Synthesis and Characterization of Flexible Resistive Humidity Sensors Based on PVA/PEO/CuO Nanocomposites

Ahmed Hashim,Yahya Al-Khafaji,Aseel Hadi 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.6

Synthesis of polyvinyl alcohol (PVA)–polyethylene oxide (PEO)–copper oxide (CuO) nanocomposites and studying their structural and optical properties for humidity sensors applications were investigated. The prepared humidity sensors have lightweight, low cost, fl exible and high sensitivity compare with other humidity sensors. The results showed that the nanocomposites have high absorption in UV region. The absorbance of (PVA–PEO) blend increases with increase in CuO nanoparticles concentrations which may be used for solar cell, transistors, diodes and other electronic applications. The optical constants increase while the transmittance and energy gap decrease as CuO nanoparticles concentrations increase. The results of application showed that the (PVA–PEO–CuO) nanocomposites with diff erent copper oxide nanoparticles concentrations have high sensitivity for relative humidity which may be used as sensors for diff erent humidity ranges.

Synthesis and Characterization of Polymer Blend-CoFe2O4 Nanoparticles as a Humidity Sensors for Different Temperatures

Ahmed Hashim,Majeed Ali Habeeb 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.2

In this paper, preparation of [carboxyl methyl cellulose (CMC)–polyvinyl pyrrolidone (PVP)–cobalt iron oxides nanoparticles (CoFe 2 O 4 )] nanocomposites for humidity sensors at diff erent temperatures have been investigated. The synthesized humidity sensors have low cost, lightweight, fl exible, high corrosion resistance, high sensitivity compare with other sensors. The structural and optical properties of nanocomposites have been studied. The experimental results of optical properties showed that the absorbance, absorption coeffi cient of (CMC–PVP) blend increase while the transmittance and energy band gap decrease with increase in CoFe 2 O 4 nanoparticles concentrations. The results of humidity sensors showed that the electrical resistance of (CMC–PVP–CoFe 2 O 4 ) nanocomposites decreases with an increase in CoFe 2 O 4 nanoparticles concentrations and temperature. The (CMC–PVP–CoFe 2 O 4 ) nanocomposites have high sensitivity for humidity for diff erent temperatures.

Structural, Optical and Electronic Properties of Novel (PVA–MgO)/SiC Nanocomposites Films for Humidity Sensors

Hind Ahmed,Hayder M. Abduljalil,Ahmed Hashim 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.3

The polyvinyl alcohol (PVA) and magnesium oxide (MgO) nanocomposites and (PVA–MgO) nanocomposites doped by Silicon carbide (SiC) nanoparticles have been fabricated with diff erent concentrations of Silicon carbide and (PVA–MgO) nanocomposites. Both experimental and theoretical studies on structural and optical properties of novel (PVA–MgO–SiC) nanocomposites for humidity sensors were examined for fi rst time with low cost, fl exible and high sensitivity. The (PVA–MgO–SiC) nanocomposites were intended with various concentrations of Silicon carbide nanoparticles. The experimental results of optical properties for (PVA–MgO–SiC) nanocomposites indicated that the absorbance, absorption coeffi cient, extinction coeffi cient, refractive index, imaginary and real dielectric constants and optical conductivity of (PVA–MgO) nanocomposites increase with an increase in Silicon carbide nanoparticles concentrations. The absorbance increases from 0.432 to 2.55 a.u while the transmittance decreases from 0.779 to 0.230 a.u. The energy gap decreases from 4.4 to 2.1 eV. The energy gap theoretically decreases from 7.07 to 3.04 eV. The experimental results of novel (PVA–MgO–SiC) nanocomposites applications showed that (PVA–MgO–SiC) nanocomposites have high sensitivity for relative humidity. The results obtained were compared with theoretic results obtained by using Gaussian 09 program and Gaussian view 5.0.8 program and using density functional theory (DFT) at B3LYP level with 6 - 31G basis set.

Analysis of Structural, Optical and Electronic Properties of Polymeric Nanocomposites/Silicon Carbide for Humidity Sensors

Hind Ahmed,Hayder M. Abduljalil,Ahmed Hashim 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.3

The nanocomposites are really promising for industrial, environmental and medical applications. In this work, new types of nanocomposites have been prepared from (PVA–TiO 2 ) nanocomposites doped by SiC nanoparticles for humidity sensor with high sensitivity, fl exible, high corrosion resistance and low cost. The experimental and theoretical studies on structural and optical properties of (PVA–TiO 2 –SiC) nanocomposites have been investigated. The optical microscope and FTIR studies were examined. The optical properties of nanocomposites were examined in wavelength range (220–800) nm. The results showed that the optical absorbance of (PVA–TiO 2 ) nanocomposites increases with increasing of the SiC nanoparticles concentrations. The energy band gap of (PVA–TiO 2 ) nanocomposites decreases while the optical constants increase with the increase in SiC nanoparticles concentrations. The (PVA–TiO 2 –SiC) nanocomposites tested for humidity sensors at relative humidity range (40–80) RH.%. The experimental results showed that the electrical resistance for (PVA–TiO 2 –SiC) nanocomposites decreases with increase in relative humidity. The (PVA–TiO 2 –SiC) nanocomposites have highly sensitivity for relative humidity.

Analysis of Composition and Diversity of Natural Regeneration of Woody Species in Jebel El Gerrie Dry Land Forest East of Blue Nile State, Sudan

Abuelbashar, Ahmed Ibrahim,Ahmed, Dafa-Alla Mohamed Dafa-Alla,Siddig, Ahmed Ali Hassabelkreem,Yagoub, Yousif Elnour,Gibreel, Haithum Hashim Institute of Forest Science 2022 Journal of Forest Science Vol.38 No.2

The study aims to assess composition, diversity and population indices of natural regeneration of woody species in Jebel El Gerrie forest reserve, Blue Nile State, Sudan. We conducted field work between December 2018 and January 2019. We used random sampling to collect vegetation data in the forest where we made a total of 90 circular sample plots (radius 17.84 m) and distributed them proportionally to the area of each of the four density-based vegetation classes of the forest i.e. high density (C1), medium density (C2), low density (C3) and crop land (C4). In each sample plot we identified all regenerating tree species and counted their regeneration frequencies. We calculated ecological metrics of regeneration frequency, density, abundance, richness, evenness, diversity and importance value index (IVI) and drew abundance rank curve. Results revealed that out of fifteen mature tree species present, natural regeneration of 8 species, which belong to 6 families, was observed. The relatively most frequently naturally regenerating and abundant species were Anogeissus leiocarpa and Combretum hartmannianum. Richness, evenness and diversity of regenerating species were 1.33, 0.82 and 1.7, respectively. One-way ANOVA (α=0.05) of mean regeneration densities disclosed that there were significant differences (F_3,86=16.77, p=0.000) between C2 & C3 (p=0.000) and C2 & C4 (p=0.000). While regeneration of seven tree species were absent, two, two and four species were of good, poor and fair regeneration status, respectively. A comparison of mean density of natural regeneration with that of parent trees reflects a poor regeneration status of the forest. The study provides empirical results on the regeneration status of species and signifies the need for management interventions for species conservation and restoration, maintenance of biodiversity and sustainable production.

Lightweight, Flexible and High Energies Absorption Property of PbO2 Doped Polymer Blend for Various Renewable Approaches

Hind Ahmed,Ahmed Hashim 한국전기전자재료학회 2021 Transactions on Electrical and Electronic Material Vol.22 No.3

This work reports a theoretical study to investigate the electronic structure and optimized geometry for (PVA-PEG-PbO 2 ) (78Atom) by using DFT at B3LYP level with bases set LanL2DZ. The electronic characteristics which contain total energy, cohesive energy, energy of highest occupied molecular orbital (HOMO), energy of lowest unoccupied molecular orbital (LUMO), energy gap, ionization potential, electronic affinity, hardness, softness, electronegativity and electrophilicity. The spectroscopic characteristics (IR, NMR and UV) for (PVA-PEG-PbO 2 ) (78Atom) were investigated at the same large level of theory. The results showed that the functional used in the description of the studied molecular systems has been proved its validity in calculating the geometrical parameters and it is a suitable for studying the geometry optimization and calculating the HOMO and LUMO energies for the organic molecular systems. The final results indicated to the PVA-PEG-PbO 2 structure can be considered as promising materials for various renewable energies approaches.

Design of Polymer/Lithium Fluoride New Structure for Renewable and Electronics Applications

Hind Ahmed,Ahmed Hashim 한국전기전자재료학회 2022 Transactions on Electrical and Electronic Material Vol.23 No.3

In this work, design of (polystyrene-lithium fluoride) structure and studying the structural, electronic (energy gap, cohesive energy, ionization potential, electron affinity, chemical hardness, chemical softness, electronegativity, electrophilicity and density of states) and spectroscopic (Raman, IR and UV–Vis) properties using density functional theory have been investigated. The structure of PS-LiF is designed at Gauss View 5.0.8, and relax by employing the 6-31G method with the hybrid functional B3LYP-DFT at Gaussian 09 package of programs. The results showed that good relax of the polystyrene and lithium fluoride compound. Finally, the results indicated to the (PS-LiF) structure can be used for various renewable and electronics applications like energy storage, capacitors, transistors, electronic circuits, etc.

Structural, Optical and Electronic Properties of Novel (PVA–MgO)/SiC Nanocomposites Films for Humidity Sensors

Hind Ahmed,Hayder M. Abduljalil,Ahmed Hashim 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.2

The polyvinyl alcohol (PVA) and magnesium oxide (MgO) nanocomposites and (PVA–MgO) nanocomposites doped by Silicon carbide (SiC) nanoparticles have been fabricated with diff erent concentrations of Silicon carbide and (PVA–MgO) nanocomposites. Both experimental and theoretical studies on structural and optical properties of novel (PVA–MgO–SiC) nanocomposites for humidity sensors were examined for fi rst time with low cost, fl exible and high sensitivity. The (PVA–MgO–SiC) nanocomposites were intended with various concentrations of Silicon carbide nanoparticles. The experimental results of optical properties for (PVA–MgO–SiC) nanocomposites indicated that the absorbance, absorption coeffi cient, extinction coeffi cient, refractive index, imaginary and real dielectric constants and optical conductivity of (PVA–MgO) nanocomposites increase with an increase in Silicon carbide nanoparticles concentrations. The absorbance increases from 0.432 to 2.55 a.u while the transmittance decreases from 0.779 to 0.230 a.u. The energy gap decreases from 4.4 to 2.1 eV. The energy gap theoretically decreases from 7.07 to 3.04 eV. The experimental results of novel (PVA–MgO–SiC) nanocomposites applications showed that (PVA–MgO–SiC) nanocomposites have high sensitivity for relative humidity. The results obtained were compared with theoretic results obtained by using Gaussian 09 program and Gaussian view 5.0.8 program and using density functional theory (DFT) at B3LYP level with 6 - 31G basis set.

Analysis of Structural, Optical and Electronic Properties of Polymeric Nanocomposites/Silicon Carbide for Humidity Sensors

Hind Ahmed,Hayder M. Abduljalil,Ahmed Hashim 한국전기전자재료학회 2019 Transactions on Electrical and Electronic Material Vol.20 No.2

The nanocomposites are really promising for industrial, environmental and medical applications. In this work, new types of nanocomposites have been prepared from (PVA–TiO 2 ) nanocomposites doped by SiC nanoparticles for humidity sensor with high sensitivity, fl exible, high corrosion resistance and low cost. The experimental and theoretical studies on structural and optical properties of (PVA–TiO 2 –SiC) nanocomposites have been investigated. The optical microscope and FTIR studies were examined. The optical properties of nanocomposites were examined in wavelength range (220–800) nm. The results showed that the optical absorbance of (PVA–TiO 2 ) nanocomposites increases with increasing of the SiC nanoparticles concentrations. The energy band gap of (PVA–TiO 2 ) nanocomposites decreases while the optical constants increase with the increase in SiC nanoparticles concentrations. The (PVA–TiO 2 –SiC) nanocomposites tested for humidity sensors at relative humidity range (40–80) RH.%. The experimental results showed that the electrical resistance for (PVA–TiO 2 –SiC) nanocomposites decreases with increase in relative humidity. The (PVA–TiO 2 –SiC) nanocomposites have highly sensitivity for relative humidity.

Assessing Trees Diversity in Jebel Elgarrie Forest Reserve in the Blue Nile State, Sudan

Dafa-Alla Mohamed Dafa-Alla,Ahmed Ibrahim Abuelbasher,Haytham Hashim Gibreel,Yousif Elnour Yagoub,Ahmed Ali Hassabelkreem Siddig,Ahmed Mustafa Morad Hasoba 강원대학교 산림과학연구소 2022 Journal of Forest Science Vol.38 No.3

The study aims to examine population indices of mature trees in Jebel Elgarrie forest, Blue Nile State, Sudan. We used remote sensing techniques to stratify the forest into vegetation classes depending on tree density. We distributed 97 circular sample plots (0.1 ha) proportionally to the area of the vegetation classes. In each sample plot we identified, counted and recorded all mature trees (DBH ≥10 cm). We calculated frequency, density, abundance, richness, evenness and diversity for each species and we drew abundance rank curve of mature trees. We used One-Way ANOVA to test for differences (=0.05) in mean density (No./ha) of mature trees between vegetation classes. Results revealed that the forest was conveniently sub-divided into high density (C1), medium density (C2), low density (C3) and bare farm land (C4) classes. We identified fifteen tree species that belong to 10 families and 14 genera. Combretaceae and Fabaceae were the common families while Anogeissus leiocarpa was the most frequently occurring species. While species diversity varied between vegetation classes, diversity of the forest as a whole is low. While mean density of mature trees in C1, C2, C3 and C4 it was 100, 74, 10, and 0, respectively, it was 54 for the whole forest indicating low stocking, Following One-Way ANOVA, multiple comparisons revealed significant differences in mean density of mature trees between C1 & C3 and C2 & C3. The study provided empirical results on population indices of mature tree species, which would be of importance for successful management and conservation of the forest.