Исследование диэлектрических функций слоя наночастиц Ag на кремнии с помощью спектроэллипсометрии и спектрофотометрии

An investigation of the optical characteristics of a layer of Ag nanoparticles deposited from an AgNO3 solution on the surface of single-crystal Si is presented. The measurements were carried out using spectroscopic ellipsometry and spectrophotometry at the same tilt angle and sample probe location in a wide spectral range from 200 to 1700 nm. From the obtained experimental data, the parameters of the Drude-Lorentz model and the complex dielectric function were determined, which was compared with the pseudo-dielectric function. Both dependences revealed resonances of a bulk plasmon near the energy E = 3.8 eV, while a localized plasmon was detected in the pseudo-dielectric function at E = 1.65 eV, and in the dielectric function at E = 1.84 eV.

POTENSI EKSTRAK KULIT JERUK KUNCI (Citrus microcarpa Bunge) SEBAGAI BIOREDUKTOR DALAM SINTESIS NANOPARTIKEL PERAK

Nowadays silver nanoparticles (AgNPs) synthesized so often by plant extracts as a reductor. The synthesis of AgNPs was carried out by Citrus microcarpa Bunge fruit peel extract a reductor in various extract concentrations (10, 15, and 20%), concentration of AgNO3 solution of 0.15M and temperature of 700C. The presence of AgNPs was determined by color test and the formation of Surface Plasmon Resonance (SPR) using UV-Vis Spectrophotometer while to determine the morphology and size of the nanoparticles using Scanning Electron Microscope (SEM). The results of the analysis showed that AgNPs was formed at colloidal phase with dark brown color with wavelengths of 457.30 nm, 478.90 nm, and 422.80 nm for variation concentration of 10, 15 and 20% with slightly spherical, slightly elongated and jagged morphology with average size of 253.8 nm (10%), 254.2 nm (15%) and 253.9 nm (20%).

Superfast Synthesis of Stabilized Silver Nanoparticles Using Aqueous Allium sativum (Garlic) Extract and Isoniazid Hydrazide Conjugates: Molecular Docking and In-Vitro Characterizations

Green synthesis of silver nanoparticles (AgNPs) was synthesized from fresh garlic extract coupled with isoniazid hydrazide (INH), a commonly used antibiotic to treat tuberculosis. A molecular docking study conducted with the selected compounds compared with anthranilate phosphoribosyltransferase (trpD) from Mycobacterium tuberculosis. The aqueous extract of garlic was prepared and mixed with silver nitrate (AgNO3) solution for the superfast synthesis of stable AgNPs. INH was then conjugated with AgNPs at different ratios (v/v) to obtain stable INH-AgNPs conjugates (AgNCs). The resulting AgNCs characterized by FTIR spectra revealed the ultrafast formation of AgNPs (<5 s) and perfectly conjugated with INH. The shifting of λmax to longer wavelength, as found from UV spectral analysis, confirmed the formation of AgNCs, among which ideal formulations (F7, F10, and F13) have been pre-selected. The zeta particle size (PS) and the zeta potential (ZP) of AgNPs were found to be 145.3 ± 2.1 nm and −33.1 mV, respectively. These data were significantly different compared to that of AgNCs (160 ± 2.7 nm and −14.4 mV for F7; 208.9 ± 2.9 nm and −19.8 mV for F10; and 281.3 ± 3.6 nm and −19.5 mV for F13), most probably due to INH conjugation. The results of XRD, SEM and EDX confirmed the formation of AgNCs. From UV spectral analysis, EE of INH as 51.6 ± 5.21, 53.6 ± 6.88, and 70.01 ± 7.11 %, for F7, F10, and F13, respectively. The stability of the three formulations was confirmed in various physiological conditions. Drug was released in a sustainable fashion. Besides, from the preferred 23 compounds, five compounds namely Sativoside R2, Degalactotigonin, Proto-desgalactotigonin, Eruboside B and Sativoside R1 showed a better docking score than trpD, and therefore may help in promoting anti-tubercular activity.

Decoration of Ag Nanoparticle on ZnO Nanowire by Intense Pulsed Light and Enhanced UV Photodetector

Zinc oxide (ZnO) nanowires (NWs) are wide-bandgap semiconductors that absorb ultraviolet (UV) radiation. Various post-treatment processes have been studied to improve the optical properties of the as-grown ZnO NWs. Among them, Ag nanoparticles (NPs) effectively improved the optical properties on the surface of the ZnO NWs. In this study, ZnO NWs were synthesized via the hydrothermal synthesis method. ZnO NWs were decorated with Ag NPs on the surface of the ZnO NWs in a silver nitrate (AgNO3) aqueous solution by intense pulsed light (IPL) irradiation. Ag NPs were successfully decorated under the following conditions: aqueous AgNO3 solution of 100 nM, an energy of 1 J/cm2, and an exposure time of 8 ms. The responsivity and sensitivity of the ZnO NW UV photodetectors increased by 7.43 and 3.37 times, respectively. The IPL process makes it possible to decorate Ag NPs in a simple manner within an extremely short time.

Synthesis and Characterization of Silver Nanoparticles Prepared with Carrasquilla Fruit Extract (Berberis hallii) and Evaluation of Its Photocatalytic Activity

In this study, silver nanoparticles (AgNPs) were obtained using a green-chemistry procedure. For this protocol, the Carrasquilla extract (CE) (Berberis hallii) and a AgNO3 solution were used as the reducing agent and the metal precursor, respectively. The as-prepared AgNPs after characterization were then used to evaluate the degradation of the methylene blue (MB), the safranin (SF), and the mixture of both dyes in the aqueous phase under solar light irradiation. The photocatalytic activity of AgNPs for the degradation of the MB (k = 0.0092 min−1) was higher than the SF (k = 0.00016 min−1) due to the susceptibility of the thiazine ring of the MB to photodegradation contrasted to the phenyl phenazine of the SF. However, SF was mostly removed by adsorption with a maximum uptake of 2907 mg/g. Overall, this eco-friendly and green conversion of silver ions to metallic elements avoids the use of toxic chemicals and could be applied for the degradation/adsorption of dyes used in several industrial processes.

Modeling Contaminant Transport of Nitrate in Soil Column

Soil forms solution when it is in contact with water or any liquid. This soil solution disperses into the ground in different parts, at different velocities. Hence, the chemical contents of the soil are leached gradually from soil with infiltrating water. Soil parameter characterizing this phenomenon is referred to as Solute dispersivity. The objective of this study is to model contaminant transport of nitrate in soil, calibrate and verify the model derived. Dispersion studies were performed in the laboratory using soil columns filled with silver nitrate (AgNO3) solution. Samples were collected from the column outlet at intervals of 5minutes and the dispersion coefficient calculated. The dispersion coefficient calculated was incorporated into existing Notordamojo’s model and solved. Results obtained from the research showed that the R2values ranging from 0.741 to 0.896 and 0.484 to 0.769 were obtained for the modified model and the existing Notordamojo’s model respectively. The model verified with the experimental data showed predicted transport was in close agreement with experimental values having coefficient of correlation (r) ranging from 0.86 to 0.98. The difference between the experimental and predicted results, when expressed as a percentage of the experimental value was less than 5%. The study has established that the modified model which accounted for variability in dispersion coefficient offered a better approach than the conventional one. Doi: 10.28991/esj-2021-01290 Full Text: PDF

A Zero-Waste Process for the Treatment of Spent Potliner (SPL) Waste

This work presents a deep analyses of an environmentally friendly process to recover all valuable minerals contained in the spent potliner (SPL) such as graphite carbon and aluminum fluoride (AlF3) and production of sodium sulfate (Na2SO4) and gypsum (CaSO4) when H2SO4 is used as the leaching agent. The level of emission of hazardous gases such as HCN (weak acid) and HF are minimized by direct scrubbing of the HCN in aqueous AgNO3 solution to produce a stable silver cyanide (AgCN) product. The HF can be recovered as a liquid by condensation and used within the process and/or in production of metal fluorides such as the highly-soluble potassium fluoride (KF); a main source of fluoride in industry. Almost pure CO2 gas is also recovered from the process gas streams.

Development of wound healing hydrogels using bio synthesized silver nano particles and its antibacterial activity of Major Wound pathogens

In this present study, biosynthesis of AgNp’s from methanolic extracts of H. Colorata and its wound healing activity was documented. The synthesis of AgNp’s was done by treating AgNO3 solution with an aqueous extract of H. colorata. The production of AgNp’s was confirmed by a color change of the solution from clear to brown color. The reduced AgNp’s were characterized by Scanning Electron Microscope (SEM), UV–vis spectroscopy. From UV analysis peak was observed at 415nm and spherical shaped AgNp’s were observed. The antibacterial activity and Minimum inhibitory Concentration (MIC) of the silver nanoparticles were determined. The results suggest that biosynthesized AgNp’s from aqueous extracts ofH.coloratashowed a significant antibacterial activity against wound pathogens.

Silver-Releasing Micro-/Nanoporous Coating on Additively Manufactured Macroporous Ti-Ta-Nb-Zr Scaffolds with High Osseointegration and Antibacterial Properties

The two major problems of titanium alloy surface of bone/dental implants were the lack of native tissue integration and associated infection. To solve these problems, the development of self-defending implants with intrinsic osteogenic properties has been highlighted, in which titanium alloy surfaces of bone/dental implants are endowed with antibacterial property by silver (Ag) incorporated in biomaterials. In this study, we biofunctionalized the surface of selective laser melting (SLM) manufactured volume-porous Ti-Ta-Nb-Zr scaffolds by using plasma electrolytic oxidation (PEO) as a way to eliminate the peri-operative bacterial load and promote osseointegration. In the experiment, the PEO process operated with three different concentration (1, 1, and 2 g/L) of a AgNO3 solution. As a result, a titanium oxide coating embedded with calcium and phosphorous and Ag was formed by one-step PEO treatment, and a presence of HAp was detected by X-ray diffraction (XRD) and XPS. In addition, Ag ions were found to be released from the scaffolds for at least 28 days, resulting in an effective prevention of bacterial adhesion and a decrease of the number of planktonic bacteria, with no sign of cytotoxicity shown simultaneously. Highly porosity micropores were formed on the surface of scaffolds after oxidation, and the mechanical properties did not show any signs of change. Besides, a strong calcium deposition and osteoconductive effect were found on the surface of PEO-treated Ag scaffolds. To sum up, this study reveals the potential of PEO coatings to biofunctionalize SLM Ti-Ta-Nb-Zr scaffolds with antibacterial agents. The biomaterials developed here, therefore, exploit the biofunctionalized behavior of Ag to offer strong antibacterial behavior and osteogenic promotion without cytotoxicity of Ag against mammalian cells.

Green Synthesis of Ag Nanoparticles for Anti-Microbial Applications using Aloe Barbadensis Miller Extract

The green synthesis of nanomaterials is becoming much popular as a result of worldwide problems associated with environmental concerns. In the present work, leaf extract of Barbadensis Miller, (commonly known as Aloe vera) was used for bio-reduction of silver ions to silver nanoparticles. Aloe vera extract and AgNO3 solution in different volumes were treated and it resulted in the reduction of Ag+ ions to Ag metal atoms, which further accumulated as Ag nanoparticles. The prepared nanoparticles were characterized by UV-vis spectroscopy, SEM, FT-IR spectroscopy and XRD analysis. The present study established that the shape and size of the silver nanoparticles can be effectively controlled and modulated using green synthesis technique. The scope of the prepared particles for anti-microbial applications were also investigated.