Araya Asfaw

Addis Ababa University, Physics, Faculty Member

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Norazian Mohamed Noor (PhD)

Universiti Malaysia Perlis (UniMAP)

David Seamon

Kansas State University

Antonio Bula

Universidad del Norte - Barranquilla, Colombia

Kiran Dasari

University of Illinois at Urbana-Champaign

Syukri Muhammad Nur

Darma Persada University

Engr Sajid Chaudhary

University of Gujrat

Mohamed Abdrabbo

Agricultural Research Center

Akash Raza

University of Gujrat

Ihab Farag

University of New Hampshire

Sibel Pamukcu

Lehigh University

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Papers by Araya Asfaw

Air Quality Monitoring Assists Meeting the Sustainable Development Goals in Ethiopia

Advances in Science, Technology & Innovation/Advances in science, technology & innovation, 2024

Low-Cost Hourly Ambient Black Carbon Measurements at Multiple Cities in Africa

Environmental science & technology, Jul 2, 2024

The National Institute of Standards and Technology Very High Resolution Spectrometer, in Proceedings of the 8th Natl. Conf. on Synchrotron Radiation Research

Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 1994

High-resolution VUV absolute photo-absorption cross sections of N2 and rare gases

Optical Society of America Annual Meeting, 1992

We present absolute total photoabsorption cross sections measured with the Very High Resolution S... more We present absolute total photoabsorption cross sections measured with the Very High Resolution Spectrometer at the SURF-II synchrotron radiation source at the National Institute of Standards and Technology, with a resolution of 9 mÅ at 835 Å in the first order. The cross sections of N2 at the wavelengths of the OΠ(2s2p4-4P2s22p3 4S) multiplet are found to be 10 Mb at 834.467 Å, 0.3 Mb at 833.332 Å, and 0.05 Mb at 832.862 Å. This new high-resolution measurement confirms the 10 Mb value, which has given rise to some still-unsolved discrepencies in interpreting atmospheric observations of the OΠ emission.1 We also measure absolute cross sections in the continua of rare gases, including the argon 3s3p6np absorption windows at 425 Å.

The Waste Crisis

Time-resolved temperature measurements of radiatively heated tamped MgO foils by Kα absorption spectroscopy

Journal of Quantitative Spectroscopy & Radiative Transfer, Jul 1, 1995

In this paper we present time-resolved temperature measurements of a radiatively heated, thin tam... more In this paper we present time-resolved temperature measurements of a radiatively heated, thin tamped foil via Ka absorption spectroscopy. The sample foil was 1500 A MgO, tamped on both sides with 1000 A paralyene, and was heated by soft x-rays transmitted through the back side of a separate laser-irradiated 1500 A Au foil. The resulting plasma was then backlit by a separate laser-irradiated front-surface U foil, providing a time-resolved K-shell absorption spectrum over the duration of the heating phase. We compare the resulting data to synthetic spectra obtained from detailed simulations of the heating and expansion of the tamped foils, and find poor agreement. Much better agreement is obtained when we determine the temperatures through best-fit absorption spectra which assume temperatures >35% higher than predicted; the reason for this discrepancy is not yet understood.

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In-kitchen aerosol exposure in twelve cities across the globe

Environment International, 2022

Poor ventilation and polluting cooking fuels in low-income homes cause high exposure, yet relevan... more Poor ventilation and polluting cooking fuels in low-income homes cause high exposure, yet relevant global studies are limited. We assessed exposure to in-kitchen particulate matter (PM2.5 and PM10) employing similar instrumentation in 60 low-income homes across 12 cities: Dhaka (Bangladesh); Chennai (India); Nanjing (China); Medellín (Colombia); São Paulo (Brazil); Cairo (Egypt); Sulaymaniyah (Iraq); Addis Ababa (Ethiopia); Akure (Nigeria); Blantyre (Malawi); Dar-es-Salaam (Tanzania) and Nairobi (Kenya). Exposure profiles of kitchen occupants showed that fuel, kitchen volume, cooking type and ventilation were the most prominent factors affecting in-kitchen exposure. Different cuisines resulted in varying cooking durations and disproportional exposures. Occupants in Dhaka, Nanjing, Dar-es-Salaam and Nairobi spent > 40% of their cooking time frying (the highest particle emitting cooking activity) compared with ∼ 68% of time spent boiling/stewing in Cairo, Sulaymaniyah and Akure. The highest average PM2.5 (PM10) concentrations were in Dhaka 185 ± 48 (220 ± 58) μg m-3 owing to small kitchen volume, extensive frying and prolonged cooking compared with the lowest in Medellín 10 ± 3 (14 ± 2) μg m-3. Dual ventilation (mechanical and natural) in Chennai, Cairo and Sulaymaniyah reduced average in-kitchen PM2.5 and PM10 by 2.3- and 1.8-times compared with natural ventilation (open doors) in Addis Ababa, Dar-es-Salam and Nairobi. Using charcoal during cooking (Addis Ababa, Blantyre and Nairobi) increased PM2.5 levels by 1.3- and 3.1-times compared with using natural gas (Nanjing, Medellin and Cairo) and LPG (Chennai, Sao Paulo and Sulaymaniyah), respectively. Smaller-volume kitchens (<15 m3; Dhaka and Nanjing) increased cooking exposure compared with their larger-volume counterparts (Medellin, Cairo and Sulaymaniyah). Potential exposure doses were highest for Asian, followed by African, Middle-eastern and South American homes. We recommend increased cooking exhaust extraction, cleaner fuels, awareness on improved cooking practices and minimising passive occupancy in kitchens to mitigate harmful cooking emissions.

Fine particulate pollution concentration in Addis Ababa exceeds the WHO guideline value

Environmental Epidemiology, 2021

Background: Real-time monitoring of fine particulate matter (PM2.5) concentrations and assessing ... more Background: Real-time monitoring of fine particulate matter (PM2.5) concentrations and assessing the health impact are limited in Ethiopia. The objective of this study is to describe current levels of PM2.5 air pollution in Addis Ababa and examine temporal patterns and to consider the health impact of current PM2.5 exposure levels. Methods: PM2.5 concentrations were measured using a centrally-located Beta Attenuator Monitor (BAM-1022) for 3 years (1 April 2017 to 31 March 2020), with data downloaded biweekly. Deaths attributable to current PM2.5 concentration levels were estimated using the AirQ+ tool. The daily average was estimated using hourly data. Results: The daily mean (SD) PM2.5 concentration was 42.4 µg/m3 (15.98). Two daily extremes were observed: morning (high) and afternoon (low). Sundays had the lowest PM2.5 concentration, while Mondays to Thursdays saw a continuous increase; Fridays showed the highest concentration. Seasons showed marked variation, with the highest values during the wet season. Concentration spikes reflected periods of intensive fuel combustion. A total of 502 deaths (4.44%) were attributable to current air pollution levels referenced to the 35 µg/m3 WHO interim target annual level and 2,043 (17.7%) at the WHO 10 µg/m3 annual guideline. Conclusion: PM2.5 daily levels were 1.7 times higher than the WHO-recommended 24-hour guideline. The current annual mean PM2.5 concentration results in a substantial burden of attributable deaths compared to an annual mean of 10 µg/m3. The high PM2.5 level and its variability across days and seasons calls for citywide interventions to promote clean air.

Spectroscopic line shape measurements at high densities

Journal of Quantitative Spectroscopy and Radiative Transfer, 1997

... To further test the reliability of these experiments estimates of Ne are deter mined from the... more

Experimental results on line shifts from dense plasmas

Journal of Quantitative Spectroscopy and Radiative Transfer, 2000

The dynamics of the implosion of a deuterium-"lled microsphere has been investigated via the deta... more The dynamics of the implosion of a deuterium-"lled microsphere has been investigated via the detailed analysis of the Ar 1s}1s3pP line shape. Ar is doped into the deuterium core for diagnostic purposes. For the analysis calculations of Ar 1}3 line shape including lithium-like dielectronic satellites were compared with time-resolved data. Three "tting parameters were used: (a) electron temperature, (b) electron density, and (c) relative shift of the wavelength axis between calculation and data. The temporal evolution of the core electron temperature and density were derived, and the shot-to-shot formation of the core plasma was shown to be reliable and reproducible. We report on the wavelength shift of the Ar 1s}1s3pP line shape between electron densities of 10}10 cm\, results indicate a systematic red shift with increasing density.

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$Research paper thumbnail of Time-resolved x-ray diffraction from laser-irradiated crystals$

Time-resolved x-ray diffraction from laser-irradiated crystals

ABSTRACT Not Available

A call for action: Air Pollution, a serious health and economic hazard suffocating Africa

Clean air journal, Dec 22, 2022

Air pollution research has been conducted in Europe and North America as well as in Asia and Sout... more Air pollution research has been conducted in Europe and North America as well as in Asia and South America for decades, but there has, so far, only been a limited amount of studies on air pollution and its health effects conducted in Africa. Until recently, global inventories of pollutants from North America Europe and Asia have been used for air quality and climate change modelling in Africa (

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Soft x-ray fluorescence spectroscopy excited by synchrotron radiation: Inelastic and resonant scattering near threshold

X-rays have been used as a scientific tool for almost 100 years. The presence of x-ray fluorescen... more X-rays have been used as a scientific tool for almost 100 years. The presence of x-ray fluorescence has been detected almost since the day x-rays were discovered. This talk will be a report on the valence band emission intensity as a function of the energy of the photon excitation in the 100-500 eV energy band. Emission measurements from silicon and several wide band gap insulators will be presented.

Variable groove‐spaced grating monochromator for soft x‐ray emission spectroscopy at CAMD/LSU

Review of Scientific Instruments, Feb 1, 1995

Several generic spectrometer types have been developed for research using VUV light at synchrotro... more Several generic spectrometer types have been developed for research using VUV light at synchrotron radiation sources. They all have used gratings with a constant groove spacing and they all have tried to incorporate high resolution, high throughput, rejection of second and higher order radiation, and design simplicity in their construction. The use of gratings ruled with variable spaced grooves to reduce defocus, coma, and spherical aberration was suggested almost twenty years ago. An instrument using this grating concept was built five years ago for conventional sources. The first monochromator using a variable line spaced grating was installed at the National Synchrotron Light Source almost two years ago, and a high resolution version of such an instrument has been built at the Synchrotron Radiation Center operated by the University of Wisconsin. In this presentation we review the development of monochromators using variable line space gratings and the possible applications of this type of instrumentation.

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Competing effects of collisional ionization and radiative cooling in inertially confined plasmas

Physical review, Apr 1, 1998

We describe an experimental investigation, a detailed analysis of the Ar XVII 1s 2 1 S-1s3p 1 P ͑... more We describe an experimental investigation, a detailed analysis of the Ar XVII 1s 2 1 S-1s3p 1 P ͑He␤͒ line shape formed in a high-energy-density implosion, and report on one-dimensional radiation-hydrodynamics simulation of the implosion. In this experiment trace quantities of argon are doped into a lower-Z gas-filled core of a plastic microsphere. The dopant level is controlled to ensure that the He␤ transition is optically thin and easily observable. Then the observed line shape is used to derive electron temperatures (T e) and electron densities (n e). The high-energy density plasma, with T e approaching 1 keV and n e ϭ10 24 cm Ϫ3 , is created by placing the microsphere in a gold cylindrical enclosure, the interior of which is directly irradiated by a high-energy laser; the x rays produced by this laser-gold interaction indirectly implode the microsphere. Central to the interpretation of the hydrodynamics of the implosions is the characterization and understanding of the formation of these plasmas. To develop an understanding of the plasma and its temporal evolution, time-resolved T e and n e measurements are extracted using techniques that are independent of the plasma hydrodynamics. Comparing spectroscopic diagnostics with measurements derived from other diagnostic methods, we find the spectroscopic measurements to be reliable and further we find that the experiment-toexperiment comparison shows that these implosions are reproducible. ͓S1063-651X͑98͒05504-4͔

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CO2 exposure, ventilation, thermal comfort and health risks in low-income home kitchens of twelve global cities

Journal of Building Engineering

X-ray laser photopumped resonance fluorescence

Journal of Quantitative Spectroscopy and Radiative Transfer, 1997

A calculation of the resonance fluorescence spectrum of the 146.526 Å 3d-2p transition of fluorin... more A calculation of the resonance fluorescence spectrum of the 146.526 Å 3d-2p transition of fluorine-like magnesium photopumped by the 146.515 Å zirconium X-ray laser line is discussed in connection with an experimental measurement in a hot, dense laser produced plasma. The calculation of the fluorescence spectral profile is based on a recent extension of the Frequency Fluctuation Model (FFM) that

Study on renewable biogas energy production from cladodes of Opuntia ficus indica

Investigation of Waste Coffee Ground as a Potential Raw Material for Biodiesel Production

International Journal of Renewable Energy Research, 2013

In this study, the utilization of waste coffee ground for biodiesel production was investigated. ... more In this study, the utilization of waste coffee ground for biodiesel production was investigated. Waste coffee ground sample was collected from TOMOCA PLC, Addis Ababa, Ethiopia. The oven dried sample was then soxhlet extracted using n- hexane to yield 19.73 %w/w oil. The biodiesel was obtained by a two-step process, i.e. acid catalyzed esterification followed by base catalyzed transesterification using catalysts sulphuric acid and sodium hydroxide respectively. The conversion of waste coffee ground oil in to biodiesel, was about 73.4%w/w. Various parameters that are essential for biodiesel quality were evaluated using the American Standard for Testing Material (ASTM D 6751- 09) and all comply with the specification except acid value. The fatty acid composition of the biodiesel was analyzed by Gas chromatography and the major fatty acids were found to be linoleic acid (39.8%), palmitic acid (37.6%), oleic (12.7%), and stearic acid (7.6%). In addition, preliminary investigation on the...

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Advances in Biochemistry & Biotechnology-Bioethanol production from coffee husk using fruit yeast isolates and baker yeast

The aim of the study was to optimize maximal ethanol production from acid hydrolyzed coffee husk ... more The aim of the study was to optimize maximal ethanol production from acid hydrolyzed coffee husk to identify the optimal condition to bio-ethanol production from substrate using yeast isolates reference to commercial bread yeast. The results showed that the content of sugars increased as the acid (H2SO4) was increased from 0.25M - 3 M and decreased as the acid concentrations increased beyond 3 M. At the optimal acid concentration (3M, H2SO4), the sugar yield obtained was 85% from the coffee husk. The optimum condition for acid hydrolysis was 3M H2SO4, 10 min hydrolysis time, pH 5 and 30°C temperature at 48 hrs fermentation time. Under the optimum conditions the maximum yield of ethanol (5.56% v/v) was obtained using AAUP1 yeast isolate. The results indicated that locally available cheap substrate which occurs in excess and non-edible material, coffee husk will be a potential feedstock for bio-ethanol production.

Air Quality Monitoring Assists Meeting the Sustainable Development Goals in Ethiopia

Advances in Science, Technology & Innovation/Advances in science, technology & innovation, 2024

Low-Cost Hourly Ambient Black Carbon Measurements at Multiple Cities in Africa

Environmental science & technology, Jul 2, 2024

The National Institute of Standards and Technology Very High Resolution Spectrometer, in Proceedings of the 8th Natl. Conf. on Synchrotron Radiation Research

Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment, 1994

High-resolution VUV absolute photo-absorption cross sections of N2 and rare gases

Optical Society of America Annual Meeting, 1992

The Waste Crisis

Time-resolved temperature measurements of radiatively heated tamped MgO foils by Kα absorption spectroscopy

Journal of Quantitative Spectroscopy & Radiative Transfer, Jul 1, 1995

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In-kitchen aerosol exposure in twelve cities across the globe

Environment International, 2022

Fine particulate pollution concentration in Addis Ababa exceeds the WHO guideline value

Environmental Epidemiology, 2021

Spectroscopic line shape measurements at high densities

Journal of Quantitative Spectroscopy and Radiative Transfer, 1997

... To further test the reliability of these experiments estimates of Ne are deter mined from the... more

Experimental results on line shifts from dense plasmas

Journal of Quantitative Spectroscopy and Radiative Transfer, 2000

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$Research paper thumbnail of Time-resolved x-ray diffraction from laser-irradiated crystals$

Time-resolved x-ray diffraction from laser-irradiated crystals

ABSTRACT Not Available

A call for action: Air Pollution, a serious health and economic hazard suffocating Africa

Clean air journal, Dec 22, 2022

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Soft x-ray fluorescence spectroscopy excited by synchrotron radiation: Inelastic and resonant scattering near threshold

Variable groove‐spaced grating monochromator for soft x‐ray emission spectroscopy at CAMD/LSU

Review of Scientific Instruments, Feb 1, 1995

Download

Competing effects of collisional ionization and radiative cooling in inertially confined plasmas

Physical review, Apr 1, 1998

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CO2 exposure, ventilation, thermal comfort and health risks in low-income home kitchens of twelve global cities

Journal of Building Engineering

X-ray laser photopumped resonance fluorescence

Journal of Quantitative Spectroscopy and Radiative Transfer, 1997

Study on renewable biogas energy production from cladodes of Opuntia ficus indica

Investigation of Waste Coffee Ground as a Potential Raw Material for Biodiesel Production

International Journal of Renewable Energy Research, 2013

Download

Advances in Biochemistry & Biotechnology-Bioethanol production from coffee husk using fruit yeast isolates and baker yeast

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