A SURFACE LAYER MODEL FOR THE TOTAL RESISTIVITY OF THERMOMETRIC-GRADE PLATINUM WIRE

1964 ◽  
Vol 42 (11) ◽  
pp. 2264-2285 ◽  
Author(s):  
D. R. Lovejoy
Keyword(s):  
Subsurface Layer ◽  
Small Diameter ◽  
Surface Contamination ◽  
Platinum Wire ◽  
Impurity Level ◽  
Platinum Resistance ◽  
Calibration Data ◽  
Band Theory ◽  
Basic Model ◽  
Total Resistivity

A model for the temperature dependence of the total resistivity of thermometric-grade platinum wire is developed. The evidence supports as a basic model the two-electronic conduction-band theory of Sondheimer and Wilson. However, in the small-diameter (~80 μm) wire, here considered, surface contamination would lead to deviations from the simple model. A theory of multiple conduction bands, due to surface contamination, has been developed. The theory enables us to infer, from known calibration data on platinum resistance thermometers, that there are two regions of contamination. One is a region of heavily concentrated impurity over a few atomic layers at the surface, which accounts for variations in resistivity near 700 °K. The other is a subsurface layer about 0.1 μm thick with about 0.1% impurity level, which accounts for variations in resistivity in the region of 90 °K.

The Subsurface Hydrogen Barrier Layer in Plasma-Treated Silicon

1985 ◽  
Vol 59 ◽  
Author(s):  
A. E. Jaworowski ◽  
L. S. Wielunski ◽  
G. Bambakidis
Keyword(s):  
Thermal Stability ◽  
Barrier Layer ◽  
Molecular Hydrogen ◽  
Subsurface Layer ◽  
Surface Region ◽  
Surface Contamination ◽  
Near Surface ◽  
Surface Hydrogen

ABSTRACTThe near-surface hydrogen profile was measured using the 15N hydrogen profiling technique in silicon. By depositing an adlayer of Al on the surface we were able to observe the separation of the near-surface hydrogen profile in silicon from the surface contamination layer. The hydrogen profiling of the near-surface region revealed the existence of a subsurface hydrogen layer which acts as a barrier to the transfer of hydrogen into the bulk. The observed subsurface layer is saturated with molecular hydrogen and its profile drops off sharply with increasing depth. The structure of this molecular hydrogen barrier and its thermal stability were studied.

scholarly journals A comparison of platinum and gas thermometers, including a determination of the boiling point of sulphur on the nitrogen scale: an account of experiments made in the laboratory of the bureau international des poids et mesures, at Sèvres

1900 ◽  
Vol 65 (413-422) ◽  
pp. 327-329
Keyword(s):  
Wide Temperature Range ◽  
Boiling Point ◽  
Electrical Resistance ◽  
Platinum Resistance Thermometer ◽  
Platinum Wire ◽  
Platinum Resistance ◽  
Resistance Thermometer ◽  
General Application ◽  
Made In

In 1886, Professor Callendar drew attention to the method of measuring temperature, based on the determination of the electrical resistance of a platinum wire. He showed that the method was capable of a very general application, and that the platinum resistance thermometer was an instrument giving consistent and accurate results over a very wide temperature range.

Research on Simulation of Resilient Wheel Dynamometer

2020 ◽  
Author(s):  
Zhang Jimin ◽  
Wan Jingyuan ◽  
Li Wen ◽  
Zhong Xujie ◽  
Zhou Hechao ◽  
...  
Keyword(s):  
Force Measurement ◽  
Direct Method ◽  
Rapid Development ◽  
Standard Form ◽  
Small Diameter ◽  
Rolling Stock ◽  
Test Accuracy ◽  
Calibration Data ◽  
Distribution Analysis ◽  
External Interference

Abstract Among many testing items of infrastructure, wheel-rail force is an important factor that causes track failure, damage, train derailment and vehicle parts damage. It is also used to evaluate the ride stability, safety and as the main basis for speed limit and speed increase. Among many methods of wheel-rail force detection, the method of wheel-rail force measurement is the most accurate and direct method of wheel-rail force measurement. The method of measuring wheel-rail interaction force using wheelset of railway locomotive and rolling stock as force sensor has the highest accuracy among all wheel-rail force measurement methods. Force-measuring wheelset is the core sensor in the dynamic test research of railway vehicles, and its performance directly affects the evaluation results of the tested objects. Before the actual line test, it is necessary to calibrate the dynamometer wheelset on the test bench. The calibration of dynamometer wheelset is an important link in the research and application of dynamometer wheelset. With the rapid development of rail transit in various countries and the great improvement of locomotive and rolling stock manufacturing technology, higher and higher requirements has been put forward for the performance of force-measuring wheelsets, which are mainly embodied in obtaining ideal sensitivity and linearity, minimizing cross-interference and all kinds of possible external interference, and reducing the influence of the change of the position of the action point on the measurement results. For the rigid wheelset, the calibration of the force-measuring wheelset is basically perfect from the actual production to the algorithm. The relevant countries also determine the calibration in the standard form. At present, more and more urban rail low floor vehicles are using independent resilient wheels. The mechanical structure of the bogie with resilient wheels is complex. At the same time, because of the small diameter of the resilient wheels and the rubber layer between the wheel hoop and the wheel center, it is difficult to find the strain/stress sensitive area accurately, as well as the unique installation process, the calibration of resilient wheels is rather difficult. This paper takes the low floor resilient wheels as the research object, and studies how to make the calibration method of high precision and suitable for the independent rotating wheels of resilient wheels and the processing and analysis of calibration data. The main research contents are as follows: the development of force-measuring wheelset which is based on the finite element simulation of a resilient wheel, stress distribution analysis, and the fabrication scheme of force-measuring wheelset which meets the requirement of test accuracy is proposed by using virtual bridge formation.

A Replica Technique for the Inside Surfaces of Small Diameter Pipes and Tubes

1967 ◽  
Vol 25 ◽  
pp. 352-353
Author(s):  
T. G. Gregory
Keyword(s):  
Polyvinyl Chloride ◽  
Small Diameter ◽  
Replica Technique ◽  
Tube Size ◽  
Inside Diameter ◽  
Complete Inspection ◽  
Operating Limits

A nondestructive replica technique permitting complete inspection of bore surfaces having an inside diameter from 0.050 inch to 0.500 inch is described. Replicas are thermally formed on the outside surface of plastic tubing inflated in the bore of the sample being studied. This technique provides a new medium for inspection of bores that are too small or otherwise beyond the operating limits of conventional inspection methods.Bore replicas may be prepared by sliding a length of plastic tubing completely through the bore to be studied as shown in Figure 1. Polyvinyl chloride tubing suitable for this replica process is commercially available in sizes from 0.037- to 0.500-inch diameter. A tube size slightly smaller than the bore to be replicated should be used to facilitate insertion of the plastic replica blank into the bore.

Structural Organization and Distribution of Fiber Types in Extraocular Muscles of Cats

1972 ◽  
Vol 30 ◽  
pp. 34-35
Author(s):  
Asish C. Nag ◽  
Lee D. Peachey
Keyword(s):  
Fiber Type ◽  
Light And Electron Microscopy ◽  
Small Diameter ◽  
Extraocular Muscles ◽  
Fiber Types ◽  
Distinctive Features ◽  
Superior Rectus ◽  
Adult Cats ◽  
Different Diameters ◽  
Orbital Region

Cat extraocular muscles consist of two regions: orbital, and global. The orbital region contains predominantly small diameter fibers, while the global region contains a variety of fibers of different diameters. The differences in ultrastructural features among these muscle fibers indicate that the extraocular muscles of cats contain at least five structurally distinguishable types of fibers.Superior rectus muscles were studied by light and electron microscopy, mapping the distribution of each fiber type with its distinctive features. A mixture of 4% paraformaldehyde and 4% glutaraldehyde was perfused through the carotid arteries of anesthetized adult cats and applied locally to exposed superior rectus muscles during the perfusion.

Prospects for convergent beam electron diffraction with a 200kV cold field-emission transmission electron microscope

1991 ◽  
Vol 49 ◽  
pp. 466-467
Author(s):  
J W Steeds ◽  
R Vincent
Keyword(s):  
Field Emission ◽  
High Performance ◽  
Small Diameter ◽  
Convergent Beam Electron Diffraction ◽  
Zone Axis ◽  
Medium Voltage ◽  
Transmission Electron ◽  
Good Crystallinity ◽  
Special Modification ◽  
Convergent Beam

We review the analytical powers which will become more widely available as medium voltage (200-300kV) TEMs with facilities for CBED on a nanometre scale come onto the market. Of course, high performance cold field emission STEMs have now been in operation for about twenty years, but it is only in relatively few laboratories that special modification has permitted the performance of CBED experiments. Most notable amongst these pioneering projects is the work in Arizona by Cowley and Spence and, more recently, that in Cambridge by Rodenburg and McMullan.There are a large number of potential advantages of a high intensity, small diameter, focussed probe. We discuss first the advantages for probes larger than the projected unit cell of the crystal under investigation. In this situation we are able to perform CBED on local regions of good crystallinity. Zone axis patterns often contain information which is very sensitive to thickness changes as small as 5nm. In conventional CBED, with a lOnm source, it is very likely that the information will be degraded by thickness averaging within the illuminated area.

Ab initio band theory approach to electron energy loss near edge structures

1988 ◽  
Vol 46 ◽  
pp. 506-507
Author(s):  
Xudong Weng ◽  
O.F. Sankey ◽  
Peter Rez
Keyword(s):  
Ab Initio ◽  
Local Density ◽  
Interpolation Method ◽  
Atomic Orbital ◽  
Plane Waves ◽  
Large Set ◽  
Theory Approach ◽  
Band Theory ◽  
Atomic Orbitals ◽  
Pseudopotential Calculations

Single electron band structure techniques have been applied successfully to the interpretation of the near edge structures of metals and other materials. Among various band theories, the linear combination of atomic orbital (LCAO) method is especially simple and interpretable. The commonly used empirical LCAO method is mainly an interpolation method, where the energies and wave functions of atomic orbitals are adjusted in order to fit experimental or more accurately determined electron states. To achieve better accuracy, the size of calculation has to be expanded, for example, to include excited states and more-distant-neighboring atoms. This tends to sacrifice the simplicity and interpretability of the method.In this paper. we adopt an ab initio scheme which incorporates the conceptual advantage of the LCAO method with the accuracy of ab initio pseudopotential calculations. The so called pscudo-atomic-orbitals (PAO's), computed from a free atom within the local-density approximation and the pseudopotential approximation, are used as the basis of expansion, replacing the usually very large set of plane waves in the conventional pseudopotential method. These PAO's however, do not consist of a rigorously complete set of orthonormal states.

Applications of SIMS to electronic materials and devices

1992 ◽  
Vol 50 (2) ◽  
pp. 1682-1683
Author(s):  
S.F. Corcoran
Keyword(s):  
Depth Distribution ◽  
Secondary Ion Mass Spectrometry ◽  
Semiconductor Device ◽  
Electronic Materials ◽  
Profile Analysis ◽  
Semiconductor Industry ◽  
Small Diameter ◽  
Depth Resolution ◽  
Detection Sensitivity

Over the past decade secondary ion mass spectrometry (SIMS) has played an increasingly important role in the characterization of electronic materials and devices. The ability of SIMS to provide part per million detection sensitivity for most elements while maintaining excellent depth resolution has made this technique indispensable in the semiconductor industry. Today SIMS is used extensively in the characterization of dopant profiles, thin film analysis, and trace analysis in bulk materials. The SIMS technique also lends itself to 2-D and 3-D imaging via either the use of stigmatic ion optics or small diameter primary beams.By far the most common application of SIMS is the determination of the depth distribution of dopants (B, As, P) intentionally introduced into semiconductor materials via ion implantation or epitaxial growth. Such measurements are critical since the dopant concentration and depth distribution can seriously affect the performance of a semiconductor device. In a typical depth profile analysis, keV ion sputtering is used to remove successive layers the sample.

Improved immunolabelling of ultrathin cryosections using antibody conjugated with 1nm gold particles

1990 ◽  
Vol 48 (3) ◽  
pp. 928-929
Author(s):  
Morten H. Nielsen ◽  
Lone Bastholm
Keyword(s):  
Pituitary Gland ◽  
Liquid Nitrogen ◽  
Electron Density ◽  
Small Diameter ◽  
Cytochemical Staining ◽  
Gold Particles ◽  
Labelling Density ◽  
Ultrathin Cryosections ◽  
Mouse Pituitary ◽  
Electron Microscopical

During the last 5 years the diameter of the gold probes used for immuno-cytochemical staining at the electron microscopical (EM) level has been decreased. The advantage of small diameter gold probes is an overall increased labelling density. The disadvantage is a lower detectability due to the low electron density of smaller gold particles consequently an inconvenient high primary magnification needed for EM examination. Since 1 nm gold particles are barely visible by conventional EM examination the need for enlargement by silverenhancement of the gold particles has increased.In the present study of ultrathin cryosectioned material the results of immunostaining using 5 nm gold conjugated antibody and 1 nm gold conjugated antibodies are compared after silverenhancement of the 1 nm gold particles.Slices of freshly isolated mouse pituitary gland were immersion fixed for 20 min in 2 % glutaraldehyde /2 % paraformaldehyde. Blocks cryoprotected with 2.3 M sucrose were frozen in liquid nitrogen and ultra-cryosectioned on a RMC cryoultra-microtome.

Copper-dependent ATP7B up-regulation drives the resistance of TMEM16A-overexpressing head-and-neck cancer models to platinum toxicity

2019 ◽  
Vol 476 (24) ◽  
pp. 3705-3719 ◽  
Author(s):  
Avani Vyas ◽  
Umamaheswar Duvvuri ◽  
Kirill Kiselyov
Keyword(s):  
Oxidative Stress ◽  
Head And Neck ◽  
Transcriptional Activation ◽  
Platinum Resistance ◽  
Mrna Levels ◽  
Strong Positive Correlation ◽  
Platinum Compounds ◽  
Copper Chelation ◽  
Novel Approach ◽  
Cancer Models

Platinum-containing drugs such as cisplatin and carboplatin are routinely used for the treatment of many solid tumors including squamous cell carcinoma of the head and neck (SCCHN). However, SCCHN resistance to platinum compounds is well documented. The resistance to platinum has been linked to the activity of divalent transporter ATP7B, which pumps platinum from the cytoplasm into lysosomes, decreasing its concentration in the cytoplasm. Several cancer models show increased expression of ATP7B; however, the reason for such an increase is not known. Here we show a strong positive correlation between mRNA levels of TMEM16A and ATP7B in human SCCHN tumors. TMEM16A overexpression and depletion in SCCHN cell lines caused parallel changes in the ATP7B mRNA levels. The ATP7B increase in TMEM16A-overexpressing cells was reversed by suppression of NADPH oxidase 2 (NOX2), by the antioxidant N-Acetyl-Cysteine (NAC) and by copper chelation using cuprizone and bathocuproine sulphonate (BCS). Pretreatment with either chelator significantly increased cisplatin's sensitivity, particularly in the context of TMEM16A overexpression. We propose that increased oxidative stress in TMEM16A-overexpressing cells liberates the chelated copper in the cytoplasm, leading to the transcriptional activation of ATP7B expression. This, in turn, decreases the efficacy of platinum compounds by promoting their vesicular sequestration. We think that such a new explanation of the mechanism of SCCHN tumors’ platinum resistance identifies novel approach to treating these tumors.

Sign in / Sign up

Export Citation Format

Share Document