Adama University

About: Adama University is a education organization based out in Nazrēt, Ethiopia. It is known for research contribution in the topics: Population & Adsorption. The organization has 840 authors who have published 1010 publications receiving 5547 citations. The organization is also known as: Adama Science and Technology University & ቴክኖሎጂ ዩኒቨርሲቲ, አዳማ ሳይንስና ቴክኖሎጂ ዩኒቨርሲቲ.

Solar UV-assisted sample preparation of river water for ultra-trace determination of uranium by adsorptive stripping voltammetry

Abstract: The article describes how solar ultraviolet-A radiation can be used to digest samples as needed for voltammetric ultratrace determination of uranium(VI) in river water. We applied adsorptive stripping voltammetry (AdSV) using chloranilic acid as the complexing agent. Samples from the river Warnow in Rostock (Germany) were pretreated with either soft solar UV or wit artificial hard UV from a 30-W source emitting 254-nm light. Samples were irradiated for 12 h, and both methods yielded the same results. We were able to detect around 1 μg·L−1 of uranium(VI) in a sample of river water that also contained dissolved organic carbon at a higher mg·L−1 levels. No AdSV signal was obtained for U(VI) without any UV pre-treatment. Pseudo-polarographic experiments confirmed the dramatic effect of both digestion techniques the the AdSV response. The new method is recommended for use in mobile ultratrace voltammetry of heavy metals for most kinds of natural water samples including tap, spring, ground, sea, and river waters. The direct use of solar radiation for sample pre-treatment represents a sustainable technique for sample preparation that does not consume large quantities of chemicals or energy.

Improved DC Performances of Gate-all-around Si-Nanotube Tunnel FETs Using Gate-Source Overlap

Abstract: In this work, a novel structure of Gate-all-Around Si-Nanotube Tunnel FET (GAA Si-NTTFET) has been proposed to improve its electrical characteristics by overlapping a portion of source with its gate terminal. Using 3-D TCAD simulation, it has been found that the on-state current and subthreshold swing of GAA Si-NTTFET can be significantly improved with an optimum length of gate-source overlapping (GSO) i.e. 27-nm only, thus not limiting the scalability of source region. Furthermore, GSO has also caused a reduction in the turn-on voltage of GAA Si-NTTFET which may help to scaling the supply voltages. Moreover, due to reduction in the lateral electric field at source-channel interface caused by GSO, the off-state current has been observed to be smaller as compared to the conventional GAA Si-NTTFET which eventually reduces the stand-by power dissipation. Additionally, the ambipolar current has also been found to be reduced in the proposed structure which makes it more suitable for its application in the digital circuits.

Ge-Source Based L-Shaped Tunnel Field Effect Transistor for Low Power Switching Application

Abstract: In this work, the performance of the heterojunction L-Tunnel Field Effect Transistor (LTFET) has been analyzed with different engineering techniques such as bandgap engineering, pocket engineering, work-function engineering, and gate dielectric engineering, respectively. The electrical characteristics of the device has been investigated by using Synopsys Sentaurus TCAD tool and compared with some recent other TFETs. The device has been analyzed in terms of DC as well as AC analysis and offers ON-state current of 2.12*10−5 Aμm−1, OFF-state current of 1.09*10−13 Aμm−1, current ratio of ~108 and sub-threshold slope (SS) of 21 mV/decade and the threshold voltage of 0.26 V and compared to the conventional Si/Ge source L-shaped TFETs without pocket simulation result. The pocket engineering techniques suppress the leakage without degrading the ON current, threshold voltage and SS of the proposed device. The simplified fabrication steps of the proposed device have also been discussed. The proposed L-TFET is free from ambipolarity issues and can be used to develop low-power switching devices.

Synthesis of amino acid functionalized Fe3O4 nanoparticles for adsorptive removal of Rhodamine B

Abstract: L-Aspartic acid (L-Asp) functionalized magnetite nanoparticles (Fe3O4 NPs) were synthesized through a facile co-precipitation method using L-Asp as a capping agent. UV–Vis, FTIR, XRD, SEM, EDS, TEM, and VSM techniques were used to investigate the formation, morphology, elemental composition, and magnetic properties of the synthesized Fe3O4 NPs. Highly crystalline and spherical shaped pure phase Fe3O4 NPs were successfully synthesized using amino acid as a capping agent. The magnetic measurement analysis confirms the superparamagnetic nature of the synthesized L-Asp capped Fe3O4 NPs. The adsorption efficiency of L-Asp capped Fe3O4 NPs was assessed by the removal of Rhodamine B (RhB). The optimum removal efficiency was found to be 7.7 mg g−1 using 1 mg mL−1 adsorbent, and 30 mg L−1 RhB at pH 7 and 25 °C. The regression (R2adj) and standard deviation (SD) analysis were used to validate both kinetic and isotherm models. Avrami fractional-order and Liu models were selected as the best kinetic and isotherms, respectively. The maximum adsorption capacity (Qo) of L-Asp Fe3O4 NPs toward RhB Liu’s model was found to be 10.44 mg g−1.

Recent advances in fluorescent upconversion nanomaterials: novel strategies for enhancing optical and magnetic properties to biochemical sensing and imaging applications

Abstract: Upconversion fluorescence is the process of converting optical energy from low absorption energies to high emission energies. The upconversion (UC) materials exhibit significant advantages such as ...