Solvothermal synthesis has shown to have a great potential to synthesize Zinc Oxide nanoparticles (ZnO NPs) with less than 10 nm size. In this study, we present a rapid synthesis of ZnO NPs in which ...ZnO NPs with more uniform shape and highly dispersed were synthesized using zinc acetate dihydrate (Zn(CH3COO)2 2H2O) and potassium hydroxide (KOH) as a precursor and absolute ethanol as solvent via solvothermal method. Few techniques were exploited to characterize synthesized ZnO NPs including X-ray diffraction (XRD), transmission electron microscope (TEM), Brunauer-Emmett-Teller (BET), energy-dispersive X-ray spectroscopy (EDX), fourier transform infrared (FT-IR) spectroscopy, and ultraviolet visible (UV-Vis) spectroscopy. Synthesized ZnO NPs that were prepared via solvothermal synthesis method at 60 °C for 3 hours exhibited a wurtzite structure with a crystalline size of 10.08 nm and particle size of 7.4 ± 1.2 nm. The UV-vis absorption spectrum has shown peak at 357 nm indicate the presence of ZnO NPs. Hence, better quality with uniform size ZnO NPs can be easily synthesized with reduced amount of time via solvothermal synthesis method rather than using other complicated and lengthy synthesis methods.
A novel technique was employed to optimize the CO2 sorption performance of spent shale at elevated pressure–temperature (PT) conditions. Four samples of spent shale prepared from the pyrolysis of oil ...shale under an anoxic condition were further modified with diethylenetriamine (DETA) and ethylenediamine (EDA) through the impregnation technique to investigate the variations in their physicochemical characteristics and sorption performance. The textural and structural properties of the DETA- and EDA- modified samples revealed a decrease in the surface area from tens of m2/g to a unit of m2/g due to the amine group dispersing into the available pores, but the pore sizes drastically increased to macropores and led to the creation of micropores. The N–H and C–N bonds of amine noticed on the modified samples exhibit remarkable affinity for CO2 sequestration and are confirmed to be thermally stable at higher temperatures by thermogravimetric (TG) analysis. Furthermore, the maximum sorption capacity of the spent shale increased by about 100% with the DETA modification, and the equilibrium isotherm analyses confirmed the sorption performance to support heterogenous sorption in conjunction with both monolayer and multilayer coverage since they agreed with the Sips, Toth, Langmuir, and Freundlich models. The sorption kinetics confirm that the sorption process is not limited to diffusion, and both physisorption and chemisorption have also occurred. Furthermore, the heat of enthalpy reveals an endothermic reaction observed between the CO2 and amine-modified samples as a result of the chemical bond, which will require more energy to break down. This investigation reveals that optimization of spent shale with amine functional groups can enhance its sorption behavior and the amine-modified spent shale can be a promising sorbent for CO2 sequestration from impure steams of the natural gas.
Shorea macrophylla belongs to the Shorea genus under the Dipterocarpaceae family. It is a woody tree that grows in the rainforest in Southeast Asia. The complete chloroplast (cp) genome sequence of ...S. macrophylla is reported here. The genomic size of S. macrophylla is 150,778 bp and it possesses a circular structure with conserved constitute regions of large single copy (LSC, 83,681 bp) and small single copy (SSC, 19,813 bp) regions, as well as a pair of inverted repeats with a length of 23,642 bp. It has 112 unique genes, including 78 protein-coding genes, 30 tRNA genes, and four rRNA genes. The genome exhibits a similar GC content, gene order, structure, and codon usage when compared to previously reported chloroplast genomes from other plant species. The chloroplast genome of S. macrophylla contained 262 SSRs, the most prevalent of which was A/T, followed by AAT/ATT. Furthermore, the sequences contain 43 long repeat sequences, practically most of them are forward or palindrome type long repeats. The genome structure of S. macrophylla was compared to the genomic structures of closely related species from the same family, and eight mutational hotspots were discovered. The phylogenetic analysis demonstrated a close relationship between Shorea and Parashorea species, indicating that Shorea is not monophyletic. The complete chloroplast genome sequence analysis of S. macrophylla reported in this paper will contribute to further studies in molecular identification, genetic diversity, and phylogenetic research.
Adhesion between dust particles and indoor surfaces can lead to negative effects on human health by triggering allergic and asthmatic reactions. In this study, adhesion forces of indoor office dust ...and activated carbon (AC, as model soot) particles to four common indoor materials (Al, Cu, PVC, and glass) were measured by colloidal probe atomic force microscopy. Chemical analysis of office dust shows it is largely made up of oxygenated hydrophilic organic carbon material. Both metal surfaces experienced weaker dust and AC adhesion than PVC or glass by up to 2-12 times lower primarily due to the presence of attractive electrostatic forces in the latter two (non-conducting) surfaces. Dust and AC adhesion were also highly sensitive to surface roughness, with an inverse relationship between adhesion force and roughness due to the reduction in contact area between the particle and a rougher material surface. Capillary forces play only a minor or negligible role in dust and AC surface adhesion. Adhesion models utilizing a purely van der Waals approach such as the simple Hamaker model and modified Rumpf's model are insufficient to determine the actual particle-surface contact radii and requires the accounting of non-van der Waals forces to adhesion.
Copyright 2014 American Association for Aerosol Research
Background
Various parts of
Anacardium occidentale
plant possess curative qualities like antidiabetic, anti-inflammatory, antibacterial, antifungal, and antioxidant. Aqueous extract of this plant ...leaf was used in biosynthesizing zinc oxide (ZnO) nanoaggregates using two precursors of zinc salt (zinc acetate dihydrate Zn(CH
3
COO)
2
∙2H
2
O and zinc chloride ZnCl
2
). The synthesized ZnO samples were used in a comparative study to investigate the antibacterial activity against selected Gram-positive and Gram-negative microbes
Staphylococcus aureus
,
Exiguobacterium aquaticum
(Gram +ve) and
Escherichia coli
,
Klebsiella pneumoniae
,
Acinetobacter baumannii
(Gram −ve). The synthesized ZnO nanoaggregates from the two precursors were characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive x-ray spectroscopy (EDX) techniques.
Results
Micrographs of SEM and TEM confirmed nanoparticles agglomerated into aggregates. While spherical nanoaggregates were identified in samples prepared from Zn(CH
3
COO)
2
∙2H
2
O, flake-like structures were identified in samples synthesized from ZnCl
2
. Particle size determined by TEM was 107.03 ± 1.54 nm and 206.58 ± 1.86 nm for zinc acetate dihydrate and zinc chloride precursors respectively. ZnO nanoaggregate synthesized using zinc acetate as precursor gave higher antibacterial activity than its counterpart, zinc chloride with
K. pneumonia
recording the highest inhibition zone of 2.08 ± 0.03 mm (67.53%) whereas
S. aureus
recorded the least inhibition zone of 1.06 ± 0.14 mm (34.75%) for ZnO nanoaggregate from zinc chloride precursor. Also, antibacterial activity increases with increasing concentration of the extract in general. However,
A. baumannii
,
E. aquaticum
, and
K. pneumoniae
did not follow the continuity trend with regards to the 250 ppm and 500 ppm concentrations.
Conclusion
Biosynthesis of ZnO nanoaggregates using aqueous extract of
A. occidentale
leaf from zinc acetate dihydrate and zinc chloride as precursors was successful with the formation of nanospheres and nanoflakes. The study suggested that
A. occidentale
sp. could be an alternative source for the production of ZnO nanoparticles and are efficient antibacterial compounds against both Gram +ve and Gram −ve microbes with its promising effect against infectious bacteria.
The study compared the antibacterial activity of synthesized ZnO nanoparticles (NPs) from fresh leaf and fresh stem bark aqueous extracts of Carica papaya against five selected microbes: ...Staphylococcus aureus, (Gram positive (+ve)), Escherichia coli (Gram negative (–ve)), Acinetobacter baumanni (Gram–ve), Exiguobacterium aquaticum (Gram+ve), and Klebsielia pneumonia (Gram +ve). The morphological features of the biosynthesized ZnO NPs were analyzed using transmission electron microscope (TEM) and scanning electron microscope (SEM); the Fourier-transform infrared spectrometer (FTIR) technique was used to observe the surface functional groups. The experimental results indicated that ZnO NPs were successfully synthesized using modified hydrothermal technique, which showed agglomerated flake-like or petal-like shapes with the organic extract surrounding the formed particles. The average particle size of the synthesized ZnO nanoparticles determined by SEM ranged between 54-97 nm with the width and length of the petal-like structures been 30 nm and 62 nm respectively. The average ZnO NPs from fresh stem bark extract of Carica papaya with higher concentrations (100-1000 ppm) demonstrated a higher antibacterial activity than the fresh leaf extracts. On the other hand, ZnO NPs from fresh leaf extracts of lower concentrations (25-50 ppm) rather showed a suitable result than the fresh stem bark. In general, ZnO NPs showed a positive antibacterial result towards the selected microbes. This shows that, the synthesized ZnO NP can be a substitute to chemical methods.
Mushroom harvesting, specifically mushroom picking, is a labor-intensive and time-consuming activity. This article presents a literature survey of the design and evaluation of mushroom harvesting ...robots and technologies to address the labor-intensive and time-consuming task of manual mushroom harvesting. We classify and look at different classes of harvesting robots and technologies from the 1970s to 2022. We present the robot's overall system and capabilities, including sensors and control systems where available. We also summarized the advantages and disadvantages of each system and the performance metrics where data are available.
Zinc oxide is an important material with numerous applications due to its unique properties. Due to their thermal and chemical stability are used in wide applications such as LEDs, sensors, ...catalysts, and photodetectors. Different chemical, physical, and biological methods have been adopted to achieve the intended result, as enumerated in many pieces of literature. Therefore, selecting an efficient synthesis process is essential, which is a key factor that significantly influences the efficacy of the synthesized nanocrystalline materials. The chemical synthesis of nanoparticles (NPs) via hydrothermal, solvothermal, and sol-gel routes is considered effective as high-quality crystalline structures are produced. Control of parameters of processes yields excellent morphological features of the synthesized samples. This review explored the different parameters of processes and their effect on the morphology of ZnO nanostructures via hydrothermal, solvothermal, and sol-gel techniques. Finally, some ZnO nanocomposites molecules are reviewed as per the dopant used and its effect on the sample compound synthesized.
PDF
