Development of Electrical Quantities Primary Standards

2021 ◽  
pp. 014233122110301
Author(s):  
Rasha S. M. Ali
Keyword(s):  
Lower Cost ◽  
Primary Standard ◽  
Quantum Hall ◽  
Hall Resistance ◽  
Improve Performance ◽  
Sensing System ◽  
Primary Standards ◽  
Definition Of ◽  
Cross Capacitor ◽  
Thermal Voltage

The developments of primary standards for electrical quantities that practically realize the electrical units such as ampere (A), volt (V), ohm (Ω), and farad (F) are introduced in this manuscript. These quantities are achieved in consistency with their definitions. According to the new definition of ampere, current can be realized directly such as single electron transport (SET) pump or indirectly using Ohm’s law. For the SET pump, developments are ongoing as trials to obtain higher current values with lower associated uncertainty to be suitable for metrological applications. With the discoveries of the Effects of Josephson and quantum Hall, it has become possible to consider quantum electrical standards that relate the volt and ohm units to h and e through the Josephson and the von Klitzing constants, respectively. The dc programmable Josephson standard was developed to overcome the problems of conventional standards such as stability and noise immunity with lower cost. Developments are continuing on ac Josephson standards to improve performance and increase output voltages and frequencies. For ac voltage measurements for voltages up to 1000 V, thermal voltage converters are introduced to extend the traceability for measuring the ac voltages in the frequency range from 10 Hz to 100 MHz where quantum-based ac standards still have limitations. Thermal current converters are used as the most accurate and precise standard for measurement of ac currents. The realization of ohm is done by the quantum Hall effect through a quantum Hall resistance (QHR) standard. Developments are occurring to make it simpler, more precise and accurate. The efforts that have been made to increase the values of the resistance quantum hall standard to disseminate its accuracy to other standard resistors to help in industry are also introduced. The farad is practically achieved by the calculable cross-capacitor. The calculable capacitor acts as the ac impedance primary standard because it can transfer the traceability to other impedances by using bridges such as the quadrature bridge. The development is occurring on its displacement sensing system to allow greater accuracy.

scholarly journals Characterization and Quantification of Selenoprotein P: Challenges to Mass Spectrometry

2021 ◽  
Vol 22 (12) ◽  
pp. 6283
Author(s):  
Jérémy Lamarche ◽  
Luisa Ronga ◽  
Joanna Szpunar ◽  
Ryszard Lobinski
Keyword(s):  
Mass Spectrometry ◽  
State Of The Art ◽  
Animal Health ◽  
Primary Standard ◽  
Selenoprotein P ◽  
Primary Standards ◽  
Analytical Approaches ◽  
Careful Investigation ◽  
Accurate Quantification

Selenoprotein P (SELENOP) is an emerging marker of the nutritional status of selenium and of various diseases, however, its chemical characteristics still need to be investigated and methods for its accurate quantitation improved. SELENOP is unique among selenoproteins, as it contains multiple genetically encoded SeCys residues, whereas all the other characterized selenoproteins contain just one. SELENOP occurs in the form of multiple isoforms, truncated species and post-translationally modified variants which are relatively poorly characterized. The accurate quantification of SELENOP is contingent on the availability of specific primary standards and reference methods. Before recombinant SELENOP becomes available to be used as a primary standard, careful investigation of the characteristics of the SELENOP measured by electrospray MS and strict control of the recoveries at the various steps of the analytical procedures are strongly recommended. This review critically discusses the state-of-the-art of analytical approaches to the characterization and quantification of SELENOP. While immunoassays remain the standard for the determination of human and animal health status, because of their speed and simplicity, mass spectrometry techniques offer many attractive and complementary features that are highlighted and critically evaluated.

Anomalous quantum-Hall resistance in bilayer counterflow transport

2007 ◽  
Vol 4 (2) ◽  
pp. 485-488
Author(s):  
Z. F. Ezawa ◽  
S. Suzuki ◽  
G. Tsitsishvili
Keyword(s):  
Quantum Hall ◽  
Hall Resistance

Preliminary results on GaAs-algaas heterostructure quantum Hall resistance standard by the NIM

CPEM 2010 ◽  
2010 ◽  
Author(s):  
Y. Zhong ◽  
Q. Zhong ◽  
Q. He ◽  
Y. F. Lu ◽  
J. T. Zhao ◽  
...  
Keyword(s):  
Quantum Hall ◽  
Hall Resistance ◽  
Preliminary Results ◽  
Resistance Standard

INFLUENCE OF NEARBY QD LAYER ON 2DES IN QUANTUM HALL REGIME

2007 ◽  
Vol 21 (08n09) ◽  
pp. 1445-1449
Author(s):  
K. TAKEHANA ◽  
Y. IMANAKA ◽  
T. TAKAMASU ◽  
M. HENINI
Keyword(s):  
Magnetic Field ◽  
Transport Properties ◽  
Gate Voltage ◽  
Quantum Hall ◽  
Electron System ◽  
Hall Resistance ◽  
Field Range ◽  
Voltage Range ◽  
Quantum Hall Regime ◽  
Hall Regime

We have investigated transport properties in high magnetic field of a gated two-dimensional electron system (2DES) separated by a thin barrier from a layer of self-assembled InAs quantum dots (QDs) in the quantum Hall regime. The quality of 2DES was found to be high enough to observe both integer and fractional quantum Hall effect (QHE), despite the proximity of the QD layer to the 2DES. However, significant suppression of the magnetoresistance (ρ xx ) and Hall resistance (ρ xy ) were observed in higher magnetic field range of filling factor ν < 1 when a positive voltage was applied to the front gate. The gate voltage dependence of ρ xx and ρ xy shows a well-defined hysteresis loop at the narrow gate voltage range between -0.2 and +0.2 V at ν < 1, while no anomaly was observed at ν > 1. We deduce that charging and discharging of QDs occurs when the gate voltage is varied around Vg ~ 0 V, which indicates that the electron charge states of the QDs affect the transport properties of the nearby 2DES only at ν < 1. We infer that the spin-flip process induces a non-equilibrium state in the 2DEG, which causes the suppression of ρ xx and ρ xy .

scholarly journals Resposta de Handroanthus heptaphyllus Mattos em diferentes volumes de substrato e adubação de base.

FLORESTA ◽  
2020 ◽  
Vol 50 (4) ◽  
pp. 1770
Author(s):  
Thaise Da Silva TONETTO ◽  
Maristela Machado Araujo ◽  
Álvaro Luís Pasquetti Berghetti ◽  
Márcio Carlos Navroski
Keyword(s):  
Controlled Release ◽  
Quality Index ◽  
Lower Cost ◽  
Dry Mass ◽  
High Dose ◽  
Native Forest ◽  
Forest Species ◽  
Definition Of ◽  
Appropriate Practices ◽  
Dickson Quality Index

Handroanthus heptaphyllus (Martius) Mattos response in different volumes of substrate and base fertilization. The native forest species require the adoption of appropriate practices in the nursery, such as the definition of the container volume and base fertilizer, to develop seedlings at lower cost. Thus, this study aimed to verify the performance of Handroanthus heptaphyllus seedlings grown in nurseries in different sizes of containers and different dosage of controlled release fertilizer (CRF). There was interaction between the volume of container and the fertilization for the height (H), stem diameter (SD), and H/SD relation. The shoot dry mass variable (SDM), root dry mass (RDM), total dry mass (TDM), SDM/RDM relation, Dickson quality index (DCI) and leaf area (LA) were influenced only by the base fertilizer. The highest values for these variables were, respectively, 15.68 cm; 6.55 mm, 2.58 cm mm-1; 2.05 g; 2.03 g; 3.84 g; 1.46; 1.15 and 246.97 cm². The H. heptaphyllus species is nutritionally demanding, positively responding to the high dose of CRF. Seedlings of H. heptaphyllus produced in tubes of 180 cm³ with 7.0 g L-1 of CRF present adequate growth.

scholarly journals Recommendations for Reporting Ion Mobility Mass Spectrometry Measurements

2018 ◽  
Author(s):  
Valerie Gabelica ◽  
Alexandre A. Shvartsburg ◽  
Carlos Afonso ◽  
Perdita E. Barran ◽  
Justin L. P. Benesch ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Cross Section ◽  
Ion Mobility ◽  
Collision Cross Section ◽  
Ion Mobility Mass Spectrometry ◽  
Gas Temperature ◽  
Mobility Data ◽  
Community Effort ◽  
Primary Standards ◽  
Definition Of

Here we present a guide on ion mobility mass spectrometry experiments, which covers both linear and nonlinear methods: what is measured, how the measurements are done, and how to report the results, including the uncertainties on mobility and collision cross section values. The guide aims to clarify some possibly confusing concepts, and the reporting recommendations should help researchers, authors and reviewers to contribute comprehensive reports, so that the ion mobility data can be reused more confidently. Starting from the concept of the definition of the measurand, we emphasize that (i) mobility values (K0) depend intrinsically on ion structure, the nature of the bath gas, temperature, and E/N, (ii) ion mobility does not measure surfaces directly, but collision cross section (CCS) values are derived from mobility values using a physical model, (iii) methods relying on calibration are empirical (and thus may provide method-dependent results) only if the gas nature, temperature or E/N cannot match those of the primary method. Our analysis highlights the urgency of a community effort towards establishing primary standards and reference materials for ion mobility, and provides recommendations to do so. <br><br><br>

scholarly journals RR Lyrae stars: prime calibrators of the first rung of the distance ladder

2012 ◽  
Vol 8 (S289) ◽  
pp. 101-108 ◽  
Author(s):  
Carla Cacciari
Keyword(s):  
Local Group ◽  
Primary Standard ◽  
Empirical Methods ◽  
Rr Lyrae Stars ◽  
Rr Lyrae ◽  
The Galaxy ◽  
Definition Of ◽  
Near Future ◽  
Lyrae Stars ◽  
Distance Indicators

AbstractRR Lyrae variables are the primary standard candles for old stellar populations, and the traditional first step in the definition of the distance scale. Their properties are known on the basis of well-established physical concepts and their calibration is based on several empirical methods. Both aspects are critically reviewed, and their application as distance indicators within the Galaxy and the Local Group are discussed, also in view of the observing facilities that will be available in the near future.

FISDW in quasi-one dimensional organic conductors with the dimerized gap due to anion ordering

2002 ◽  
Vol 12 (9) ◽  
pp. 381-384
Author(s):  
N. Matsunaga ◽  
A. Ayari ◽  
P. Moncea ◽  
K. Yamashita ◽  
A. Ishikawa ◽  
...  
Keyword(s):  
Phase Transition ◽  
Ground State ◽  
Quantum Hall ◽  
Organic Conductors ◽  
Hall Resistance ◽  
Cooling Rates ◽  
One Dimensional ◽  
Stable Quantum ◽  
New Phase ◽  
Quantum Hall State

Magnetoresistance and Hall resistance measurements have been carried out in the FISDW phase of deuterated (TMTSF)2C1O4 for various cooling rates through the anion ordering temperature. The Hall resistance in the intermediate cooled state, observed a very stable quantum Hall state above 9.0 T for slowly cooled, shows a step-like change from the phase between 10 and 17 T to the phase between 20 and 25 T with hysteresis between 14 and 21 T. This result suggests that there is a new phase transition around 15 T in deuterated (TMTSF)4ClO4. A possible ground state of the FISDW phase of (TMTSF)2C1O4 for various cooling rates is discussed from the viewpoint of the peculiar SDW nesting vector stabilized by the dimerized gap due to anion ordering.

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