Effect of PVP on the Morphology and Growth of Cu Hierarchical Nanostructures Prepared by Electroless Deposition

2019 ◽  
Vol 821 ◽  
pp. 183-188
Author(s):  
Mary Donnabelle L. Balela ◽  
Vina Ingrid Cabiles
Keyword(s):  
Electroless Deposition ◽  
Reduction Rate ◽  
Particle Diameter ◽  
The Other ◽  
Mixed Potential ◽  
Cu Nanoparticles ◽  
Structure Directing Agent ◽  
Hierarchical Nanostructures ◽  
Mean Particle Diameter

Octahedral Cu hierarchical nanostructures were prepared by electroless deposition in aqueous solution at 80 °C. Polyvinyl pyrrolidone (PVP) was employed as the protective and structure directing agent to prevent oxidation and agglomeration of the Cu products. Addition of higher amounts of PVP (about 1.275 g) resulted in smaller but irregularly-shaped Cu nanoparticles. The Cu nanoparticles have a mean particle diameter of about 200 nm with excellent size distribution. On the other hand, Cu octahedrals were produced when 0.425 to 0.850 g PVP was used. In situ mixed potential monitoring of the solution during electroless deposition revealed that the mixed potential was more positive at larger amounts of PVP. This can be attributed to slower reduction rate due to the decrease in the activity of Cu(II) ions. Consequently, smaller Cu nanoparticles were produced.

In Situ Electrochemical Study of Copper Nanoparticles Stabilized with Food Grade Gelatin

2016 ◽  
Vol 705 ◽  
pp. 163-167 ◽  
Author(s):  
Ellaine M. Datu ◽  
Mary Donnabelle L. Balela
Keyword(s):  
Electroless Deposition ◽  
Reduction Rate ◽  
In Situ Monitoring ◽  
Mixed Potential ◽  
Cu Nanoparticles ◽  
Environment Friendly ◽  
Food Grade ◽  
Alternative Material ◽  
Kinetics Of

Commercially available conductive inks are typically made up of precious metal nanoparticles, such as gold (Au) and silver (Ag). Thus, cheaper metals like copper (Cu) are currently being explored as alternative material. Though Cu has a comparable conductivity to that of Ag, they tend to oxidize easily when exposed to air and water, which could limit their application. In this work, oxidation-stable Cu nanoparticles with mean diameter as small as 57 nm were prepared by simple electroless deposition in water. Food-grade gelatin was used as stabilizer, which makes the process more economical and environment-friendly. In situ monitoring of mixed potential was carried out during synthesis to understand the kinetics of the reaction. The mixed potential of the solution shifted negatively as the amount of gelatin was increased. This suggests faster reduction rate.

Formation of Cobalt Nanoparticles from Co(OH)2 Suspension

2014 ◽  
Vol 974 ◽  
pp. 50-54
Author(s):  
Mary Donnabelle L. Balela ◽  
Shunsuke Yagi ◽  
Eiichiro Matsubara
Keyword(s):  
Room Temperature ◽  
Electroless Deposition ◽  
Reduction Potential ◽  
Particle Diameter ◽  
Mixed Potential ◽  
Potential Measurement ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Co Nanoparticles

Metallic cobalt (Co) nanoparticles with mean diameters in the range of 50-500 nm are formed by electroless deposition at room temperature in the presence of increasing concentration of NaOH. Co deposition was investigated by in situ mixed potential measurement. Increasing concentration of NaOH shifts the mixed potential negatively, leading to faster Co deposition and smaller apparent particle diameter. The decrease in mixed potential with increasing NaOH concentration is attributed to the decrease in the activity of Co2+ aquo ions in equilibrium with Co (OH)2. Consenquently, the oxidation-reduction potential of Co (II)/Co redox pair is reduced. This leads to more negative mixed potential.

In situ mixed potential study of the growth of zinc oxide hierarchical nanostructures by wet oxidation of zinc foil

2016 ◽  
Vol 52 (4) ◽  
pp. 2319-2328 ◽  
Author(s):  
Mary Donnabelle L. Balela ◽  
Christian Mark O. Pelicano ◽  
Zainovia Lockman
Keyword(s):  
Zinc Oxide ◽  
Wet Oxidation ◽  
Mixed Potential ◽  
Hierarchical Nanostructures ◽  
Potential Study

Preparation and Photocatalytic Property of Cubic WO3

2014 ◽  
Vol 1081 ◽  
pp. 304-307
Author(s):  
Fu Liang Shang ◽  
Hai Tao Yang ◽  
Ling Gao
Keyword(s):  
Photocatalytic Activity ◽  
Monoclinic Phase ◽  
Uv Light ◽  
Sol Gel ◽  
Particle Diameter ◽  
Photocatalytic Property ◽  
Structure Directing Agent ◽  
Uv Light Irradiation ◽  
Petal Shape ◽  
Mean Particle Diameter

The cubic WO3powder was prepared by sol-gel method with WCl6as the soure of tungsten and P123as the structure-directing agent. The crystalline phase and microstructure of the powder were characterized through TG-DSC, XRD and SEM techniques, respectively. It was found the powder annealed at 250°C for 4h mainly was cubic WO3with a little monoclinic phase. The SEM micrographs revealed the powder has a petal shape with about 200 nm mean particle diameter. The photocatalytic activity of the powder was evaluated by methyl orange as mode compound to photocatalytic degradation under UV light irradiation. The results show the cubic WO3powder has much higher photocatalytic activity than the monoclinic phase.

Electroless Deposition of Nickel Nanoparticles at Room Temperature

2014 ◽  
Vol 974 ◽  
pp. 107-111 ◽  
Author(s):  
Mary Donnabelle L. Balela ◽  
Shunsuke Yagi ◽  
Eiichiro Matsubara
Keyword(s):  
Electroless Deposition ◽  
Electrochemical Quartz Crystal Microbalance ◽  
Metallic Nickel ◽  
Mixed Potential ◽  
Ni Nanoparticles ◽  
Potential Measurement ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Reaction Solution

Metallic nickel (Ni) nanoparticles with a mean diameter of about 70 nm are successfully formed by electroless deposition in an aqueous solution at 273 K. The formation of Ni nanoparticles is investigated by in situ mixed potential measurement in combination with thermodynamic calculation. The deposition rate of Ni is measured using an electrochemical quartz crystal microbalance (EQCM). The mixed potential of reaction solution drastically decreases below the oxidation-reduction potential of Ni (II)/Ni redox pair at about-0.60 v vs SHE after 30 min reaction. This coincides with a sharp increase in the deposited mass, suggesting Ni deposition.

A very rapid in situ Kikuchi technique to determine relative crystal misorientation

1988 ◽  
Vol 46 ◽  
pp. 830-831
Author(s):  
J. I. Bennetch
Keyword(s):  
Electron Beam ◽  
Analytical Techniques ◽  
Superplastic Forming ◽  
The Other ◽  
Kikuchi Pattern ◽  
Kikuchi Line ◽  
Line Analysis

In a recent study of the superplastic forming (SPF) behavior of certain Al-Li-X alloys, the relative misorientation between adjacent (sub)grains proved to be an important parameter. It is well established that the most accurate way to determine misorientation across boundaries is by Kikuchi line analysis. However, the SPF study required the characterization of a large number of (sub)grains in each sample to be statistically meaningful, a very time-consuming task even for comparatively rapid Kikuchi analytical techniques.In order to circumvent this problem, an alternate, even more rapid in-situ Kikuchi technique was devised, eliminating the need for the developing of negatives and any subsequent measurements on photographic plates. All that is required is a double tilt low backlash goniometer capable of tilting ± 45° in one axis and ± 30° in the other axis. The procedure is as follows. While viewing the microscope screen, one merely tilts the specimen until a standard recognizable reference Kikuchi pattern is centered, making sure, at the same time, that the focused electron beam remains on the (sub)grain in question.

Preparation and Evaluation of Chitosan Loaded Naproxen Nanoparticles by Emulsion Interfacial Reaction Method

2019 ◽  
Vol 9 (2) ◽  
pp. 89-96
Author(s):  
Abbaraju Krishna Sailaja ◽  
Juveria Banu
Keyword(s):  
Drug Release ◽  
Interfacial Reaction ◽  
Polymer Concentration ◽  
Chitosan Nanoparticles ◽  
Particle Diameter ◽  
Entrapment Efficiency ◽  
Reaction Method ◽  
Release Data ◽  
Mean Particle Diameter

Aim: The aim of this investigation was to develop and characterize naproxen loaded chitosan nanoparticles by emulsion interfacial reaction method. Methodology: For emulsion interfacial reaction method chitosan was used as a polymer. In this method, eight formulations were prepared by varying drug to polymer concentration. Discussion: Out of eight formulations prepared using emulsion interfacial reaction method EI8 formulation was found to be the best formulation. The drug content was observed as 94.4%, entrapment efficiency and loading capacity were found to be 87.5% and 75%, respectively. The mean particle diameter was measured as 324.6nm and the Zeta potential value was found to be -42.4mv. In vitro drug release data showed 97.2% of drug release rate sustained up to 12hrs. Conclusion: The results clearly reveal that EI8 formulation having the highest amount of drug was considered as the best formulation because of its small mean particle diameter, good entrapment efficiency, and stability.

scholarly journals A Study on the Effect of Alumina on the Morphology and Reduction Behavior of Sinter by In Situ Observation

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 740
Author(s):  
Sang Gyun Shin ◽  
Wan Ho Kim ◽  
Dong Joon Min
Keyword(s):  
Reduction Rate ◽  
Al2o3 Content ◽  
Confocal Laser ◽  
In Situ Observation ◽  
Sintering Process ◽  
Reduction Behavior ◽  
Reducing Gas ◽  
Interfacial Chemical Reaction ◽  
Reaction Routes

The effects of Al2O3 content on the morphology and reducibility of sinter were respectively investigated using confocal laser microscopy and thermogravimetric analysis at 1273 K under CO gas. To understand the effects of the sintering process, separate samples were prepared via the equilibrium and metastable reaction routes. In the equilibrium samples, the addition of Al2O3 led to the formation of the silico-ferrite of calcium and alumino phase and a decrease in the reduction rate due to the lowered reactivity of iron oxide. In contrast, in the metastable samples, the reduction rate increased after the addition of 2.5 mass% Al2O3. The addition of Al2O3 decreased the fraction of the liquid phase and increased the fraction of pores in the sample. As a result, the reduction rate is proportional to the Al2O3 content owing to the changes in the sinter morphology. In determining the reduction rate of the sinter, the influence of the microstructure on the diffusion of the reducing gas is more significant than that of the interfacial chemical reaction due to the formation of the SFCA phase. The microstructure changes of the sinter with the addition of Al2O3 and the corresponding reduction behaviors are further discussed.

Extensive Enteric Leiomyolysis Due to Cytomegalovirus Enterocolitis in Vertically Acquired Human Immunodeficiency Virus Infection in Infants

2000 ◽  
Vol 3 (6) ◽  
pp. 591-596 ◽  
Author(s):  
Virpi V. Smith ◽  
Amanda J. Williams ◽  
Vas Novelli ◽  
Marian Malone
Keyword(s):  
Human Immunodeficiency Virus ◽  
Vascular Endothelium ◽  
Muscularis Propria ◽  
The Other ◽  
Muscularis Mucosae ◽  
Immunodeficiency Virus ◽  
Acquired Immunodeficiency ◽  
Immunodeficiency Syndrome ◽  
Viral Inclusions

We report two infants with the acquired immunodeficiency syndrome (AIDS) and rectal bleeding due to cytomegalovirus (CMV) ileitis and colitis with minimal focal mucosal ulceration but with extensive leiomyolysis of the muscularis propria. Immunostaining and in situ hybridization for CMV showed numerous viral inclusions in the myocytes of the muscularis propria and vascular endothelium/smooth muscle with only occasional inclusions present in the muscularis mucosae. Colectomy was curative in one patient; in the other the bowel was only examined at postmortem.

Did Ground Cover Change Over Geologic Time?

2000 ◽  
Vol 6 ◽  
pp. 171-182 ◽  
Author(s):  
Ben A. LePage ◽  
Hermann W. Pfefferkorn
Keyword(s):  
Fossil Record ◽  
Ground Cover ◽  
The Other ◽  
Detailed Account ◽  
Geologic Time ◽  
The Past ◽  
Other Hand ◽  
Plant Fossil

When one hears the term “ground cover,” one immediately thinks of “grasses.” This perception is so deep-seated that paleobotanists even have been overheard to proclaim that “there was no ground cover before grasses.” Today grasses are so predominant in many environments that this perception is perpetuated easily. On the other hand, it is difficult to imagine the absence or lack of ground cover prior to the mid-Tertiary. We tested the hypothesis that different forms of ground cover existed in the past against examples from the Recent and the fossil record (Table 1). The Recent data were obtained from a large number of sources including those in the ecological, horticultural, and microbiological literature. Other data were derived from our knowledge of Precambrian life, sedimentology and paleosols, and the plant fossil record, especially in situ floras and fossil “monocultures.” Some of the data are original observations, but many others are from the literature. A detailed account of these results will be presented elsewhere (Pfefferkorn and LePage, in preparation).

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