scholarly journals Bio-conjugated silver nano-materials and shape-directing role of cetyltrimethylammonium bromide

2013 ◽  
Vol 2 (1) ◽  
pp. 57-67 ◽  
Author(s):  
Zaheer Khan ◽  
Qamer Faisal ◽  
Rabia Ahmad
Keyword(s):  
Cetyltrimethylammonium Bromide ◽  
Electron Microscopic ◽  
Tem Analysis ◽  
Alstonia Scholaris ◽  
Irregular Shapes ◽  
Transmission Electron ◽  
Electron Microscopic Technique ◽  
Visible Spectra ◽  
Transmission Electron Microscopic ◽  
20 Nm

Conventional UV-visible spectrophotometric and transmission electron microscopic technique were used to determine the morphology of silver nanoplates (AgNP) using Alstonia scholaris aqueous leaves extract for the first time. The visible spectra showed the presence of three well defined surface plasmon absorption (SRP) bands at 500, 550 and 675 nm which attributed to the anisotropic growth of Ag-nanoplates. Transmission electron microscopic (TEM) analysis of AgNP showed formation of truncated triangular, polyhedral with some irregular shapes nanoplates in the size range 7-20 nm. Cetyltrimethylammonium bromide (CTAB) has no significant effect on the shape of the spectra, position of SRP bands, size and the size distribution of AgNP. Effects of various [CTAB] were also discussed in the green extra-cellular synthesis of AgNP using Alstonia scholaris leaves extract.

Effect of Magnesium Coating Prior to Lithium Loading over SBA-15 for Stabilization of its Mesostructure

2014 ◽  
Vol 917 ◽  
pp. 3-9
Author(s):  
Muhammad Ayoub ◽  
Ahmad Zuhairi Abdullah
Keyword(s):  
Pore Size ◽  
Pore Volume ◽  
Mesoporous Material ◽  
Mesoporous Structure ◽  
Electron Microscopic ◽  
Tem Analysis ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
The Stability ◽  
Basic Strength

Mesoporous material SBA-15 was synthesized using P123 and TEMOS as the templates. Lithium in the form of LiOH was loaded over a previously prepared SBA-15. The basic strength of the prepared samples of SBA-15 was found to increase but the mesoporous structure was severely destroyed. The mesoporous structure of the prepared SBA-15 was retained after coating it with 30 wt. % magnesium prior to LiOH loading. The stability of mesoporous structure was strongly influenced by the extent of magnesium coating. It was also noted that this structure was also affected by LiOH loading and significantly destroyed structure when magnesium coating value exceeded 20 %. These samples were thoroughly characterized for their surface area, pore volume, pore size, basic strength, SAXRD patterns and transmission electron microscopic (TEM) analysis.

Electrical, Optical and Structural Properties of Thin SiO2 Films On Si

1987 ◽  
Vol 105 ◽  
Author(s):  
N. M. Ravindra ◽  
O. L. Russo ◽  
D. Fathy ◽  
J. Narayan ◽  
A. R. Heyd ◽  
...  
Keyword(s):  
Breakdown Voltage ◽  
Dielectric Strength ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Current Voltage ◽  
Current Conduction ◽  
Transmission Electron Microscopic ◽  
State Densities ◽  
20 Nm

AbstractBreakdown voltage, static current-voltage, spectroscopic ellipsometry (SE), electrolyte electroreflectance (EER) and high resolution transmission electron microscopic (HRTEM) studies of thermally grown thin films of SiO2 on silicon (800°C - dry) are reported here. The investigation of the electrical properties of these films lead us to suggest the criteria for determining the breakdown voltage of these 20nm thick SiO2 films. The Fowler-Nordheim tunneling contribution to current conduction mechanisms in SiO2 has been considered in evaluating these criteria. SE, EER & HRTEM studies have been performed on SiO2 films of thicknesses in the range of 1–20 nm. These studies lead us to determine the thickness of the non-stoichiometric silicon-rich oxide existing at the Si-SiO2 interface. EER studies show that the relative surface state densities for different film thicknesses can be determined. The role of the transition region in determining the dielectric strength of thin SiO2 films is discussed.

Preparation and Loading Process of Single Crystalline Samples into a Gas Environmental Cell Holder for In Situ Atomic Resolution Scanning Transmission Electron Microscopic Observation

2016 ◽  
Vol 22 (3) ◽  
pp. 515-519 ◽  
Author(s):  
Rainer Straubinger ◽  
Andreas Beyer ◽  
Kerstin Volz
Keyword(s):  
Ion Beam ◽  
Electron Microscopic Observation ◽  
Atomic Resolution ◽  
Electron Microscopic ◽  
Tem Analysis ◽  
Single Crystalline ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Environmental Cell

AbstractA reproducible way to transfer a single crystalline sample into a gas environmental cell holder for in situ transmission electron microscopic (TEM) analysis is shown in this study. As in situ holders have only single-tilt capability, it is necessary to prepare the sample precisely along a specific zone axis. This can be achieved by a very accurate focused ion beam lift-out preparation. We show a step-by-step procedure to prepare the sample and transfer it into the gas environmental cell. The sample material is a GaP/Ga(NAsP)/GaP multi-quantum well structure on Si. Scanning TEM observations prove that it is possible to achieve atomic resolution at very high temperatures in a nitrogen environment of 100,000 Pa.

Studies of Circular DNA Using a New Electron Microscopic Technique

1973 ◽  
Vol 31 ◽  
pp. 596-597
Author(s):  
C. N. Gordon
Keyword(s):  
Electron Microscopy ◽  
Aqueous Salt Solution ◽  
Contour Length ◽  
Cleavage Surface ◽  
Mica Substrate ◽  
Electron Microscopic ◽  
Replica Technique ◽  
Circular Dna ◽  
Transmission Electron ◽  
Electron Microscopic Technique

Gordon and Kleinschmidt have described a new preparative technique for visualizing DNA by electron microscopy. This procedure, which is a modification of Hall's “mica substrate technique”, consists of the following steps: (a) K+ ions on the cleavage surface of native mica are exchanged for Al3+ ions by ion exchange. (b) The mica, with Al3+ in the exchange sites on the surface, is placed in a dilute aqueous salt solution of DNA for several minutes; during this period DNA becomes adsorbed on the surface. (c) The mica with adsorbed DNA is removed from the DNA solution, rinsed, dried and visualized for transmission electron microscopy by Hall's platinum pre-shadow replica technique.In previous studies of circular DNA by this technique, most of the molecules seen were either broken to linears or extensively tangled; in general, it was not possible to obtain suitably large samples of open extended molecules for contour length measurements.

The blister of porphyria cutanea tarda: A Scanning and Transmission Electron Microscopic study

1986 ◽  
Vol 44 ◽  
pp. 334-335
Author(s):  
Veronika Burmeister ◽  
R. Swaminathan
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Basement Membrane ◽  
Middle Age ◽  
Porphyria Cutanea Tarda ◽  
Minor Trauma ◽  
Electron Microscopic ◽  
Transmission Electron Microscopic Study ◽  
Transmission Electron ◽  
Transmission Electron Microscopic

Porphyria cutanea tarda (PCT) is a disorder of porphyrin metabolism which occurs most often during middle age. The disease is characterized by excessive production of uroporphyrin which causes photosensitivity and skin eruptions on hands and arms, due to minor trauma and exposure to sunlight. The pathology of the blister is well known, being subepidermal with epidermodermal separation, it is not always absolutely clear, whether the basal lamina is attached to the epidermis or the dermis. The purpose of our investigation was to study the attachment of the basement membrane in the blister by comparing scanning with transmission electron microscopy.

TEM comparison of osmium vs osmium with potassium ferricyanide secondary fixatives and the impact of secondary fixative temperature on tissue preservation/contrast quality

1996 ◽  
Vol 54 ◽  
pp. 910-911
Author(s):  
J. W. Horn ◽  
B. J. Dovey-Hartman ◽  
V. P. Meador
Keyword(s):  
Osmium Tetroxide ◽  
Potassium Ferricyanide ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Microscopic Evaluation ◽  
Cacodylate Buffer ◽  
Transmission Electron Microscopic ◽  
Glutaraldehyde Solution ◽  
Temperature Impact ◽  
The Impact

Osmium tetroxide (OsO4) is a universally used secondary fixative for routine transmission electron microscopic evaluation of biological specimens. Use of OsO4 results in good ultrastructural preservation and electron density but several factors, such as concentration, length of exposure, and temperature, impact overall results. Potassium ferricyanide, an additive used primarily in combination with OsO4, has mainly been used to enhance the contrast of lipids, glycogen, cell membranes, and membranous organelles. The purpose of this project was to compare the secondary fixative solutions, OsO4 vs. OsO4 with potassium ferricyanide, and secondary fixative temperature for determining which combination gives optimal ultrastructural fixation and enhanced organelle staining/contrast.Fresh rat liver samples were diced to ∼1 mm3 blocks, placed into porous processing capsules/baskets, preserved in buffered 2% formaldehyde/2.5% glutaraldehyde solution, and rinsed with 0.12 M cacodylate buffer (pH 7.2). Tissue processing capsules were separated (3 capsules/secondary fixative.solution) and secondarily fixed (table) for 90 minutes. Tissues were buffer rinsed, dehydrated with ascending concentrations of ethanol solutions, infiltrated, and embedded in epoxy resin.

Radial mass analysis of unstained STEM images of molluscan hemocyanins

1990 ◽  
Vol 48 (3) ◽  
pp. 810-811
Author(s):  
M.G. Hamilton ◽  
T.T. Herskovits ◽  
J.S. Wall
Keyword(s):  
Image Analysis ◽  
Hollow Cylinder ◽  
Electron Micrographs ◽  
Side View ◽  
Mass Analysis ◽  
Mass Measurements ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Transmission Electron Microscopic ◽  
Microscopic Studies

The hemocyanins of molluscs are aggregates of a cylindrical decameric subparticle that assembles into di-, tri-, tetra-, penta-, and larger multi-decameric particles with masses that are multiples of the 4.4 Md decamer. Electron micrographs of these hemocyanins typically show the particles with two profiles: circular representing the cylinder viewed from the end and rectangular representing the side-view of the hollow cylinder.The model proposed by Mellema and Klug from image analysis of a didecameric hemocyanin with the two decamers facing one another with collar (closed) ends outward fits the appearance of side-views of the negatively-stained cylinders. These authors also suggested that there might be caps at the ends. In one of a series of transmission electron microscopic studies of molluscan hemocyanins, Siezen and Van Bruggen supported the Mellema-Klug model, but stated that they had never observed a cap component. With STEM we have tested the end cap hypothesis by direct mass measurements across the end-views of unstained particles.

Transmission Electron Microscopic Observations of Al3Li and Al3Ti Precipitation in A Rapidly Solidified Al-3Li-0.2Ti ALLOY

1980 ◽  
Vol 38 ◽  
pp. 336-337
Author(s):  
J. E. O’Neal ◽  
K. K. Sankaran ◽  
S. M. L. Sastry
Keyword(s):  
Rapid Solidification ◽  
Metallic Substrate ◽  
Deformation Characteristics ◽  
Phase Decomposition ◽  
Electron Microscopic ◽  
Transmission Electron ◽  
Supersaturated Solid Solutions ◽  
Transmission Electron Microscopic ◽  
Rapidly Solidified ◽  
Microstructural Homogeneity

Rapid solidification of a molten, multicomponent alloy against a metallic substrate promotes greater microstructural homogeneity and greater solid solubility of alloying elements than can be achieved by slower-cooling casting methods. The supersaturated solid solutions produced by rapid solidification can be subsequently annealed to precipitate, by controlled phase decomposition, uniform 10-100 nm precipitates or dispersoids. TEM studies were made of the precipitation of metastable Al3Li(δ’) and equilibrium AL3H phases and the deformation characteristics of a rapidly solidified Al-3Li-0.2Ti alloy.

Utilizing Nanoprobing and Circuit Diagnostics to Identify Key Failure Mechanism of Otherwise Nonvisible Defects in 20 nm Logic Devices

2014 ◽  
Author(s):  
M.K. Dawood ◽  
C. Chen ◽  
P.K. Tan ◽  
S. James ◽  
P.S. Limin ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Contact Layer ◽  
Fault Isolation ◽  
Tem Analysis ◽  
Logic Devices ◽  
Technology Advancement ◽  
Transmission Electron ◽  
Voltage Contrast ◽  
Almost All ◽  
20 Nm

Abstract In this work, we present two case studies on the utilization of advanced nanoprobing on 20nm logic devices at contact layer to identify the root cause of scan logic failures. In both cases, conventional failure analysis followed by inspection of passive voltage contrast (PVC) failed to identify any abnormality in the devices. Technology advancement makes identifying failure mechanisms increasingly more challenging using conventional methods of physical failure analysis (PFA). Almost all PFA cases for 20nm technology node devices and beyond require Transmission Electron Microscopy (TEM) analysis. Before TEM analysis can be performed, fault isolation is required to correctly determine the precise failing location. Isolated transistor probing was performed on the suspected logic NMOS and PMOS transistors to identify the failing transistors for TEM analysis. In this paper, nanoprobing was used to isolate the failing transistor of a logic cell. Nanoprobing revealed anomalies between the drain and bulk junction which was found to be due to contact gouging of different severities.

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