitious materials (SCMs) to improve the mechanical properties and sustainability of concrete. CNCs were incorporated into Ordinary Portland Cement (OPC) at varying percentages (5%, 10%, and 15%), and their effects on consistency, setting times, compressive strength, and unit weight were analyzed. Results reveal that CNCs enhance the hydration process, delay setting times within acceptable standards, and significantly improve compressive strength at optimal replacement levels. The study highlights a 10% CNC incorporation as the optimal mix, achieving a compressive strength of 42.4 MPa, representing a 13.9% improvement compared to the control mix (37.2 MPa). These findings demonstrate CNCs’ potential to enhance concrete performance while reducing the environmental footprint of cement production, offering a sustainable pathway for Ethiopia's construction industry.

关键词：

来源：评论

学校读者我要写书评

暂无评论

New fragmented electro-active biofilm (FAB) reactor to increase anode surface area and performance of microbial fuel cell

引用

Environmental Systems Research 2021年第1期10卷 1-16页

作者： Atnafu, Tesfalem Leta, Seyoum Center for Environmental Science Addis Ababa University Addis Ababa Ethiopia Department of Biological Science College of Natural and Computational Sciences Mettu University Mettu Ethiopia

Background: Microbial fuel cell (MFC) technology is a promising sustainable future energy source with a renewable and abundant substrate. MFC critical drawbacks are anode surface area limitations and electrochemical loss. Recent studies recommend thick anode biofilm growth due to the synergetic effect between microbial communities. Engineering the anode surface area is the prospect of MFC. In this study, a microbial electrode jacket dish (MEJ-dish) was invented, first time to the authors’ knowledge, to support MFC anode biofilm growth. The MFC reactor with MEJ-dish was hypothesized to develop a variable biofilm thickens. This reactor is called a fragmented electro-active biofilm-microbial fuel cell (FAB-MFC). It was optimized for pH and MEJ-dish types and tested at a bench-scale. Results: Fragmented (thick and thin) anode biofilms were observed in FAB-MFC but not in MFC. During the first five days and pH 7.5, maximum voltage (0.87 V) was recorded in MFC than FAB-MFC;however, when the age of the reactor increases, all the FAB-MFC gains momentum. It depends on the MEJ-dish type that determines the junction nature between the anode and MEJ-dish. At alkaline pH 8.5, the FAB-MFC generates a lower voltage relative to MFC. On the contrary, the COD removal was improved regardless of pH variation (6.5–8.5) and MEJ-dish type. The bench-scale studies support the optimization findings. Overall, the FAB improves the Coulombic efficiency by 7.4–9.6 % relative to MFC. It might be recommendable to use both FAB and non-FAB in a single MFC reactor to address the contradictory effect of increasing COD removal associated with the lower voltage at higher pH. Conclusions: This study showed the overall voltage generated was significantly higher in FAB-MFC than MFC within limited pH (6.5–7.5);relatively, COD removal was enhanced within a broader pH range (6.5–8.5). It supports the conclusion that FAB anode biofilms were vital for COD removal, and there might be a mutualism even though not

关键词： Microbial fuel cells

来源：评论

学校读者我要写书评

暂无评论

Amharic Semantic Information Retrieval System 1

引用

12th International Joint Conference on Knowledge Discovery, Knowledge Engineering and Knowledge Management, IC3K 2020

作者： Yeshambel, Tilahun Mothe, Josiane Assabie, Yaregal IT PhD Program Addis Ababa University Addis Ababa Ethiopia INSPE Univ. de Toulouse IRIT UMR5505 CNRS Toulouse France Department of Computer Science Addis Ababa University Addis Ababa Ethiopia

ISBN: (数字)9783031146022

ISBN: (纸本)9783031146015

Amharic is the official language of Ethiopia, currently having a population of over 118 million. Developing effective information retrieval (IR) system for Amharic has been a challenging task due to limited resources coupled with complex morphology of the language. This paper presents the development of Amharic semantic IR system using query expansion based on deep neural learning model and WordNet. In order to optimize the retrieval result, we propose Amharic text representation using root forms of words applied for stopword identification, indexing, term matching and query expansion. Comparisons are made with the conventional stem-based text representation for information retrieval, and we show that using the root forms of words is better for both resource construction and system development. The effectiveness of the proposed Amharic semantic IR system is evaluated on Amharic Adhoc Information Retrieval Test Collection (2AIRTC). © 2022, Springer Nature Switzerland AG.

关键词： Information retrieval

来源：评论

学校读者我要写书评

暂无评论

Nutritional and Functional Potentials of Wheat, Cowpea, and Yam Composite Flours on Bread Formulations: Effect of Blending Ratio and Baking Parameters

SSRN

引用

SSRN 2024年

作者： Tsegay, Negasi Admassu, Habtamu Tizazu, Belachew Zegale Gosu, Amsalu Department of chemical Engineering Addis Ababa Science and Technology University Addis Ababa Ethiopia Biotechnology and bioprocess center of excellence Addis Ababa Science and Technology University Addis Ababa Ethiopia Food process Engineering program Addis Ababa Science and Technology University Addis Ababa Ethiopia

Bread, a staple food, primarily utilizes wheat as the main ingredient due to its high carbohydrate content, despite being considered nutritionally deficient. To address this limitation, this research explored the use of composite flours in combination with affordable legumes and root tubers. Additionally, composite flours offer economic advantages by reducing wheat imports and promoting local utilization of crops that are underutilized. In the present study, bread wheat flour was substituted with cowpea and yam flours. The raw materials were processed into flour, and the proximate composition, functional properties, and anti-nutritional contents of the individual and blend flours (B1= 85% bread wheat + 5% cowpea + 10% yam, B2= 70% bread wheat + 10% cowpea + 20% yam, and B3= 55% bread wheat + 15% cowpea + 30% yam) were analyzed. The main findings revealed that the incorporation of cowpea and yam flours led to significant increases (p © 2024, The Authors. All rights reserved.

关键词： Swelling

来源：评论

学校读者我要写书评

暂无评论

Analysis of Hydrological Response to Climate and Land Use Land Cover Changes of Jewha Watershed Using Swat Model, Ethiopia

SSRN

引用

SSRN 2024年

作者： Gebrie, Dereje Belliethathan, Satishkumar Ayenew, Tenalem Addis Ababa University College of Natural and Computational Science Center for Environmental Science P.O. Box 1176 Addis Ababa Ethiopia Addis Ababa University College of Natural and Computational Science School of Earth Sciences P.O. Box 1176 Addis Ababa Ethiopia

Climate variability and LULC changes can affect runoff. Water stress is a major problem in the upper and lower part of the Jewuha watershed in Ethiopia. This study aimed to examine the long-term patterns of freshwater availability in the study area under climate and land use/land cover changes by analyzing long-term climate data using SWAT models. The SWAT model was used to simulate the runoff data. Seating and validating SWAT results were done by selecting sensitive parameters in the watershed. The result of the study showed that surface runoff increased (1.59, 10.62, and 23.58 m3/s in 1995, 2005, and 2015 respectively) in S2, S3, and S4 scenarios with constant climate conditions (C1) by using S1 as a baseline. The LULC classes, including vegetation cover (natural forest and shrubland), experienced a shift from 34.87% in 1984 to 23.62% in 2015. The cultivated land, which was 38.67% in 1984, has changed to 51.44% in 2015. Due to a decrease in precipitation of 203.7 mm in climatic conditions C2, climate variability caused a decrease in runoff to 26.83 m3/s. With constant LULC (1984), an increase in precipitation to 381.6 mm (with scenarios S5 and S9) increased runoff to 96.37 m3/s. In general, the hydrology of the Jewha watershed is influenced by LULC and climatic variability in a significant and combined way. © 2024, The Authors. All rights reserved.

关键词： SWAT

来源：评论

学校读者我要写书评

暂无评论

Optimizing Ethiopian Greenhouse Gas Inventories: A Breakthrough in Cement Sector Accuracy Through Customized Clinker-Specific Emission Factors

SSRN

引用

SSRN 2024年

作者： Firdissa, Benti Degefa, Sileshi Mulugeta, Eyobel Sithole, Dingane Environmental Protection Authority Addis Ababa Ethiopia Center for environmental science Collage of Natural and computational Sciences Addis Ababa university Addis Ababa Ethiopia Addis Ababa University Ethiopia Bees Consultancy Ethiopia

Cement, vital for global construction, faces challenges in accurately quantifying CO2 emissions in Ethiopia. Discrepancies arise from country-specific factors, statistical variations, and data challenges. This study stresses emission factors (EFs) and the imperative of defining CO2 accounting boundaries. To overcome issues, factory-level measurements for diverse clinker and cement production were conducted through on-site surveys. Utilizing IPCC standards, results reveal overestimations in earlier assessments due to specific CO2 emission factors, unaddressed technological transitions, and neglected clinker-to-cement ratios. The study underscores the necessity for precise CO2 assessments, emphasizing refined methodologies for informed policy decisions and sustainable practices in the global construction sector. © 2024, The Authors. All rights reserved.

关键词： Cements

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：