2,831 research outputs found
Controlled Size Growth of Thermally Stable Organometallic Halide Perovskite Microrods: Synergistic Effect of Dual-Doping, Lattice Strain Engineering, Antisolvent Crystallization, and Band Gap Tuning Properties
No full textOrganometallic halide perovskites, as the light-harvesting material, have been extensively used for cost-effective energy production in high-performance perovskite solar cells, despite their poor stability in the ambient atmosphere. In this work, methylammonium lead iodide, CH3NH3PbI3, perovskite was successfully doped with KMnO4 using antisolvent crystallization to develop micrometer-length perovskite microrods. Thus, the obtained KMnO4-doped perovskite microrods have exhibited sharp, narrow, and red-shifted photoluminescence band, as well as high lattice strain with improved thermal stability compared to undoped CH3NH3PbI3. During the synthesis of the KMnO4-doped perovskite microrods, a low boiling point solvent, anhydrous chloroform, was employed as an antisolvent to facilitate the emergence of controlled-size perovskite microrods. The as-synthesized KMnO4-doped perovskite microrods retained the pristine perovskite crystalline phases and lowered energy band gap (similar to 1.57 eV) because of improved light absorption and narrow fluorescence emission bands (fwhm < 10 nm) with improved lattice strain (similar to 4.42 x 10(-5)), Goldsmith tolerance factor (similar to 0.89), and high dislocation density (similar to 5.82 x 10(-4)), as estimated by Williamson-Hall plots. Thus, the obtained results might enhance the optical properties with reduced energy band gap and high thermal stability of doped-perovskite nanomaterials in ambient air for diverse optoelectronic applications. This study paves the way for new insights into chemical doping and interaction possibilities in methylamine-based perovskite materials with various metal dopants for further applications.1
Fluorescent N-Doped Graphene Quantum Dots Embedded in Transparent Polymer Films for Photon-Downconversion Applications
No full textIn this work, we demonstrate a simple, facile, and efficient one-pot synthesis of polymer-quantum dot nanocomposite films where nitrogen-doped graphene quantum dots (N-GQDs) were homogeneously dispersed in UV-curable, transparent polymer host matrix via the thiol-ene "click" reaction pathway. The highly fluorescent NOA-NGQD nanocomposite films exhibited strong hydrophobicity with water contact angle (>69 degrees) owing to restructuring of the polymer chain networks. The various functional groups of the N-GQD surface, as carbonyl, amine, and hydroxyl groups, provided more interactive sites and low agglomeration to develop the strong electrostatic interactions between the NOA and N-GQDs, resulting in flexible NOA-NGQDs nanocomposites. Thus, obtained NOA-NGQD nanocomposites exhibited high transparency (>90%), low band-gap, and strong fluorescence spectral peak (>500 nm) after the homogeneous inclusion of N-GQDs in the NOA polymer matrix. This study paves the way to diverse applications of functionalized GQDs as well as transparent polymers for the development of hydrophobic polymer-QD nanocomposites by using UV catalyzed thiol-ene chemistry. Hence, as synthesized nanocomposite films would be widely applicable in flexible electronic display devices, light emitting diodes (LEDs), and optoelectronic applications.1
Exploring Rapid Photocatalytic Degradation of Organic Pollutants with Porous CuO Nanosheets: Synthesis, Dye Removal, and Kinetic Studies at Room Temperature
No full textIn this work, we report the facile, environmentally friendly, room-temperature (RT) synthesis of porous CuO nanosheets and their application as a photocatalyst to degrade an organic pollutant/food dye using NaBH4 as the reducing agent in an aqueous medium. Ultrahigh-resolution field effect scanning electron microscopy images of CuO displayed a broken nanosheet-like (a length of ∼160 nm, a width of ∼65 nm) morphology, and the lattice strain was estimated to be ∼1.24 × 10-3 using the Williamson-Hall analysis of X-ray diffraction plots. Owing to the strong quantum size confinement effect, CuO nanosheets resulted in an optical energy band gap of ∼1.92 eV, measured using Tauc plots of the ultraviolet-visible (UV-vis) spectrum, resulting in excellent photocatalytic efficiency. The RT synthesized CuO catalyst showed a high Brunauer-Emmet-Teller surface area of 30.88 ± 0.2313 m2/g (a correlation coefficient of 0.99972) with an average Barrett-Joyner-Halenda pore size of ∼20.385 nm. The obtained porous CuO nanosheets exhibited a high crystallinity of 73.5% with a crystallite size of ∼12 nm and was applied as an efficient photocatalyst for degradation of the organic pollutant/food dye, Allura Red AC (AR) dye, as monitored by UV-vis spectrophotometric analysis and evidenced by a color change from red to colorless. From UV-vis spectra, CuO nanosheets exhibited an efficient and ultrafast photocatalytic degradation efficiency of ∼96.99% for the AR dye in an aqueous medium within 6 min at RT. According to the Langmuir-Hinshelwood model, photodegradation reaction kinetics followed a pseudo-first-order reaction with a rate constant of k = 0.524 min-1 and a half-life (t1/2) of 2.5 min for AR dye degradation in the aqueous medium. The CuO nanosheets showed an outstanding recycling ability for AR degradation and would be highly favorable and an efficient catalyst due to the synergistic effect of high adsorption capability and photodegradation of the food dye. © 2021 The Authors. Published by American Chemical Society1
Bobby Mohammed … A Steelpan Legend Re-emerges
No full textThe author interviews Lennox "Bobby" Mohammed, the sprightly and spiritual 71-year old arranger as he reflects and comments on his re-emergence on the music scene. Mohammed became the youngest arranger to win a Panorama title at the age of 22 in 1965 and was honoured with one of the country's highest national awards, the Humming Bird Medal Gold
አላሁ፡መስሊ፡አለሙሀመድ፡ያለመሁዳ፡ሳቡኝ፡ካንቱ፡ዘንዳ
No full textThe entire manuscript is available for download as a single PDF file. Higher-resolution images may be available upon request. For technical assistance, please contact [email protected]. Fieldwork Team: Gabeyehu Adugna (Principal Investigator), Rachel Dwyer (Principle Investigator) Ahmed Tayib (Local Project Manager), Muhammed Jawad (Boston Facilitator). Technical Team: Prof. Fallou Ngom (Project Director and the Former Director of African Studies Center), Eleni Castro (Technical Lead, BU Libraries), and Ethan Key (Intern, BU Libraries). The fieldwork team would like to thank the following individuals and institutions who provided vital assistance in facilitation and consultation during fieldwork: Dr.Endris Mohammed, Professor, Addis Ababa University Linguistics Department, Addis Ababa, Ethiopia; Hussein Kassim Mohammedsani, PhD candidate. Addis Ababa University Linguistics Department, Addis Ababa, Ethiopia; Ethiopian Islamic Affairs Council, Addis Ababa, Ethiopia. Additional thanks to to the staff of the Rahnile Hotel in Bahir Dar.
This collection of Amharic Ajami manuscripts are copied as part of the African Studies Center's African Ajami Library.
Access Condition and Copyright: These materials are subject to copyright. All rights reserved to the author. For use, distribution or reproduction contact Professor Fallou Ngom ([email protected]).
Materials in this web edition may be cited as: Adugna, G., Dwyer,R., Ngom, F., and Castro, E. (2021). African Ajami Library: Amharic Ajami Manuscripts. Boston: Boston University Libraries: http://hdl.handle.net/2144/39804. For Inquiries: Please Contact Professor Fallou Ngom ([email protected]).Provenance / Custodial history: This manuscript is owned by Ahmed Tayib of Debre Tabor, Ethiopia. Ahmed Tayib is the son of the author. This is an original work written by Mohammed Hassan Zite in 1965 EC (1972 CE/AD). The author had studied in several regions of Ethiopia, including the Dana mosque, in Tigray, and in Yajju areas. He was a teacher in Bahir Dar, and now, in his nineties, lives in the Begemder region. Handwritten manuscript on ledger lined paper using black ink (marker?) for the rasm and i'jam, but including blue ink (ball point pen?) for the harakat (vowel diacritics). The title uses a character for "ñ" which is a "ي" with an additional dot. Photographed in Bahir Dar, Ethiopia.This manzuma expresses the longing (ናፍቆት, nafqot) to be with Allah. It uses some words and phrases in the Amharic language that relate especially to the Gondar region.The contents of this collection were developed with support of the Title VI National Resource Center grant # P015A180164 from the U.S. Department of Education. However, those contents do not necessarily represent the policy of the U.S. Department of Education, and you should not assume endorsement by the Federal Government
Implications of the Improvement of Teaching Quality for Professional Development (PD) of Academics at the Colleges of Applied Sciences (CASs) in the Sultanate of Oman
No full textThe Oman Accreditation Council (OAC), which is called later the Oman Academic Accreditation Authority (OAAA), designed a higher education institution (HEI) Quality Assurance (QA) framework for Omani public and private Higher Education Institutions (HEIs), starting with a quality audit process in 2008. The Colleges of Applied Sciences (CASs), as a public HEI, are required to ensure the quality of all services and activities to meet particular national standards (specified in the framework) in order to gain a HEI and programme certificate. In line with a quality audit scope, the quality of the fields of PD and related teaching quality should be ensured and enhanced by the promotion and contribution of the former field to the maintenance and improvement of the latter one.
The chief purpose of this study was to identify the uptake and implications of the growing requirement to improve teaching quality and the PD of academics at the CASs in the Sultanate of Oman especially in the context of the application of the QA framework. The study focused on examining the academics’ participation in professional development programmes (PDPs) and current perceptions of PD with respect to the improvement of teaching quality improvement at these colleges. The current study also dealt with a reorganization and prioritization of academics’ PD needs, barriers to effective PD, and factors to enhance PD of academics regarding teaching quality improvement in the colleges.
Based on the purpose and research objectives, the current study adopted both positivist (quantitative) and interpretive (qualitative) research paradigms. Because the study perused quantitative and qualitative data regarding certain variables, it chose a mixed-research design. The researcher designed survey questionnaire to collect quantitative data and a semi-structured interview and a focus group discussion to probe and interpret quantitative findings. After fulfillment of the validity and reliability measurements, a self-completion questionnaire was distributed to a stratified random sample of academics (170) over the six CASs. A total of 150 questionnaires (out of 170) were completed and returned and the response-rate reached 88.2%. The quantitative data was analyzed by appropriate analysis using the Statistical Package for Social sciences (SPSS), while the qualitative data was analyzed by appropriate qualitative analysis.
The findings of the study showed that the level of academics’ participation in PDPs to improve teaching quality in the last two years in the CASs seems to be unsatisfactorily low. The current perceptions of the PD situations in the colleges, relating to teaching quality improvement, signified a shortage in the number of available PDPs and/or a discouragement of academics’ participation in these programmes in the last two years. The study also revealed all the 22 PD needs of academics regarding the improvement of teaching quality are significantly demanded by participants; the higher rated needs focused on a development of ‘student centred’ skills, such as critical thinking and problem-solving skills.
Furthermore, the study illustrated that the highest significant perceived barriers to effective PD in the CASs, as related to teaching quality improvement, focus on a lack of a clear institutional PD policy and a lack of appropriately systematic PD plans. The study also revealed all 10 perceived factors to enhance PD regarding teaching quality improvement are very important. The most significant factors represented and stressed particular problematic issues (the high rated barriers) and a reduction of a heavy workload to enhance academics’ participation in PD regarding the improvement of teaching quality.
Conclusions drawn from the discussion of the findings of study include a lack of a clear PD policy at national and institutional levels and absence of a particular authority/unit concerning PD issues in Omani HEIs. The two problematic issues resulted in a lack of systematic and realistic PD plans in the CASs, involving a lack of academics’ involvement in PD plans, a misconnection of academics’ PD needs to PD, inappropriate facilities and resources allocation, and inappropriate evaluation processes of PD. In addition, the conclusions also include that PD of academics regarding the improvement of teaching quality in the colleges requires more attention and focus to manage particular significant issues perceived by participants as both barriers and potential facilitators relating to PD of academics.
Based on identified conclusions, particular implications for policy and practice to enhance PD to improve teaching quality were set at three levels: governmental, institutional, and individual. Moreover, achievements of the current study according to the research questions were identified and contributions of the study to the fields of PD, teaching quality, and the context of QA and quality audit in HE were addressed. Based on the findings and conclusions, particular directions and recommended issues were suggested to be studied by further research to benefit the enhancement of PD and related teaching quality improvement
Corrigendum: Transient analytical solution of temperature distribution and fracture limits in pulsed solid-state laser rod by Khalid S. Shibib, Mohammed A. Munshid, Mohammed Jalal Abdul Rayyak, and Luma Hasan Salman* , doi reference: https://doi.org/10.2298/TSCI141011090S
No full textSimeon Oka, Editor-in-Chief of the journal Thermal Science request that it
is necessary to name of the 3rd author of the paper TRANSIENT ANALYTICAL
SOLUTION OF TEMPERATURE DISTRIBUTION AND FRACTURE LIMITS IN PULSED
SOLID-STATE LASER ROD by Khalid S. SHIBIB, Mohammed A. MUNSHID, Mohammed
Jalal ABDUL RAYYAK, and Luma Hasan SALMAN* Laser and Optoelectronics
Engineering Department, University of Technology, Baghdad, Iraq published
in the journal Thermal Science, Year 2017, Vol. 21, No. 3, pp. 1213-1222
since due to typing error of the Editorial staff, name of the 3rd author
was not correctly written. Name of the 3rd author written as Mohammed
Jalal ABDUL RAYYAK has to be written as: Mohammed Jalal ABDULRAZZAQ <br><br><font color="red"><b> Link to the corrected article <u><a href="http://dx.doi.org/10.2298/TSCI141011090S">10.2298/TSCI141011090S</a></b></u></jats:p
R01. HIV-1 Tat Dysregulates the Hypothalamic-Pituitary-Adrenal Stress Axis and Potentiates Oxycodone-mediated Psychomotor and Anxiety-like Behavior of Male Mice
No full textCorresponding author (BioMolecular Sciences): Mohammed Salahuddin, [email protected]://egrove.olemiss.edu/pharm_annual_posters/1000/thumbnail.jp
Tilman Nagels " ‚Authentizität‘ in der Leben-Mohammed-Forschung". Eine Antwort
No full textThis contribution is a response to Tilman Nagel's essay " ‘Authentizität' in der Leben-Mohammed-Forschung” [‘Authenticity' in the research on the Life of Mohammed] in which the author again presents the main theses argued in his monograph Mohammed. Leben und Legende and responds to criticism. Whereas his critics agree with Nagel that complete ‘authenticity' is unattainable in principle, yet an asymptotic approximation of Mohammed as a figure is indeed possible, the way to attain such an approximation remains a matter of dispute. Contrary to Nagel, the proponents of the so-called isnad-cum-matn analysis hold this method, which offers the possibility to date ḥadīṯs (traditions) and reconstruct texts in circulation in the 1st cent. H., for one of the most successful towards achieving this goal. Another successful procedure of proven value is the evaluation and appraisal of the corpus of traditions traced back to ʿUrwa b. az-Zubayr (d. c. 712), one of the earliest and most important collectors of historical material in Islam. Proponents of both of these procedures do not apply the term ‘authentic', as asserted by Nagel, in the sense of ‘what exactly happened', but rather use this term if the transmitters of a tradition are historical figures and when the process of transmission is proven to have ensued as indicated in the chain of transmissio
Tilman Nagels „,Authentizität‘ in der Leben-Mohammed-Forschung“. Eine Antwort
No full textThis contribution is a response to Tilman Nagel's essay “ ‘Authentizität’ in der Leben-Mohammed-Forschung” [‘Authenticity’ in the research on the Life of Mohammed] in which the author again presents the main theses argued in his monograph Mohammed. Leben und Legende and responds to criticism. Whereas his critics agree with Nagel that complete ‘authenticity’ is unattainable in principle, yet an asymptotic approximation of Mohammed as a figure is indeed possible, the way to attain such an approximation remains a matter of dispute. Contrary to Nagel, the proponents of the so-called isnad-cum-matn analysis hold this method, which offers the possibility to date ḥadīṯs (traditions) and reconstruct texts in circulation in the 1st cent. H., for one of the most successful towards achieving this goal. Another successful procedure of proven value is the evaluation and appraisal of the corpus of traditions traced back to ʿUrwa b. az-Zubayr (d. c. 712), one of the earliest and most important collectors of historical material in Islam. Proponents of both of these procedures do not apply the term ‘authentic’, as asserted by Nagel, in the sense of ‘what exactly happened’, but rather use this term if the transmitters of a tradition are historical figures and when the process of transmission is proven to have ensued as indicated in the chain of transmission
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