High-voltage hold-off of large surface area metal electrodes with dielectric surface layers

2004 ◽  
Author(s):  
D.J. Johnson ◽  
H.C. Ives ◽  
M.E. Savage ◽  
W.A. Stygar
Keyword(s):  
Surface Area ◽  
High Voltage ◽  
Dielectric Surface ◽  
Large Surface Area ◽  
Surface Layers ◽  
Metal Electrodes

A vacuum modification for the philips CM30 electron microscope

1993 ◽  
Vol 51 ◽  
pp. 446-447
Author(s):  
N. D. Evans ◽  
J. Bentley ◽  
A T. Fisher
Keyword(s):  
Electron Microscope ◽  
Surface Area ◽  
High Voltage ◽  
Voltage Stability ◽  
Large Surface Area ◽  
Vacuum System ◽  
Maximum Pressure ◽  
Conservative Approach ◽  
Slow Recovery ◽  
Vacuum Line

For the Philips CM30 (or earlier EM430), the large surface area in the gun, the relatively poor pumping speed at the base of the gun, and the use of the same 100 l/s ion getter pump (IGP) for the column and gun, all lead to a significant degradation of gun vacuum (and slow recovery) following the gas burst involved in specimen exchange, even with extended pumping in the airlock. Since the vacuum quality in the gun is important for LaB6 filament life and high voltage stability, we adopted a conservative approach to the maximum pressure Pc allowed for the application of high voltage or filament emission; we chose an IGP reading of 22 (5 × 10−5 Pa). Delays of ~15 min typically occurred following specimen insertion. To avoid these problems the vacuum system has been modified. The goals were threefold: (1) To increase the pumping speed at the gun. The conductance of the original 600-mm-long vacuum line with three 90° elbows and a valve (V5) results in a pumping speed of < 10 l/s at the base of the emission chamber and a routine pressure of 3 × 10−5 Pa (1.5 × 10−7 torr).

The electrochemical reduction of α-nitrocumene in a protic and basic medium on large surface area (porous) electrodes: electronation-protonation or electrocatalytic hydrogenation?

1999 ◽  
Vol 77 (5-6) ◽  
pp. 687-694 ◽  
Author(s):  
Elisa Soazara Chan-Shing ◽  
Denys Boucher ◽  
Jean Lessard
Keyword(s):  
Electrochemical Reduction ◽  
Surface Area ◽  
Product Distribution ◽  
Porous Electrodes ◽  
Large Surface Area ◽  
Basic Medium ◽  
Electrocatalytic Hydrogenation ◽  
Polycrystalline Nickel ◽  
Metal Electrodes ◽  
Controlled Potential

The electrochemical reduction of α-nitrocumene (1) has been investigated under controlled potential, at a mercury pool cathode and at Raney metal (Raney nickel, Raney cobalt and Devarda copper) and fractal nickel electrodes in basic aqueous ethanol. A comparison of the product distribution from the reduction at Hg (electronation-protonation (EP) mechanism) and that from the reduction at Raney metals and fractal nickel has shown that both the electrocatalytic hydrogenation (ECH) and EP mechanisms can be involved at large surface area (porous) transition metal electrodes in a basic protic medium. Cyclic voltammetry was used to determine the reduction potential of 1 at Hg and at bright polycrystalline nickel, cobalt, and copper cathodes in the same medium.Key words: electrocatalytic hydrogenation, electroreduction, 2-nitro-2-phenylpropane, Raney metal cathodes, mechanism.

Functional Two-Dimensional Black Phosphorus Nanostructures towards Next-Generation Devices

2021 ◽  
Author(s):  
Mengke Wang ◽  
Jun Zhu ◽  
You Zi ◽  
Zheng-Guang Wu ◽  
Haiguo Hu ◽  
...  
Keyword(s):  
Surface Area ◽  
Biomedical Applications ◽  
Black Phosphorus ◽  
Large Surface Area ◽  
Two Dimensional ◽  
Next Generation

In recent years, two-dimensional (2D) black phosphorus (BP) has been widely applied in many fields, such as (opto)electronics, transistors, catalysis and biomedical applications due to its large surface area, tunable...

Research on metallic chalcogen-functionalized monolayer-puckered V2CX2 (X = S, Se, and Te) as promising Li-ion battery anode materials

2021 ◽  
Author(s):  
Chunmei Tang ◽  
Xiaoxu Wang ◽  
Shengli Zhang
Keyword(s):  
Surface Area ◽  
Anode Materials ◽  
Large Surface Area ◽  
Two Dimensional ◽  
Li Ion Batteries ◽  
Li Ion Battery ◽  
Li Ion ◽  
Battery Anode

Two-dimensional MXene nanomaterials are promising anode materials for Li-ion batteries (LIBs) due to their excellent conductivity, large surface area, and high Li capability.

scholarly journals Strategic use of nanotechnology in drug targeting and its consequences on human health: A focused review

2019 ◽  
Vol 11 (1) ◽  
pp. 38-54 ◽  
Author(s):  
Anand Maurya ◽  
Anurag Kumar Singh ◽  
Gaurav Mishra ◽  
Komal Kumari ◽  
Arati Rai ◽  
...  
Keyword(s):  
Human Health ◽  
Surface Area ◽  
Medical Diagnosis ◽  
Drug Targeting ◽  
Pharmaceutical Market ◽  
Large Surface Area ◽  
Mass Ratio ◽  
Disease Therapy ◽  
Significant Interest ◽  
Medical Benefits

Since the development of first lipid-based nanocarrier system, about 15% of the present pharmaceutical market uses nanomedicines to achieve medical benefits. Nanotechnology is an advanced area to meliorate the delivery of compounds for improved medical diagnosis and curing disease. Nanomedicines are gaining significant interest due to the ultra small size and large surface area to mass ratio. In this review, we discuss the potential of nanotechnology in delivering of active moieties for the disease therapy including their toxicity evidences. This communication will help the formulation scientists in understanding and exploring the new aspects of nanotechnology in the field of nanomedicine.

Synthesis of functional hollow WS2 particles with large surface area for Near-Infrared (NIR) triggered drug delivery

2021 ◽  
Vol 875 ◽  
pp. 160034
Author(s):  
Na Liu ◽  
Fan Fan ◽  
Wei Xu ◽  
Hao Zhang ◽  
Qi Zhou ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Surface Area ◽  
Near Infrared ◽  
Large Surface Area

Accelerating ion diffusion with unique three-dimensionally interconnected nanopores for self-membrane high-performance pseudocapacitors

Nanoscale ◽  
2017 ◽  
Vol 9 (46) ◽  
pp. 18311-18317 ◽  
Author(s):  
Yuan Gao ◽  
Yuanjing Lin ◽  
Zehua Peng ◽  
Qingfeng Zhou ◽  
Zhiyong Fan
Keyword(s):  
Aspect Ratio ◽  
Surface Area ◽  
Structural Stability ◽  
High Aspect Ratio ◽  
High Performance ◽  
Three Dimensional ◽  
Rate Capability ◽  
Large Surface Area ◽  
Nanoporous Structure ◽  
Ion Diffusion

Three-dimensional interconnected nanoporous structure (3-D INPOS) possesses high aspect ratio, large surface area, as well as good structural stability. Profiting from its unique interconnected architecture, the 3-D INPOS pseudocapacitor achieves a largely enhanced capacitance and rate capability.

Transport of Ions and Molecules in Nanofluidic Devices

2008 ◽  
Author(s):  
Rohit Karnik ◽  
Chuanhua Duan ◽  
Kenneth Castelino ◽  
Rong Fan ◽  
Peidong Yang ◽  
...  
Keyword(s):  
Surface Charge ◽  
Surface Area ◽  
Field Effect ◽  
Electrostatic Interactions ◽  
Surface Reactions ◽  
Molecular Transport ◽  
Large Surface Area ◽  
Ionic Concentrations ◽  
Nanofluidic Devices ◽  
Transport Of Ions

Interesting transport phenomena arise when fluids are confined to nanoscale dimensions in the range of 1–100 nm. We examine three distinct effects that influence ionic and molecular transport as the size of fluidic channels is decreased to the nanoscale. First, the length scale of electrostatic interactions in aqueous solutions becomes comparable to nanochannel size and the number of surface charges becomes comparable to the number of ions in the channel. Second, the size of the channel becomes comparable to the size of biomolecules such as proteins and DNA. Third, large surface area-to-volume ratios result in rapid rates of surface reactions and can dramatically affect transport of molecules through the channel. These phenomena enable us to control transport of ions and molecules in unique ways that are not possible in larger channels. Electrostatic interactions enable local control of ionic concentrations and transport inside nanochannels through field effect in a nanofluidic transistor, which is analogous to the metal-oxide-semiconductor field effect transistor. Furthermore, by controlling surface charge in nanochannels, it is possible to create a nanofluidic diode that rectifies ionic transport through the channel. Biological binding events result in partial blockage of the channel, and can thus be sensed by a decrease in nanochannel conductance. At low ionic concentrations, the effect of biomolecular charge is dominant and it can lead to an increase in conductance. Surface reactions can also be used to control transport of molecules though the channel due to the large surface area-to-volume ratios. Rapid surface reactions enable a new technique of diffusion-limited patterning (DLP), which is useful for patterning of biomolecules and surface charge in nanochannels. These examples illustrate how electrostatic interactions, biomolecular size, and surface reactions can be used for controlling ionic and molecular transport through nanochannels. These phenomena may be useful for operations such as analyte focusing, pH and ionic concentration control, and biosensing in micro- and nanofluidic devices.

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